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This document describes modeling of a notional integrated power and energy system (IPES), generally based on that described in [1], intended for use in demonstrating concepts related to robust combat power and energy controls (RCPC) and derived from requirements established in [2].

[1] James Langston, Harsha Ravindra, Michael Steurer, Tom Fikse, Christian Schegan, and Joseph Borraccini. Priority-based management of energy resources during power-constrained operation of shipboard
power system. In Electric Ship Technologies Symposium (ESTS), 2021 IEEE. IEEE, 2021.
[2] James Langston, Tyler Boehmer, Multan Biswas, and Alexander Johnston. Model requirements document: System model for RCPC demonstration 1, draft version 0.1. Technical report, RCPC, June
2021.

Recent increases in dc power system usage have created a need for dc capable circuit breakers. One method to achieve this is through the development of solid state circuit breakers (SSCB) that utilize power electronics to break the circuit. The use of power electronics allows for the breaking of a circuit quickly with no need for a natural current zero-crossing point for arc-less interruption of current. This report details the development of a 1 kV 0.2 kA SSCB. The control scheme is discussed as well as its implementation in real-time simulation (RTS).

This document describes planned efforts in the development and evaluation of robust combat power and energy controls (RCPC) for shipboard power systems under the RCPC future naval capability (FNC). As insights into control functions and necessary interfaces are typically gained in the process of implementation and testing, the planned efforts are structured around a sequence of demonstrations to progressively improve the control approaches, the metrics and processes for evaluation, and the level of realism in the systems of interest. Here, the term demonstration is intended to more broadly refer to an evaluation of concepts, rather than to a single test or exhibition. Thus, each demonstration is intended to focus on evaluation of a defined set of RCPC control implementations for one or more specific system implementations in terms of a set of defined scenarios and evaluation metrics. By progressively building on previous demonstrations, the intent is to identify and refine useful RCPC functions and viable control approaches, identify and refine suitable controls interfaces, and gain insights into the strengths, weaknesses, and sensitivities of the considered approaches. It is intended that this process will also result in the development of a framework to support model development, verification and validation, and evaluation of system performance.

A five-year program is proposed to develop the Power Electronic Power Distribution System (PEPDS). PEPDS is a new power, energy, and control distribution concept enabled by ONR-developed technology, including high-power-density high-efficiency power electronics, silicon-Carbide (SiC) power semiconductors, and modeling and simulation design and analysis tools.

The goal of the PEPDS program is to achieve revolutionary changes to system design and operation by leveraging recent technology advances and developing both the applications to use them and the control and modeling capabilities needed to employ them, culminating in a megawatt-level test bed that will demonstrate the applicability to a Navy shipboard electrical system.

The following document presents a notional four-zone medium voltage DC (MVDC) ship-board cooling system model formulated for piping network design, system-level thermal analysis, and co-simulation purposes. In particular, this model description document (MDD) elaborates on mathematical equations describing the complete notional four-zone ship cooling network along with modeling assumptions and pertinent numerical methods.The modelling approach employed herein incorporates all major thermal-fluid components present in any zone to ensure proper operation of corresponding thermal loads, and it is not bounded by a particular cooling network layout nor the number of thermal loads. The major thermal-fluid components treated herein are gate valves, pumps, pipes, chillers, and heat exchangers. The model is therefore expandable to a larger system as long as the considered assumptions remain valid and a similar fidelity is sought

• The model described herein is intended for Medium Bandwidth (MBW) simulation of system where in the time-step, Δt is bound within limits: (25 µs ≤ Δt ≥ 50 µs)
• The notional four zone MVDC SPS model described in this document is intended to be platform
agnostic and can be implemented on various simulation platforms with the intent to run in real time on various DRTS platforms such as RSCAD/RTDS, OPAL-RT, Typhoon-HIL, etc.
• The suggested characteristics/requirements of the system model described herein should be
incorporated into various simulation platforms
• The model described in this document will support controls evaluation. More specifically, the model design will allow efficiently interfacing a diverse set of controls through a well-defined interface in a modular manner. Such controls may be in various forms including software only or a given hardware controller with embedded control logic. Controls can be evaluated by modifying model parameters and observing system responses.
• The characterized system model presented here in will aid in various efforts under the ESRDC project aiming to study areas such as control architecture, advanced control algorithms and strategies, stability analysis, fault management, energy storage, power and energy management, electric plant load analysis and more
• The information, data and characteristics provided in this document should help with traceability, verification and validation of the SPS model implementation across various simulation platforms since their implementation may vary between different simulation platforms and also on type of model implementation

These reports detail the development of a simplified average model (AVM) for an MMC at CAPS. The AVM can emulate the steady state and transient behaviors seen in experimental results. The purpose of the model is to achieve less complexity and faster time domain simulation studies of the MMCs at CAPS, while still maintaining sufficient converter dynamic accuracy. The method utilized applies equivalent circuit models of the power stage and the duty-cycle generation circuitry to describe the low frequency behavior of switching model (SWM) systems.

The workshop held at Florida State University’s Center for Advanced Power Systems on December 4-5, 2018 convened Navy, industry, and academic partners to generate dialogue and advance commonality in thinking about flexibility for unknown future requirements. The goal to achieve a common, definitional understanding about the concept of flexibility in future navy ship design and operation. This intent was scoped to include bounding the problem with initial lexicon as well as generating design considerations, areas of focus, and possible approaches to flexibility. The result was a structured facilitation approach with a generative workshop design.
The group also had a stretch goal of developing a path forward for building flexibility into Naval Power and Energy Systems. However, the discussion about lexicon continued for a more significant portion of the Day 2 agenda, resulting in clearer agreement about common attributes of flexibility as a power and energy system concept but forgoing the road mapping activity in the initial workshop design.
Preparatory sessions with the workshop team were integral in correctly scoping the focus of the workshop and defining its intended objectives. These objectives are the basis for the final workshop plan and facilitation design.

This semi-annual report summarizes the progress on each research project for the period from August 2016 to March 2018. Research results for the most recent six-month reporting period from October 2017 to March 2018 have been highlighted red in this report.

Advanced single-input/single-output and multi-input/multi-output modeling techniques, such as the Volterra Series are highly applicable to nonlinear systems modeling and identification. Consequently, a methodology in which parts of the simulation/modeling data can be identified by an available experimental setup will be beneficial to analyze system performance under more realistic scenarios. Our methods are focused on the kernel measurement and simulation of the developed model without assuming a model structure. This effort will develop the Volterra Series technique into a comprehensive toolset that can provide a mathematically and physically rigorous and acceptable method to analyze nonlinear system classes, including high-power converters, with the added benefit of model portability across other platforms and greater transparency with regard to model detail. In addition, the toolset can be utilized with IMUs in order to create nonlinear models by extracting the terminal behavior of devices.

The ship service converter module regulates the in-zone bus voltage. The topology of the converter module is shown in Figure 1.  Voltage regulation is achieved through a combination of the feedback and feed forward control paths that are shown in Figure 2. In addition, a droop setting is used to regulate the sharing between converter modules within each zone. Also implemented is a stabilizing filter that acts to counteract the destabilizing influence of constant power loads [1]. The output of the regulator is a commanded inductor current that is used for hysteresis-based switch-level control.

The Office of Naval Research is developing science and technology for advanced electric ships that utilize an integrated power system. This project was motivated by the success and feasibility of impedance measurements and impedance-based controls at the low voltage level. An extension of impedance measurement units (IMU) to the medium voltage (MV), megawatt-class converter levels would provide significant benefits to the U.S. Navy. The primary objective of this project was to evaluate the suitability of such a novel instrument for use of frequency domain characteri-zation of megawatt scale equipment, which will eventually be used for system integration studies. This project was the first test and use of an IMU at these voltage and power levels, following the design and preliminary testing of the MV IMU. The technical objectives included demonstration of the IMU design concept and impedance measurement capabilities within both AC- and DC-systems.
The testing approach was derived in coordination between the Center for Advanced Power Sys-tems (CAPS) at Florida State University and the Center for Power Electronics Systems (CPES) at Virginia Tech. The IMU’s power stage design is based on the PEBB (Power Electronic Building Block) concept, and individual stages were evaluated before operating the unit as an impedance measurement device. Test applications feasible at CAPS concerned 3.3 kV/60 Hz, and 4.16 kV/60 Hz, and 4 kV DC-systems. Guided by modeling and simulation efforts in the related ESRDC Impedance-based Controls task, commissioning and test plans were established. The pre-testing work addressed issues of experiment selection and design. One critical aspect was the pro-tection of experiments due to the uniqueness of the proposed tests. The system-based tests were conducted with the help of a Real Time Simulator (RTS) to facilitate Control Hardware-in-the-Loop simulations and control of the surrounding power system components.

The Florida State University Center for Advanced Power Systems 5 MW/6.25 MVA, 4.16 kV Variable AC and DC Voltage Source Converter (VVS) is a PEBB-based power amplifier which serves as an amplifier for power hardware–in–the–loop (PHIL)  simulation experiments. The VVS was tested in both an open circuit configuration and under inductive loading to determine its ability to perform at frequencies greater than 60 Hz. Empirical data from these tests was used in preliminary
validation of a Matlab/Simulink – PLECS simulation model. This report shows that the VVS can perform at frequencies higher than its rated 60 Hz, but not without certain limitations, such as filter capacitor current levels. For both test configurations, comparison of the empirical and simulation data showed an error calculated less than 8.4%. The simulation model is fundamentally accurate for open circuit and load testing configurations. This report provides a baseline for maturing the
facility’s controller hardware–in–the–loop (CHIL) simulation model of the VVS and initiates the need for a more diligent model verification and validation (V&V) process.

Future naval MVDC power systems will contain a considerable amount of power electronic devices (PEDs). The switching events from these PEDs will cause added harmonic content to the system a produce undesirable effects, such as common-mode (ground) current through coupling of the power system and the ship’s hull. Even in a fully ungrounded ship system, there will exist inherent parasitic coupling. Research in the area of EMI/EMC characterization and standards provides insight into common-mode and conduction currents within a specified component. Yet currently, there is no universal methodology to understand the impacts of these common-mode drivers in the
system context. This report utilizes a common-mode equivalent circuit derivation methodology to begin the discussion and research into common-mode issues at the system-level. Review of the methodology is provided, along with further insight into the definitions and assumptions needed for application. Verification of common-mode voltage characterization is applied to a simulation of an ideal diode rectifier. The methodology is also applied to a representative notional two-zone MVDC simulation case developed within ESRDC.

The MVDC architecture with 12 kV DC distribution represents a shift from traditional 60 Hz AC shipboard power distribution system and has the potential to provide superior power density, power quality while being affordable. The report here in provides information on ‘the two zone MVDC shipboard power system model’.
The main contribution of this report is the development of shipboard power system model in digital real-time simulator (DRTS), RTDSTM. The model is based on the zonal integrated power distribution system architecture proposed by N. Doerry in [1]. The purpose of the model described in this report is to aid the investigation of fault management (fault identification, localization and recovery) in MVDC shipboard power systems.
The individual modules implemented for model will allow the user to comprehensively test different methods of fault detection algorithms while providing useful insight into behavior of different modules. The two model versions described herein feature two distinctly different types of power generation modules (PGMs): a modular multi-level converter (MMC) based PGM and a thyristor controlled rectifier based PGM. Technical data for various modules modeled in the report have been provided along with simulation results depicting the performance of the two versions of the models.
The shipboard power system model provided in this report acts as a first pass for simulation assisted studies involving fault management in MVDC systems. The outcomes from the simulation could be useful in understanding and paving a path for controller hardware-in-the-loop (CHIL) and power hardware-in-the-loop (PHIL) testing.

While extensive research in the area of energy storage has been conducted with the focus on a) the storage media and b) the power system interface of individual storage devices the focus of this task is optimal and rapid utilization of energy storage distributed throughout the ship power system.

In order to quantify the availability of distributed energy storage embedded in the ship power systems to the mission loads this task will develop a probabilistic approach to allow objective comparisons between centralized energy storage allocations and mission load centric energy storage to support dynamic mission load profiles. An analysis framework will be developed along with supporting software tools which takes into account the controllability of localized energy storage via the supervisory control approach and interface characteristics.

The characteristic of the rotating machines, which normally dominate the system behavior under fault conditions in AC systems, can be completely decoupled from the MVDC distribution system if certain converter topologies such as full bridge modular multi cell (MMC) converters or “active power distribution nodes” are employed. Note, that while SCR-type converters can interrupt fault currents at the next zero crossing of the AC current significant transients remain on the DC side. Moreover, fast interruption may not leave enough time to identify the fault location in meshed systems. However, employing converters which limit the fault current on the DC side to levels around nominal current values open up the opportunity to essentially eliminate the impact of high transient fault currents on the MVDC side. This in turn is expected to have substantial impact on the overall MVDC system design (no DC breakers, substantially reduced bracing against dynamic forces, etc.). Therefore, building upon work conducted previously at USC, this subtask seeks to develop and demonstrate a complete "fault current free" MVDC system.

This effort in this Task synergistically interacts with 5.2.4 and 5.2.5. by using the results of the tasks to refine the models and feed the model optimizations to improve the designs of hardware
components developed in 5.2.5.

As the HTS technology components are still under development, prototype testing to validate the designs and capture their attributes to aid in model development and refinement is essential. The task will take advantage of the infrastructure at FSU-CAPS to facilitate the proposed component technology development and prototype testing and validation with the systems view in focus. In
particular, this task will focus on generating scalable electrical and thermal models for HTS cables that can be used in systems analysis to quantify the benefits, risks, and identifying potential challenges that needs to be tackled for successful implementation of HTS cables on AES. This task will also involve collecting and maintaining the relevant data on HTS cables that would be necessary to update the electrical models developed as the technology matures and new
design features are added. There are many efforts underway throughout the world on developing HTS cables for terrestrial utility applications and some of the development can directly be
implemented for HTS cables for Navy MVDC system applications. This task will review the ongoing development to assess the relevance to the Navy of various design features of the superconducting components and cryogenic system components and collecting and maintaining the data necessary to create electrical models. 

S-parameters are needed when one is attempting to characterize/measure the wide-bandwidth behavior of power systems, including switching-induced electromagnetic fields, and the behavior of the system in response to faults. This promising approach has been investigated on a very limited set of components. This task will expand the work into the realm of MW scale equipment by analyzing such devices already existing in ESRDC labs. Power electronics converters of the megawatt class need to be characterized regarding their capacitive, inductive, resistive and radiative coupling to the ground plane. This will be accomplished by S-parameter measurement using a vector network analyzer (VNA). The main converters of interest are the 5-MW variable voltage source inverter at CAPS, the MVDC converters to be installed at CAPS before the end of 2013, various medium scale converters also available at CAPS, and the converters of the 750-V testbed at Purdue University. These converters are ungrounded by design. However, they do have a parasitic impedance to ground that can be measured by VNA measurements while not energized and by fault tests when in operation. Additional impedances to ground can be added for calibration purposes.

This report describes the on-going effort to define a process for developing a multi-level, rule-based design specification for naval ship electrical systems that can be implemented in the smart ship system design (S3D) enviroment. A generalized process for designing electric warships proposed by Doerry [1] consists of the following steps:

1. Analyze requirements,
2. Allocate requirements to mission systems,
3. Develop initial Concept of Operations (CONOPS),
4. Assign mission systems to ship zones,
5. Develop derived requirements for ship systems,
6. Develop distributed system architectures,
7. Calculate distributed system component ratings,
8. Synthesize the ship,
9. Evaluate total ship mission effectiveness, and
10. Iterate until total ship mission effectiveness requirements are met.

The principal focus of the study performed under this project was to provide the ship architect with information and tools for completing steps 1 and 5 for the design of the baseline MVDC ship electrical system. The section that follows describes the process of defining the “rules-base” for this ship system. This report details the preliminary work for extracting ship design guidelines and rules from well-known resources. Furthermore, the guidelines and rules extracted through this task will be integrated into the S3D environment to enable applying well-established engineering principles to the automation of design evaluation

An important contributor to U.S. military superiority is the continued superiority in computing and communications. For the last few decades, military superiority in this area has rested in a large part on Moore’s Law, which is a description of the fact that investment in appropriate semiconductor technology led to better performance, which led to new products that organizations and individuals would buy, which led to further investment in the technology. The Department of Defense has learned to exploit this rapid change in technology even though it does not fit well with its budget or procurement cycles. This ability to manage technological
change has helped achieve superior capability.

But Moore’s Law growth has ended. In a purely technological level, we can still double the density of the components on a processor chip, but it does not lead to sufficient system improvement to warrant the investment. So, the Department of Defense, as well as companies needing a competitive advantage, must find other solutions.

The ESRDC was not alone in recognizing this situation. Within the government broadly, this is an issue being addressed by the Office of Science and Technology Policy, who has staff focused on this finding a good solution for the U.S, government. In Defense, DARPA has staff members that recognize the need to help maintain military superiority while transitioning from an environment driven by Moore’s Law. Outside of DOD, this is one of the top technical
challenges being addressed by the IEEE, the leading global technical organization in the field of electrotechnology.

The ESRDC was early in recognizing the issue because the development of future ships that are efficient, effective, and employ emerging technology requires exhaustive simulation before and after their construction. Today, however, it is not possible to conduct the required simulations of large shipboard models due to the length of time required to complete the solution when using commercial software and desktop computers.

This led to the ESRDC exploring three options:
 Use of special purpose computers:
The ESRDC does have access to special purpose computer systems to address appropriate near term problems. And this has been successful. The need for hardware procurement and training costs coupled with the historical concerns over the longevity of special purpose computing have suggested this will be a valuable
research tool, but it will not be widely adopted within the Navy and the shipbuilding industry.

 Use of Field-Programmable Gate Arrays (FPGA’s):
FPGA’s can be considered quasi-special-purpose computers that provide excellent computational speed by limiting functionality. They have found use, for example, in control systems. The ESRDC explored with ONR the possibility of exploiting this technology for ship simulation. The challenge, however, was that ONR was already
exploring this technology in general, but the anticipated progress was expected to be too slow to support ship design. Furthermore, some of the issues cited for special purpose computers would likely prevail with the FPGA alternative.

 Use of technologies that are in the mainstream of computer evolution:
The computer industry has been evolving to more parallel systems to compensate for lack of speed on a given processor. Multicore systems provide promise for continued improvement and are commercially available for decreasing cost. The primary challenge is that legacy software typically must be rewritten to operate with best
efficiency on such systems. For adaption to ship power system design, the major challenge was automated model partitioning and parallelization into subsystems of less computational burden to facilitate the use of legacy systems. The ESRDC has made a significant contribution to solving this problem.

The ESRDC solution has been developed over time to match the needs of the Navy and the shipbuilding community while also being sensitive to the relevant commercial development. Discussion with ship yard leaders led to a strong endorsement to have a solution as close to Simulink [4-6] as possible. This is an understandable constraint as most engineers today graduate being competent in such program. A different approach would increase training costs
and thus overall costs. The ESRDC approach meets this need by Simulink as the user interface.

To make the capability available to as wide an audience as possible, the initial development will be made available to all users under Navy-sponsored programs. To move the capability from the
ESRDC to the Navy, the ESRDC will make the software available on the web to students at the Naval Postgraduate School to help support their research. This is a research environment
involving naval officers and the system is helping them improve the quality of their education during their limited time at NPS. The arrangement is that the program is provided on the web
through a private link between NPS and the University of Texas at Austin. The developer in Austin can monitor performance and quickly help students resolve any problems. Discussions
are underway to next open the link to research projects at the U.S. Naval Academy after the system is sufficiently robust to be used by less experienced users.

The next step would be to transfer the capability to NAVSEA and to the shipyards. Those implementations must be even more robust, however, as much of the information they process is classified. That is, moving from research to production, the penalty for failure is higher.

A widely accessible accelerated simulation approach provides key Navy users with early capability to use emerging software approaches to modeling. The open structure permits the
focus to be on a structure that works for the application. In addition, collaboration with software vendors permits the information developed in this project to help inform the commercial
development.

The US Navy continues to support applied research on the design, development, and simulation of their future fleet of all-electric ships (AES). Central to the Navy's vision is the use of electricity as the primary energy transport means for the majority of ship systems. For example, ship propulsion has historically been handled by dedicated gas turbines connected directly to reduction gears, which drive a propeller. In the AES concept, prime movers are connected directly to generators, from which electrical power is sent to propulsors (via motor drives), and also to other ship systems. 

The motivation behind this design approach is threefold. First, a future surface ship must be robust and reconfigurable; with an optimal power distribution grid, ship sectors damaged during combat can be isolated from the rest of the grid, thus minimizing damage and prolonging the ship's operability. Second, with a standard modular power grid, maintenance and cost of repair to ship power systems would be more efficient and cost-effective. Finally, the Navy expects to integrate various high-energy weapons and radar systems in future warships. An optimized power distribution grid would allow the ship to employ large pulses of energy required to implement these advanced systems. However, the introduction of advanced electronics and pulsed-energy systems on a surface ship is not without consequences. From a heat generation point of view, the AES will produce significant thermal side effects that have the potential to produce catastrophic failures at both the system and component level. Thermal management is considered an enabler for the technologies likely to appear on an AES.

Currently, the Arleigh Burke DDG-51 class destroyer employs five 200-ton marine chiller units to handle active cooling of ship systems and components. Every shipboard component, from the smallest processor chip to the largest gas turbine, contributes dynamically to this thermal management challenge due to the generation of “waste heat” that must be managed. It has been estimated [1] that, on average, approximately 681 tons of waste heat is rejected from an Arleigh Burke class warship. However, this average value does not capture the magnitude of peak waste heat during transient situations. On a highly dynamic, controls-oriented ship, such as the notional AES, steady-state values provide little utility from a reconfiguration or system failure perspective. When a fully capable AES is deployed, shipboard cooling requirements are predicted to have increased by as much as 700% [1]. However, this steady-state value does not include the integrated effects of dynamic power buildup and adaptive grid response following the introduction of high-energy weapons and sensors. It is the objective of the research reported in this paper to simulate shipboard thermal load management from a dynamic, controls-based, system-level perspective.

This paper explores various power cable challenges for notional electric ship applications including future technology trends for shipboard power cables. To meet the demands of an “all electric ship,” the cabling requirements of the design are not a trivial issue which can result in significant error in estimating final size, weight, and cost at time of construction along with costly failures and early repairs that impact lifecycle cost. This paper provides information on the development of a design tool known as a “Generic Cable Calculator” to estimate parameters such as impedances, weights, and bending radii for ship power cabling. Analysis of actual experience in designing ship cabling suggests improvements in early design tools needed to capture additional requirements in terms of grounding, shielding, and satisfying current standards for cables used in the variable frequency drive train. Also addressed are results specific to future trends of cable insulation and future standards.

This paper presents a model to simulate electrical trees in dielectric materials. The model accounts for the characteristic tree patterns and the partial discharges associated with the propagation of trees. This simulation model is used as basis to develop a diagnostic tool to determine the remaining life of insulation materials by relating the fractal dimension of the tree to the supply voltage and material properties. Simulation results are presented to show the performance of the prognosis method.

The research presented in this thesis has been performed at the Center for Advanced Power Systems of Florida State University in 2012. Topic of research is the concept for the future All-electric ship of the United States Navy.

Primary focus of this thesis is on a novel approach on modeling and simulation of electrical power system components using scattering parameters for the analysis of different system grounding architectures.

In chapter 1 and 2 a short introduction to the All-electric ship concept and the topic of grounding of direct current power system operated at medium voltage level is given, while in chapter 3 the modeling approach based on S-parameters is presented. This approach allows the modeling of power system components such as cables, bus bars, machines, power electronic converters and the ship hull based on generated or measured S-parameters for the development of simulation models. These models can be used to perform simulation studies.

The S-parameter approach is a novelty in the field of power simulations. Available simulation software packages for power system modeling such as PSCAD/EMTDC or MATLAB/Simulink usually do not allow the direct integration of linear network blocks characterized by S-parameters. A generic N-port block has been developed which allows to embed models of subsystems based on their S-parameter in power systems software packages in the manner of linear time invariant networks.

The model implementation is presented and validation studies have been performed which show very good modeling performance. As a result of the research, investigations can now be performed for studying the experimental power system setup of Purdue University to support the research for All-electric ship.

We continue the development of an overall architectural model for an all-electric ship using a physics-based simulation environment to perform fully-integrated simulation of electrical, hydrodynamic, thermal, and structural components of the ship operating in a seaway.  The goal of this architectural model is to develop an early-stage design tool capable of performing tradeoff studies on concepts such as AC vs. DC distribution, frequency and voltage level, inclusion of reduction gears, energy and power management options, and effect of arrangements and topology.  The results of the studies will be presented in standard metrics including cost, weight, volume, efficiency/fuel consumption, reliability and vulnerability.  We will specifically look at the hull, mechanical and electrical (HM&E) systems that support the ship and its missions; specifically, the electrical generation and distribution system, propulsion equipment, fresh- and saltwater pumping and distribution, control systems, and structural components.

We have previously created a basic design tool which uses hullform, drive train particulars, and operational employment of the vessel to determine resistance, powering and fuel usage.  This report details the specification of the notional ship and modeling thereof in Paramarine, the analysis and prioritization of the electrical load on the notional ship, the initial modeling of in-zone power conversion equipment, and the development of pertinent metrics, especially the vulnerability metric.

The Electric Ship Research and Development Consortium (ESRDC) objectives have been to develop and apply methodologies for the design and operation of the all-electric ship (AES), taking into account the multiscale, multi-domain, and multi-disciplinary aspects of the problem. This project will provide methods, algorithms and corresponding software tools for design, especially early design. It is a fundamental tenet of complex system design that early decisions have very serious consequences, both in the later stages of design and development, and in the operation of the ship. ESRDC is accelerating the development and demonstration of technologies, modeling, and simulation tools to provide critical design and operational capabilities of AES program. The consortium continues to address the national shortage of electrical power engineers.

The work under this program addressed a broad spectrum of issues, related to the development of electric ship systems including methods and models for design and simulation of highly-integrated multidisciplinary ship systems, methods for power routing and control, methods for characterizing and understanding the performance of the electric plant, and methods for controlling the plant. It is impossible to capture the full breadth and depth of the research in this one report, so instead the report content has been developed to provide a detailed insight into some of the achievements in illustrative areas. The reader is then encouraged to review the list of publications at the end of this report to comprehend the full breadth of the achievements and to refer to the appropriate publications where this report provides insufficient information. Broadly speaking, the topics of this team‟s investigations can be classified into the categories of Simulation Tools, Power Systems, and Control Systems. Highlights in each of these areas are mentioned next.

A simple equivalent circuit model for EC capacitors can be established based on electrochemical impedance spectroscopy. The circuit consists of an ohmic resistor and a finitelength Warburg Element in series. The EC capacitor’s performance including the transient/pulse response and energy density as a function of power density (Ragone plot) can be stimulated by the equivalent circuit model with three useful parameters including an ohmic resistance, total ionic resistance and total capacitance of the electrodes.

The synchronous machine and excitation system is illustrated in Figure 1.  In this system, the voltage regulator has two parts; a control algorithm to determine the field current of the brushless exciter, and a power converter which achieves this command.  The brushless exciter machine rotor voltage is rectified – which in turn supplies the field current to the synchronous machine.

The PS consists of a transformer, a 3-phase controlled rectifier, and a low pass filter to reduce the noise on the output depicted in Fig. 1. In the case of a 3-phase controlled rectifier, the thyristors conduct whenever they are forward biased and the gating signal, delayed by firing angle , is present. The purpose of delaying the gating signal is to regulate the dc voltage level.

The inverter module is a DC/AC converter that provides clean 3-phase AC power to a variety of loads. . Figure 1 depicts the power converter topology used to implement the inverter module. As shown, this component consists of an input capacitor, a 3-phase fully controlled bridge converter, an output LC filter, and the control algorithms. The LC filter, illustrated in Figure 2, is used to filter the switching frequency component harmonics from the output in order to provide clean ac power to its loads.

The overall control of the inverter module contains a voltage control loop and a synchronous current regulator (SCR).  A diagram of the voltage control loop is shown in Figure 3.  The voltage control loop drives the error in the output voltage to zero by generating a current command through the use of a PI regulator with decoupling and feed-forward control.  The voltage control loop takes as inputs the desired output voltage and the desired output frequency.  A synchronous current regulator shown in Figure 4, uses the current command from the voltage control loop and actively regulates the fundamental component of the current so the command is exactly achieved.  A hysteretic/delta modulator regulates the current in the output filter inductors to the SCR commanded value.  It generates the switching commands for the power semiconductors.

The power load (CPL) consists of a buck converter and a switching control that is designed to dissipate a constant power for a given input voltage range. Figure 1 shows the constant power load configuration. The commanded inductor current is obtained from the ratio of the commanded power to the output voltage.

The employed constant power load controller generates commanded inductor current. The commanded inductor current is used in the hysteresis modulator to produce switching signal for the buck converter to achieve the desired output power level.

The freshwater cooling loop circulates freshwater between the “cold plate” component heat exchanger and the fluid heat exchanger. The component heat exchanger removes waste heat from heat producing devices and the freshwater to seawater exchanger dumps the waste heat from the freshwater loop to seawater which is then discharged overboard.

Power component heat dissipation is removed through conduction from the power components to a “cold plate” heat sink. This cold plate is then cooled via convective heat transfer to a cooling fluid as illustrated in the figure 1. Typically the cooling fluid is saltwater (seawater), freshwater, or chilled water.

The freshwater to seawater heat exchanger cools the freshwater cooling loop fluid using seawater which is then discharged overboard.

Heat transfer from the freshwater to the seawater occurs through the freshwater tube wall as depicted in figure 1.

Neglecting the spatial component of the transient fluid thermodynamics along the interior of the heat exchanger produces lumped parameter fluid models. 

The propulsion drive model consists of an uncontrolled rectifier model connected to an induction motor with a control algorithm. The system structure is very similar to that of the induction motor and the employed control algorithm is also very close to that used in the motor controller.

The motor controller, shown in Figure 1 is used to represent the system-level effects of machine/drive units. The controls of the inverter have been developed to provide a means to control the speed or torque of a standard 3-phase induction machine.

Heat transfer by convection is a complicated process involving transfer of thermal energy through momentum and thermal gradients. The convection model developed for the VTB makes simplifying assumptions to minimize the solver computation time and to reduce number of independent equations that must be solved at each time step. These assumptions are:

• Control volume with only conservation of energy employed across the boundaries
• Explicit and transient in time and with a lumped element spatial representation; spatial gradients cannot be resolved
• Thermal physical properties are temperature dependent with an option to remove this dependency
• Heat transfer by conduction and radiation are neglected

The model uses two thermal nature ports and is represented schematically by a cooling fin. The port located at the icon’s center is the input node (port 0) and the output node (port 1) located near the bottom is connected to either a temperature source/sink or it can be linked to another thermal port on a separate model. It is not necessary to adhere to this input/output guideline as long as the user understands that all state data follows this convention. For instance, Temperature0 is the temperature of port 0.

The driving force behind developing the convection model was to remove the user burden of specifying the convective coefficient, historically a difficult and computationally intensive task. This procedure is aided through the use of empirical and experimental correlations that have been documented extensively in the literature. Although such correlations have, at best, 10-20% accuracy, they provide basic understanding of how a system may respond given user identifiable parameters such as geometric attributes, free stream velocities, and surface orientation relative to the flow field. Such attributes are conveyed to the user through a custom dialog window. Convection parameters can be accessed and changed before and during run time, providing a parametric approach to system behavior. The complete list of correlations and the steps required to determine the correct correlations are presented in the Appendix.

Use of convective correlations requires intrinsic thermo-physical property data, such as density, specific heat, kinematic viscosity, thermal conductivity, coefficient of thermal expansion, etc. Property values are computed at each time step using curve-fitted equations derived from published tables. If the user chooses to use a specified heat transfer coefficient, thermo-physical properties are no longer required and this solve block is not called by the solver.

• When natural coupled (layer 1) this model functions as a voltage (pressure, speed, ect.), current (mass
  flow, torque, ect.), resistive, or power load.
• When signal coupled (layer 2) this model functions as a signal generator that can be used for
  controlling signal dependent source models.
• The load is time dependent, and it is characterized by a look up table in an Excel
  spread sheet.
• The model reads values directly off the Excel spread sheet rather than from a saved data file.
• Optionally, the model can communicate directly with VBA functions in Excel to customize the loads
  behavior.

The model represents an ideal CCVS with gain factor.

The model represents an ideal CCCS with gain factor.

The model represents the client part of a symmetrical linking model. A symmetrical
linking model is intended for simulating different parts of large circuits on separate
computers, connected by a network. These parts are combined by the linking models. The
server and the client parts with the same endpoint value represent one connection.

The communications between a server and a client part may be realized using RPC
(remote procedure call, in this case workstations may be connected by a network) or
using a pipe (a section of shared memory that processes use for communication).

This version of model is intended for simulation of linear circuits that were
distributed only on two parts.

This model represents a Nonlinear model of a permanent magnet DC motor with a
rack-and-pinion mechanical drive. Motor icon is shown in Fig. 1. Terminals A and
B are the electrical nodes. Node C is a linear motion node representing the tip of the
moving rack. The rack-and-pinion drive dimensions are such that when the rotor turns by
on radian the rack moves by one meter. The rack moves in the positive direction when
the voltage at node A with respect to node B positive. In this model, linear magnetic
circuit is considered without magnetic saturation and dissertation.

VTB-Matlab interface uses and requires a registered copy of Matlab to be loaded onto the host computer.
The input and output ports are modeled as signal ports. The VTB-Maltab interface requires a Matlab .m file
to be located in an active or permanent path of Matlab. The voltage at the input of the VTB model is sent to
the Matlab function as input parameter, together with a flag to identify init phase. The user can freely
specify the sampling time of the Matlab function.

This is a level-2 physics-based diode model. It includes the transient characteristics of
diode such as forward overshoot and reverse recovery. It also contains the effects of
emitter recombination and junction capacitance.

A Permanent Magnet Synchronous Motor (PMSM) is constructed by fitting the
magnet inside the rotor cage, which is necessary for induction starting. The PMSM are
usually considered a linear device over its entire operating range of torque and speed,
with practically linear speed-torque characteristic.

The main advantage of Permanent Magnet Synchronous Motors (PMSM) is the
absence of the excitation winding. An important application area for the synchronous
machine is large-scale power generation. In the majority of power stations synchronous
machines operate as generators and their design depends on the rotational speed required.
Multipole machines with salient poles are used for relatively slow rotation speeds
whereas for higher speeds (for example gas turbine driven generators) the machines have
lower pole numbers and cylindrical rotors - so-called turbo rotors. But such big machines
are also employed in electrical drives for traction, rolling mills, mining etc. A special
type is the Permanent Magnet Synchronous Machines (PMSM), which is often used for
servo systems up to 100 kW.

The stator has usually cylindrical shape with slots on the inner surface where the
stator windings are placed. In general the number of slots is large for distributed windings
(typically 6 per phase). The stator is manufactured using laminated metallic sheets to
minimize the eddy currents induced by the rotating flux. (figure 1).

The rotor of a permanently magnetized synchronous machine can have the
magnets applied either on the rotor surface or buried deep into the rotor. The most
common materials for the permanent magnets are Samarium-Cobalt and Neodynium-
Boron Iron, which are very durable (resist to vibration and to relatively high
temperatures) and allow high magnetic flux densities.

This type of motors uses a permanent magnet to generate the magnetic field in
which the armature rotates, the electrical circuit in the armature alone can model the
motor. In this model Rs and Ls indicate the equivalent armature coil resistance and
inductance respectively. The model for the electrical part is shown in figure 3.

This model wraps a model made by ACSL. The model allows for various numbers of inputs and outputs to
the circuit. The connection is a signal coupling done by modified nodal analysis.

This model represents a permanent magnet DC motor with a rack-and-pinion mechanical
drive. Terminals A and B are the electrical nodes as shown in the above figure. Node C is
a linear motion node representing the tip of the moving rack. The rack-and-pinion drive
dimensions are such that when the rotor turns by on radian the rack moves by one meter.
The rack moves in the positive direction when the voltage at node A with respect to node
B positive.

This model represents Bipolar Junction Transistor (BJT).

Indicated below in the figure is the switch topology, based on which BoostConverter
model (no filter elements included) is developed. The switching waveform (without
transients) is obtained according to the circuit behavior, the duty cycle inputs, and the
frequency parameters.

This model wraps a model created in ACSL. The ACSL_Entity model allows for a natural coupling
between the VTB system and the ACSL model.

This model represents a multiphase lossy transmission line. The user selectable parameters include the conductor
materials, and the size and physical arrangement of the conductors. The model is based on the equivalent series resistance
and inductance matrix, and takes into account the mutual inductances among the line conductors.

The breaker is modeled as a device with three possible states:

● Closed

● Arcing

● Open

The breaker is always initialized in the closed state. In this state, it behaves as an ideal resistor of a user specified value.
The breaker state changes from closed to arcing, when the RMS current through it exceeds its current rating. The RMS current is evaluated as the average of the square of the breaker current over a user specified time interval.
While in the arcing state, the breaker is modeled as a constant voltage source. The voltage magnitude is user specified (arcing voltage parameter). The polarity of the voltage is the same as the current flow direction.
The breaker finally switches from arcing to open state, when the current falls below the extinction current.
While in the open state, the breaker is modeled as an ideal resistor (Off-Conductance).

The Electric Ship Research and Development Consortium (ESRDC) has created a notional ship for use as a test case in developing research to advance the state of the art in electric ship concepts. The notional ship is a nominal 100MW, 10,000 ton displacement surface combatant, using data compiled from open source documentation. This document provides data relative to the ship, for use by ESRDC researchers.

A model of the ship was created in the Smart Ship Systems Design (S3D) design environment, to include electrical, piping and mechanical schematics along with three-dimensional placement of equipment on a ship hull in a naval architecture view.

Please note that this ship was designed by ESRDC researchers and is not intended to meet or represent any current or future Navy designed vessel. It is merely a somewhat realistic representative example for testing electrical and thermal system concepts.

The systems delineated in this document are a single, baseline reference ship. It is intended that alternative designs can be tested against this design; these alternatives may make adjustments such as replacing single pieces or classes of equipment, rearranging equipment using different topology and connectivity, or replacing entire support systems with systems using a different paradigm entirely.

Document Use and Modification

This document will be updated as additional information becomes available, and the revision history will be tabulated above. Please make changes in the Word version of this document using track changes. When sufficient recommendations for change are made, they will be incorporated and a new revision will be released.

This document will be stored on the ESRDC website in .pdf format, along with a Word format and an Excel spreadsheet containing the data.

This content will be a rolling release of documentation to provide a continuously improving set of snapshots of the technical history of the ESRDC. As new documents become available, they will be appended to this post. Check back regularly to see if new content has been added.

2006 - Dynamic Reconfiguration of Ship Power Systems

2009 - Simulation Environment for Dynamic Thermal Modeling

2012 - Thermal-Electrical Co-simulation

2014 - Development of Capability to Model Ship Power Systems

2014 - Effective Ship Power System Simulation

2016 - Framework for Analysis of Distributed Energy Storage

2017 - Electric Shipboard Design for High Reliability Metrics

2017 - MVDC Fault Management

2017 - Common-Mode and Grounding 

2017 - Testing a MW-scale Impedance Measurement Unit at Medium Voltage Levels

2017 - Metamodeling of Power System Components 

2017 - Control of Power-System-Induced Ship Hull Currents in 20 kV DC Architectures

2018 - Impedance Measurements Techniques in PHIL Environment

Ongoing - Controls Evaluation and Partitioning Framework

Ongoing - Notional System Modeling

The Electric Ship Research and Development Consortium (ESRDC) was tasked by the Office of Naval Research (ONR) with using the Smart Ship Systems Design (S3D) software to develop and compare several ship system designs demonstrating key elements of a 100 MW Medium Voltage Direct Current (MVDC) electric power distribution architecture suitable for integration into a future 10,000 ton surface combatant. The goals of this exercise were twofold: first, perform a study of several ship system variants and quantify the differences between the variants; and second, provide user evaluation of the S3D design environment, user-driven refinement of the environment, and improved understanding of the design processes it enables. The team developed a notional “Baseline Design” with an array of mission loads for a 10,000 ton surface combatant using 10kV dc distribution and conventional silicon-based solid state power conversion. Then, several design variants were developed to explore the impact of alternative topologies and advanced materials. These included:

• High speed power generation
• Advanced materials for solid-state power conversion
• Alternative power system topologies
• Mechanical/electrical hybrid (developed but not evaluated)

Designs were compared for changes in weight, volume, number of components, and range. Additionally, a notional time-based mission consisting of three mission segments was developed to compare the performance of each design variant against an operational vignette; selected results are presented in the report. In addition to developing notional designs for the 10,000 ton surface combatant, the ship design project provided important feedback to the S3D software development team. The project led to several enhancements of the design tool including new equipment library components, e.g., bus nodes and IPNCs, as well as new functionality, e.g. the mission alignment comparison tool. Recommendations for future enhancements to S3D as a result of this exercise include semi-automated design assistance; review of the role of margins, allowances, uncertainty and risk, treatment of aggregated loads and assemblies; verification and validation of models and an expanded model library; expansion of the catalog of scalable models; inclusion of high-level controls for mission analysis; and improvements to the individual discipline-specific design tools.

Existence of adequate power hardware-in-the-loop (PHIL) interface algorithms is important to ensure accuracy and stability of PHIL experiments. Developing and testing of such algorithms is even more important at higher power levels since a) inherent latencies in high power PHIL amplifiers are significantly higher than latencies in low power amplifiers and b) risks and cost of damages to devices under test or amplifier due to instabilities caused by inadequate PHIL are higher at higher power levels. This particular effort focused on assessment of accuracy and stability of HIL interface algorithms applied PHIL testing of an inductive type superconducting fault current limiter (FCL) using the 5 MW PHIL test bed at CAPS. A number of interface algorithms have been identified in the literature, such as those described in [1], for example. As preliminary simulations indicated stability issues using the Ideal Transformer Method (ITM), variants of the Damping Impedance Method (DIM) algorithm were explored for application. Thus, this work focused on PHIL testing of the FCL with multiple surrounding systems, operating conditions, and using several different variations of the DIM interface algorithm. As the modified DIM approach seemed to show improvement in performance over the classical DIM approach, it is believed that this may hold the potential for improved accuracy in many cases. However, it was also noted that stability may be an issue with this approach. Filtering of the feedback impedance was used to attempt to develop a compromise between stability and performance. In general, future work should explore ways to better optimize the tradeoff between stability and performance for a given application.

This work on interface algorithms for PHIL is an addition to the submitted ESRDC report in [2].

The software infrastructure for operation and control of the 5 MW variable voltage source at CAPS had to be upgraded to ensure continued support and improved controls development and implementation environment. The upgrade included the corresponding CHIL setup, and furthermore, actually used the CHIL in the upgrade process to reduce the risks involved. The upgrade process was successfully completed and the PHIL facility has already been used for experiments including power conversion module testing and superconducting fault current limiters. While the upgrade process described here is specific to CAPS’ facility, the advantage of using CHIL in testing the newly implemented tools is of value to any institution or company faced with the same need. Concurrent with this upgrade, a new study of the applicable power electronics models was initiated and reported here. A CHIL interface for an MVDC simulation was also initiated.

This short report provides an overview of the failure mode and effects analysis (FMEA) studies undertaken to date for the MVDC shipboard power system (SPS) architecture. It is intended to highlight the approach, benefits and initial outcomes with respect to research approaches. The important benefits of the preliminary functional-FMEA (F-FMEA) to date are as follows:

• Indication of relative vulnerability of certain sections, components and subsystems to focus studies on their respective faults and failures
• An understanding of the need for detailed hardware information which would eventually lead to a more exhaustive hardware FMEA (H-FMEA). This would help to enhance the detail of the overall analysis
• Help focus diagnostic efforts to manage identified risks using well established AI techniques or the need to develop novel ones
• Aid efforts to enhance decision support by tapping into the data-rich FMEA resources.

The emphasis is laid on a F-FMEA which serves as the most appropriate method to start analysing failure cause and effects in a novel system such as the zonal shipboard power distribution architecture studied. The F-FMEA will be shown in a tabular format in the report.

To summarise, the contents of this preliminary report are:

• Introduction to the relevance and need to utilize FMEA as a starting point in this research
• Example of a fundamental F-FMEA conducted on the MVDC system
• Potential uses of FMEA data for benefiting future research

This report explains the F-FMEA process applied to a notional MVDC ship system model already available on the Real-Time Digital Simulator (RTDS) at CAPS. The relevant outputs are highlighted along with future directions for this particular research. Observing the merits of beginning at a more superficial F-FMEA are evident, mainly in the fact that the current research is centered around modeled representative systems with more generic than specific hardware information. F-FMEA is a logical start to understanding system and subsystem level risks and studying ways to mitigate their effects with accurate diagnostics.

Even though an F-FMEA is relatively less exhaustive than an H-FMEA, its outcomes form the driving force behind further research and eventually aid H-FMEA by narrowing down critical sections and devices. This in turn aids focusing and informing further research. While applying FMEA to a relatively detailed point design such as the notional MVDC ship system model represented on the RTDS explored and demonstrated the approach it will be of particular importance to incorporate FMEA into the ESRDC’s early stage design environment S3D as soon as possible.

The objective of this report is to set forth a group of time-domain models for the earlydesign stage study of shipboard power systems. These models are highly simplified abstractions of shipboard power system components. The motivation for the simplification is two-fold. First, at an early design stage it is doubtful if the parameters needed for a more detailed system representation would be available. A highly detailed simulation would be based on many
assumptions leading to results which are no more indicative of actual performance than a highly simplified simulation. The second reason for the creation of highly simplified model is for the sake of computational speed, so that system simulations based on the component models will run at speeds compatible with the needs imposed by exploring the system behavior under a large variety of conditions.

The types of model simplifications used are three-fold. First, throughout this report average-value models are used. In particular, the switching of the power semiconductors is only represented on an average-value basis. Secondly, reduced-order models are typically used. Thus, high-frequency dynamics have been neglected. Simulation based on these models cannot be used to predict behaviors such as the initial response to a fault. In general, temporal predictions of features on a time scale of ~100 ms or less will not be reliable. The third simplification that has been made is that many components are represented in the abstract based on the operation goals of the component rather than on the details of what might physically be present.

The set of models provided herein is fairly extensive and adequate to serve as a basis for studying a variety of power system architectures. In particular, the set of models is currently being used to study a notional medium voltage ac shipboard power system, a notional highfrequency ac shipboard power system, and a notional dc shipboard power system. In order to support these studies, the models set forth include: turbines, turbine governors, wound-rotor
synchronous machine based ac generators, generator paralleling controls, rectified wound-rotor synchronous machine based dc generation systems, ac input permanent magnet synchronous machine based propulsion drives, dc input permanent magnet synchronous machine based propulsion drives, hydrodynamic models, ac and dc pulsed load models, isolated dc/dc conversion models, dc loads, non-isolated dc/ac inverter modules, ac loads, active zonal rectifiers, circuit breakers and controls, as well as a variety of supporting components.

For the purposes of brevity and because of the resources available, model validation results are not presented herein. However, comments on model maturity have been included with each component to provide the reader with a sense of the degree of model confidence for each component.

Finally, the reader should be aware that a follow-on report will be delivered in the January 2014 time frame. This report will include an update of the models presented herein, but also include examples of their application in the simulation of notional medium voltage ac, highfrequency ac, and dc shipboard power distribution systems.

The objective of this report is to set forth a group of time-domain models for the early-stage design study of shipboard power systems, and to demonstrate their use on various system architectures. The effort stemmed out of an earlier effort in which waveform-level models of three notional architectures – a Medium Voltage AC System, a High-Frequency AC System, and a Medium Voltage DC System were partially developed. Unfortunately, these codes were extremely computationally intense, limiting their usefulness for early design studies in which large numbers of runs, and a degree of user interactiveness, is required.

This effort again considered three systems - a Medium Voltage AC System, a High-Frequency AC System, and a Medium Voltage DC System. However, this effort was focused on simplified models to serve the needs of interactive early stage design. Within this context, this work focused on two distinct aspects. The first aspect was the development of a set of component models in mathematical form. Such a description is advantageous in that it is language independent. The second aspect of this effort was the use of the component models to study the three aforementioned systems.

With regard to the first aspect of this work, that is the component modeling, fundamental component models (in mathematical form) were defined in sufficient detail to represent a notional system using the three aforementioned architectures. The component models are highly simplified abstractions of shipboard power system components. The motivation for the simplification is two-fold. First, at an early design stage it is doubtful if the parameters needed for a more detailed system representation would be available. A highly detailed simulation would be based on many assumptions leading to results which are no more indicative of actual performance than a highly simplified simulation. The second reason for the creation of highly simplified model is for the sake of computational speed, so that system simulations based on the component models will run at speeds compatible with the needs of exploring the system behavior under a large variety of conditions.

The types of model simplifications used are three-fold. First, throughout this report average-value models are used. In particular, the switching of the power semiconductors is only represented on an average-value basis. Secondly, reduced-order models are typically used. Thus, high-frequency dynamics have been neglected. Simulation based on these models cannot be used to predict behaviors such as the initial response to a fault. In general, temporal predictions of features on a time scale of ~100 ms or less will not be reliable. The third simplification that has been made is that many components are represented in the abstract based on the operation goals of the component rather than on the details of what might physically be present.

The set of models provided herein is fairly extensive and adequate to serve as a basis for studying a variety of power system architectures. The models set forth include: turbines, turbine governors, wound-rotor synchronous machine based ac generators, generator paralleling controls, rectified wound-rotor synchronous machine based dc generation systems, ac input permanent magnet synchronous machine based propulsion drives, dc input permanent magnet synchronous machine based propulsion drives, hydrodynamic models, ac and dc pulsed load models, isolated dc/dc conversion models, dc loads, non-isolated dc/ac inverter modules, ac loads, active zonal rectifiers, circuit breakers and controls, as well as a variety of supporting components.

For the purposes of brevity and because of the resources available, model validation results are not presented herein. However, comments on model maturity have been included with each component to provide the reader with a sense of the degree of model confidence for each component.

The component models developed under this effort were set forth in a previous report, “Notional System Report,” but are included again herein in Appendix A. The remainder of this effort focused on applying the component models in Appendix A to MVAC, HFAC, and MVDC instantiations of a notional architecture. Unfortunately, this aspect of the effort was only partially successful. It is demonstrated herein that the models developed are computationally effective; however, in the case of all three systems either only partial system models are used or there are remaining simulation issues to be resolved.

The primary reason for this failure to completely model the systems was related to the choice of simulation engine. In particular, Simscape was used. This proved to be rather trying on the part of the simulationists involved in this effort. The reason that Simscape was chosen were the results of a study of a small notional system also considered by the group, and set forth in [1]. Therein, it was shown that Simscape yielded superior performance over a number of simulation implementations. Unfortunately, as the system scope grew, this language proved problematic. In retrospect, it is recommended that Simulink be used instead, preferably with a user defined solver of the network interconnection equations, also as described in [1]. Such an approach should be much more robust, and more open to modification if needed.

This report discusses the process, product, and purpose of the PEPDS System Model Version 2.0 which captures diverse stakeholder needs, analyzes black box and white box functions, defines black box and white box context and interfaces, and identifies measures of effectiveness and performance. The foregoing elements distill into a set of system requirements that result in the PEPDS functional architecture. This report is intended to accompany the PEPDS System Model Version 1.0 and 2.0 with the purpose of assisting the reader with navigating and understanding the model.