【正文】 he resistive panion method (RCM). The RCM solver interprets and solves naturally coupled models, enforcing physical conservation laws at the object provides a library of model objects, which represent systems or devices from different disciplines. These models can be interconnected to form largescale systems on the schematic editor.As mentioned before, important applications in SPS are the electric drives that correspond to the propulsion system of the allelectric ship. To demonstrate the effectiveness of VTB at modeling and simulating AC/DC phenomena, a simple motor drive example is presented next.The DC motor drive shown in Fig. 4 is built using the VTB schematic editor. In this simple application example, thesystem is posed of an AC voltage source, a rectifier bridge, resistors, capacitors, a PEBB (power electronic building block), and a DC motor. The motor speed is controlled in open loop by means of the duty cycle applied to the PEBB. The VTB simulation results are shown in Fig. 5and Fig. 6. Fig. 5 shows that the motor reaches 20% of its rated speed (557 RPM or rad/s), that is rad/s ,inapproximately sec. Fig. 6 depicts the DC bus voltage transient, where the switching phenomenon produced by the PEBB and the motor is accurately reflected in the VTB simulation.Other activities in modeling and simulation relate to real time digital simulator (RTDS), National Instruments (NI),dSpace Controller and CIM modeling. Hardware in the loop(HIL) simulation refers to a system in which parts of a pure simulation have been replaced with actual physical ponents. HIL simulation is often used to understand the behavior of a new device and to predict an oute underdifferent conditions. MSU researchers are involved with HIL using four different platforms, i) VTB realtime and dSpace,ii) NI realtime engine, PXI controller and Simulink, iii)RTDS, and iv) MATLAB real time workshop and Simulink. The mon information model (CIM) provides an opportunity to integrate with other applications and is based on object oriented data modeling and thesemodels need to be developed for SPS equipment, which does not exist in a utility system.III. PROTECTION OF SPSResearchers are developing control strategies for protection of integrated AC/DC power system, which will be different from conventional protection system as used by utilities. Figure 7 summarizes the research activities related to protection activities at MSU. Researchers are using VTB,MATLAB and CAPE with SEL relay to develop protection strategiesAuthors in [7] discussed integrated protection for shipboard power system. Sensor placement on a ship in the most optimized way for better security is important. MSU researchers are investigating this and also advantages of centralized versus decentralized approach to address the protection of the electric ship.The development and advancement to protect the zones area critical issue to address towards research of DC protection. One key feature is to make sure that the DC buses/systems and converters/rectifiers are protected from faults/arcing, transients, and other malicious events that can cause unwantedinterferences, shutdown, and possible damage or destruction. DC faults/arcing can have a detrimental impact on the shipper formance. DC protection should allow for high speed and high sensitivity detection of faults enhancing reliability in the supply of electric power. DC fault protection geared towards ship systems on a lower voltage scenario/system (LVDC) has not yet been studied and analyzed rigorously. The research goal at MSU has been to develop a method in which the system can detect a DC fault or arcing and perform a possible soft shutdown on the line/bus without having to open a circuitbreaker and return the system to normal operating conditions once the fault is removed. In order to protect the DC buses/systems and converters/rectifiers lodged on the electric ship, a flexible protection method needs to be developed and employed for full detection of any type of DC fault. The use of power electronics will be employed to solve how to protect the system’s stability and longevity. Agent based protection and DC protection are current research activities going on in this area at MSU.IV. RECONFIGURATION AND STABILITY OF SPSResearchers are using mercial analysis tools, such as LINGO, PSCAD, ETAP, PSS/E, MATLAB and VTB to simulate the AC/DC shipboard power systems and understand the impact of distributed generation, intentional islanding and ship operational changes on survivability and fightthroughfeatures of the power system.Additionally MSU researchers are developing customized tools in the areas of reconfiguration to calculate unbalanced power flow and to implement multiagent based systems for restoration. An agent based approach to reconfiguration has been presented in [8,9] while a centralized optimization basedapproach has been taken in [1011].A posite system of AC/DC system will have differentdynamics with pulse load, which need to be studied for stability issues. The MSU team is investigating this using continuation power flow. Fast and rough estimation of voltage stability based on index based approach and developing benchmark tool is the main focus. Figures 8 and 9 summarize the reconfiguration and stability activities at MSU.V. POWER ELECTRONICS RESEARCH FOR SPSFuture shipboard power systems will be largely posed of power electronic converters. Converters will be needed at the AC/DC system interfaces as well as throughout both the AC and DC sections of the distribution system. The ultimate objective of a shipboard Integrated Power System is to manage energy flow through the ondemand reassignment of power electronic converter functions. This objective requires open and hierarchical system architecture with standardized modules. There has been progress in this area due to continued research and development of the power electronics building blocks (PEB