Accepted version of the manuscript in IEEE Electric Ship Technologies Symposium (ESTS), 3-6 August 2021, Arlington, VA, USA, Page(s): 1-9. DOI: 10.1109/ESTS49166.2021.9512333 Shipboard Zonal Load Center Modeling and Characterization on Real-Time Simulation Platform Md Multan Biswas*, Tyler Deese*, James Langston † , Harsha Ravindra † , Karl Schoder † , Michael Steurer † , Herbert Ginn*, Christian Schegan ‡ Email: {mbiswas}@email.sc.edu {langston}@caps.fsu.edu {steurer}@caps.fsu.edu {ginnhl}@cec.sc.edu {christian.schegan}@navy.mil *Dept. of Electrical Engineering, University of South Carolina, Columbia, SC 29208, USA † Center for Advanced Power Systems, Florida State University, Tallahassee, FL 32310, USA ‡ Philadelphia Division, Naval Surface Warfare Center, Philadelphia, PA 19112, USA Abstract—This paper presents detailed modeling of a Zonal Load Center (ZLC) for a Shipboard Power System (SPS) in a Real-Time (RT) simulation platform. The system being modeled includes the main Power Conversion Module (PCM) and Battery Energy Storage Module (BESM) with interfacing bidirectional converter, where both converters are implemented with their designed control schemes to manage diverse operational modes. To establish confidence and achieve more insight into the ZLC power converters model, a set of cross-platform Verification and Validation (V&V) activities and frequency characterization are defined and executed. These cross-platform V&V activities include small-signal characterization of terminal impedances and disturbances propagation of ZLC converters and large-signal characterization of the PCM to elicit the response to over/under- voltage. The Opal-RT technologies and MATLAB/Simulink were adopted for the RT simulation and V&V activities. Keywords—battery energy storage, dual-active bridge, Opal-RT, Power Conversion Module (PCM), Shipboard Power System (SPS), Verification and Validation (V&V) I. INTRODUCTION The Medium-Voltage DC (MVDC) based Shipboard Power System (SPS) is an emerging technology for all-electric ship systems. An SPS is a mini-grid system having over 100 MW of cumulative loads with a wide spectrum of features. The envisioned all-electric ship will comprise diverse power systems components that are required to pass through vigorous research, modeling, characterization, and testing [1], [2]. Different nations and industrial entities are working on the development and assessment of this novel technology, and system engineering to minimize the risk and costs of early decisions [3-5]. The power requirements could vary from continuous loads, such as motor- driven propulsion systems, to nonlinear, stochastic, and fast varying high-power mission loads [6], [7]. To fulfill this variety of load demands, the shipboard MVDC system should consist of superior power density, high power quality, reliability, and resiliency [7], [8]. A focus of the Electric Ship Research and Development Consortium (ESRDC) team is on performing modeling and Real-Time (RT) simulation of multidisciplinary shipboard technologies. The principal purpose of running RT co- simulation testing of SPS is performing controller hardware-in- the-loop (CHIL) testing for evaluation of competing shipboard control architectures. Towards these goals, several US universities are working in the ESRDC team. The ESRDC has developed a Model Description Document (MDD) that describes the simulation platform independent structure of a notional four-zone SPS based on MVDC distribution system architecture [9]. Adopting the structure outlined in the MDD, various efforts have been taken to model and evaluate different components and corresponding control techniques of the SPS [10]-[13]. In a similar effort, a Thyristor Controlled Rectifier (TCR) driven Power Generation Module (PGM) of the SPS was modeled and simulated in different Real-Time Simulator (RTS) platforms in [14]. The latest version of the ESRDC MDD has defined a Zonal Load Center (ZLC) and associated components. With the intent of modeling the ZLC on an RT platform, it is essential to establish confidence in power converter models implemented, through different Verification and Validation (V&V) activities to characterize the model behavior. These V&V activities also provide valuable insights into the model features under various disturbances and non-ideal conditions. In this work, a detailed modeling and several cross- platform V&V characterizations of the shipboard ZLC utilizing an RT simulation platform are presented. A supervisory system to co-ordinate the switching of control modes in RT based on ZLC operation was also developed and verified. The main contributions of this research work are as follows:  Execution of RT simulation of the ZLC outlined in the latest version of ESRDC SPS model description document in the Opal-RT environment.  Considering stochastic and non-linear behavior of the high- power mission loads in an electric ship, a variety of small- signal and large-signal frequency characterizations are utilized to verify and validate the presented models and control schemes. The remainder of the paper is organized as follows: a brief description of the reference SPS architecture and associated principal elements are outlined in section II. Section III contains a detailed description of the RT simulation models and control strategies for the ZLC components. The RT simulation results of the SPS ZLC and a discussion are presented in Section IV. Finally, Section V depicts a set of V&V activities and frequency characterization results of different converters operating within the ZLC. Remarks and future work are given in Section VI. This work was supported by the U.S. Office of Naval Research under the grant N00014-16-1-2956 and was approved for Distribution A public release under request ID #NSWCCD-002206. Distribution is Unlimited.