Modeling and simulation of The CERTS Microgrid: a comparative study using PSCAD and MATLAB SIMSCAPE

Abstract

The legacy electric power system has grown in magnitude and complexity since its conception. This was a result of various advancements, such as the need to match the increase in power demand, and to address the shortage of conventional sources (e.g. oil and gas). This led to the integration of Distributed Generators (DGs) into the legacy grid, thereby facilitating the incorporation of microgrids. An adverse effect can be seen with the large-scale penetration of various distributed generation (DGs) caused by the utilization of switching devices and inconsistent performance of the DGs. The effects of incorporating switching devices has led to issues such as an increase in harmonics, voltage, frequency regulation, power quality degradation, and reverse power flow. A cost-effective approach to study the abovementioned impacts is via modelling and simulating the system in well-known simulating platforms such as Power System Computer Aided Design (PSCAD) and MATLAB Matlab-Simscape. To that note, the fundamental difference between the two simulation environments is that Matlab-Simscape is based on solving a system of ordinary differential equations (ODEs) represented in the form of matrices using ODE45 and its variations, while PSCAD utilizes electromagnetic transient including DC (EMTDC). EMTDC represents the system as differential equations for both electromagnetic and electromechanical systems in the time domain. Solutions are based on a fixed time step and the results are solved as instantaneous values in time. Therefore, modelling the same component in either of them can result in some inconsistencies in the output quantities. In this work, the modeling of the microgrid in both simulation platforms is studied and the model transformation approach is introduced, which highlights the procedure to model any component in the two simulation environments to generate consistent results. Additionally, both simulation platforms are studied in detail utilizing a standardized microgrid benchmark system, known as the Consortium for Electric Reliability Technology Solution (CERTS) microgrid. This CERTS configuration defines the framework necessary to measure and adjust the performance of both simulation platforms in a quantitative and qualitative manner. Furthermore, a methodology is proposed to model the various components of the microgrid in a uniform and interchangeable manner. Ultimately, the proposed methodology overcomes the differences in modelling some electrical components in each platform. In addition, the properties of each component in both software have been highlighted in detail to facilitate the transition between each platform. Finally, this work introduces a comparative study between PSCAD and Matlab-Simscape based on the CERTS microgrid. The performance of both simulating platforms is studied in both the grid connected mode of operation and in the island mode of operation. The performance of both simulating platforms is evaluated, and the results are presented to demonstrate the validity of the modeling techniques. The results have shown that the difference between the quantities measured at the same point of measurement in both simulation platforms are less than 1%, which verifies that the modeling technique results in uniform outcomes in both PSCAD and Matlab-Simscape.