A New Frequency Control Strategy in an Islanded Microgrid Using Virtual Inertia Control-Based Coefficient Diagram Method

Renewable energy sources (RESs) are growing rapidly and highly penetrated in microgrids (MGs). As a result of the replacement of the synchronous generators with a large amount of RESs, the overall system inertia might be dramatically reduced which negatively affected the MG dynamics and performance in face of uncertainties, leading to weakening of the MG stability, which considers being a serious challenge in such grids. Therefore, in order to cope with this challenge and benefit from a maximum capacity of the RESs, robust control strategy must be applied. Hence, in this paper, a new application of robust virtual inertia control-based coefficient diagram method (CDM) controller is proposed in an islanded MG considering high-level RESs penetration for enhancement the system's validity and robustness in face of disturbances and parametric uncertainties. The proposed controller's proficiency has been checked and compared with H-infinite controller using MATLAB/Simulink which approved that the CDM controller achieved superior dynamic responses in terms of accurate reference frequency tracking and disturbance reduction over H-infinite in all test scenarios. Thus, the proposed controller alleviates the difficulties of H-infinite controller such as the experience and necessary abilities to design the form of the weighting functions for the system. Consequently, the frequency stability is improved and approved that the proposed CDM-based virtual inertia controller can significantly support a low-inertia islanded microgrid against RESs and load fluctuations.