Renewable power systems dynamic security using a new coordination of frequency control strategy based on virtual synchronous generator and digital frequency protection

The renewable power systems have become more susceptible to the system insecure than traditional power systems due to reducing of the total inertia and damping properties that result from replacing the conventional generators with Renewable Energy Sources (RESs) as well as decoupling of the RESs from the AC grid using power converters. Therefore, maintaining the dynamic security of renewable power systems is the key challenge for integrating more RESs. This paper addresses a new strategy of frequency control including virtual inertia control based on Virtual Synchronous Generator (VSG), which emulates the behavior of conventional synchronous generators in large power systems, thus adding some inertia to the system control loop virtually and accordingly stabilizing the system frequency during high penetration of RESs. Moreover, the proposed virtual inertia control system-based VSG is coordinated with digital frequency protection for improvement the frequency stability and preservation the power system dynamic security because of the high integration level of the RESs. The effectiveness of the proposed coordination scheme is tested and verified through small and large scales of power systems, Microgrid (mu G) and real hybrid power system in Egypt, respectively. System modelling and simulation results are carried out using Matlab/Simulink (R) software. The simulation results validated that the proposed coordination scheme can effectively regulate the system frequency and ensure robust performance to maintain the dynamic system security with high share of RESs for different contingencies.