Optimal control of SVC-MERS and application in SCIG powered micro-grid

In squirrel-cage induction generator (SCIG) powered micro-grid, continuously variable reactive power (CVRP) should be provided to stabilize the grid voltage when load is constantly changing. This paper proposes a novel CVRP compensator, which name is static VAR compensation magnetic energy recovery switch (SVC-MERS). Comparing with static compensator (STATCOM), the proposed device has some advantages in line frequency switching, small dc-capacitor and robustness. To begin with, operation principle of SVC-MERS has been briefly described in this paper. Secondly, optimal direct-voltage control (ODVC), which aims to broaden the reactive power compensating range, is proposed and verified by simulation in PSIM. It also has the advantages of sinusoidal output-current waveforms and restrains dc-capacitor voltage. Thirdly, a three phase SVC-MERS has been designed with delta connection and applied to voltage regulation in a 15kW SCIG powered micro-grid. Then experiments have been finished under different load conditions. Finally, experimental results confirm the conclusion.