DC voltage ancillary controller for dynamic security of shunt-compensated microgrids

Abstract

Abstract Modern power systems require special features from the distributed energy resources especially to meet the power quality and dynamic security. The distribution static synchronous compensator (DSTATCOM) has a safe DC voltage operating range that is often unexplored. Self-excited induction generators (SEIGs) with a shunt DSTATCOM is a well-known solution for low-power, low-cost generation. These systems may have poor robustness against surges and contingencies. This paper proposes an ancillary controller as a supplement in the shunt compensation of an off-grid distributed generation system powered by SEIGs. The controller consists of a variable structure that uses an adequate DC bus capacitor voltage range to provide fast frequency response (FFR) with soft recovery. The control performance for fault rejection is evaluated as well as for load disturbances and generation contingency. Simulation results are presented to demonstrate system operation and compensator performance.