Reactive power control for voltage stability of standalone hybrid wind–diesel power system based on functional model predictive control

This study investigates the application of the model predictive control (MPC) approach for voltage stability of an isolated hybrid wind-diesel generation system based on reactive power control. This scheme consists of a synchronous generator (SG) for a diesel-generator (DG) system and an induction generator (IG) for a wind energy conversion system. A static voltage automatic regulator (VAR) compensator (SVC) is connected at terminal bus to stabilise load voltage through compensating of reactive power. Two control paths are used to stabilise load bus voltage based on MPC. The first one by controlling the total reactive power of the system that by controlling the SVC firing angle and hence the load voltage. The second control path by controlling the SG excitation voltage and hence the load bus terminal voltage. The MPC is used to determine the optimal control actions including system constraints. To mitigate calculations effort and to reduce numerical problems, especially in large prediction horizon, an exponentially weighted functional MPC (FMPC) is applied. The proposed controller has been tested through step change in load reactive power plus step increase in input wind power. Also, the performance of the system with FMPC was compared with the classical MPC. Moreover, this scheme is tested against the parameters variations.