Voltage and frequency control of an autonomous hybrid generation system based on linear model predictive control

Abstract

This paper presents an adaptive control for voltage and frequency regulation of a stand-alone hybrid wind-diesel power system based on constrained linear model predictive control (MPC). The proposed system mainly consists of a wind turbine driving a self-excited induction generator (SEIG) connected via a DC link to a synchronous generator (SG) driven by a diesel engine. The SG is equipped with a voltage regulator and a static exciter. The wind generator and the synchronous generator together cater for the local load and power requirement. However, the load bus voltage and frequency are governed by the SG. To extract maximum available wind power, it is assumed that the wind generation system operates free without control. The control objective aims to control the load voltage and frequency. This is achievement via controlling the field voltage and rotational speed of the SG. The MPC controller is based on the minimization of a cost function of voltage and rotor speed errors while respecting the given constraints. The hybrid wind-diesel energy system with the proposed MPC has been tested through a turbulent and step change in wind speed and load impedance respectively. Simulation results show that accurate tracking performance of the system has been achieved.