Super-twisting sliding mode control of a static synchronous compensator: An application in a wind–diesel hybrid system

Abstract

The dynamic nature of load and wind power could lead to reactive power imbalance, and hence the voltage deviations in a wind–diesel power system. These deviations, if not controlled, may drive the system to operate in an unstable manner. Therefore, in this paper, a static synchronous compensator (STATCOM) is interconnected to the system to achieve reactive power balancing and minimize voltage deviations. To improve the dynamic performance of STATCOM and achieve the effective operation of the system, an optimized sliding mode controller (SMC) is designed. With the help of the design of a first-order switching manifold, an SMC is designed, which generates a control law to control the converter firing angle, and hence the reactive power output of the STATCOM. To eliminate the chattering drawback of SMC and improve the convergence characteristics, a second-order super-twisting sliding mode controller (STSMC) is proposed. The asymptotic stability of the proposed controller is guaranteed through the Lyapunov stability analysis. Particle swarm optimization (PSO) is employed to fine-tune controller parameters and achieve optimal performance. Validation of the improved performance of the system through this proposed scheme has been carried out in the MATLAB/Simulink environment and presented in the simulation studies.