EKF Based Fuzzy PI Controlled Speed Sensorless Power Optimal Control of a Direct Drive Power System

Abstract

Faced with wave irregularity, the corrosion of the mechanical sensor in wave power generation systems, hazardous working conditions, and the inaccuracy of conventional control methods in the shifting system, a new type of irregular wave maximum wave energy capture strategy are proposed. The motivation behind the strategy is speed sensorless power optimal control of a direct drive wave power system by an extended Kalman filter (EKF) and self-tuning fuzzy proportional integral (PI) control. In our strategy, a fast Fourier transform (FFT) is utilized to analyze the spectrum of the irregular wave excitation force, and the maximum superposition control condition of the wave energy extraction is constructed by the vector superposition principle. Taking the voltage and current parameters of the generator as the input, based on two stages of prediction and update, an EKF observer system is established to estimate the speed and position of the power generation system. The fuzzy parameters are used to dynamically adjust the PI parameters so as to achieve optimal power state tracking control. The simulation results show that the FFT can meet the power optimal tracking requirements of unknown irregular waves. The proposed speed sensorless control scheme has good dynamic characteristics, small degree and position observation errors, and strong robustness, and allows the system to follow a given value.

Keywords

• Fast Fourier transform
• wave power generation
• linear permanent magnet synchronous generator
• parameter self-tuning fuzzy PI
• extended Kalman filter
• optimal power