Uncertainty Considered Automatic Voltage Regulator of Synchronous Generator

A fuzzy proportion plus integral (FPI)control strategy is investigated for the automatic voltage regulator (AVR)of synchronous generators (SGs). The Takagi-Sugeno-(T-S)fuzzy state observer is employed to solve the SG state estimation over its full operating range, where approximation error due to parameter uncertainty and fuzzy approximation have been considered. Based on the obtained observer, a H2 controller with PI structure is proposed to control the excitation system of a SG, where a robust stabilization technique is also proposed to override the effect of the approximation error. Then, the FPI controller design is formulated as a H2 sub-optimization problem with constrain of robust stabilization, which can be transformed into eigenvalue problems (EVPs)with linear matrix inequality (LMI)constrains. The EVP is a convex optimization, and it can be tackled easily by using MATLAB/LMI toolbox. Simulation results show the effectiveness of the proposed controller.