The method of harmonic compensation of UPQC based on Euler-Lagrange model

In order to overcome the error caused by using PLL (Phase Locked Loop) in current detecting method of the UPQC (Unified Power Quality Controller) compensation quantities, this paper proposes the dq0 detection method of voltage and current harmonic based on the clock in phase with power grid frequency without using PLL. To improve the control of UPQC, the EL(Euler-Lagrange) mathematical model of UPQC in dq0 coordinates is set up, and the hybrid passivity based controller is designed according to the EL model and the passivity of UPQC. Using the proposed detection method and hybrid passivity based controller, the voltage and current can be compensated effectively, which make the load voltage and power supply current sinusoidal. The simulation model of UPQC is built based on MATLAB/simulink. The simulation results show the effectiveness of the proposed detection method and hybrid passivity based control strategy.