Power Quality Improvement in a HVDC Transmission System Based on a Modified Active Power Filter-ENG

AbstractNonlinear loads absorb reactive power and produce harmonics. The demand of reactive power and harmonics cancellation are usually met by employing passive and active power filters. In this paper, a new active power filter topology is suggested in order to improve the power quality on both sides of the HVDC transmission system. A modified harmonics pulse width modulation (MHPWM) control strategy of the new active power filter is presented in this paper. The goal of the modified controller is to enhance the fundamental supply current of the HVDC converters and reduce the total harmonic distortion as lower as possible. The methodology to generate MHPWM signals is based on harmonics error current as reference signal and a triangle wave as carrier signal. Simulation results using Matlab/Simulink show that the suggested active filter is effective for transient and steady-state operating conditions. Therefore PWM pulses simulated by Matlab/Simulink are compared with the Matlab/System generator (SysGen) black box and done experimentally by the Xilinx Field Programmable Gate Array (FPGA). The VHDL codes used in the design process of the MHPWM is implemented firstly in Matlab/SysGen black box and secondly in the Xilinx FPGA Spartan3. These results show that the suggested MHPWM technique for modified active power filter is effectively closed to each other.