FRT Capability Enhancement of Offshore Wind Farm by DC Chopper

Abstract

Offshore wind farms (OWF) are establishing their position to be the next strategy to expand the growth horizon of wind power production. For proper integration of OWFs into the existing grid, the voltage source converter (VSC)-based high voltage direct current (HVDC) transmission is being vastly utilized. For the stable operation of the existing grid, these VSC-HVDC-connected OWFs need to abide by the fault ride through (FRT) grid codes. Though there are many proposed solutions to tackle the FRT problem of the onshore wind farms, all of them cannot be applied to the OWFs. The OWFs cannot respond to the onshore faults depending solely on local measurements. Additionally, there are very few techniques available for FRT capability enhancement of the doubly fed induction generator (DFIG)-based OWFs. One notable solution is the use of the DC chopper resistor across the HVDC line. No intelligent controller is yet to be reported for better control of the DC chopper resistor. To enhance the performance of the DC chopper resistor in enhancing the FRT capability of the DFIG-based OWF, a particle swarm optimization (PSO)-based nonlinear controller is proposed. Simulations carried out in the Matlab/Simulink environment reveal that the PSO-optimized nonlinear controller-based DC chopper is very effective in maintaining the FRT of the DFIG-based OWF systems. Additionally, the proposed method provides better FRT performance than that of the conventional controller-based DC chopper.