Enhanced Voltage Control of VSC-HVDC-Connected Offshore Wind Farms Based on Model Predictive Control

Abstract

This paper proposes an enhanced voltage control strategy (EVCS) based on model predictive control (MPC) for voltage-source-converter-based high-voltage direct-current (VSC-HVDC)-connected offshore wind farms (OWFs). In the proposed MPC-based EVCS, all wind turbine generators (WTGs) and the wind-farm-side VSCs are optimally coordinated to keep voltages within the feasible range and reduce system power losses. Considering the high R/X ratio of the OWF collector system, the effects of active power outputs of WTGs on voltage control are also taken into consideration. The predictive model of the VSC with a typical cascaded control structure is derived in detail. The sensitivity coefficients are calculated by an analytical method to improve the computational efficiency. A VSC-HVDC-connected OWF with 64 WTGs was used to validate the proposed voltage control strategy.