Reactive-voltage coordinated control of offshore wind farm considering multiple optimization objectives

Abstract

Reactive power-voltage (Q-V) control of wind turbine (WT) is an effective method to realize voltage control of a grid-connected wind farm system. However, the variation in the output reactive power of WTs would aggravate the system power loss and converter electro-thermal stress. That is, it would reduce the system economy and accelerate the aging failure process of wind power converters. Considering this, a multi-objective Q–V coordinated control strategy for wind farms considering voltage deviation, converter junction temperature, and power loss is proposed in this paper. In this method, the reactive power instruction matrix of the WTs is used as the decision variable, and the system voltage deviation, power loss, and converter junction temperature are used as the state variables. A linear reactive power flow optimization model for wind farms based on the sensitivity analysis method is proposed to map the coupling relationship between decision variables and state variables. It is aimed at enhancing the voltage control of the system while considering the junction temperature of the converter and active power loss of the system. In addition, two control modes are designed to achieve a trade-off among optimization objectives. A wind farm power-flow model and RT-Lab semi-physical simulation are used for verification. The results show that the proposed method can improve the overall performance of the system compared with other methods.