Theoretical Study on Control Strategy of Grid-Connected High Voltage Ride Through in Doubly-Fed Wind Farm

Aiming at the problem of high voltage disconnection when doubly-fed wind farms are merged into weak power grids, this paper researches the theory of rotor excitation control and proposed an additional control model of DFIG grid-connected rotor flux based on structure decentralization theory. In this model, the high voltage ride-through capability for grid-connected wind farms is enhanced by designing the d-axis and q-axis adaptive terminal sliding mode controllers of the synchronous rotating coordinate system. Using the simulation software of MATLAB/Simulink, this paper established a simulation model of wind farm high voltage ride through composed of 2MW doubly fed wind turbines and carried out the off-line simulation of the whole process of high voltage traversing. Real-time simulation experiment of high voltage ride-through was also conducted on a self-developed real-time simulation platform for grid-connected doubly-fed wind farms. Real-time simulation results prove the accuracy of theoretical and offline simulation analysis and the feasibility of control strategy.