Research On Control Strategy For Power Grid Fault In Doubly Fed Wind Power Generation

Renewable energy has obvious environmental benefits and social benefits, so it gets more and more attention. Because of wind energy can reserve, has a wide range of distribution, and can be regenerated, wind power generation is one of the most common form in renewable energy. VSCF doubly-fed wind power generation system of wind power has become a major focus topics.The model of wind speed is a key in the simulated system of wind generation. Accurate model of wind speed can not only reflect the factual variety of wind speed, but also provide the study of wind generation with the accurate sources. This paper enumerates several models of wind speed, analyzes their advantages and disadvantages.This paper found an combined mathematic model of wind speed by Matlab/simulink. The result of simulation shows the model can reflect factual wind speed ideally and be more suitable for wind power system dynamic simulation.A fault control strategy of DFIG is proposed in the paper.In conventional case, the active of DFIG rotor side uses the MPPT control and the reactive uses the rated power factor control. It can get the largest wind energy utilization efficiency and better power factor, but it can't when power grid fault occurred. And the power grid voltage and frequency will fluctuate. So the MPPT control and the rated power factor control switch to frequency control and voltage control strategy when power grid fault occured, by controlling the active current and reactive current component to reduce or increase active and reactive power output, to maintain the system frequency and voltage stability. The model of controlling under fault conditions is set up. The simulation is running in two conditions such as single-phase grounding and two-phase short-circuit.The results of simulation show the correctness of fault control strategy. The stability of wind power system is enhanced under fault conditions.