Research On Reactive Power Compensation Strategy Of Wind Farms Connected To Power System

With the large-scale centralized development of wind farm,there is a contradiction during the increasing demands which are required by connecting to network, voltage fluctuation of wind power access point and low power factor. Aiming at the stragety of reactive power compensation devices,this article conducted a series studies, proposed a reactive power compensation strategy using capacitor and SVC to compensate reactive power commonly, to maintain the voltage stability of wind farm access point and meet the requires of connecting the network.The model of constant speed constant frequency wind-driven generator, OARS elongation control model,wind speed model and wind power model are researched. The average wind, stochastic wind, gradient wind and gusty wind were taken consider in the wind speed model. Simulated output characteristic of wind farm using average wind gusts wind, gradient wind and mixing of different wind speed as input, analysed the cause of fluctuation of voltage and power; Analyzes the the output characteristics of wind farm when the wind speed is different or there is a three-phase short-circuit fault in system.Researched the work principle of reactive power compensation devices,set up the simulation model based on PSCAD; Compensated the reactive power which the wind farm needed using parallel capacitor ,SVC and STATCOM, analyzes the voltage support ability of the three devices on wind farm, made a synthetic comparison on the compensation effect.of three reactive compensation devices. Set up a low voltage protection module in PSCAD according to the actual situationof wind power, and analysed the system which contains the model; Analysis the mechanism why reactive power compensation equipment can increase the low voltage ride through ability of wind farm, analysed the effects which was taken by compensation devices when they improve the low-voltage ride through capability of wind farm; Proposed a reactive power compensation strategy using paralle capacitor and SVC to compensate the reactive power on the wind farm export.Established a network model which contain two wind farms, and compensated the reactive power using capacitor and SVC commonly on the wind farm export. Analysed the voltage support capability of the wind farm access point using capacitor and SVC to compensate commonly when there is different faults occurred at the wind farm export,contrast the voltage and rotor speed of wind generator before and after compensation by the strategy that was proposed in this article.