Research Of LVRT Characteristics Of Wind Turbine And Dynamic Reactive Power Compensation Technology

As a green non-polluting renewable energy, Wind energy has endowed with a veryhigh value for development and commercial. Wind power generation has became arenewable power which is most likely to close to and replace conventional powergeneration. Rapid development has brought us not only considerable economic benefitsand significant social benefit, but also caused influence of power system stability whichcan’t be ignored. To encourage the healthy development of the wind power industry andimprove the power system stability, power-related departments require that wind turbineshould have Low Voltage Ride Through capability and also the dynamic reactive powercompensation. This article focuses on DFIG with1.5MW as the research object, buildingmodel under the environment of German power system simulationsoftware—DIgSILENT/Power Factory, and combines with the test result of LVRT andshort circuit experiment to verify the control strategy and wind turbine model.The paper focuses on the model eastablishement of wind source and wind turbine.Firstly, Modeling of wind turbine meanwhile derive mathematical model of doubly fedinduction generator under ABC three-phase stationary coordinate system and dq two-phasesynchronous rotating coordinate system; lay the theoretical foundation for modeling workof entire doubly fed induction generator. According to PWM converter model and theprinciple of vector control, set up the Grid converter model on the basis of under stator fluxoriented control strategy and the network-side converter model based on the grid voltageoriented control strategy, and establish a simplified transmission mechanism model andpitch angle control model at the same time. And then, analyzing the transient characteristicduring voltage drop for grid, proposing during grid voltage drop period, to achieve theLVRT for wind turbine, Crowbar protection coordinating with reactive power supportcontrol strategy is required. Then processing the simulation of three-phase faults andsingle-phase failure when voltage drops for grid to its rating of20%, results turn out toshow that the control strategies are reasonable and effective.At last, analyzing the reactivecompensation technology for doubly fed induction generator and wind farm entire reactive power compensation technology, building a wind farm model by make use of slip coherentfor wind generator polymerization method, proposing wind generator reactive powercompensation method by combining with numerical examples.This paper analyzes of test principle and process of the LVRT short circuitexperiment, combining with the test data, and comparing to the simulation results, drawingthe conclusion of effective control strategy and correct model structures and also reflectingthe reliable of all the analysis in the paper.