Research On Reactive Power And Voltage Control System In Wind Farm Based On STATCOM And DFIG

With the intensification of energy crisis, environmental pollution and other problems, human’s attention to renewable energy generation is increasing. Among much renewable energy generation, wind power for its rich resources, security, pollution-free, good industrial basis is favored by people. However, large-scale wind power will cause many adverse effects to power system due to randomness and volatility of wind energy. One important aspect is that wind farms PCC voltage stability, such as voltage fluctuation, voltage sag and so on. It is particularly necessary to establish a wind farm level reactive power and voltage control system.This article does detailed research on STATCOM and DFIG, it analyzes their operating principle, mathematical model and control strategy. Build a complete STATCOM device model, which contains control model composed of the inner and outer control rings in Matlab/Simulink. The paper builds the mathematical model of main components of double-fed variable speed constant frequency wind power system, such as wind turbine, mechanical transmission, double-fed asynchronous generator and converter. It also establishes the whole controller model composed of converter power decoupling control model, the maximum wind energy capture and speed control model and the pitch angle control model. These work is finished by transforming the DFIG model owned by Matlab. Grid simulation and calculation are done on basis of these work to verify the correctness of the two model.Considering the reactive regulation capacity and operating constraints of DFIG, the article establishes the DFIG cluster voltage control system composed of the decision-making layer of reactive demand and the optimal allocation layer of reactive power. The wind farm AVC system is built on basis of the DFIG cluster system and the voltage control mode of STATCOM through high-side voltage control theory. An improved DFIG control strategy is proposed as the emergency voltage control scheme of wind farm AVC system when failure happens. This wind farm AVC model is built and simulated in Matlab/Simulink.At last, the configuration, data interface, functional requirements, performance standard, software development process and precautions of wind farm side AVC system are discussed. In order to solve the flaws of PI control law, an AVC control strategy that combines PI control and calculation model is proposed in this paper. All these work done is aim to playing a constructional role in the development and deployment of wind farm side AVC system in the implementation of actual projects.