Research On Inductive Filtering Method And Reactive Power Compensation Method Applied To Grid-connected Wind Power System

With the continuous development of wind power, a large number of wind turbines accessed to the power system. Since the wind farm usually contains a variety of nonlinear devices and converters, inevitably bringing a lot of problems, such as harmonics and reactive power loss, which hinder the safety, stability, and economic operation of power system as well as causing electromagnetic interference in normal operation of other electrical equipment. Therefore, finding an effective way to solve the power quality problems in wind power generation is becoming to a hot issue.In this paper, we proposed a new grid-connected wind power system, which combines the theory of inductive filtering and dynamic reactive power, to settle the mentioned power quality problems in wind power generation.First of all, the current research status and development of wind power generation in China are introduced. In addition, the harmonic and fluctuation of wind power in grid-connected wind power system are presented and their influences on power network are also expounded. At the same time, the previous methods of improving power quality problems are summarized.Secondly, the topology structure of the new grid-connected wind power system and its corresponding wiring scheme are presented. The three-phase equivalent circuit model of the new system is established. Based on this, the implement conditions of inductive filtering method in grid-connected wind power system are obtained. Moreover, the structure of cascaded STATCOM and its working mechanism are investigated. The harmonic suppression and reactive compensation characteristics are analyzed in depth, respectively, which further illustrates the proposed system has a good overall performance in theory.Thirdly, based on the research of the frequently-used design methods of the tuning device, we proposed an optimizing design method, which establishes a mathematic model, to obtain the parameters of tuning device by using of matrix algorithm. Comparing the proposed optimizing design method with the frequently-used design methods, it is demonstrates that matrix-based optimizing design method has a better adaptability performance on the detuned condition.Finally, simulation studies of the proposed grid-connected wind power system are carried out by PSCAD/EMTDC. The harmonic suppression characteristic of the new system is investigated in the case of different active power output of the wind farm, respectively. The reactive compensation characteristics of the system on both the steady state operation condition and the transient operation condition are investigated as well. Simulation results indicate the new grid-connected wind power system has good performance in harmonic suppression and dynamic reactive compensation.