SVC-based Wind Farm Reactive Power Compensation Technology

Under the background of today’s growing energy shortages, deteriorating environment and increasing electricity consumption, wind energy as a clean, renewable energy source gets widespread attention around the world. Seeing the wind power situation from all over the world, the installed capacity of wind turbines also shows increasing trend in recent years. However, currently the majority of wind farms are in the end of the grid and the grid structure is not strong enough, so the wind power is bound to bring some adverse effects on the stability of entire grid. Especially for induction wind power systems, due to the asynchronous machine provides active power to the grid at the same time and it also absorbs a certain reactive power from the grid to excite itself. This characteristic of asynchronous machine will bring a lot of pressure to the entire grid. If the asynchronous machine connects power grid directly, it will not only affect the power factor of the entire system, but also it will reduce the stability of the power system and increase line losses and other issues. Therefore, since the reactive power compensation plays an important role to improve the stability of the entire power system, research on the wind farm reactive power compensation will bring great significance. This thesis is on this basis conducting in-depth study of SVC reactive power compensation of wind power. A novel reactive power control strategy of SVC was proposed, and the control strategy was verified in the wind farm reactive compensation. It can improve the transient stability. A wind farm asynchronous simulation model of reactive power compensation also was built. The specific studies are as follows:Firstly, wind power system for asynchronous model was established including wind speed model, aerodynamic model and mathematical models of induction wind turbine. Then dynamic compensation principle of SVC device was introduced and through modeling and simulation of reactive power compensation, its characteristics were verified.Secondly, based on the analysis of the shortcomings and deficiencies of the common p-q detection method, an improved p-q detection method of SVC reactive power compensation device was applied in wind farm. The principle of detection method was introduced. The detection quickness and the accuracy of tracking of improved p-q detection method were verified through modeling and simulation.Finally, SVC on the wind transient stability of power system was analyzed. The control strategy of wind farm reactive power based on SVC was proposed and the improved detection was applied to new control strategy. A simulation was made under the condition of wind disturbance and fault disturbance for the new SVC control strategy and the original control strategy. Through the simulation the effectiveness of new control strategy was verified. It is proved that the SVC could provide reactive power to wind power system more steadily and rapidly. And it could make sure that wind power system can have a stable operation state.