双馈风电场新型无功补偿与电压控制方案

为均衡双馈感应发电机感性和容性无功调节能力,改善电压稳定性,提出双馈风电场并联无功补偿方案:在各机组机端装设电容器,其电容值为双馈感应发电机定子电感的倒数;同时在主变的低压侧装设静止无功补偿器(static varcompensator,SVC)进行集中补偿。在此基础上,设计电压协调控制方案:稳态时通过三层无功分配策略充分发挥双馈风电机组无功调节能力,减小风电场内有功损耗;电网故障时则结合送出线路纵联差动保护控制SVC的等效电纳,避免保护动作时发生电压过冲的现象,同时改变机组内部无功分配以提高双馈风电机组故障穿越能力。最后以实际算例仿真表明上述无功补偿与电压控制方案的可行性和有效性。

A New Scheme of Reactive Power Compensation and Voltage Control for DFIG Based Wind Farm

In order to coordinate positive and negative reactive power capacity of doubly fed induction generator(DFIG) and improve voltage stability of the grid,a parallel reactive power compensation scheme of DFIG based wind farm was proposed.By this scheme,capacitor whose capacitance equals to countdown of stator inductance of DFIG is installed at the terminal of every wind turbine,and static var compensator(SVC) is installed in low voltage side of step-up transformer of the wind farm.Based on the reactive power compensation,a coordinated voltage control scheme was introduced.In steady state,three-level reactive power allocation can not only make full use of reactive power capability of DFIG driven wind turbines,but also reduce wind farm’s power loss.Combined with pilot protection of output delivery line,equivalent susceptance of SVC is controlled to avoid voltage overshoot after fault clearing.Meanwhile,reactive power allocation inside generator is changed to improve fault ride through capability.Finally,the simulation of a practical example verifies the feasibility and efficiency of the proposed scheme.