无功优先控制对风电场集电线保护影响分析及改进措施研究

Analysis of the Influence of Reactive Power Priority Control on the Protection of Wind Farm Collector and Research on Improvement Measures

电网电压跌落时能够向系统提供无功支撑是对并网风电机组的基本要求。风电机组无功支撑对故障电流有着直接影响,可能使集电线电流速断保护灵敏度下降,同时可能使保护失去选择性。文章首先根据双馈异步电机(double feed induction generator,DFIG)数学模型及无功电流支撑原理,分析了浅、深度故障运行下DFIG分别通过转子侧变流器(rotor-side converter,RSC)与网侧变流器(grid-side converter,GSC)调节输出无功对故障电流的影响。针对DFIG无功优先控制可能造成集电线电流速断保护灵敏度降低以及其与箱变熔断器失去配合的问题,提出了在DFIG无功优先控制计算整定初值基础上根据集电线电压跌落程度附加自适性补偿量的定值调整方法。通过仿真验证,表明整定值改进后能够在保证全线速动的前提下大幅提升保护的选择能力。

It is a basic requirement for grid connected wind turbines to provide reactive power support to the system when the grid voltage drops.The reactive power support of wind turbine has a direct impact on the fault current,which may reduce the sensitivity of the current quick break protection of the collector line,and may also make the protection lose its selectivity.Firstly,based on the mathematical model of DFIG(double feed induction generator)and the principle of reactive current support,we analyzed the influence of DFIG regulating output reactive power on fault current through rotor side converter(RSC)and grid side converter(GSC)respectively under shallow and deep fault operation.Aiming at the problem that DFIG reactive power priority control may reduce the current quick break protection sensitivity of the collector line and lose coordination with the box transformer fuse,we proposed a set value adjustment method based on DFIG reactive power priority control calculation of the initial setting value and additional adaptive compensation according to the collector line voltage sag.The simulation results show that the improved setting value can greatly improve the selection ability of protection on the premise of ensuring the rapid operation of the whole line.