新能源电源送出线路不同类型距离保护动作性能比较

A comparison of the operational performance of different types of distance protec⁃tion in new energy power transmission lines

新能源交流送出线路故障后,新能源电源的故障响应特性会影响距离保护的动作行为。为此,结合新能源电源控制策略,分析故障前后新能源电源阻抗、系统功角及故障电气量的变化,比较相极化电压距离保护、正序极化电压距离保护、突变量距离保护3种类型距离保护的动作性能。由于在线路出口故障时相电压为零,相极化电压距离保护存在动作死区;由于故障后正序电压相位受控制影响发生偏移,正序极化电压相间距离保护存在线路区内故障时拒动、区外故障时误动的风险;对于突变量距离保护,故障后补偿电压相位受控制影响发生偏移,导致保护可能发生拒动或误动。利用RTDS(实时数字仿真系统)建立新能源经交流线路送出的系统模型,仿真分析线路不同类型故障情况下3种距离保护的动作性能,仿真结果与理论分析结论一致。

Following a fault on an AC transmission line for new energy,the fault response of the new energy power supply can influence the operation of distance protection.Therefore,leveraging the control strategy of the new en⁃ergy power supply,this study delves into alternations in impedance,system power angle,and faulty electrical quan⁃tity prior to and post-fault.It also contrasts the performance of three distance protection mechanisms:phase polariza⁃tion voltage,positive-sequence polarization voltage,and sudden magnitude variation.Given that the phase voltage drops to zero when faults occur at the line outlet,a non-responsive zone is inherent in the action area of phase polar⁃ization voltage distance protection mechanism.After a fault,the phase of the positive sequence voltage is influenced by control and shifts.This presents risks of refusal to trip during an internal fault and false tripping during an exter⁃nal fault for positive-sequence polarization voltage phase-sequence distance protection mechanism.Regarding the sudden magnitude variation distance protection mechanism,a fault can compel a shift in the compensated voltage phase due to control influences,which could result in protection refusal or false tripping.Using the real-time digital simulator(RTDS),a system model demonstrating the transmission of new energy via AC lines is established.A simulation analysis of the performance of the three mechanisms is performed.The findings from the simulation align seamlessly with the theoretical scrutiny.