The single-line-to-ground faults with line breaks(SLGFs-LBs)occur more and more frequently in distribution networks and can cause major safety accidents.It is difficult to distinguish the single-line-to-ground faults(...The single-line-to-ground faults with line breaks(SLGFs-LBs)occur more and more frequently in distribution networks and can cause major safety accidents.It is difficult to distinguish the single-line-to-ground faults(SLGFs)in resonant grounding systems and ungrounding systems due to the same electrical characteristics on the source side and uncertain operation conditions of distribution networks.This paper proposes a method for distinguishing SLGFs-LBs and SLGFs.First,the source-side and load-side voltage characteristics of SLGFs and SLGFs-LBs are analyzed,and the phase difference between the voltages of the fault phase and non-fault phase on the load side is selected as the identification criterion.Phasor measurement units(PMUs)are selected as measuring devices.Then,the effects of operation conditions and external devices in distribution networks on the proposed method are discussed,and the phase errors caused by them are calculated to correct the identification method.Finally,the field testing and simulation experiments are conducted to verify the effectiveness and robustness of the proposed method.展开更多
High-impedance faults(HIFs)in distribution networks may result in fires or electric shocks.However,considerable difficulties exist in HIF detection due to low-resolution measurements and the considerably weaker time-f...High-impedance faults(HIFs)in distribution networks may result in fires or electric shocks.However,considerable difficulties exist in HIF detection due to low-resolution measurements and the considerably weaker time-frequency characteristics.This paper presents a novel HIF detection method using synchronized current information.The method consists of two stages.In the first stage,joint key characteristics of the system are extracted with the minimal system prior knowledge to identify the global optimal micro-phase measurement unit(μPMU)placement.In the second stage,the HIF is detected through a multivariate Jensen-Shannon divergence similarity measurement using high-resolution time-synchronized data inμPMUs in a high-noise environment.l2,1 principal component analysis(PCA),i.e.,PCA based on the l2,1 norm,is applied to an extracted system state and fault features derived from different resolution data in both stages.An economic observability index and HIF criteria are employed to evaluate the performance of placement method and to identify HIFs.Simulation results show that the method can reliably detect HIFs with reasonable detection accuracy in noisy environments.展开更多
随着分布式新能源渗透率不断提高,智能配电网电力电子化趋势明显,电气参数更加复杂,亟需研究适用于配电网的同步相量测量装置(Synchrophasor measurement unit for distribution network,D-PMU)。然而,现有通信协议与条件无法满足D-PMU...随着分布式新能源渗透率不断提高,智能配电网电力电子化趋势明显,电气参数更加复杂,亟需研究适用于配电网的同步相量测量装置(Synchrophasor measurement unit for distribution network,D-PMU)。然而,现有通信协议与条件无法满足D-PMU的接入需求。针对该问题,该文设计一种适用于D-PMU的基频相量、谐波/间谐波同步测量、异步传输的结构框架,提出一种谐波/间谐波的数据传输协议,减少了通信负担。在上述框架的条件下,分析网络通信延时与丢包率的影响因素,搭建通信性能测试平台,进行通信性能实际测试,验证所提通信方法的可行性,并根据测试结果提出一种D-PMU通信接入参数的设置方法。展开更多
该文面向存在脉冲干扰的配电网信号环境,研究脉冲干扰检测、精确定位和基于干扰剔除的同步相量测量算法。首先,根据同步相量测量单元(phasormeasurementunit,PMU)测量值进行基波重构,通过分析重构残差序列定义特征参数残差总向量(total ...该文面向存在脉冲干扰的配电网信号环境,研究脉冲干扰检测、精确定位和基于干扰剔除的同步相量测量算法。首先,根据同步相量测量单元(phasormeasurementunit,PMU)测量值进行基波重构,通过分析重构残差序列定义特征参数残差总向量(total vector of the residual,TVR),用以表征PMU测量误差。其次,提出基于TVR和残差瞬时功率异常值判别的方法,实现脉冲干扰检测和精确定位。最后,基于相量测量的最优滤波原理设计出改进加权最小二乘算法,实现脉冲干扰下同步相量的快速准确测量。仿真结果表明,在数据窗长为2个周波(P类测量),当脉冲干扰长度不超过半个周波时,该文算法在典型配电网环境下达到IEEE标准规定的测量误差要求(TVE<1%),且对脉冲干扰持续时间和强度表现出较强的鲁棒性。展开更多
基金supported in part by National Science Foundation of China(No.51707117)。
文摘The single-line-to-ground faults with line breaks(SLGFs-LBs)occur more and more frequently in distribution networks and can cause major safety accidents.It is difficult to distinguish the single-line-to-ground faults(SLGFs)in resonant grounding systems and ungrounding systems due to the same electrical characteristics on the source side and uncertain operation conditions of distribution networks.This paper proposes a method for distinguishing SLGFs-LBs and SLGFs.First,the source-side and load-side voltage characteristics of SLGFs and SLGFs-LBs are analyzed,and the phase difference between the voltages of the fault phase and non-fault phase on the load side is selected as the identification criterion.Phasor measurement units(PMUs)are selected as measuring devices.Then,the effects of operation conditions and external devices in distribution networks on the proposed method are discussed,and the phase errors caused by them are calculated to correct the identification method.Finally,the field testing and simulation experiments are conducted to verify the effectiveness and robustness of the proposed method.
基金supported in part by the National Key Research and Development Program of China(No.2017YFB0902800)Science and Technology Project of the State Grid Corporation of China(No.52094017003D)。
文摘High-impedance faults(HIFs)in distribution networks may result in fires or electric shocks.However,considerable difficulties exist in HIF detection due to low-resolution measurements and the considerably weaker time-frequency characteristics.This paper presents a novel HIF detection method using synchronized current information.The method consists of two stages.In the first stage,joint key characteristics of the system are extracted with the minimal system prior knowledge to identify the global optimal micro-phase measurement unit(μPMU)placement.In the second stage,the HIF is detected through a multivariate Jensen-Shannon divergence similarity measurement using high-resolution time-synchronized data inμPMUs in a high-noise environment.l2,1 principal component analysis(PCA),i.e.,PCA based on the l2,1 norm,is applied to an extracted system state and fault features derived from different resolution data in both stages.An economic observability index and HIF criteria are employed to evaluate the performance of placement method and to identify HIFs.Simulation results show that the method can reliably detect HIFs with reasonable detection accuracy in noisy environments.
文摘随着分布式新能源渗透率不断提高,智能配电网电力电子化趋势明显,电气参数更加复杂,亟需研究适用于配电网的同步相量测量装置(Synchrophasor measurement unit for distribution network,D-PMU)。然而,现有通信协议与条件无法满足D-PMU的接入需求。针对该问题,该文设计一种适用于D-PMU的基频相量、谐波/间谐波同步测量、异步传输的结构框架,提出一种谐波/间谐波的数据传输协议,减少了通信负担。在上述框架的条件下,分析网络通信延时与丢包率的影响因素,搭建通信性能测试平台,进行通信性能实际测试,验证所提通信方法的可行性,并根据测试结果提出一种D-PMU通信接入参数的设置方法。
文摘该文面向存在脉冲干扰的配电网信号环境,研究脉冲干扰检测、精确定位和基于干扰剔除的同步相量测量算法。首先,根据同步相量测量单元(phasormeasurementunit,PMU)测量值进行基波重构,通过分析重构残差序列定义特征参数残差总向量(total vector of the residual,TVR),用以表征PMU测量误差。其次,提出基于TVR和残差瞬时功率异常值判别的方法,实现脉冲干扰检测和精确定位。最后,基于相量测量的最优滤波原理设计出改进加权最小二乘算法,实现脉冲干扰下同步相量的快速准确测量。仿真结果表明,在数据窗长为2个周波(P类测量),当脉冲干扰长度不超过半个周波时,该文算法在典型配电网环境下达到IEEE标准规定的测量误差要求(TVE<1%),且对脉冲干扰持续时间和强度表现出较强的鲁棒性。
