基于μPMU的主动配电网故障定位方法研究

准确的故障定位有助于提高配电网络的稳定性。随着分布式发电和电动汽车的接入,传统配电网逐渐向主动配电网发展,传统故障和保护装置已无法满足,这对故障定位技术和装置提出了新的要求。文章提出了一种基于微型同步相量测量单元(也叫做μPMU或者微同步相量)的新方法对主动配电网的故障进行定位。该方法运用单端μPMU采集的电压电流信息,查找故障线路,得到候选故障点并计算其故障距离。并根据两端μPMU测量电压和故障电压之间的相位关系,排除伪故障点,确定故障点位置。仿真结果表明,在主动配电网下,该定位方法具有较高的定位精度,仅需在线路的两端配置μPMU即可满足对不同类型故障进行准确地定位。在高渗透率DG和高阻故障的情况下,该定位方法依然可以准确地对故障进行定位。     

基于μPMU同步量测数据的配电网故障定位方法

通过在辐射型多分支配电网络配置微型同步相量测量单元(μPMU),提出了一种基于μPMU同步量测数据的配电网故障定位方法。该方法首先通过单端μPMU电压、电流同步相量求取初始故障距离。然后,根据双端μPMU电压、电流同步相量排除伪故障点,迭代确定故障在主网络上的具体位置,通过与初始故障距离比较,判断故障发生在主网络还是分支线路上。最后,通过伪故障点的迭代排除,确定分支上故障到主网络的距离。该方法考虑了线路电容对故障定位精度的影响,通过线路对地电容分析,减小了定位误差。仿真结果验证了该方法的有效性。     

基于μPMU同步量测数据的配电网故障定位方法

通过在辐射型多分支配电网络配置微型同步相量测量单元(μPMU),提出了一种基于μPMU同步量测数据的配电网故障定位方法。该方法首先通过单端μPMU电压、电流同步相量求取初始故障距离。然后,根据双端μPMU电压、电流同步相量排除伪故障点,迭代确定故障在主网络上的具体位置,通过与初始故障距离比较,判断故障发生在主网络还是分支线路上。最后,通过伪故障点的迭代排除,确定分支上故障到主网络的距离。该方法考虑了线路电容对故障定位精度的影响,通过线路对地电容分析,减小了定位误差。仿真结果验证了该方法的有效性。     

一种基于双端电压相量测量的故障测距新算法

基于测距方法的研究,提出了一种仅利用线路两端电压相量实现测距的新方法,根据故障后各节点组成的电压变化量矩阵方程求得故障距离。采用全球定位系统(GPS)提供的时间为基准,利用同步相量测量单元(PMU),对电力系统不同节点电压基波相量进行同步测量,借此技术可以解决高压输电线路两端相量测量的同步问题,同步精度可达1μs,能够满足实际电力系统故障测距精度的要求。由于仅利用电压相量进行测距,消除了由于电流互感器饱和所带来的测距误差,并且可以应用于对称和不对称高压输电线路中。仿真结果表明该方法增强了双端测距的灵活性,测距精度高,并且避免了由电流互感器饱和所造成的测距误差。     

长距离输电线路中间带并联电抗器的双端非同步故障定位算法

针对线路中间带并联电抗器的长距离输电线路提出了基于双端工频量的非同步故障定位算法。对于等值阻抗固定的并联电抗器,采用故障前的双端相量估计并联电抗器的实际等值阻抗,从而基于故障后正序网络得到故障点位置。对于可控并联电抗器或故障前数据无法获取的情况,还提出了一种与并联电抗器模型无关的故障定位算法,根据不同故障类型的故障边界条件,利用故障点电压电流相位特性构造定位函数,分析表明该函数在相应定位区间具有单调变化特性,因而各定位区间不存在伪根,求解快速。所提算法均基于分布参数模型,双端数据不同步角采用故障前或故障后测量相量进行补偿。基于PSCAD/EMTDC和MATLAB的仿真结果表明,所提方法计算简单、精度高,对不同步角、故障类型、过渡电阻、故障位置均有较好的适用性。     

基于双端不同步数据的故障定位算法

基于故障时沿线电压的分布规律提出了两种实用性较强的故障测距算法,利用线路两侧的电压和电流正弦相量计算故障距离,不要求双端数据的同步,能消除过渡电阻的影响,具有较高的工程实用价值.着重对输电线路故障测距方法进行可行性验证,采用ATP仿真获得故障线路的电气量值,并用Matlab计算故障点位置,仿真结果表明该方法有较高的精度,能满足现场实际要求.     

基于Fibonacci搜索的含DG配网故障定位最小故障电抗法

分布式电源接入配网会影响配网故障定位。文中提出了一种基于最小故障电抗概念、利用Fibonacci搜索算法的含分布式电源配网故障定位方法。首先分析了不同配网故障类型下最小故障点抗法计算故障电抗的方法;然后提出了Fibonacci搜索算法来估计故障距离,该方法使用的搜索点数更少、搜索步长不全依赖故障电抗准确度。提出了基于Ladder的潮流计算方法,以估计每个分布式电源对故障电流的贡献值。该方法仅利用分布式电源节点的智能电子设备提供的同步电流量测相量。最后利用IEEE34节点分析了故障电抗的影响、故障距离的影响、负荷波动的影响和分布式电源量测误差场景下故障定位误差,并对比其他求解方法说明了提出方法的有效性和准确性。     

基于分布参数模型的输电线路相间距离保护

采用分布参数建模,利用保护安装处的测量电压和测量电流计算等效故障点电压,根据保护区外故障时等效故障点电压相量在测量电压和补偿电压相量一侧和保护区内故障时等效故障点电压相量在测量电压和补偿电压相量之间这一故障特征构成判据,提出一种适用于高压/超高压/特高压输电线路的相间距离保护新方法。该方法有良好的耐故障电阻和抗负荷电流影响的能力,具有良好动作灵敏度。该保护原理适用于距离保护I段,具有良好的保护范围。EMTDC仿真结果验证了该保护原理的正确性和有效性。     

基于同步相量测量单元的串联补偿线路自适应故障定位算法

针对串联补偿线路提出了基于同步相量测量单元的自适应故障定位算法。基于串联补偿线路两侧同步相量,采用最小二乘法在线估计串联补偿线路实时参数。线路故障后,采用分布参数模型,基于故障通路电压、电流相位特性构造故障定位函数,无需串补模型。理论分析及仿真表明,所构造的故障定位函数在定位区间具有单调近似线性变化的特性,采用二分法或弦截求根法即可快速精确求解故障点。基于PSCAD/EMTDC和Matlab的仿真结果表明,故障定位方法实现简单,计算速度快、精度高,对不同的故障类型、过渡电阻和故障位置均有较好的适用性。     

基于双端非同步数据的混合线路故障测距方法

现有大部分电缆–架空线混合输电线路故障测距算法无法从原理上消除双端数据不同步的影响,针对这一问题,提出一种基于双端非同步数据的混合线路故障测距方法。首先,针对不对称短路故障,利用系统两侧的电流、电压推算故障点电压,通过正序电压分量与负序电压分量的比值消除不同步角;然后给出混合线路故障测距函数,根据测距函数的单调性可知仅在故障点处其函数值为零,因此可采用二分法等搜索算法求解故障点;最后针对对称短路故障,提出采用正序电压分量与正序电压故障分量的比值消除不同步角,从而求出故障点。基于PSCAD的仿真结果表明,该方法测距精度高,且不受故障位置、过渡电阻和不同步角等因素的影响。     

基于同步相量测量技术的配电网故障定位

配电网的故障定位是配电网自动化系统中的一项高级功能。为此,针对配电网的特点,结合同步相量测量技术对节点电压方程进行了处理,导出了一种新型的故障定位矩阵算法。该算法具有较强的通用性,求解过程简单快捷,故障定位快速,对于部分类型的故障还可以具体解出故障距离。最后结舍IEEE13节点系统和[EEE36节点系统,说明了该算法的定位方法并证实了其有效性。     

A new PMU-based fault detection/location technique for transmission lines with consideration of arcing fault discrimination-part I: theory and algorithms

A new fault detection/location technique with consideration of arcing fault discrimination based on phasor measurement units for extremely high voltage/ultra-high voltage transmission lines is presented in this two-paper set. Part I of this two-paper set is mainly aimed at theory and algorithm derivation. The proposed fault detection technique for both arcing and permanent faults is achieved by a combination of a fault detection index |M| and a fault location index |D|, which are obtained by processing synchronized fundamental phasors. One is to detect the occurrence of a fault and the other is to distinguish between in-zone and out-of-zone faults. Furthermore, for discriminating between arcing and permanent faults, the proposed technique estimates the amplitude of arc voltage by least error squares method through the measured synchronized harmonic phasors caused by the nonlinear arc behavior. Then, the discrimination will be achieved by comparing the estimated amplitude of arc voltage to a given threshold value. In addition, in order to eliminate the error caused by exponentially decaying dc offset on the computations of fundamental and harmonic phasors, an extended discrete Fourier transform algorithm is also presented.     

Neuro-fuzzy networks for voltage security monitoring based onsynchronized phasor measurements

The ability to rapidly acquire synchronized phasor measurements from around a power network opens up new possibilities for power system operation and control. A novel neuro-fuzzy network, the fuzzy hyperrectangular composite neural network, is proposed for voltage security monitoring (VSM) using synchronized phasor measurements as input patterns. This paper demonstrates how neuro-fuzzy networks can be constructed offline and then utilized online for monitoring voltage security. The neuro-fuzzy network is tested on 3000 simulated data from randomly generated operating conditions on the IEEE 30-bus system to indicate its high classification rate for voltage security monitoring     

Accurate fault location algorithm for double-circuit series compensated lines using a limited number of two-end synchronized measurements

This paper presents a new fault location algorithm for double-circuit series compensated lines based on synchronized phasor measurements. Only the sequence current phasors from both ends of the line and the sequence voltage phasors from one local end are taken as input, limiting thus the amount of data needed to be exchanged between the line terminals. In addition, the proposed algorithm does not utilize the model of the series compensation device, eliminating thus the errors resulting from modeling such devices. The new algorithm consists of three steps. In the first step, the fault type and the circuit(s) involved in the fault are determined using a synchrophasor-based fault type selection method. In the next step, the algorithm applies two subroutines designating for locating faults on particular line sections which are defined according to the series compensation placement along the line. In these subroutines, the sequence voltages and currents at the fault point are expressed with respect to the known sequence voltages and currents at the two measuring ends and the distance to fault. Then, using the fault boundary conditions that exist for a given fault type, the fault location is solved by an iterative method. Finally, in the last step a procedure for selecting the valid subroutine is applied. Due to zero sequence mutual coupling, it is not straightforward to express the zero sequence voltage and current at the fault point as a function of the zero sequence voltages and currents at the measuring ends and the distance to fault. To overcome this problem, a modal transformation matrix is introduced to obtain the modal networks, which are decoupled and can be analyzed independently. Based on distributed parameter line model, the proposed algorithm fully considers the effects of shunt capacitances and thus achieves superior locating accuracy, especially for long lines. Mutual coupling between circuits, source impedances and fault resistance does not influence the locating accuracy of the algorithm. Simulation results using ATP-EMTP and MATLAB demonstrate the effectiveness and accuracy of the proposed algorithm.     

Fault location on a transmission line using synchronized Voltage measurements

Many methods for fault location using synchronized phasor measurement have been reported in literature. Most of these methods use voltage and current measurements at one or both ends of a transmission line. Accuracy of current measurement is limited by the accuracy of the current transformers (CT) used. This paper describes a fault-location method for transmission lines using only synchronized voltage measurements at both ends of the line, eliminating the inherent error due to CT. The method can be applied to transposed and untransposed lines. The method is tested using results from a steady state fault-analysis program and EMTP.     

基于同步相量测量的电力系统等值及电压稳定评估

提出了一种基于同步相量测量的电力系统等值方法。该方法只需利用同步相量测量,即被监测负荷节点同步电压相量和电流相量,将系统等值成两节点系统。在此基础上以负荷阻抗模与系统等值阻抗模的差值和负荷阻抗模相比,作为判断电压稳定与否的指标,并且推导了在负荷模型为阻抗模型和功率模型时,该指标的正确性。采用EPRI-36节点系统进行仿真,验证了方法的正确性及合理性。     

基于同步相量测量的同杆双回路继电保护方案的研究

所提出的基于同步相量测量的同杆双回线路保护方案通过相模转换对同杆双回线进行解耦,消除了线间互感对保护的不利影响。并从分布参数线路的相关理论出发,推导出了模量形式的保护判据,从原理上消除了线路参数分布性对保护的影响。该方案通过在模域中检测故障来实现保护,可对同杆双回线路的各种故障作出正确、快速的反应,同时还能提供相应的故障测距信息。对保护动作特性的分析证明了所提出保护方案的可行性。EMTP仿真结果表明该保护方案的可靠性和灵敏度较高、几乎不受过渡电阻的影响,且故障测距结果比较精确。     

基于同步相量测量的电压稳定指标

针对输电网提出了一种基于同步相量测量信息的电压稳定指标。电力系统可以分解成许多电能传输路径,以传输路径首节点电压与末节点电压在首节点电压上的投影之差与首节点电压的比值作为计算电压稳定与否的指标。该指标根据最弱电能传输路径利用局部电压相量测量信息直接计算得出,避免了复杂的潮流计算。局部电压相量测量数据由相量测量单元PMU提供。基于一种快速有效的PMU配置方法,利用直接测量或间接计算的数据作为此稳定指标计算所需要的电压相量信息。运用图论的基本思想寻找电能最弱传输路径。通过计算电能最弱传输路径的电压稳定指标和系统无功储备情况判断系统电压稳定度,当系统接近不稳定状态时,最弱传输路径的电压稳定指标值趋向于临界值0.5。在IEEE5节点和IEEE30节点系统上的仿真表明了该指标预测系统电压崩溃的有效性和正确性。     

基于广域测量系统的在线电压稳定预测指标的应用

基于相量测量单元(phasor measurement unit,PMU)的广域测量系统(wide area measurement system,WAMS)为在线电压稳定估计提供了新的思路和方法。采用π型支路模型,利用同步测量数据推导了可用于高压电网的支路在线电压稳定指标,从物理意义层面将该指标解释为虚拟有功裕度指标IVAM,并提出了一种改进的考虑某一断面IVAM变化趋势的实时电压稳定预测指标。IEEE14节点算例和某省实际电网算例验证了该指标的准确性。改进的电压稳定预测指标算法结构简单、准确度高,便于实现在线应用。