High Impedance Fault Detection of Distribution Network by Phasor Measurement Units

This paper proposes a new algorithm for High Impedance Fault (HIF) detection using Phasor Measurement Unit (PMU). This type of faults is difficult to detect by over current protection relays because of low fault current. In this paper, an index based on phasors change is proposed for HIF detection. The phasors are measured by PMU to obtain the square summation of errors. Two types of data are used for error calculation. The first one is sampled data and the second one is estimated data. But this index is not enough to declare presence of a HIF. Therefore another index introduces in order to distinguish the load switching from HIF. Second index utilizes 3rd harmonic current angle because this number of harmonic has a special behaviour during HIF. The verification of the proposed method is done by different simulation cases in EMTP/MATLAB.

Optimal Placement of Phasor Measurement Units Using a Modified Canonical Genetic Algorithm for Observability Analysis

This paper proposes a method for optimal placement of synchronized PMUs （phasor measurement units） in electrical power systems using a MCGA （modified canonical genetic algorithm）, which the goal is to determine the minimum number of PMUs, as well as the optimal location of these units to ensure the complete topological observability of the system. In case of more than one solution, a strategy of analysis of the design matrix rank is applied to determine the solution with the lower number of critical measurements. In the proposed method of placement, modifications are made in the crossover and mutation genetic operators, as well as in the formation of the subpopulation, and are considered restrictive hypotheses in the search space to improve the performance in solving the optimization problem. Simulations are performed using the IEEE 14-bus, IEEE 30-bus and New England 39-bus test systems. The proposed method is applied on the IEEE 118-bus test system considering the presence of observable zones formed by conventional measurements.

Subsynchronous oscillation monitoring and alarm method based on phasor measurements

Owing to the large-scale grid connection of new energy sources, several installed power electronic devices introduce sub-/supersynchronous inter-harmonics into power signals, resulting in the frequent occurrence of subsynchronous oscillations(SSOs). The SSOs may cause significant harm to generator sets and power systems;thus, online monitoring and accurate alarms for power systems are crucial for their safe and stable operation. Phasor measurement units(PMUs) can realize the dynamic real-time monitoring of power systems. Based on PMU phasor measurements, this study proposes a method for SSO online monitoring and alarm implementation for the main station of a PMU. First, fast Fourier transform frequency spectrum analysis is performed on PMU current phasor amplitude data to obtain subsynchronous frequency components. Second, the support vector machine learning algorithm is trained to obtain the amplitude threshold and subsequently filter out safe components and retain harmful ones. Finally, the adaptive duration threshold is determined according to frequency susceptibility, amplitude attenuation, and energy accumulation to decide whether to transmit an alarm signal. Experiments based on field data verify the effectiveness of the proposed method.

A Robust Asynchrophasor in PMU Using Second-Order Kalman Filter

Phasor Measurement Units(PMUs)provide Global Positioning System(GPS)time-stamped synchronized measurements of voltage and current with the phase angle of the system at certain points along with the grid system.Those synchronized data measurements are extracted in the form of amplitude and phase from various locations of the power grid to monitor and control the power system condition.A PMU device is a crucial part of the power equipment in terms of the cost and operative point of view.However,such ongoing development and improvement to PMUs’principal work are essential to the network operators to enhance the grid quality and the operating expenses.This paper introduces a proposed method that led to lowcost and less complex techniques to optimize the performance of PMU using Second-Order Kalman Filter.It is based on the Asyncrhophasor technique resulting in a phase error minimization when receiving the signal from an access point or from the main access point.The MATLAB model has been created to implement the proposed method in the presence of Gaussian and non-Gaussian.The results have shown the proposed method which is Second-Order Kalman Filter outperforms the existing model.The results were tested usingMean Square Error(MSE).The proposed Second-Order Kalman Filter method has been replaced with a synchronization unit into thePMUstructure to clarify the significance of the proposed new PMU.

基于HT-STWLS的配电网PMU设计

随着分布式能源和可调负荷大量接入配电网,其随机性和间歇性增加了配电网信号量测的难度,同时配电网存在节点分支类型变化多、通信条件受限等不确定因素,使相量量测单元(PMU)在配电网中应用受到限制。针对配电网节点多分支特点和量测估计高精度要求等问题,提出了基于HT-STWLS的新型配电网同步量测单元,并搭建了实验装置。首先,该装置采用多核分布式结构,通过网络路由模式,能够有效解决节点多分支量测问题,增强节点边缘计算能力;然后,对装置采集信号进行希尔伯特变换(HT)处理后,将数据代入到对称泰勒加权最小二乘(STWLS)过程中进行信号参数估计,获取高精度基波参数值;最后,通过算法验证和实际电网信号的测试,表明所提装置的HT-STWLS算法能够实现配电网信号参数的高精度估计。

基于PMU梯度动态偏差的新型电力系统快速稳定性

在能源转型和科技进步双重推动下,高比例可再生能源和高比例电力电子设备正成为电力系统发展重要趋势和关键特征.新型电力系统动态行为随之发生重大变化,传统小干扰稳定性分析方法满足使用需要,在应对运行工况快速变化场合时尚存在亟需解决问题.提出基于同步相量测量装置(PMU)数据梯度动态偏差李雅普诺夫直接分析法对新型电力系统小干扰稳定性进行分析,利用PMU数据矩阵降维得到低维矩阵,代入含双馈异步风力发电机组的电力系统矩阵模型,求解李雅普诺夫方程式得到对角矩阵,通过判定矩阵正定性对系统稳定性作出判断.利用求解后得到的对角矩阵计算相应状态变量动态偏差值,对相应状态变量曲线使用梯度下降法迭代计算该曲线极值点数值,时间加权计算整个振荡过程时间加权动态偏差量,为阻尼稳定控制器配置位置提供指导.利用含风力发电新英格兰10机39节点系统仿真验证方法可以达到改善系统小干扰稳定性以及对新型电力系统快速稳定性分析的有效性.

基于有限个μPMU和压缩感知理论的主动配电网复故障定位方法

主动配电网(Active distribution network,ADN)动态行为相较传统电网更为复杂,亟需解决其故障检测和定位问题。针对配电网系统中微型同步相量测量装置(Micro phasor measurement unit,μPMU)的运用,提出基于有限个μPMU的复故障定位策略。首先,根据任意线路故障下全网可观的μPMU优化配置方案建立短路、断线故障线路等效模型,通过分析模型将电流故障分量等效至相邻两端节点形成虚拟注入电流向量。其次,利用压缩感知理论求解故障网络节点电压方程,根据重构电流向量中非零元素的位置得到可疑故障节点,并基于可疑故障节点及μPMU配置位置划分动态候选故障域。最后,先分别构建短路、断线区域判据,确定故障区间,再进一步根据区域两端推算电压构造线路判据,精确判断故障线路及类型。基于改进的IEEE 33节点配电网系统进行仿真分析,仿真结果表明,基于有限个μPMU的复故障定位策略是可行的,该策略能够有效判断故障的精确位置。

Curvature Quantified Douglas-Peucker-based Phasor Measurement Unit Data Compression Method for Power System Situational Awareness

Facing constraints imposed by storage and bandwidth limitations,the vast volume of phasor meas-urement unit(PMU)data collected by the wide-area measurement system(WAMS)for power systems cannot be fully utilized.This limitation significantly hinders the effective deployment of situational awareness technologies for systematic applications.In this work,an effective curvature quantified Douglas-Peucker(CQDP)-based PMU data compression method is proposed for situational awareness of power systems.First,a curvature integrated distance(CID)for measuring the local flection and fluc-tuation of PMU signals is developed.The Doug-las-Peucker(DP)algorithm integrated with a quan-tile-based parameter adaptation scheme is then proposed to extract feature points for profiling the trends within the PMU signals.This allows adaptive adjustment of the al-gorithm parameters,so as to maintain the desired com-pression ratio and reconstruction accuracy as much as possible,irrespective of the power system dynamics.Fi-nally,case studies on the Western Electricity Coordinat-ing Council(WECC)179-bus system and the actual Guangdong power system are performed to verify the effectiveness of the proposed method.The simulation results show that the proposed method achieves stably higher compression ratio and reconstruction accuracy in both steady state and in transients of the power system,and alleviates the compression performance degradation problem faced by existing compression methods.Index Terms—Curvature quantified Douglas-Peucker,data compression,phasor measurement unit,power sys-tem situational awareness.

次/超同步间谐波影响下PMU基波频率测量误差机理分析及抑制

高比例新能源和高比例电力电子设备在电网中产生了大量的次/超同步间谐波,导致同步相量测量装置(PMU)的基波频率测量出现较大偏差,影响各类频率相关应用的效果。因此,文中提出了一种次/超同步间谐波影响下基波频率测量误差机理分析及其抑制方法。首先,建立了频率测量算法的频域特性模型,基于此推导了单个间谐波和对称次/超同步间谐波影响下的基波频率振荡数学模型,揭示了间谐波干扰下的基波频率测量误差机理。其次,根据频率的振荡行为,建立了多分量叠加的拟合模型,提出了基于傅里叶变换和最小二乘法的短时窗频率振荡分量抑制方法,大幅降低了基波频率偏差。最后,仿真和现场录波数据测试表明,所提方法极大降低了频率测量误差。

基于线性最小二乘回归和PMU量测的输电线路参数估计分析方法

电力系统中的架空输电线路参数经常被用于故障定位保护算法、状态估计以及稳定性分析中,而同步相量测量技术能够在线估测电力系统的传输线路参数。提出了一种简单的基于线性最小二乘回归的线路参数的估测方法,其通过线路两端的相量测量单元的电压和电流数据进行正序线路参数估测。所提出的方法计算简单且不需要进行迭代,同时在两个不同电力系统中的四条不同线路中采集的实际相量数据进行了全面测试。测试结果表明:所提出的线路参数估测方法不仅计算简单,同时可以在不同的线路模型中可以快速准确地估测线路电抗和线路电纳,具有较强的通用性和可扩展性。

Estimation Method of Center of Inertia Frequency Based on Phasor Measurement Data

In the world, recent increased disturbances, congestion management problems, and increases of complexity in operating power systems have brought the need for integrations and improvements of power systems. Advanced applications in WAMPAC （wide area monitoring, protection, and control） systems provide a cost effective solution to improve system planning, operation, maintenance, and energy trading. Synchronized measurement technology and the application are an important element of WAMPAC. In addition, PMUs （phasor measurement units） are the most accurate and advanced time-synchronized technology available for WAMPAC application. Therefore, the original measurement system of PMUs has been constructed in Japan. This paper describes the estimation method of a center of inertia frequency by applying actual measurement data. The application of this method enables us to extract power system oscillations from measurement data appropriately. Moreover, this proposed method will help to the clarification of power system dynamics and this application will make it possible to realize the monitoring of power system oscillations associated with the power system stability.

考虑关键节点和重要线路的电力系统PMU优化配置

相量测量单元(PMU)是一种测量电压和电流的设备,随着电力系统的规模和结构越来越复杂,PMU的数量也大幅增加.利用改进蝠鲼觅食优化算法(IMRFO)对PMU进行了配置,使电力系统在正常运行、考虑关键节点和考虑重要线路时都能完全可观测,同时使PMU配置数最少.在蝠鲼觅食算法的基础上增加了混沌映射以提升算法的收敛速度,增加了跳跃因子以提高算法的勘测能力,从而避免算法陷入局部最优.通过度、特征向量和接近度三种指标,利用TOPSIS综合评价寻找系统的关键节点,利用线的中间中心度判断系统的重要线路.对IEEE-14和IEEE-69节点系统进行了实验仿真,结果表明:IMFRO算法与未改进时相对比,在配置时所需的PMU数和迭代次数均有一定的减少,验证了所提方法对解决PMU优化配置问题的有效性和优越性.

基于μPMU和二分搜索法的辐射状配电网电压暂降源定位

快速准确地定位电压暂降源,对提高供电可靠性和明确供需双方责任具有重要意义。文中提出一种基于微型同步相量测量装置(micro-phasor measurement unit,μPMU)和二分搜索法的辐射状配电网电压暂降源精确定位方法,首先利用装设μPMU的分层电路求解暂降源电流,在各分层电路分别假设暂降源电流注入各母线节点,进而计算末端母线虚拟电压变化量,并与实测的末端母线电压变化量求误差,根据误差大小确定暂降源邻近母线。然后在暂降源邻近母线相邻区段的中点设置虚拟母线,利用二分搜索法快速缩小定位区间,实现暂降源的精确定位。最后在MATLAB中利用IEEE 33节点模型对文中方法进行验证,结果表明该方法对辐射状配电网中不同位置、不同类型的电压暂降源定位精度高,且具有一定的抗干扰能力。

基于MMoE和GRU的PMU数据有损压缩算法

为解决同步向量量测装置广泛部署带来的数据冗余度与数据量快速增长、系统数据储存及传输成本大幅增加的问题,本文提出一种基于多任务学习和门控循环单元自编码器的有损数据压缩算法。首先,根据同步向量量测装置三相量测数据具有相关性的特点,采用多门控混合专家模型和门控循环单元构建了变分自编码器一次数据压缩模型,将各相数据进行特征融合,利用多任务学习挖掘三相量测数据之间的相关性;其次,使用无损压缩算法对一次压缩数据进行二次压缩,得到最终压缩数据;最后,通过算例分析表明,所提算法能够充分利用各相数据之间的相关性,实现对压缩数据的高精度重构,提高数据压缩效率。

基于μPMU测量数据的配电网线路阻抗参数估计

为解决长期以来低压配电网线路阻抗参数缺失的问题,基于微型同步相量测量单元(micro phasor measurement unit,μPMU)提供的测量数据,首先,以线路阻抗参数为变量,根据测量数据推算台区首端状态值,以推算值与实测值的差值作为目标函数,将阻抗参数的求解转化为多目标最优化问题;然后,通过实验确定合适的目标函数权重系数取值和数据集大小,以减少误差对求解结果的影响,使模型求解精度达到较高水准;最后,搭建了包含26个负荷节点、34条线路支路的低压配电网台区算例,在考虑实际测量误差的情况下,线路阻抗参数计算平均误差为3.87%。算例结果表明,所提方法实现了阻抗参数的精确计算,验证了所提模型的有效性。

基于流聚类的PMU异常数据辨识算法

为保证同步相量测量装置(phasor measurement unit,PMU)采集数据的准确应用,须排除其量测值中的异常数据。现有PMU异常数据辨识算法存在算法复杂度高、难以在线更新、多源数据难以校准、依赖多源数据应用难度大等不足。为此,文中从PMU事件数据和异常数据模型及PMU异常数据判别信息熵定义出发,提出基于该信息熵的异常数据辨识框架。在此框架基础上,基于利用层次方法的平衡迭代规约和聚类(balanced iterative reducing and clustering using hierarchies,BIRCH)算法提出PMU异常数据辨识算法;然后,对所提出的算法进行原型实现,并针对某变电站的PMU采集数据集进行算法实验验证。实验结果表明,与一类支持向量机(one-class support vector machine,OCSVM)算法与间隙统计算法相比,文中算法的准确度及实时性均具有较强的优势。

基于改进蝙蝠算法的PMU优化配置研究

传统单一的能源系统正过渡为多能流耦合综合能源系统,综合能源系统正面临量测误差问题。受投资约束,同步相量测量装置(phasor measurement unit,PMU)无法大面积配置,而系统内节点数多,供需不平衡,影响系统平稳运行。为此,提出一种适用于综合能源系统内PMU优化布点的方法,监测系统运行状况。首先,考虑热电气之间的耦合特性建立综合能源系统状态估计模型;然后,限制系统内PMU配置个数,以提高状态估计精度为目标,利用改进的蝙蝠算法(improved bat algorithm,IBA)对PMU进行优化选址;最后,通过IEEE 30节点系统算例,将所提算法与遗传算法和模拟退火算法对比,算例结果表明该算法具有更高的可行性和优越性。

基于无功损耗的线路两端PMU相角差时变偏差修正方法

相量测量单元(PMU)的优势之一是提供同步的相角数据。然而,因时间同步异常、装置故障等因素,部分实测PMU相角数据存在异常,影响PMU应用。提出一种基于无功损耗的线路两端PMU相角差时变偏差修正方法。首先,基于线路无功损耗量测值与估计值构造单时刻相角差偏差估计模型;然后,针对单时刻估计模型受噪声影响大的问题,基于相角差和线路参数间关系,将利用单时刻数据的时变偏差估计模型转化为利用多时刻数据的恒定线路参数估计模型;最后,通过黄金分割算法估计获取线路参数后,结合PMU幅值、功率数据反推出PMU相角差偏差,实现PMU时变相角差偏差的估计与修正。仿真和某省实测PMU数据测试结果表明:该方法可准确估计相角差偏差,抗噪能力强;与现有方法相比,该方法仅需单工况数据即可实现估计与修正,适用于不同时变类型偏差的修正。

Optimal Placement of Phasor Measurement Unit in Smart Grids Considering Multiple Constraints

The distribution of measurement noise is usually assumed to be Gaussian in the optimal phasor measurement unit(PMU)placement(OPP)problem.However,this is not always accurate in practice.This paper proposes a new OPP method for smart grids in which the effects of conventional measurements,limited channels of PMUs,zero-injection buses(ZIBs),single PMU loss contingency,state estimation error(SEE),and the maximum SEE variance(MSEEV)are considered.The SEE and MSEEV are both obtained using a robust t-distribution maximum likelihood estimator(MLE)because t-distribution is more flexible for modeling both Gaussian and non-Gaussian noises.The A-and G-optimal experimental criteria are utilized to form the SEE and MSEEV constraints.This allows the optimization problem to be converted into a linear objective function subject to linear matrix inequality observability constraints.The performance of the proposed OPP method is verified by the simulations of the IEEE 14-bus,30-bus,and 118-bus systems as well as the 211-bus practical distribution system in China.

计及节点故障率的微电网μPMU多目标优化配置策略

微电网动态行为相较传统电网更为复杂,亟须解决其故障检测和定位问题。针对微电网系统中微型同步相量测量单元(μPMU)的优化配置问题进行研究,提出了计及成本、节点故障率和冗余度的μPMU多目标优化配置策略。以μPMU装设成本最低、节点故障率总和最高、可观冗余度最高为多目标函数,在考虑零注入节点的基础上,根据系统正常状态和任意线路故障下的约束条件,建立了多目标优化配置模型。采用差分进化算子对非支配排序遗传算法(NSGA-Ⅱ)进行改进,并用改进后的算法对模型进行求解,选择出最优折中解。基于改进的IEEE 30节点微电网系统进行仿真分析,仿真结果表明,计及节点故障率的多目标优化配置策略是可行的。所提策略能够有效地对微电网系统进行全网可视化监测,并兼顾经济性和准确性。