A fast quality assessment algorithm for phasor measurements

This paper proposes two procedures to compute the quality of phasor estimations. These procedures will enable phasor measurement units (PMUs) to report, with each measurement, the quality of the estimated phasor. The procedures rely solely on measured data and are independent of the algorithm used to obtain the phasor estimate. These procedures were conceived by requiring a reduced number of numerical operations to make its implementation possible in microcontroller-based PMUs. Perhaps the most important contribution of this paper is the suggestion that phasor measurements should, along with the time stamp, carry information on the quality of the phasor estimation.     

Robust Measurement Design by Placing Synchronized Phasor Measurements on Network Branches

This paper is concerned about optimal placement of synchronized phasor measurements that can monitor voltage and current phasors along network branches. Earlier investigations on placement of phasor measurement units (PMUs) have assumed that a PMU could be placed at a bus and would provide bus voltage phasor as well as current phasors along all branches incident to the bus. This study considers those PMUs which are designed to monitor a single branch by measuring the voltage and current phasors at one end of the monitored branch. It then determines the optimal location of such PMUs in order to make the entire network observable. The paper also addresses the reliability of the resulting measurement design by considering loss or failure of PMUs as well as contingencies involving line or transformer outages. Developed placement strategies are illustrated using IEEE test systems.      

智能变电站同步相量测量装置研制

同步相量测量装置因测量精度高、数据具有精确时标等特点已成为电网的重要监测设备,但目前在智能变电站中应用不多,还处于探索阶段。提出应用于智能变电站的同步相量测量装置,该装置采用嵌入式软硬件平台,在实现传统同步相量测量装置相量计算、故障录波、实时纪录分析、实时通信等功能的基础上,实现了符合 IEC 61850 标准的设备建模、采样值报文接收和解析、与站内监控及其他智能电子设备数据共享等功能。     

Optimal allocation of phasor measurement unit for full observability of the connected power network

This paper presents binary particle swarm optimization (BPSO) technique for the optimal allocation of phasor measurement units (PMUs) for the entire observability of connected power network. Phasor measurement units are considered as one of the most important measuring devices in the prospect of connected power network. PMUs function may be incorporated to the wide-area connected power networks for monitoring and controlling purposes. The optimal PMU placement (OPP) problem provides reference to the assurance of the minimal number of PMUs and their analogous locations for observability of the entire connected power networks. Binary particle swarm optimization (BPSO) algorithm is developed for the solution of OPP problem. The efficacy and robustness of the proposed method has been tested on the IEEE 14-bus, IEEE 30-bus, New England 39-bus, IEEE 57-bus, IEEE 118-bus and Northern Regional Power Grid (NRPG) 246-bus test system. The results obtained by proposed approach are compared with other standard methods and it is observed that this BPSO based placement of phasor measurement units is found to be the best among all other techniques discussed.     

Placement of Synchronized Measurements for Power System Observability

This paper presents a method for the use of synchronized measurements for complete observability of a power system. The placement of phasor measurement units (PMUs), utilizing time-synchronized measurements of voltage and current phasors, is studied in this paper. An integer quadratic programming approach is used to minimize the total number of PMUs required, and to maximize the measurement redundancy at the power system buses. Existing conventional measurements can also be accommodated in the proposed PMU placement method. Complete observability of the system is ensured under normal operating conditions as well as under the outage of a single transmission line or a single PMU. Simulation results on the IEEE 14-bus, 30-bus, 57-bus, and 118-bus test systems as well as on a 298-bus test system are presented in this paper.      

电力系统中基于PMU同步数据的应用研究综述

基于同步相量测量技术的广域测量系统为电力系统各领域中新应用功能的研究开发提供了全新的数据支撑平台。文章简要介绍了同步相量测量技术及在此基础之上的广域测量系统的发展现状;着重分析了PMU量测数据在包括阻尼控制、暂稳分析及控制、电压稳定、解列控制在内的电力系统动态领域以及包括线路参数测量、状态估计、潮流计算在内的电力系统稳态领域和继电保护领域中的应用研究情况;同时对这些应用研究的特点、优点以及存在的主要问题进行了相应的评述。     

A robust SMES controller design for stabilization of inter-area oscillations based on wide area synchronized phasor measurements

This paper proposes a robust power controller design of superconducting magnetic energy storage (SMES) based on wide area synchronized phasor measurement units (PMUs) for stabilization of inter-area oscillation. The structure of active and reactive power controllers of SMES is the first-order lead/lag compensator. Assuming multiple PMUs are located in an interconnected power system, the steady state phasor data are obtained by applying the small load perturbation. Using the phasor data, the simplified oscillation model (SOM) included with SMES power controllers can be identified and applied to estimate the dominant inter-area oscillation modes. In the robust control design, unstructured system uncertainties such as various operating conditions, system parameters variation, etc., are represented by the inverse additive perturbation and included in the SOM. To enhance the system robust stability margin, the optimization of SMES control parameters is solved by genetic algorithm in the SOM. Simulation studies in the West Japan 6-machine power system confirm that the robustness of the proposed SMES is much superior to the conventional SMES against various operating conditions and fault locations.     

基于相量测量与能量分析的在线失稳预警

在全网主要厂站设置相量测量单元,以及中调与各主要厂站间的高速通信可往返的环境下,运用实测、预测事故时轨线与能量分析相结合的方法可使在线暂态稳定分析实现超实时计算,以便有足够的“可用反应时间”用于失稳预警或就地控制。对于事故时轨线实时测量中的发电机相角预测算法,采用“当前”统计模型的自适应跟踪算法。运用基于稳定域边界的主导不稳定平衡点方法计算临界能量及稳定裕度,以便判别失稳与否。在经典模型下对简化的华东17机60节点进行仿真,系统仿真结果表明所提算法是可行的。     

PMU电压幅值与频率量测一致性的在线评估方法

相量测量单元(PMU)的广泛应用,为实现电网的动态安全监控提供了数据基础,也是建设智能电网的重要技术内容。然而各厂家在实际运行环境中PMU产品的精度和相量量测的一致性并没有经过严格的检验。文中提出一种PMU电压幅值与频率量测一致性的在线评估方法,分别给出了电压一致性、频率一致性与电压—频率一致性指标及其计算方法。此外,还重点分析了可能造成电压幅值及频率量测一致性差异的原因,即系统偏离额定频率对PMU量测的影响,指出应对偏离额定频率情况下的计算相量进行修正,以进一步改善实测相量的质量。     

风电并网系统次/超同步振荡的动态监测方法研究

近年来,我国大规模风电基地中出现了新型次/超同步振荡问题,其频率具有时变特性。已有的同步相量测量单元(PMU)和广域测量系统无法准确监测其动态发展过程。鉴于此,本文首先探讨了次/超同步谐波对传统PMU算法的不良影响,剖析谐波引起基频相量测量误差的根源。其次,提出一种具有频率自适应控制能力的次/超同步谐波相量检测方法,能够准确判断系统中是否出现次同步振荡,并检测出基波相量和次/超同步谐波相量。最后,通过搭建实际系统的电磁暂态仿真模型分析验证了改进算法的有效性和精确性。     

Instability prediction of the inter-connected power grids based on rotor angle measurement

The online detection and prediction of the unstable conditions for interconnect power grids are important tasks to avoid blackout. The increasing installation of phasor measurement units (PMUs) in power systems and the development of the wide-area measurement systems (WAMS) make it possible to analyze the system dynamics using a large amount of real-time synchronous data. This paper proposes a rotor angle measurement based application for online out-of-step monitoring and predicting of the interconnected power systems. An improved Prony analysis method is presented to determine whether and when a power oscillation will lead to power system instability. The accuracy and reliability of the model free dynamic prediction are obtained by adopting an energy-like weight coefficient approximation of the decomposed signals. The self-adaptive resampling of the data and the changeable time-window are designed to make the method suitable for both transient instability and oscillation instability conditions. The effectiveness of the proposed scheme is verified on three test power systems.     

Phasor-Based Synchronized Frequency Measurement in Power Systems

Phasor-based frequency measurement techniques have very good steady-state performance, but their dynamic performance is not well documented. This paper analyzes a phasor-based frequency measurement method that considers the effect of dynamic frequency, and proposes a method to improve the dynamic performance of the phasor-based frequency measurements. Simulation results verify the effectiveness of the proposed method. Results of laboratory experiments are presented to show the performance of the proposed method compared to frequency measurements obtained from commercial phasor measurement units (PMUs).     

基于线性整数规划模型的高适应性PMU配置算法

PMU布点问题需要在满足一定约束的条件下同时优化2个相互冲突的指标：配置PMU的数目(或费用)最少和测量冗余度最高。文章提出基于线性0-1整数规划的模型并用来求解系统正常运行方式下完全可观测的PMU配置方案,还分别给出了线路N-1故障时以及PMU N-1故障时系统仍可观测的PMU配置模型,该模型不仅考虑了PMU实测数据,还计及了可用的潮流数据和零注入节点。文章通过将零注入节点转化为潮流已知线路巧妙地回避了模型的非线性问题。通过对IEEE测试系统和浙江电网进行仿真,验证了所提方法的有效性和灵活性。     

便携式同步相量测量装置现场测试仪

介绍了一种实用的相量测量装置（PMU）的现场校核方法。采用比对测量和模拟发电机信号输出的方法,使新研制的便携式PMU现场测试仪能对现场的PMU进行校核。现场试验表明,该方法可较方便地对跨空间分布的PMU进行客观的性能评价,并可对PMU进行异地校核。     

动态条件下的T形输电线路故障测距算法

当电力系统在功率低频振荡等动态情况下发生故障时,电力信号幅值和频率往往表现出一定的动态特性,影响了传统的T形输电线路故障测距算法的精度.因此,提出了动态条件下T形输电线路故障测距算法.该方法拓展了传统的静态信号模型,建立了时变的信号模型使其能正确表示信号的动态特性,并加入基于同步相量测量单元(PMU)的动态同步相量测量...     

Phasor measurement unit placement techniques for complete and incomplete observability

This paper presents techniques for identifying placement sites for phasor measurement units (PMUs) in a power system based on incomplete observability. The novel concept of depth of unobservability is introduced and its impact on the number of PMU placements is explained. Initially, we make use of spanning trees of the power system graph and a tree search technique to find the optimal location of PMUs. We then extend the modeling to recognize limitations in the availability of communication facilities around the network and pose the constrained placement problem within the framework of Simulated Annealing (SA). The SA formulation was further extended to solve the pragmatic phased installation of PMUs. The performance of these methods is tested on two electric utility systems and IEEE test systems. Results show that these techniques provide utilities with systematic approaches for incrementally placing PMUs thereby cushioning their cost impact.     

An Optimal PMU Placement Method Against Measurement Loss and Branch Outage

This paper presents a new method for an optimal measurement placement of phasor measurement units (PMUs) for power system state estimation. The proposed method considers two types of contingency conditions (i.e., single measurement loss and single-branch outage) in order to obtain a reliable measurement system. First, the minimum condition number of the normalized measurement matrix is used as the criteria in conjunction with the sequential elimination approach to obtain a completely determined condition. Next, a sequential addition approach is used to search for necessary candidates for single measurement loss and single-branch outage conditions. These redundant measurements are optimized by binary integer programming. Finally, in order to minimize the number of PMU placement sites, a heuristic technique to rearrange measurement positions is also proposed. Numerical results on the IEEE test systems are demonstrated     

Transmission network fault location observability with minimal PMU placement

This paper presents a concept of fault-location observability and a new fault-location scheme for transmission networks based on synchronized phasor measurement units (PMUs). Using the proposed scheme, minimal PMUs are installed in existing power transmission networks so that the fault, if it occurs, can be located correctly in the network. The scheme combines the fault-location algorithm and the fault-side selector. Extensive simulation results verify the proposed scheme.     

同步相量测量装置校准器参考相量计算方法

电力电子设备的广泛应用导致电力系统逐渐出现了新的稳定性与可靠性问题,亟需高精度实时测量与感知技术,为解决上述问题提供数据基础。作为最有效的动态监测手段之一,同步相量测量装置(PMU)的测量精度至关重要。提出了一种PMU校准器的参考相量计算方法,为PMU测试提供校准参考值。该方法分析了电力系统典型静动态信号特性,建立了基波相量通用信号拟合模型,可表征PMU测试标准中除阶跃测试外的所有静动态测试信号。提出了基于非线性拟合的相量幅值、相角与频率迭代求解方法,并根据所得频率提出了基于最小二乘法的频率变化率计算方法。进一步,分析揭示了迭代初始值、计算时间窗长和拟合阶数对计算精度的影响及其设置方法。仿真与实验测试结果表明,该方法精度至少比标准规定的精度要求高1个数量级,可用于PMU的测试与校准。     

基于系统同调性的PMU最优布点

从电力系统的同调性出发，优化相量测量单元(PMU)的布点，以最少数量的PMU反映系统在各种扰动下的主要动态行为。该方法利用扩展等面积准则(EEAC)稳定性理论中的主导模式概念，识别所有可能出现的暂态功角失稳模式，并据此将所有的发电机节点划分为不同的同调群。在每个群中选择一台发电机安装PMU，以捕捉关键的功角动态信息。同时，利用暂态电压稳定和暂态电压跌落可接受性的概念，识别所有可能出现暂态电压问题的相邻母线的子集。在每个子集中选择一条母线安装PMU，以捕捉关键的电压动态信息。根据该最小PMU集提供的动态信息，不但可以正确地定性判断系统的同步稳定性和电压稳定性，并可通过数据挖掘方法评估其稳定裕度。结合华东电网验证了该方法的有效性。