环状多源配电网中考虑扰动源定位的PQM优化配置

兼顾网络化电能质量监测系统(NPQMS)构建成本和电能质量扰动源(PQDS)定位需求,提出了一种适用于环状多源配电网络的电能质量监测器(PQM)优化配置方法。通过分析环状多源配电网络拓扑结构特点,定义了系统结构信息描述矩阵、PQM配置一般性准则以及对应于不同属性端点的权重因子,建立PQM优化配置模型,并通过监测可观矩阵检验系统模糊度,筛选出最优的PQM配置方案。与通用PQDS定位方法中拓扑结构正方向的匹配性定义,保证了基于PQM优化配置结果实现PQDS精确定位的可行性,且可为采用阶段式NPQMS构建方案提供PQM最优配置决策依据。以IEEE-14节点环状多源配电系统为例,验证了所提PQM优化配置方法的可行性和有效性。     

计及分布式电源的电能质量监测点优化配置

为实现智能配电网对电能质量(PQ)进行全面监测和扰动事件智能诊断,并考虑系统成本优化和分布式电源影响,分析了现有监测点配置方法存在的三个缺陷,提出需要同时考虑节点电压凹陷域和电流信息全网可观测的优化思路。改进了二进制粒子群优化算法(BPSO)的模型和步骤,并构建评价函数,提出一种基于改进粒子群优化的电能质量监测点配置的算法。通过改进的BPSO迭代,智能地布置监测点,实现了系统性能和经济成本的最优化。最后,在四种不同结构的配电网络中进行仿真应用。结果表明,该算法能有效地实现PQ监测点优化配置,以较低的成本实现了配电网的全面监测并满足扰动事件智能诊断和精确定位的需求,且算法具有较好的收敛性和适用性。     

Probabilistic power quality indices for electric grids with increased penetration level of wind power generation

In future electric grids it is expected that the share of power produced by renewable energy systems will increase to supply large deficits in power demand. Wind energy is one of the most important sources of renewable energy generation systems. With increased penetration level of wind energy conversion systems in modern electric grid, the quality of power will inevitably be affected. Power quality (PQ) indices are used to quantify the quality of the power. They serve as the basis for comparing negative impacts of different disturbances on power networks. Previous research of PQ indices with electric grids including wind energy sources was mainly based on fixed wind speed. Therefore, the PQ indices were calculated as instantaneous values that do not reflect the overall power quality impact of the grid connected wind energy systems. The main objective of this paper is to propose new probabilistic PQ indices for electric grids including wind energy systems. The proposed PQ indices combine both the probabilistic nature of wind speed using discrete Markov analysis and the electric grid behavior. The main PQ indices proposed are those concerning harmonics, flicker, and voltage sag. The developed indices are suitable for electric grids that include high penetration level of wind based power sources. The method used is general and can be applied to other power quality indices or power system performance indices.     

基于多智能体的电气化铁道电能质量监控系统

近年来,基于多智能体(Agent)的分布式智能系统已成功地应用于众多领域.文章针对目前电气化铁道电能质量监控系统不能满足分布地域广、实时性要求强的电能质量监控任务的需要,提出了基于多Agent技术的分布式电能质量监控系统,该系统结合了电能质量监控装置分散配置的特点,通过各电能质量Agent之间的相互协调共同完成电能质量监控任务.并分析了各电能质量Agent的结构以及它们之间的协调合作问题,还结合控制任务介绍了CORBA结构和多Agent间的通信.     

基于DSP和虚拟仪器技术的电能质量监测系统设计

针对电能质量监测系统,由即时的电参量测试仪表向分布式监测和基于WEB的网络监测发展,给出了ADC和DSP为核心组成的电能质量监测系统的数据采集子系统的硬件和软件的设计及实现方案.     

基于WebGIS的电能质量监测系统设计及应用

传统的电能质量监测系统通常采用客户机/服务器模式,且只用文字或结合简单图形显示分析结果,表现能力差.文中提出一种基于互联网地理信息系统(WebGIS)的电能质量监测系统,将电能质量信息与地理分布信息结合起来提供给电网管理人员,且用户终端只需一个支持Java编程语言的Web浏览器就可以完成监测的基本操作,降低了系统维护和管理费用.文章介绍了该系统的监测内容、结构和实现方法.     

智能电网技术框架下的电能质量监测与分析技术综述

提高用户电能质量是当前智能电网研究的主要目标之一。针对电能质量监测系统中包含的监测终端、通信系统和监控中心3个组成部分,对智能电网技术框架下电能质量监测与分析技术进行了综述,涉及电能质量检测算法、电能质量监测终端的最优布点、数据通信方式、电能质量类型识别、电能质量扰动源定位、电压暂降起因分析、电能质量综合评估方法、电能质量信息发布等内容,较全面地分析了电能质量研究的背景和现状,并比较各类常用分析方法的优缺点。     

Power quality evaluation in smart grids considering modern distortion in electric power systems

High power quality level is required in smart grids especially for non-stationary situations due to increased use of nonlinear loads and PQ disturbances such as dips, swells, transients and interruptions. Many power quality indices (PQIs) are available. In this paper a new fuzzy-wavelet packet transform-based power quality Index (FWPTPQI) is developed to amalgamate existing power quality indices as the output of a fuzzy based module based on fuzzy inference systems, knowledge base and existing PQI as input. Fuzzy systems allow handling the uncertainties associated with the electric power quality evaluation. The proposed approach has been applied to two case studies; stationary balanced and non-stationary unbalanced three-phase systems. The results are compatible with prevalent situations. The new index gives significant sense of the quality of transmitted electrical power. A comparative study of using different wavelet basis functions is considered and results indicate that Daubechies 10 and Daubechies 15 could be considered as the overall best wavelet basis functions. Since the new index represents an amalgamation of the PQ indices with less number of wavelet coefficients, it helps reduce the size of data processed which is required in smart grid applications.     

Hybrid demodulation concept and harmonic analysis for single/multiple power quality events detection and classification

A novel real-time analysis of power quality (PQ) events has been presented using amplitude and frequency demodulation concepts. The earlier techniques were analyzing the few cycles of the power signal based upon wavelets, having the computational complexity of the order O(n²). In the proposed method, PQ events can be considered as similar to various modulating signal forms. In this paper, the concept of demodulation has been used to separate various single/multiple event patterns and MUSIC harmonics algorithm has been used to detect the presence of the various harmonics. These techniques have been well tested on transient, sag, swell harmonics and their combinations in real-time. Fuzzy classifiers have been used for the classification of PQ events from the knowledge base, obtained from amplitude demodulation, frequency demodulation and MUSIC harmonic algorithm. It is concluded from the confusion tables that the efficiency of single/multiple PQ events recognition of fuzzy product aggregation reasoning rule (FPARR) classifier is higher.     

基于网络的用户侧电能质量监测仪设计

直接影响用户的电能质量问题主要出现在配电系统和低压侧,而目前的电能质量监测系统主要是基于中、高压系统侧来考虑的或者是简单的手持式监测仪,均不能满足普通用户的监测要求。本文分析了与普通用户密切相关的电能质量指标,指出从墙上电源插座采集电压信号,就可以完全掌握普通用户的电能质量状况,在此基础上提出了基于普通用户侧的电能质量监测仪的思路,探讨了相关的网络结构和关键技术方法。     

广域测量技术在电力系统分析及控制中的应用综述

综述了广域测量系统(wide-Area Measurement System,WAMS)在电力系统稳态分析、全网动态过程记录和事后分析、电力系统动态模型辨识和模型校正、暂态稳定预测及控制、电压和频率稳定监视及控制、低频振荡分析及抑制、全局反馈控制、故障定位及线路参数测量等方面的应用.通过这些应用可以看到,WAMS给电力系统分析与控制提供了新的视角和解决方法,值得深入研究.     

混合动力系统电能质量扰动分析及治理

基于并联有源滤波器(shunt active power filter,SAPF)和动态电压调节器(dynamic voltage restorer,DVR),首先,搭建了包含光伏和风机的混合动力系统,用以模拟分布式电源接入配电网中产生的电能质量(power quality,PQ)扰动.其次,利用模糊逻辑、神经网络和自...     

配电系统电压跌落幅值估算分析

电力市场的快速发展及敏感负荷的逐年增多，要求发展相关的评估指标和方法，来衡量整个配电网络或者评估不同馈线之间的暂态电能质量优劣。然而实际系统中不能保证对每一个点都进行实时监测，因此必须根据己知的不完整监测数据来准确地估计其余各未知点的电压跌落幅值。为了解决该问题，提出了“电压跌落幅值估算”的概念，并且基于最小二乘原理发展了实用的幅值估算算法，该算法通过判断故障相位，搜索故障路径，估计出未知点的电压跌落幅值。理论分析和仿真表明，该算法的提出为配电系统电压跌落的状态评估和数据统计提供了有力的保障。     

分布式电能质量监测系统硬件平台的设计

现代社会的快速发展对电能质量,特别是暂态电能质量的要求越来越高,原有的测量技术、装置已不能满足要求,必须发展新的监测技术.本文根据电能质量监测新技术的各项指标和要求,提出了分布式电能质量监测系统的思路,探讨了相关的硬件监测平台的特点和设计方法,并结合具体装置详细分析了DSP技术、GPS同步技术、TCP/IP通讯协议等关键技术在分布式电能质量监测系统中的应用.     

基于网络的行波故障定位软件设计

基于整个输电网的行波故障定位方法,综合网络中各变电站测量到的故障行波到达时刻计算故障点位置,能有效提高定位结果的精度和可靠性。文中基于该方法,设计了基于网络的故障行波定位软件。包括故障计算单元、数据库管理单元、GPRS(通用分组无线电业务)无线通信单元、故障信息发布单元。实现了全网故障定位计算、分散分布的行波定位装置与故障定位主机之间GPRS无线通信、全网故障信息数据的管理以及基于Web的故障信息发布等功能。现场运行表明,该软件稳定可靠,定位准确,完全符合工程要求。     

Impact assessment of reliability of phasor measurement unit on situational awareness using generalized stochastic Petri nets

Situational awareness (SA) in power systems enables timely and right decisions by the system operators to prevent a blackout. Real-time monitoring of the grid provides adequate SA for successful grid operations. Phasor measurement units (PMUs) are instrumental in providing with a comprehensive real-time view of the grid. They provide with time-aligned phasor measurements (synchrophasors) from different locations of the network. Therefore, PMUs are instrumental in SA. In this paper, effect of reliability of PMU modules on SA of the power system has been analysed. Reliability modelling of PMU and its modules has been done using generalized stochastic Petri nets (GSPNs). They provide a strong graphical representation and model minute details of a system accurately. The results of reliability analysis of modules obtained are employed to investigate their effect on SA through event tree analysis (ETA).     

开放式电能质量管理系统动态报表的实现

针对当前电能质量监测系统的数据特征,提出了一种基于数据库、服务器应用程序和客户机三层结构体系的新型电能质量报表软件包的模块化设计思想.多报表生成采用分层技术,报表管理采用面向对象的方法,使得软件包具有通用性、可维护性和可扩展性.     

基于分段离散余弦变换的电能质量数据压缩算法实现

采用分段离散余弦变换对电能质量数据进行压缩,用小波变换对原始信号进行奇异值检测,然后以检测到的奇异值作为端点进行分段,对每段信号分别作离散余弦变换。仿真试验结果显示,谐波信号直接采用离散余弦变换的压缩效果要优于小波变换;对于短时电压变动信号,采用分段离散余弦变换的信号压缩效果要好于直接采用离散余弦变换和小波变换。     

Comparative evaluation of two models of UPQC for suitable interface to enhance power quality

Majority of the dispersed generations from renewable energy sources are connected to the grid through power electronic interface, which introduce additional harmonics in the distribution systems. Research is being carried out to integrate active filtering with specific interface such that a common power quality (PQ) platform could be achieved. For generalized solution, a unified power quality conditioner (UPQC) could be the most comprehensive PQ protecting device for sensitive non-linear loads, which require quality input supply. Also, load current harmonic isolation needs to be ensured for maintaining the quality of the supply current.     

Detection and classification of single and combined power quality disturbances using fuzzy systems oriented by particle swarm optimization algorithm

In this paper, a new approach for the detection and classification of single and combined power quality (PQ) disturbances is proposed using fuzzy logic and a particle swarm optimization (PSO) algorithm. In the proposed method, suitable features of the waveform of the PQ disturbance are first extracted. These features are extracted from parameters derived from the Fourier and wavelet transforms of the signal. Then, the proposed fuzzy system classifies the type of PQ disturbances based on these features. The PSO algorithm is used to accurately determine the membership function parameters for the fuzzy systems. To test the proposed approach, the waveforms of the PQ disturbances were assumed to be in the sampled form. The impulse, interruption, swell, sag, notch, transient, harmonic, and flicker are considered as single disturbances for the voltage signal. In addition, eight possible combinations of single disturbances are considered as the PQ combined types. The capability of the proposed approach to identify these PQ disturbances is also investigated, when white Gaussian noise, with various signal to noise ratio (SNR) values, is added to the waveforms. The simulation results show that the average rate of correct identification is about 96% for different single and combined PQ disturbances under noisy conditions.