含DG复杂配电网的电压暂降源定位研究

Voltage sag is among major power quality (PQ) problem in power system, which has focused the much attention of PQ studies due to the impact on sensitive industrial loads and huge costs led by the damages and maintenance. Voltage sag source location is always a very important and difficult issue for PQ studies in recent years. With a high penetration of distributed generation (DG) into distribution networks, it is more difficult and complex to locate the voltage sag source reliably. The problem of voltage sag source location in the complex distribution network with distributed generation will be studied in this project. The main researching contents include following four parts. First, a valid signal analysis method will be invented to deal with non-stationary signal during voltage sag event, and a dynamic phasor measurement algorithm with good dynamic performances will be studied with the method during fault transient responses. Thus a time-varying dynamic phasor model will be constructed, with its parameters gotten too. Second, with above time-varying dynamic phasor model, an equivalent model for the complex distribution network with DG will be established with its parameters. Also an algorithm of parameters dynamic tracking and estimation for synthesis load model and synthesis source model of up and down system will be analyzed, and the inner mechanism of sag producing will be explored by studying the relation of parameters variation and voltage variation, and then a quantitative results will be derived for voltage sag source location. Third, the study of using intelligent technology to improve the accuracy, reliability and generalizability of source location method will be carried out under the environment of complex distribution system. Finally, with relation analysis between voltage sag and voltage fluctuations, voltage swells and other power quality disturbances, a systematic method for voltage quality disturbance source localization in complex distribution network will be set up, according to the aforementioned sag source location method. The research of voltage sag source location is significant for the customers and suppliers to solve the issue between them, and be helpful to compensate voltage sag, find out and remove the disturbance source.

电压暂降是电网最重要电能质量问题之一,暂降源定位一直为近年来电能质量研究领域的一个重点及难点。随着配电网中大量分布式电源的接入，要实现暂降源可靠定位更加复杂。项目主要以含分布电源复杂配电网为研究对象，对电压暂降源定位的关键技术及应用进行研究,包括：电压暂降源定位中非平稳信号的有效处理方法，实现具有暂态响应能力的动态相量测量，建立时变动态相量模型，并求取模型参数；利用时变动态相量模型，研究含DG复杂配电网在暂降源定位中动态等效方法，分析监测点上、下游等效综合负荷和电源及其时变参数的动态跟踪估计，研究参数时变与电压变化关系分析形成电压暂降的内在机理，并推导源定位的定量结果；在复杂配电网环境下，研究利用智能诊断技术，改善提高定位法的精度、可靠性、泛化性；探索构建系统的配网电压扰动源定位法。意义：电压暂降源定位研究对界定分清电压暂降事故中供用电双方各自责任及有效补偿和排除暂降扰动源具有关键性作用。

本项目以含分布电源复杂配电网为研究对象，围绕电压暂降等电能质量扰动源定位的关键技术及应用展开了研究，并得到一些有意义的研究成果。首先，考虑到复杂配电网电压暂降过程中的信号暂态时变性、频率扰动及噪声，提出了非线性自适应滤波的非平稳信号处理方法，有效检测暂态过程中动态相量相位和幅值，并基于粒子群二次型优化方法实现了含DG复杂配电网的等效系统参数动态跟踪。在系统连续缓慢变化条件下等效参数跟踪误差的最大值和平均值约2.31%和0.56%，为后续扰动源定位提供良好的数据源。在信号处理及等效参数跟踪基础上，通过研究参数变化与监测点电压变化关系，建立暂降源定位机理，推导源定位定量判据，实现了多源暂降源的量化定位。另外，针对DG低电压穿越特性对定位影响，提出了考虑LVRT的电压暂降源定位判据修正方法；针对有限监测数据问题，半监督SVM法充分利用大量无暂降源位置标签监测数据，实现复杂电压暂降源智能定位，优化后的定位正确率达97.5%。研究实现了基于残留电压率的暂降源精确定位、基于虚拟阻抗的故障区段定位，有效满足复杂配电网更高的扰动源定位精度要求。另外，考虑实际电能质量监测系统成本要求，提出基于改进二进制粒子群的二阶段量测点优化配置算法，有效降低监测数量。此外，利用暂降与电压波动形成机理的相似性，通过折算支路电流流经系统阻抗所产生扰动分量及其对PCC统一电能质量扰动的正反向作用，提出新的统一电能质量扰动源定位方法，定位效果较好。另外，借鉴暂降源定位思路，研究实现了基于多重判据的闪变源智能定位法、基于HHT与闪变功率的闪变源定位，并对IEC闪变仪归一化时变特性对线性精度的影响等开展了有益的研究。相关方法在孤岛检测、直流配电网暂降源定位、含DG电网脆弱线路识别等也取得不错的应用。通过上述研究取得的一系列成果，基本搞清了含DG复杂电网电压暂降等电能质量扰动源定位问题，为界定分清电能质量事故中供用电双方责任及排除扰动源起到关键参考。