交直流电网电压稳定评估方法研究

发布时间：2018-02-10 15:09

本文关键词： 交直流电网电压稳定在线评估无功补偿指标　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着高压直流输电技术(HVDC)的应用,HVDC与弱交流系统连接的电压稳定问题得到更广泛的关注。电力系统电压稳定研究面临两个问题:一是接近距离,即当前系统电压的状态距离电压不稳定的状态有多接近?二是原因,即什么原因导致系统发生稳定问题?电压水平较弱区域、较弱节点是哪些节点?换言之,电压稳定指标应能回答:一旦负荷发生大的变化引起系统态势恶化,应能预估电网是否可以在事故中不发生崩溃问题;若需要提前预防电压失稳问题,应该了解什么方法可以改善电压水平。所以,电压稳定指标应能给出电压安全性的尺度,可以更好地为提高系统运行能力、预防电压崩溃事故的发生提供决策依据。本文从在线监视的角度出发,立足本地测量,研究新型静态电压稳定指标和电压态势所处失稳模式的评估问题,并分析指标在各种交、直流条件变化时的适应性。为降低在线监视过程对通讯和控制网络的过度复杂化依赖,本文首先探讨了如何利用负荷母线本地量测构建静态电压稳定指标的问题。在分析了负荷母线最大供电能力与等效系统诺顿电流分配关系的基础上,得出了最大供电能力条件与等效系统均分诺顿电流分别供给等效电源自身和外部负荷等价的结论。基于此结论,构建了仅利用负荷母线电压、电流幅值量测信息的静态电压稳定评估指标。该指标无需监测相位且不依赖于外部网络等值,极大地降低了系统实施与管控的技术难度与成本。能够在线实时监视负荷母线电压稳定态势及母线相连负荷进线能力裕度到限情况,便于及时发现电网电压薄弱的节点及其关联的输配电能力危急的路径。为进一步研究所构建的电压稳定评估指标在各种交流系统变工况条件下的适用性,论文综合分析了无功补偿、有载调压变压器分接头调节、发电机励磁调节等方式下指标的变化情况,并通过实际电网数据仿真验证了评估指标在各种典型变工况条件均有效的结论。在获得电压稳定指标能够实时反映系统稳定状态的基础上,研究了负荷陡变时指标的实时追踪问题。为研究指标在交、直流电网中的适用性,建立了直流控制系统模型,通过对直流系统控制方式的改变考察了不同直流输送功率条件时,交流系统负荷母线(换流站母线)指标变化情况,得到了所构建指标同样适用于监视交、直流系统电压稳定态势的结论。最后,综合直流控制、无功补偿、有载调压变压器分接头调节、发电机励磁调节等方式,通过实际电网数据仿真验证了电压稳定评估指标的有效性。
[Abstract]:With the application of HVDC (HVDC) technology, the problem of voltage stability of HVDC connected to weak AC system has been paid more and more attention. There are two problems in the study of voltage stability in power system: one is the close distance, the other is the distance between HVDC and weak AC system. That is, how close is the state of the current system voltage to the unstable state of the range voltage? The second is the reason, that is, what causes the stability of the system? Which nodes are the weaker nodes in the weaker voltage level region? In other words, the voltage stability index should be able to answer: once the load changes cause the system situation to deteriorate, it should be able to estimate whether the power network can not collapse in the accident; if the voltage instability problem needs to be prevented in advance, It is important to understand what methods can improve the voltage level. Therefore, the voltage stability index should be able to give a voltage security scale, which can better improve the performance of the system. In this paper, from the point of view of on-line monitoring, based on local measurement, the evaluation of new static voltage stability index and the instability mode of voltage situation are studied, and the intersections of the indexes are analyzed. Adaptability when DC conditions change. In order to reduce the over-complicating dependence of online surveillance processes on communications and control networks, In this paper, the problem of how to construct static voltage stability index by using local measurement of load busbar is discussed, and the relationship between the maximum power supply capacity of load bus and Norton current distribution of equivalent system is analyzed. It is concluded that the maximum power supply condition is equivalent to the Norton current of the equivalent system and the equivalent power supply itself is equivalent to the external load. Based on this conclusion, only the load busbar voltage is constructed. The static voltage stability evaluation index of current amplitude measurement information. This index does not need to monitor the phase and does not depend on the external network equivalent. It greatly reduces the technical difficulty and cost of system implementation and control. It can monitor the voltage stability situation of load bus and the capacity margin of connecting load line to limit on line. It is convenient to find out in time the node with weak voltage and the critical path of its associated transmission and distribution capacity. The applicability of the voltage stability evaluation index constructed for further research under various AC system off-condition conditions, In this paper, the variation of reactive power compensation, tap adjustment of on-load transformer, excitation regulation of generator and so on are analyzed. Through the simulation of the actual power network data, the conclusion that the evaluation index is effective in various typical off-condition conditions is verified, and the voltage stability index can reflect the stable state of the system in real time. In order to study the applicability of the indexes in AC and DC networks, a DC control system model is established, and the different DC transmission power conditions are investigated by changing the control mode of the DC system. The change of AC system load busbar (converter bus) index is obtained, and the conclusion that the constructed index is also suitable for monitoring AC and DC system voltage stability situation is obtained. Finally, comprehensive DC control, reactive power compensation, The effectiveness of voltage stability evaluation index is verified by simulation of actual power network data by tap adjustment of on-load transformer and excitation regulation of generator.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM712

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