特高压直流输电换相失败特性研究

发布时间：2018-03-05 15:24

本文选题：特高压直流(UHVDC)　切入点：暂态过程　出处：《昆明理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着社会经济的迅速发展,人们对于电力的需求也在日益增加。我国虽地域辽阔,但电力能源的分布与电力负荷需求区域的分布却极不平衡,为了实现资源的合理利用以及能源的优化供应,发展远距离、大容量的交直流混合输电系统成为了发展的必然趋势。特高压直流输电系统不仅在远距离、大容量输电方面较交流输电系统具有明显的优势,而且其控制方式也灵活方便,有利于电力系统的稳定运行。特高压直流输电线路由于其电压等级高,往往需要跨越大量的山地丘陵等复杂的环境,故其线路发生短路故障的概率就较高。为了研究特高压直流输电换相失败的特性,本文首先介绍并分析了特高压直流输电系统的控制特性,在此基础上,利用云广±800kV特高压直流输电工程实际参数以及PSCAD仿真平台建立仿真模型,通过对特高压直流输电系统不同故障点的暂态控制特性进行仿真和分析,验证了其模型的准确性。换相失败是特高压直流输电系统常见的故障之一。本文详细分析了换流站逆变侧发生换相失败的机理、原因、以及影响因素,提出了一些防止特高压直流输电系统发生换相失败的预防措施,并对逆变侧交流输电系统发生各种类型的短路故障进行了仿真分析。其结果表明：逆变侧的交流母线发生各种不同类型的金属性接地故障时,逆变侧均会发生换相失败。随着接地过渡电阻的增加,各故障电气量的变化幅度会减小,当过渡电阻达到临界换相失败电阻值时,逆变侧将不会发生换相失败。当故障切除后,直流系统均能很快恢复至正常状态。直流系统逆变侧发生换相失败后,在系统的调节以及恢复的过程中不仅会产生大量的谐波分量,而且可能会造成交流系统线路发生暂态功率倒向,这都将对交流系统的保护产生影响,本文对暂态功率倒向现象进行了特性分析及仿真,并针对换相失败对交流系统产生的影响进行了分析,并提出了防止保护误动的措施。
[Abstract]:With the rapid development of social economy, people's demand for electricity is increasing day by day. Although our country has a vast territory, the distribution of power energy and the distribution of power load demand region are very unbalanced. In order to realize the rational utilization of resources and the optimization of energy supply, the development of long-distance AC / DC hybrid transmission system with large capacity has become an inevitable trend. Large capacity transmission has obvious advantages over AC transmission system, and its control mode is also flexible and convenient, which is conducive to the stable operation of power system. It is often necessary to cross a large number of mountain hills and other complex environments, so the probability of short circuit fault is higher. In order to study the characteristics of UHVDC commutation failure, this paper first introduces and analyzes the control characteristics of UHVDC system. The simulation model is established by using the actual parameters of Yunguang 卤800kV UHVDC transmission project and the PSCAD simulation platform. The simulation and analysis of transient control characteristics at different fault points of UHVDC system are carried out to verify the accuracy of the model. Commutation failure is one of the common faults in UHVDC transmission system. This paper analyzes in detail the mechanism, causes and influencing factors of commutation failure on inverter side of converter station. Some preventive measures to prevent the commutation failure of UHVDC transmission system are put forward. Simulation analysis of various types of short-circuit faults occurred in AC transmission system of inverter side shows that when various types of gold attribute grounding faults occur in AC busbar of inverter side, Commutation failure will occur in the inverter side. With the increase of the grounding transition resistance, the change of the electrical quantity of each fault will decrease. When the transition resistance reaches the critical value of the commutation failure resistance, the commutation failure will not occur in the inverter side. When the fault is removed, the commutation failure will not occur in the inverter side. DC systems can quickly return to normal condition. After commutation failure occurs in the inverter side of DC system, not only a large number of harmonic components will be produced in the adjustment and recovery process of the system, but also the transient power reversal of the AC system line may occur. All of these will affect the protection of AC system. This paper analyzes and simulates the transient power reverse phenomenon, analyzes the effect of commutation failure on AC system, and puts forward some measures to prevent the protection from maloperation.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

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