基于突变电容值的高压直流输电线路的故障定位

发布时间：2018-01-20 15:03

本文关键词： VSC-HVDC 故障定位零模网络识别电容 Bergeron模型　出处：《新疆大学》2017年硕士论文　论文类型：学位论文

【摘要】：为了满足现代电网的发展需求,柔性高压直流输电系统逐渐被采用,柔性高压直流输电系统采用全控型器件IGBT,它可以实现系统电流的自关断,相对于传统的高压直流输电系统,柔性高压直流输电系统可以向无源网络供电,远距离的孤立负荷,因此柔性直流输电系统势必将要不断地发展。而在高压直流输电系统中,线路一般都比较长,并且运行环境恶劣,所以与其他输电设备相比故障率比较高。为了保障直流输电系统的安全稳定运行,需要在直流线路发生故障时,及时确定故障点位置并且清除故障,因此精确的故障定位方法是十分必要的。通过对两种常用的故障测距方法即单端测距法和双端测距法的比较,选用双端测距法对直流线路上的单极接地故障进行故障测距;根据VSC-HVDC系统中的主要元件的特性,对直流输电线路的接地故障需要应用的VSC-HVDC的零模网络和1模网络进行了比较;文中通过零模网络与1模网络的仿真图,得出了柔性直流输电系统中的部分结构在零模网络中等效网络图,从而得出在零模网络中,VSC-HVDC系统中的整流器部分可以等效为并联电容的结论,提出了基于突变电容值的故障定位原理;为了比较零模电压、零模电流和识别电容之间的关系,还需要将零模网络中的电压电流分量进行解耦,通过解耦后的电压电流分量来计算出零模识别电容的数值;为了研究直流线路上发生故障时,故障行波波头到达的时刻,文中在PSCAD中搭建了直流输电线路,对于柔性直流输电系统的整流部分和换流部分采用的是PSCAD软件中自带的模型;对于直流线路的模型搭建选择的是远方终止模式的搭建方式,输电线路分布参数模型选用的是Bergeron模型;最后在搭建好的直流线路模型上进行单极接地故障的仿真,在全长100kM,额定直流电压为±110kV的直流线路上进行故障设置,比较零模电压、零模电流和识别电容的突变图形在直流线路上不同的位置上且经不同的过渡电阻的情况下发生的变化,从而得出结论,即在零模网络中,基于突变电容值的故障定位能够可靠识别故障发生后故障行波波头到达的时刻,并且不受故障距离,电气量波形渐变的影响以及能适应经不同过渡电阻的高阻接地故障。
[Abstract]:In order to meet the needs of the development of modern power grid, the flexible HVDC transmission system is gradually adopted. The full control device IGBT is used in the flexible HVDC transmission system, which can realize the self-turn-off of the system current. Compared with the traditional HVDC system, the flexible HVDC system can supply power to the passive network with long distance isolated load. Therefore, the flexible direct current transmission system is bound to continue to develop, but in the HVDC transmission system, the lines are generally longer, and the operating environment is poor. Therefore, compared with other transmission equipment, the failure rate is higher. In order to ensure the safe and stable operation of HVDC system, it is necessary to determine the location of the fault point and clear the fault in time when the DC line fault occurs. Therefore, accurate fault location method is very necessary. Through the comparison of two common fault location methods, one end location method and two end location method. The fault location of unipolar grounding fault on DC line is carried out by using two-terminal location method. According to the characteristics of main components in VSC-HVDC system, the zero-mode network and 1-mode network of VSC-HVDC which need to be applied to ground fault of HVDC transmission line are compared. In this paper, through the simulation diagram of zero-mode network and 1-mode network, the equivalent network diagram of some structures of flexible direct current transmission system in zero-mode network is obtained, and then the equivalent network diagram in zero-mode network is obtained. The conclusion that the rectifier part of VSC-HVDC system can be equivalent to parallel capacitance is put forward, and the fault location principle based on the value of abrupt capacitance is put forward. In order to compare the relationship between zero-mode voltage, zero-mode current and recognition capacitance, it is necessary to decouple the voltage and current components in zero-mode network. The zero-mode recognition capacitance is calculated by decoupling the voltage and current components. In order to study the arrival time of the fault wave head on the DC line, a DC transmission line is built in PSCAD. For the rectifier part and commutation part of the flexible direct current transmission system, the model included in PSCAD software is adopted. For the DC line model, the remote termination mode is chosen, and the transmission line distribution parameter model is the Bergeron model. Finally, the single-pole grounding fault simulation is carried out on the established DC line model. The fault setting is carried out on the DC line with a total length of 100kM and rated DC voltage of 卤110kV, and the zero-mode voltage is compared. The change of the zero mode current and the abrupt pattern of the recognition capacitance in different position on the DC line and the different transition resistance, thus the conclusion is drawn, that is, in the zero mode network. The fault location based on the abrupt capacitance value can reliably identify the arrival time of the fault traveling wave head after the fault occurs, and can not be subjected to the fault distance. The influence of the gradual change of electrical waveform and the ability to adapt to the high resistance grounding fault through different transition resistance.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM755

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