串补输电线路的方向保护研究

发布时间：2018-08-29 10:46

【摘要】：我国的能源基地与负荷中心的逆向分布特点突出,无论是电能的远距离大容量输送、区域电网互联,还是实现能源资源的优化配置,都需要大功率超(特)高压输电技术的强力支撑。然而,随着近年来我国新投运的高压输电工程数量不断增多,电网架构日趋复杂,如何充分利用现有的输电线路,提高线路输送效率,有效节约能源,提高系统运行可靠性、经济性、灵活性和稳定性,是目前电力系统发展方向之一。串联补偿技术是一种可以同时提高输电线路输送容量和系统稳定性的经济且有效的方法,在电力系统中得到广泛应用。但是,从保护安装处看,串联补偿电容和自身的过电压保护元件会给输电线路上快速有效的识别故障带来一定问题。容性故障阻抗、电容器过电压保护元件的非线性特性和线路故障后串补装置不对称运行特性等,都是会直接影响串补线路保护性能的主要因素。因此,研究适用串补线路的方向保护算法具有重要的理论价值和实际意义。本文首先分别介绍了两种典型串联电容补偿装置,固定串联补偿装置和可控串联补偿装置的结构、MOV运行特性、故障后动作行为以及串补装置在线路发生不同故障时的不同动态过程,为其后两种串补模型的搭建以及分析线路故障后方向保护动作特性打下基础。然后,针对串补线路中由于串补电容的接入使线路电压、电流相位关系发生变化,研究保护安装处电压反向、电流反向现象的产生条件以及影响因素,并分析二者之间的关系以及二者对传统方向保护的影响。针对串补线路存在电压反向、电流反向时传统方向保护无法正确辨识故障方向,提出适用于串补线路的工频故障分量方向保护算法,该算法既不受电压反向、电流反向的影响又不受故障后串补线路不对称运行、非线性运行特性的影响。并考虑某些特殊运行方式下线路发生短路故障,此时电压故障分量较小时无法保证方向保护灵敏度,此时引入一补偿阻抗对电压故障分量进行补偿,保证正向故障时保护灵敏度。最后,根据线路单极跳闸特点,通过电压故障分量模值比较来辨识故障类型(单相故障、多相故障)。结合故障方向辨识算法,提出一种同时辨识故障方向和故障类型的方向继电保护算法。并建立FSC、TCSC和FSC+TCSC三种串补模型,仿真验证该保护算法在这三种串补线路中的有效性。同时研究故障初始角、系统阻抗、过渡电阻、功角差、串补度和串补安装位置等因素对保护算法的影响。
[Abstract]:The reverse distribution characteristics of energy base and load center in China are prominent, whether it is the long-distance and large capacity transmission of electric energy, the interconnection of regional power grid, or the optimal allocation of energy resources. All need the strong support of high-power ultra-high voltage transmission technology. However, with the increasing number of new high-voltage transmission projects in China in recent years and the increasingly complex grid structure, how to make full use of existing transmission lines, improve transmission efficiency, effectively save energy, and improve the operational reliability of the system. Economy, flexibility and stability are one of the development directions of power system. Series compensation technology is an economical and effective method which can improve transmission capacity and system stability at the same time. It is widely used in power system. However, from the point of view of the protection installation, the series compensation capacitor and its own overvoltage protection elements will bring some problems to the fast and effective fault identification on the transmission line. Capacitive fault impedance, nonlinear characteristics of capacitor overvoltage protection elements and asymmetric operation characteristics of series compensator after line failure are all the main factors that directly affect the performance of series compensation line protection. Therefore, it is of great theoretical and practical significance to study the directional protection algorithm for series compensation lines. In this paper, two typical series capacitor compensators, fixed series compensators and controllable series compensators, are introduced respectively. The action behavior after fault and the different dynamic process of series compensator in different faults of line lay the foundation for the construction of two kinds of series compensation models and the analysis of the action characteristics of direction protection after fault of line. Then, in view of the change of voltage and current phase relationship due to the connection of series compensation capacitor in series compensation line, the conditions and influencing factors of voltage reverse and current reverse phenomenon in protection installation are studied. The relationship between them and their influence on traditional directional protection are analyzed. In view of the fact that the voltage reverse exists in the series compensation line and the traditional direction protection can not correctly identify the fault direction when the current is reversed, a direction protection algorithm of the power frequency fault component for the series compensation line is proposed, which is not subject to the voltage reverse. The effect of the reverse current is not affected by the asymmetric operation and nonlinear operation of the series compensation line after the fault. Considering the short circuit fault occurred in some special operation mode, when the voltage fault component is small, the direction protection sensitivity can not be guaranteed. At this time, a compensated impedance is introduced to compensate the voltage fault component. Ensure protection sensitivity in forward fault. Finally, according to the characteristics of line monopole tripping, the fault types (single phase fault, polyphase fault) are identified by comparison of voltage fault component modes. Combined with fault direction identification algorithm, a directional relay protection algorithm is proposed to identify both fault direction and fault type. Three kinds of series compensation models, FSC,TCSC and FSC TCSC, are established, and the simulation results show that the proposed protection algorithm is effective in the three series compensation circuits. At the same time, the effects of fault initial angle, system impedance, transition resistance, power angle difference, series compensation degree and position of series compensation installation on the protection algorithm are studied.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM75

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