适应统一潮流控制器复杂运行工况的线路继电保护原理研究

The various opertional modes and control parameters of unified power flow controller (UPFC) greatly deteriorate the performance of conventional relay protection schemes of transmission lines. From the aspects of transient component based protection and steady-state based protection, the novel relay protection schemes of transmission line are proposed to cope with the complicated operation condition of UPFC. With the theoretical analysis and hardware in loop simulation, the fault features of the power grid with UPFC are studied, and the influences of UPFC on the conventional relay protection schemes are pointed out clearly, to provide guide line for the improvement of the relay protection schemes. With respect to the transient component based protection, the boundary magnitude-frequency characteristics of UPFC are studied, and the differences of transient components among the fault occurring before UPFC, fault occurring after UPFC, lightning impulse and operation of breaker are analyzed. Subsequently, the boundary protection scheme which includes boundary element, fault phase selector, directional element and interference discrimination element is proposed. With respect to the steady-state component based protection, the influences of high-order harmonics, transition resistance, transfer characteristics of current transformer and potential transformer on the protection algorithm based on the sampling values of single terminal electrical quantities are analyzed. Consequently, the countermeasures are proposed, and the novel three-stage distance protection scheme based on parameter model of transmission line is put forward. Both of the proposed relay protection schemes can be applied practically, since the communication system or large number of sample data is not required. Hence, the research is of great significance to the widespread application of large scaled UPFC in the high-voltage power gird.

统一潮流控制器（unified power flow controller，UPFC）多运行模式和控制参数使得传统线路保护方案性能劣化，本课题将从暂态量保护和稳态量保护两方面，提出适应UPFC复杂运行工况的线路继电保护原理。通过理论分析与半实物仿真相结合的方式，对含UPFC接入的电网复杂故障机理开展深入研究，明确UPFC接入对线路保护的影响和保护特性的需求。在暂态量保护方面，研究UPFC的边界幅频特性，分析UPFC安装位置前后故障、雷电冲击、开关操作等引起的暂态量信号特征差异，构建包括边界元件、故障选相元件、方向元件和干扰辨识元件在内的边界保护方案。在稳态量保护方面，研究高频分量、过渡电阻和互感器传变特性等对基于单端电气量的瞬时值保护算法的影响，并提出相应的改进措施，构建基于输电线路参数模型的新型三段式距离保护方案。所提出的保护改进原理无需样本数据训练或依赖于通信系统，具有工程应用价值。

统一潮流控制器（unified power flow controller，UPFC）为解决电网中潮流分布不均、潮流控制手段缺乏等问题提供了新的技术手段，但是含UPFC接入的电网故障特征不同于传统交流电网，给电网继电保护带来了许多新的问题。为了推动UPFC技术在更高电压等级、更大容量场合的推广应用，本项目根据UPFC工程及其控制保护系统的结构和功能特点，建立了UPFC电磁暂态仿真模型，对UPFC控制保护策略开展了深入分析；研究了UPFC及其接入系统在不同运行工况下的故障暂态特性，基于此分析了UPFC与线路保护之间的相互作用机理；开展了UPFC接入后对电网继电保护的影响分析，研究了传统继电保护原理对UPFC及接入系统各种故障工况的适应性；分析了不同类型互感器传变特性、采样数据异常恢复算法和UPFC线路边界幅频特性，进而提出了UPFC接入电网的继电保护改进措施，形成了满足UPFC全工作区间及各种故障模式的继电保护配置及配合方案，实现UPFC接入系统保护的整体优化配合。