一种配电线路单端全线速动保护方案

A Whole-Line Quick-Action Protection Scheme for Distribution Lines Based on Single-End Electrical Parameters

不依赖电源特性,仅和线路拓扑有关的单端量全线速动保护是改善目前配电网薄弱保护配置的重要方案。针对配电线路多分支、损耗大的特点,设计了一种稳态分布补偿、暂态故障识别的边界元件,并基于边界元件提出了一种配电线路单端量全线速动方法。在配电线路各母线处并联电容作为边界元件,利用其对阶跃故障行波的反射作用,通过小波分析提取区内外故障时电压时域暂态能量差异,并综合故障前后电流幅值特点,实现全线速动保护方案配置。PSCAD仿真结果表明,该方法能够快速可靠的识别配电线路区内外相间故障,具有较高的耐过渡电阻能力;且边界电容值越大,越有利于区内外故障的识别,但电容的选取仍需考虑电网运行要求、经济性等因素的影响。

Independent of power supply property, single-ended quick-action protection, only related to line topology, is an important scheme to improve weak protection configuration of present distribution networks. This paper designs a type of boundary elements, namely the capacitors in parallel to bus, playing role of a compensation element at steady state and fault identification device during transient fault period. A method of whole-line quick-action protection for distribution lines is proposed based on single-end transient voltage energy extracted with wavelet decompositions associated with instantaneous currents. PSCAD simulation results prove that the method can quickly and reliably distinguish internal and external phase-to-phase faults in distribution lines with strong ability of enduring fault resistance. Meanwhile, the larger the boundary capacitance is, the more conducive will be to distinguish the faults, but its volume selection still depends on system operation requirements, and economic and other factors.