同杆四回线纵联差动保护新方案

New Scheme of Longitudinal Differential Protection for Four-parallel Lines on Same Tower

对于传统的纵联差动保护直接应用于同杆四回线输电线路时,易受零序互感及分布电容电流影响,致使保护产生误动或拒动。为此,首先深入研究了同杆四回线输电线路,再利用12序分量法对其线路进行参数解耦,得到相互独立的序分量,并提出了相应的反序负序网络;然后利用该反序负序分量的特征以及综合考虑电流互感器饱和等问题,从而推导出新的纵联差动保护判据。大量的PSCAD/EMTDC仿真结果表明:本方案简单可靠,不受零序互感、分布电容电流、故障类型及过渡电阻等因素影响;同时对于电源容量的变化自适应能力较强。

It is not feasible for traditional longitudinal differential protection in the four-parallel transmission lines on the same tower, because of the effect of complexity of its parameters. And the effect will lead to the protection underreach or over-reach. To tackle these problems, depth study for the four-parallel transmission lines on the same tower. Decoupling parameters by 12 sequence component method, as a result, independent sequence component and the corresponding reverse sequence negative sequence network are proposed. Afterward, a new longitudinal differential protection criterion is derived by using the characteristics of the negative sequence component and considering the current transformer saturation problems. The program is simple and reliable, and immune to the effect of zero-sequence mutual capacitive, distributed capacitance current, fault type and transition resistance and other factors. In addition, It has very strength adaptive ability for the power capacity changes.