考虑不可测T接负荷的配电网虚拟三端电流差动保护

采用电流差动保护可解决高比例分布式电源接入配电网引起的馈线保护问题。然而当馈线内存在不可测T接负荷分支时，差动保护只能利用被保护线路两端的数据构造判据，性能受到影响。为解决该问题，首先分析了不可测T接负荷对传统两端电流差动保护的影响。在此基础上，提出了一种虚拟三端电流差动保护方法。该方法将被保护线路内部的不可测T接分支等效为一个虚拟支路，利用故障前后线路两端的电压、电流数据估算该虚拟支路的电流相量，并与馈线两端的电流相量一起构成三端电流差动保护判据。仿真结果表明，该方法在无需T接负荷测量数据的前提下能够满足配电网在不同场景下的保护需求，相比传统的电流差动保护具有更高的可靠性与灵敏性。

Virtual three-terminal current differential protection for distribution networks consideringunmeasurable T-connected loads

Using current differential protection can solve the feeder protection issue caused by the connection of a high proportion of distributed generations to the distribution network. However, when there are unmeasurable T-connected load branches in the feeder, differential protection can only use the data from both terminals of the protected line to construct criteria. This affects its performance. To address this issue, the impact of unmeasurable T-connected loads on traditional two-terminal current differential protection is analyzed first, and then a virtual three-terminal current differential protection method is proposed. This method equates the unmeasurable T-connected branches inside the protected line to a virtual branch, estimates the current phasor of the virtual branch using voltage and current data at both terminals of the line before and after a fault, and finally forms a three-terminal current differential protection criterion together with the current phasors at both terminals of the feeder. The simulation results show that this method can meet the protection requirements of distribution networks in different scenarios without the need for T-connected load measurement data and has higher reliability and sensitivity than traditional current differential protection.