Analysis and countermeasures of misoperation of zero sequence pilot protection on circuit lines of same pole

Zero sequence pilot protection is widely used in high-voltage electrical power system as a main protection for transmission lines. However, zero sequence pilot protection may misoperate under the influence of zero sequence mutual inductance. A misoperation of zero sequence pilot protection of same-pole transmission lines occurred in Guangdong power grid. In this paper, the misoperation is described in detail first. Then, the reason that zero sequence mutual inductance between same-pole transmission lines leads to the misoperation of zero sequence pilot protection are summarized. Some typical power network topologies that may cause misoperation of zero sequence pilot protection are listed. Finally, several countermeasures which can eliminate the misoperation of zero sequence pilot protection are proposed.