Faulty feeder detection based on the integrated inner product under high impedance fault for small resistance to ground systems

•In terms of detection algorithm: This paper uses the inner product principle to distinguish faulty feeder from healthy feeder, and a series of inner product sequences are obtained by inner product of each feeders zero-sequence current to the neutral point zero-sequence current. These inner product sequences have practical physical significance. The sign of faulty feeder sequence is opposite to that of healthy feeder sequence, and the amplitude of faulty feeder sequence is very large. The calculation principle is simple and helpful for engineering application.•In terms of detection information: The integrated inner product value is introduced through the inner product sum. The criterion is constructed by the integrated inner product value sign and amplitude. When the result of the sign judgment and amplitude judgment are consistent, the faulty feeder is output. The two information quantities of sign and amplitude are used to improve the accuracy of fault detection.