Research and Application of the System of Relay Protection and Self-Healing for Distribution Network with Mixed Use of Circuit Breaker and Load Switch

In order to address the problem of slow fault removal and large power outage caused by the mixed use of circuit breakers and load switches in distribution networks, a high-speed relay protection and self-healing system applicable to mixed use scenarios is proposed. By constructing peer-to-peer communication between devices, a fault cutting and isolation scheme is developed by combining fault intertripping, fault memory, and no-current tripping of load switch. To solve the problem of larger power outage caused by fault cutting in scenarios of load switch configuration, a fault self-healing scheme that combines intertripping self-healing and open-loop point self-healing is proposed. Furthermore, a dynamic synchronous detection method that considers the circuit breaker closing time and changes in voltage amplitude and frequency of distributed power island areas is proposed, which improves the success rate of synchronous closing in distributed power areas and avoids disconnection of distributed power. The dynamic model experiment of real-time digital simulation has verified the accuracy of the protection action behavior of the proposed scheme in load switch configuration scenarios, which helps to improve the power supply reliability of distribution networks.