Spare power automatic switching system and method for multi-section bus annular power supply

The invention relates to the technical field of power supply, discloses a spare power automatic switching system and method for annular power supply of multiple sections of buses, and aims to solve the problem that spare power automatic switching of main wiring of closed wiring of multiple sections of power supply buses is difficult to realize in an existing spare power automatic switching mode. Each section of bus is respectively provided with a corresponding bus sensor, a current sensor, a spare power automatic switching device, a first circuit breaker, a second circuit breaker and a wire inlet port, the wire inlet port is connected with the corresponding bus through the corresponding first circuit breaker, the current sensor is arranged on the corresponding first circuit breaker, and each section of bus is annularly connected through the corresponding second circuit breaker; the spare power automatic switching device is connected with the corresponding bus sensor, the current sensor, the normally closed co