Alternating current microgrid protection method utilizing photovoltaic low-voltage ride-through characteristics

The increasingly popular inverter distributed generation in microgrids is leading to changes in system fault characteristics. The fault behaviors of inverter distributed generation are closely related to the control mode. Here, a photovoltaic power supply in constant power mode enters a low-voltage ride-through state when there is a fault in the microgrid. The output current phase in the ride-through state is analyzed, and a local protection method based on the phase difference of the feeder positive-sequence current is proposed. The method is used to avoid interpreting voltage surges as faults, and to detect and locate faults rapidly and accurately. Electromagnetic transient simulation software is used to demonstrate the efficacy of the proposed protection scheme.