Multiple Protection Strategies for Hybrid Distribution Transformer Based on DC-link Voltage Fault-tolerant Control

Consisting of the traditional distribution transformer (TDT) and two voltage source inverters, the hybrid distribution transformer (HDT) can realize the voltage level conversion while solving various power quality problems in the power distribution system. Because the reliability and service life of power electronic devices are much lower than the low-frequency transformer, the fault conditions of HDT are more complex and frequent. This paper proposes a DC-link voltage fault-tolerant control method to ensure the DC-link voltage can maintain the reference value even when a voltage source inverter fails. Multiple protection strategies for HDT are also proposed to remove the faulty part and ensure the normal operation of other functions in different fault situations. Simulation results are provided to verify the effectiveness of the proposed multiple protection strategies of HDT.