Current-Limiting-Type Fault Ride-Through Control Scheme for Converters in DC Microgrid

DC microgrid experiences a high magnitude of fault current during a pole-to-pole (PP) fault. It is difficult to interrupt such a current due to the absence of natural current zeros. In this article, the authors propose a current-limiting-type fault ride-through (FRT) scheme for converters in the dc microgrid, which reduces the steady-state fault current during a PP fault. The steady-state fault current reduction is achieved by setting the power fed by each converter to a minimum value using control. The reduced fault current further reduces the voltage and current stress on the circuit breaker (CB) for clearing the fault. The proposed scheme also ensures fast voltage restoration of the network voltage without having to go through the startup process. The proposed scheme uses locally available converter data to detect and limit the fault current. The performance of the proposed scheme is compared with systems in which converters do not have an FRT scheme or have an existing power sequence method as an FRT scheme. The viability of the proposed scheme is confirmed through detailed simulations on a 380 V low-voltage dc (LVDC) microgrid model. The performance of the proposed scheme is experimentally validated on a laboratory prototype network.