Short-Circuit Protection in a Converter-Fed Low-Voltage Distribution Network

The short-circuit protection of a low-power converter-fed low-voltage dc distribution network is investigated. In a public distribution network, the short-circuit protection is implemented by using fuses and circuit breakers, which may require a current that is over ten times the nominal currents of low-power dc/ac converter units to satisfy the recommendations. In the paper, the operation of the converter in a short circuit is studied, and the control scheme for the short-circuit current control and the fault ride through operation is proposed. The operation of the short-circuit control scheme is verified by measurements. To overcome the problem of high fault current injection, alternative short-circuit protection realizations that are based on a simple low-current compact circuit breaker (but are not approved in standards) are proposed and demonstrated by measurements.