LVDC customer-end inverter operation in short circuit

Short-circuit protection devices applied to customer-end network protection today require multiple times the nominal current to operate within the required time limits. A three-phase 400 VAC distribution network supplies sufficient short-circuit current in customer-end faults, and reaching the required protection time poses no problems. When a Low-Voltage Direct Current (LVDC) network is used to supply a DC/AC inverter at the customer, the short-circuit currents depend, in practice, only on the inverter, because the DC network services several customers and can thus feed multiple times the current required at one customer. This paper discusses customer-end inverter operation, current supply capability, and current limiting in short-circuit. The paper presents three options for short-circuit protection in different inverter structures, makes a brief comparison between them, and proposes the best solution for every structure.