Design and Implementation of a Parallel-Connected Fault Current Attenuator for Power Distribution Systems

Parallel-connected fault current attenuator (PFCA) is a novel concept for active reduction of short-circuit currents (SCCs) through circuit breakers (CBs) in power distribution grids. The sustained increase in the SCCs could exceed the rating of the CBs, dangerously spreading the fault. Several series-connected schemes, such as fault current limiters and series reactors, have been proposed in recent decades to reduce these high currents. This article designs and experimentally verifies the feasibility of a parallel-connected power converter to reduce the SCCs, operating as a controlled current source by absorbing current from the fault point. This new configuration reduces the SCCs in all CBs of an electrical substation. The proposed PFCA is implemented using a single-phase neutral-point clamped (NPC) converter and tested using a predictive current control scheme for short-circuits in a scaled-down power system. The experimental results prove the effectiveness of the proposed scheme, reducing significantly the first SCC peak, even when the ac bus voltage is close to zero.

Automated summary

This article introduces a new concept for actively reducing short-circuit currents in power distribution grids and experimentally verifies its feasibility. The new configuration uses a specific power converter to attenuate the fault current and successfully demonstrates its effectiveness in the tests.