Research on Current-Limiting Control Strategy Suitable for Ground Faults in AC Microgrid

On August 9, 2019, a blackout event with significant impacts occurred in the British power grid (BPG). The technical report submitted by the BPG points out that the accident originated from multiple independent and concurrent events, resulting in a sudden power shortage, which exceeded the fortification requirements of the relevant standards. This incident has led us to reflect on some of the technical bottlenecks that exist in the high-proportion renewable energy system, such as frequency oscillations, security defense of large power grid, current-limiting, and so on. Based on this background, this article studies a strong current-limiting control system suitable for ground faults in ac microgrid, which can limit the fault current to less than twice the rated current so that the distributed generators can go through multiple faults ride-through without offline operation. Meanwhile, this control system does not need to switch the reference inductance current between normal and faults and can realize the smaller current harmonics and lower asymmetry amplitudes in the two states. Simulation and experiment show that the method proposed in this article can adapt to a variety of ground faults.

Automated summary

This article discusses a strong current-limiting control system suitable for AC microgrid faults, which can effectively reduce fault current, ensure distributed generators to continue operation without shutdown in the event of multiple faults. The method proposed in this article can also reduce current harmonics and asymmetric amplitudes.