A New Differential Backup Protection Strategy for Smart Distribution Networks: A Fast and Reliable Approach

The integration of distributed generations (DGs) is transforming the traditional radial single-source distribution system into a complex multi-source one which requires its related protection is able to maintain proper coordination under bidirectional power flow conditions. Although the conventional backup protection methods are effective up to a certain level of DG penetration, they are incompetent for higher service demands such as high DG penetration and protective rapidity. To deal with such a problem, a fast and reliable backup protection strategy is presented on the basis of a proposed device detection method. In the proposed backup strategy, the device failure-related backup protection is started in advance to accelerate the fault isolation by locking the failed primary protection which can be predicted by the proposed device detection method. The presented strategy possesses an excellent performance on rapidity and stability. Particularly, the fault isolation area is only expanded to the upper level circuit breaker via our protection strategy. The performance of the proposed backup strategy has been validated by the realistic system and the real-time digital simulator (RTDS) system.