A novel adaptive protection coordination scheme for radial distribution networks in the presence of distributed generation

摘要

Developing micro-grids and increasing penetration of distributed generation (DG) bring significant techno-economic benefits to power systems. However, the presence of DG can affect the performance of the protection system. In particular, the coordination of over-current protection relays in the presence of DGs is a challenging task. In this article, an adaptive algorithm is proposed for protection coordination of over-current relays. Once the coordination of relays is disturbed due to the presence of DG, the characteristic curve of the backup relay is adaptively modified based on the characteristic curve of the main relay in such a way that the coordination time interval (CTI) be in the acceptable range and therefore the coordination of relays is maintained. The proposed algorithm can maintain the coordination of over-current relays locally only by controlling current parameter of backup relay and without imposing any restriction on the output power of DGs. Therefore, the proposed protection coordination scheme allows system operators and DG owners to exploit DG benefits without concerning about protection aspects related to the presence of DGs. The efficiency and applicability of the proposed method are validated using simulations on a typical industrial 20 kV radial distribution system. The simulation results show that the proposed algorithm can maintain the CTI of the main and backup relays in an acceptable range for various penetration levels of DGs.