Protection schemes for closed loop distribution network with distributed generator

The paper proposes the protection schemes for closed loop distribution network with distributed generators. Generally, Most of distribution networks are operated in radial or open loop due to the security and protection limited. With the rapid expansion of modern power systems and demand for high quality of power supply, the closed loop operation is adopted gradually. Furthermore, with the increasing penetration of distributed generators, radial operation is not suit for improving stability of system and distributed generators. This paper investigates the protection requirements of closed loop network, and then analyzes the characteristics of conventional protection schemes which are applied in closed loop distribution network. Taking into distributed generators consideration, the paper proposes pilot wire instantaneous protection for closed loop network. What´s more, non-communication over-current protection is also investigated to be applied in closed loop network. The proposed protection schemes are able to significantly improve the reliability and security of closed loop distribution network with distributed generators.