An adaptive protection scheme in active distribution networks based on integrated protection

A considerable increase in the penetration of distributed generation (DG) to the distribution networks leads to a higher possibility of malfunction of present protection schemes of these systems. One of the major problems caused by higher levels of DG penetration is the reduction of the relay reach or relay access. This problem relatively relieves using adaptive overcurrent protection techniques but in certain conditions, the minimum relay access reduces to less than 20 percent of line length, in the presence of DGs and adaptive current protection cannot be used. In this paper a combined adaptive protection method is presented, which applies overcurrent and undervoltage protection simultaneously. Function of the protection system improves because of different action areas of these two types of protection. The feasibility of the proposed method authenticated through simulation.