Research on adaptive protection based on integrated protection

Generally, the three-stage current protection and the instantaneous under voltage protection with current supervision are set to protect the low-voltage distribution system. The protection range of adaptive current instantaneous protection, irrelevant to the fault type of the power system, will be affected by the different operating mode of the system. When the parameters of power system satisfy certain relations, the minimum protection range will be less than 20% of the line length. The adaptive current instantaneous protection can not to be used in this case. This paper presents an approach to solve this problem by combining the adaptive current instantaneous protection with adaptive voltage instantaneous protection. The term “Integrated Protection” in this paper is used to denote the integration of several protection functions into one protective device. Comparing to the traditional relays on the low-voltage distribution system, which only gets the current or voltage individually, the integrated protection collects not only the message of the current but also the message of the voltage. In this way, this algorithm can be implemented. This paper gives a brief introduction of the basic principle of this algorithm and the method to achieve it in the integrated protection system; the feasibility of the method has been verified by simulation.