A study on the standard setting method of protective devices of Korean distribution system

The protection of the power system for supplying power continuously is very important. However, the power system is very large and complex, so, it cannot be protected by only one protective device. The protective devices closest to the fault location should operate preferentially in order to minimize the fault section. If this main protective device does not operate due to some reason, after the appropriate time delay, the backup protective device should operate to minimize the faulted section. This is called protective coordination. For the protective coordination, the accurate setting of each protective device is important, and these setting values are determined according to each country's guidelines. In this situation, the conventional setting values for the protective devices, which should be calculated by the operators in accordance with the instructions for setting the protective devices, requires a complicated calculation process and the results of the setting values per operator can be different. Therefore, in this paper, we propose a standard-setting value of each protective device for adaptive protective coordination of the Korean distribution system using IEC curve. The standard setting values were presented by dividing the normal distribution system and the large capacity distribution system, and the substation relay presented both of the operating current and the lever. In addition, the lever values of the remaining distribution protective devices were presented in consideration of various errors such as measurement error. Therefore, the proposed method in this paper is an innovative method that the protective coordination is smoothly performed when the operator decides only the operating current of the protective devices. The simulation describes the process of setting the operating current and also confirms that proper protective coordination is carried out.