Modeling Distribution Overcurrent Protective Devices for Time-Domain Simulations

Poor overcurrent protective device coordination can cause prolonged and unnecessary voltage variation problems. The coordination of many protective devices can be a difficult task and unfortunately, device performance and accuracy are not evaluated once the device settings are chosen and deployed. Ideally, an automated system would interrogate system data at the substation and estimate voltage variations and assess protective device performance. To test the accuracy of the automated system, a simulation model is developed to generate test data. The time-domain overcurrent protective device models can be used to estimate the duration of voltage sag during utility fault clearing operation as well. This paper presents the modeling of overcurrent protective device models created in a time-domain power system simulator. The radial distribution simulation, also made in the same time-domain software, allows testing of different overcurrent protection device settings and placement.