An Isolation Detection Technique for Distributed Generators Based on Inverter for Power Quality Improvement

Abstract

In the present paper, an isolation method of detection for the inverter-based system of Distributed generators is proposed and based on perturbing output of reactive power. In the proposed method two sets of the disturbances are designed and have different magnitudes and time durations. In the primary set of reactive power disturbance, amplitudes are periodic and small to break reactive power balancing during isolation process. The secondary set of reactive power disturbance is required for deviation of the frequency beyond its threshold limits. The characteristics of the frequency variations with primary set after isolation are considered and three criterion are designed for switching the disturbances from primary set to secondary set of RPD. All the DGs which are located at different positions have same variation in frequency characteristics and primary set of RPD can be added to different DGs without any further communication at the same instant. Here, synchronization of the secondary set of disturbances can be guaranteed for a system with the multiple DGs. The proposed method is applied to DGs which operate at UPF or for supplying of reactive power to the local loads and the method is validated with cases mentioned in the Matlab/Simulink environment.