Locking frequency band exposure method for islanding detection and prevention in distributed generation

This paper presents a novel active method in islanding detection for distributed generation and microgrids. The proposed method, Locking Frequency Band Exposure (LFBE) is a software-based algorithm that utilizes the microgrid frequency. When power demand in the microgrid exceeds the power generation, frequency falls and when the power demand from the grid matches very closely to that of local generation, the frequency does not vary appreciably. In this method, by measuring the variations of command frequency which is created by adding some disturbance to the sampled frequency at the PCC, islanding can be detected. Assuming the exact power match in the microgrid, Tank or Islanding conditions are experienced. It is also possible to discriminate between these two conditions from the microgrid´s behavior. This proposed method of detection is shown to be robust, able to detect both islanding and tank, and simple to be implemented.