Islanding detection of distributed generation based on rate of change of exciter voltage and mechanical power with circuit breaker switching strategy
This paper presents a novel anti-islanding protection method for synchronous Distributed Generation (DG). The proposed method is developed based on the combination of rate of change of exciter voltage (ROCOEV) and mechanical power (MP) and open-close circuit breaker (OCCB) strategy. Whenever the ROCOEV and MP parameters cannot be detected, the OCCB initiates its action. For the practical application of OCCB strategy, the circuit breaker (CB) which connects the DG to the grid is equipped with a recloser. Therefore, by sending a switching command, one-phase of CB at DG connection point, is opened and then immediately closed. This switching causes a variation in the ROCOEV parameter, which is used to detect the islanding. Meanwhile, one-pole opening instead three-poles can limit the transient changes caused by its operation and the amortizations of other poles of breaker are prevented. The proposed strategy only uses the CB at the DG connection point, so it is quite economical. Furthermore, the proposed method does not have any negative impact on the DG stability. The proposed approach is tested on a typical network in MATLAB/Simulink software. The simulation results show that the proposed method has advantages in reduction of non-detection zone (NDZ) and high accuracy compared with previously introduced methods.