A novel hybrid islanding detection method using dynamic characteristics of synchronous generator and signal processing technique

Integration of the distributed generators (DGs) to power system is growing thanks to their technical, economic and environment benefits. The high penetration of DGs however raises a number of technical problems. One of these problems is islanding, which occurs when one or more DGs continue to energize a portion of the power system which has been isolated from the main grid. Timely islanding detection and discrimination between islanding and non-islanding disturbance conditions are very important for the safety of the personnel and the safe operation of equipment. This paper proposes a hybrid islanding detection method for distribution systems containing synchronous distributed generation (SDG) based on two active and reactive power control loops and a signal processing technique. The operation of the control loops accelerates islanding detection at early stages of instability by processing the terminal voltage of SDG. The proposed method is validated by extensive simulations. The results demonstrate that the proposed method is able to timely and precisely detect islanding situations and can clearly distinguish between islanding and non-islanding events, even if active and reactive power between generation and demand are very close. In addition, the proposed method has negligible impacts on power quality and is capable to allow the islanded system to operate in autonomous mode after separation from the main grid.