An intelligent islanding technique considering load balance for distribution system with DGs

The island is an important operation mode of distribution system with distributed generators. The principles of islanding are presented. Based on the simplified model of distribution system, a new concept of cell is defined and an islanding mathematic model as well as a heuristic islanding algorithm through combining cells is proposed. The algorithm can well satisfy the constraint conditions while the process of islanding, and achieve a feasible islanding scheme in a short time. Thus, the operation mode of distribution system can change swiftly under fault states. The load grade attribute is utilized to enhance islanding algorithm selective to load. Thus, the method ensures not only priority services for important loads, but also be compatible with the under-frequency load shedding(1).