Abstract: The introduction of high-capacity DG into the distribution network will break through the power flow limit, and also affects the safe operation of distribution network. SNOP-based flexible distribution network provides a new way for improving the allowable DG penetration capacity. With bidirectional power regulation capability, SNOP helps to improve the bottleneck status of bus/branch in distribution network, achieves active regulation of power flow, and improves the DG penetration capacity. Firstly, this paper establishes the optimization model of DG penetration capacity in the flexible distribution network. Because of the large number of network nodes, the model belongs to high dimensional nonlinear optimization problem. Secondly, according to the actual scenario and parameter settings, the analysis is divided into three cases: 1） fixed position of DG in traditional distribution network, 2） fixed position of DG in flexible distribution network, 3） free access of DG in flexible distribution network. Next, MPGA is used to solve the problem, which can get the global optimal solution. Finally, a case of IEEE 33-bus distribution network is used for verification, the optimization result shows that the method not only helps to get the allowable DG penetration capacity, but also shows the best capacity/location scheme.

Key words:  flexible distribution network, SNOP, DG, allowable penetration capacity, MPGA