Flexibility Improvement Optimization Method of Distribution Network with High DG Penetration

High distributed generations (DGs) penetration connected into the distribution network leads to the fluctuation and uncertainty in distribution network. In order to improve the capability of uncertainty treatment of distribution network, the flexibility enhancement of distribution network with high DG penetration is studied. Firstly, the flexibility demand of distribution network with high DG penetration is explored. Then, five distribution network flexibility evaluation indexes are proposed, which include line capacity margin, transformer capacity margin upward, transformer capacity margin downward, net load fluctuation rate and maximum allowable net load fluctuation rate, what represents the flexibility adequacy of distribution network capacity and the flexibility adaption of the embedded distributed generations, respectively. A multi-objective optimal scheduling model is established to improve the flexibility considering interruptible loads and energy storage. Simulation results show that the flexibility of the distribution network with high DGs proportion can be improved by optimizing the scheduling of the flexible resources, and the hosting capability of distribution network for DG accommodation can be increased.