Optimal Planning Of Distributed Generation

Distributed generation (DG) has advantages of saving investment, reducing loss, improving system reliability, diversifying energy resources and so on. This technology will be the developing area in the 21th century. As the extension of DG, it has a great impact on node voltage, power flow, short circuit and reliability of distribution network. The degree of impact is closely relative with the site and size of DG. It will be an essential challenge for network planning and grid planners must consider the influence it brings. According to the growth of system load, distribution network expansion planning with DG gets best system scheme when system reaches capacity limits and least economic cost. The scheme includes new line and substation, site and size of DG. Reasonable site and size of DG is very importance.In this paper, the whole capacity of candidate DG is determined by total new load when considering the new load node. In the condition that DG's number, site and unit size are uncertain, the objective function with the aim of minimizing cost of investment and operation is proposed. And then the genetic algorithm is applied to optimize the site and size of DG. To each scheme of DG's site and size generated by genetic algorithm, this paper considers the effect of DG on power flow and line loading ability of distribution network. After processing distribution network expansion planning using branch exchange based simulated annealing algorithm, every result of integrated DG and network scheme is judged by economic evaluation.The method proposed in this paper can get reasonable site and size of DG through the analysis of practical example. It can also be known that the connection of DG with distribution network can reduce line investment and loss cost by comparing result of distribution network expansion planning with and without DG. DG brings great social and economic benefit.