Research On Optimization Of Access Scheme In Distributed Photovoltaic Power Generation Integrated Into Distribution Network

With the rapid development of China's social and economy, the traditional energy is consumed in large quantities, which bring serious environmental problems. Clean energy power generation is an effective way to reduce the traditional energy consumption and improve the environment quality. At present, more and more distributed generation are used and will appeare blowout growth in the future. Due to high permeability and high-density development of grid-connected distributed generation as well as volatility and intermittent characteristics of distributed power output, there are some problem and difficulty in the project of distributed generation jointed in distribution network, such as complex system structures, diverse design schemes, long design time, difficult comparison and optimization. In order to solve these problems, this paper studies improved stochastic power flow calculation method for any probability distribution of distributed generation power output, the influence of distributed generation connected to distribution network, the optimization strategy of distributed generation connected to distribution network considering the randomness of distributed generation. The paper includes the following contents:(1) Aimed at the distribution of any probability density of distributed generation, this paper presents a method for modeling the distribution of power output probability density under any probability distribution. Based on the proposed probability density distribution model, the improved Latin hypercube sampling method was used for the stochastic powe rflow calculation, and the results used the proposed method and standard Monte Carlo are compared to validate the proposed method in this paper is correct.(2) Considering the uncertainty and temporal correlation of power output of distributed generation, this paper analyses the influence of distributed generator connected to distribution network on node voltage, network loss, line power flow and voltage stability from two different scopes by improved stochastic power flow calculation proposed and deterministic power flow calculation. Finally, this paper concludes the key factors which are affected by gird-connected distributed generation.(3) According to the key factors concluded above, this paper proposes quantified indexes to evaluate distributed generation integrated into distribution network and establishes optimization model of distributed generation integrated into distribution network in considering stochastic power output of distributed generation. The objective functions are minimum network loss, highest stability and minimum voltage fluctuation of distribution network. The constraints are limitation of node voltage, power flow and voltage stability. Finally, this paper studies multiobjective optimization of distributed generation integrated into distribution network in three scenarios and solves this multiobjective optimization model using improved differential evolution algorithm.(4) In view of the problem of long design period, this paper develops software to select optimal scheme of distributed generation integrated into distribution network. The software has some practical functions such as fast searching, positioning and matching of space, quering of access information, spatial decision-making of optimal access and auto-generation of access design reports of. The software realizes comparison and optimization of access schemes, and can be used for optimization of access scheme in distributed generation integrated into distribution network in 10kV,380V, and 220V voltage level.