Reactive Power Optimization Of Distribution Network With DG Based On The Improved Bacter Colony Chemotaxis Algorithm

Reactive power optimization in distribution system can reduce network losses and improve voltage quality, which has the great significance in power system planning and designing. The access to the bulk power network of distributed generation (DG) is an important method to increase the reliability and flexibility of system network. With the rapid development of inverter technology and the diversification of grid-connected method, photovoltaic power generation and fuel cell which connect to the grid through the inverter and some wind power generations can emit or absorb reactive power as well as the active power. So combining with the traditional reactive power compensation equipment, DG can take part in the reactive compensation to realize the maximization of benefit, and it’s no doubt a subject worthy of study.Firstly, this paper shows the conception, classification and application of DG briefly, and discusses the effect of DG on power flow, line loss and voltage level of distribution network, and taking wind power and photovoltaic generation for example, describes the reactive power output capacity of DG and its adjustability, which lays the foundation for DG to participate in the reactive power compensation.Then, in algorithm ways, this paper adopts bacterial colony chemotaxis algorithm (BCC), which has the sample rules and high speed of calculation. In order to overcome the shortcoming that the basic algorithm traps into local optima easily, on this basis of adaptively adjusting the movement speed, perception range and mutation operator, chaotic mapping is added, which has the ability of traversing the entire space. Then the detailed specific methods and implementation steps of chaotic BCC algorithm is discussed. Through example analysis, the BCC algorithm with chaotic mapping has stronger global searching ability.Finally, this paper establishes a model with the objective of minimizing the active power loss, considering the constraint condition of flow equation, reactive compensation capacity and the output of the DG, and the voltage of load which is over the upper limit is disposed based on the penalty function method, and achieves the optimization objective by controlling the reactive output of DG and traditional compensation equipment. In allusion to the topological structure characteristics of distribution network, the forward-backward sweep method is adopted in power flow calculation, and its basic principle and steps are introduced briefly. By processing the uncertainty problem of DG in flow calculation and the continuous and discrete variables problem in BCC algorithm, the improved BCC algorithm is successfully used for the reactive power optimization of distribution network with DG. Calculations of IEEE33and IEEE69system indicates the improved BCC algorithm has better optimal results, meanwhile, the model and algorithm presented in this article can effectively reduce network losses-and improve voltage-quality, and have good feasibility and practicability.In a word, reactive power optimization in the distribution network with DG can be conducive to give full play to the positive role of DG and make the operation of system more economic and reliable.