Distribution Network Planning Considering DGs

Distribution network is the closest part to customers in the power system. Its scientific planning will help to ensure the reasonableness, economy and reliability of power system construction and operation. Economical, flexible and environmentally friendly, distributed generation(DG) technology has attracted much attention in recent years and is developing rapidly. It brings advantages but also impact to traditional distribution network. So there is significance to research DG and distribution network planning. Focusing on the theme of "Distribution Network Planning Considering DGs", the specific work is as follows:Firstly, the concept and classification of the distributed generation technology are introduced. The DG intervention will change power source structure and bring profound influence to power system. The impact of DG intervention on power system operation, management and planning are analyzed from the aspects of power system reliability, relay protection, power quality and network loss.Secondly, the mathematical description of multi-objective optimization problem is introduced and common solution methods are summarized. The bionic algorithms such as particle swarm optimization(PSO) algorithm opens up a new way of solving the multi-objective optimization problem. The basic principle and improvement methods of PSO are introduced, and the significance of the algorithm parameters and their setting principles are discussed. The general process of the algorithm is given as well.Thirdly, distributed power sources processing method in distribution network is discussed. And then distribution network power flow calculation with DG is introduced. A distribution network multi-objective planning model is built, and PSO-w is used to solve the planning problem.The innovation points are:(1) A planning model is built from distribution company perspective, takes minimum distribution network annual cost as object, which includes annual DG construction and maintenance costs, the annual network power loss cost, power purchase cost and financial subsidies. (2) A quantitatively environmental benefits evaluation model is introduced and adopted in DG intervention evaluation. (3) The particle swarm optimization with inertia weight (PSO-w) is used to solve the planning problem. An efficient coding scheme is presented which can determine both placement and capacity. Moreover, a boundary mutation strategy is proposed to improve global searching ability of PSO-w.Finally, the proposed method is adopted in two example system planning--a 40 nodes distribution system and IEEE 14 nodes test distribution system. The basic PSO, PSO-w and PSO-w with boundary mutation strategy are used to solve the planning problem. It shows that PSO-w with boundary mutation strategy has the best comprehensive performance. Both the example system planning achieves good resolution, which verified the correctness and generalizability of the planning model and the solving method. The planning results show that reasonable planning of DGs in distribution network is beneficial to line loss reduction, pollution reduction, voltage improvement and distribution network investment reduction.