Distributed Generation Capacity Planning Based On Bi-level Optimization

People demand on power supply increasingly much and energy crisis as well as environmental pollution problems have become increasingly prominent,which lead to traditional centralized power supply has been unable to meet the requirements of the future development of electric power.The distributed generation has the characteristics of flexible,clean,environmental protection,high efficiency and so on,which can make up the deficiencies of the traditional centralized power supply.Distributed generation has got the attention all over the world.The combination of distributed generation and public grid is the future development trend of electricity.However,the access of distributed generation brings a series of problems,such as power quality pollution,control complexity and so on.It is a subject that is worth deeply studying and has important application value to carry out the planning of distributed generation,which is beneficial to give full play to its advantages and weaken its negative effects.In the electricity market environment,the stratum characteristic of power system becomes more and more obvious,and the hierarchical coordination decision becomes the important way of system optimization.Bi-level optimization can effectively deal with the two layer hierarchical decision problem,which has a wide application space in the electricity market.In this paper,based on bi-level theory,distributed generation capacity planning models are established and solved.The main work of this paper is as follows:Based on the annual load duration curve,the model of capacity planning for distributed generation in distribution network is established.A bi-level optimization model for distributed generation planning is established,in which the subject of upper-level is distributed generation investor and the subject of lower-level is distribution network operator.In the upper-level of this model,the goal is to maximize its investment profit which can be expressed as generating profits minus investment costs.The goal of lower-level is to minimize the operating costs of distribution network.Wind power output is uncertain,and its cost of investment is relatively large,making wind power planning is more complex than the conventional generation planning.In this paper,we further study the problem of wind power capacity planning in microgrid.A bi-level optimization model of wind power investor and microgrid management is established.In this model,the stochastic characteristic of wind power is expressed by scenarios.In the upper-level,some subsidies are considered to attract the investor,and the wind power priceusing marginal price.The upper-level optimization goal is to maximize the investment profit.The lower-level optimization objective is the minimum cost of microgrid power supply.For the above capacity planning bi-level optimization models,Karush-Kuhn-Tucker optimality conditions are used to convert the lower-level optimization into the upper-level constraints.Then,the nonlinear constraints arising in the transformation process are linearized so that the bi-level optimization model can be solved easily.The effectiveness of the proposed models and algorithm are verified by numerical simulation.