Research On Dispersed Wind Generation Planning And Optimal Dispatch In Distribution Network

Dispersed wind generation(DWG)has become an important part of wind power industry with its advantages of sufficient resources,local consumption and high flexibility.When dispersed wind generation integrated to the distribution network,its location,capacity and operation mode have an impact on the power flow,node voltage and power loss of the distribution network.In order to improve the wind power accommodation capacity and ensure the economic,safe and reliable operation of distribution network with dispersed wind generation integration,it is necessary to conduct research around the planning and operation stage of dispersed wind generation.Therefore,in the planning stage,a planning method for dispersed wind generation considering both distribution network operation and wind resources is proposed to make full use of wind energy resources and reduce the adverse impact of wind power integration.In the operation stage,the distribution network optimal dispatching model considering the reactive power capacity of dispersed wind generation is established to optimize the system operation by dispatching reactive power output of dispersed wind generation.The main contents are as follows:(1)Bi-level planning method of dispersed wind generation: a dispersed wind generation planning model is established considering the time-scale characteristics of wind power and load as well as the scheduling operation of controllable distributed resources.The upper level model focues on the planning problem over a long-time scale,which decides the access location and capacity of dispersed wind generation and energy storage system under the objective of minimizing the annual comprehensive cost.The lower level model solves the operation problem on a short-time scale,which decides the operation strategy of energy storage system with the objective of minimizing the voltage deviation and network loss.Simulations based on the IEEE 33-node system and a 111-node system adapted from a real case verify that the proposed planning method can effectively reduce the investment and operating costs of the distribution network,while reducing the voltage deviation of the system operation.(2)Planning method of dispersed wind generation considering wind resource variation: due to the limitation of the current planning model which only considers the grid structure and load situation of the distribution network but ignores the wind resource situation,a planning method which considers the wind resource variation is proposed.The model is based on the above bi-level model and takes wind resource variation into account,establishing a Weibull distribution of wind speed and wind turbine output power model.To overcome the high computational cost of the model,a data-driven evolutionary algorithm is adopted with the generalized regression neural network trained by historical data from optimization process as a surrogate model assisting the real model to evaluate of the experimental solution.Finally,based on the same systems,the impact of wind resource variation on the planning results is analyzed and the improvement of the proposed algorithm in solution efficiency is verified.(3)Distribution network optimal dispatching model considering the reactive power capacity of dispersed wind generation: based on the current mainstream model of dispersed wind generation,doublyfed induction wind turbine,the equivalent circuit and power relationship are established,the range of its reactive power output is analyzed,and the linearization method of the coupled active-reactive power output constraint is proposed.Then,an optimal dispatching model for the distribution network with dispersed wind generation is developed,taking into account elements including energy storage system,capacitor banks and static reactive power compensators,with voltage stability and operationa cost as the objectives.Finally,based on the above planning results,the effectiveness of utilizing the reactive power support capacity of dispersed wind generation in reducing system voltage deviation is verified.