Coordinated Optimization Of Active And Reactive Power In Active Distribution System

With the access of distributed generation,flexible load,energy storage and reactive compensation devices,the traditional distribution network is gradually evolved into the active power distribution system with various controllable resources.And it is an important subject to handle the active and reactive power simultaneously for improving energy efficiency,guaranteeing voltage quality and taking advantage of the full benefits that distributed energy resources bring to the system.Meanwhile,how to deal with the energy uncertainty and load fluctuation has also been a great challenge to the active distribution systems.To solve these problems,this paper has done deep investigation on the mechanism and the mathematical model of active distribution systems' active/reactive power coordinated optimization as well as that taking the uncertainty into account.The main contents of this paper are as follows:(1)The mechanism of active/reactive power coordinated optimization of active distribution systems.First of all,the rules of how active/reactive power control influences the voltage quality and energy loss of distribution systems are analyzed.Then the PQ capacity model of different distributed energy resources are established according to their network synchronization modes.By analyzing the active and reactive power interactions in both distribution system and controlled devices,it is explained that active/reactive power coordinated optimization can promote system's security and economy capacities more fully.(2)Robust coordinated optimization of active and reactive power in active distribution systemsAn active and reactive power coordinated multi-period optimization model based on second-order cone programming is established firstly.Based on this model,this paper put forward a robust active and reactive power coordinated optimization with the consideration of reducing the negative effect of energy uncertainty on the system.By generating typical case sets,the robust strategy can obtain the robust control policy of the active distribution system in extreme cases,which can make the system maintain the stable performance with uncertainties.(3)Multi-time scale active and reactive power coordinated optimal dispatch in active distribution systems based on model predictive control.Considering the requirements of economic and security operations of the active distribution system,an active and reactive power coordinated optimal dispatch of active distribution systems based on model predictive control is proposed.This approach is formed by day-ahead optimization,intra-day rolling optimization and real-time feedback correction,which can handle uncertainties in renewable energy and load.Also,the prosed approach uses the active and reactive power coordinated optimal dispatch to reduce the operating losses and action times of control devices,so that the operational benefits of the network can be maximized while the security is also ensured.