The Research Of Self-healing Control Strategy For Active Distribution Network

The continuous development of national economy relies on sufficient power supply.In order to reduce the impact of energy crisis and environmental pollution,and ensure national power safety,Distributed Generation(DG)grid connected technology and related technologies have made considerable progress.Because of the active distribution network(Active Distribution Network,ADN)with active management and active control and other initiatives,and coordination of various controllable resources in the distribution network,increase the controllability of the distribution network,the whole network control system from the source of net charge of three levels,improve the system security and DG is the ability to accept,is worthy of a new generation of intelligent power distribution technology.The important function of self-healing ADN as indispensable by the parties concerned,the self-healing process of ADN need to co-ordinate various controllable resources,properly handle various faces during the healing process of the uncertainty factors,focus on grasping the timing characteristics of ADN operation,the comprehensive utilization of ADN island operation control measures to improve the security of the system.In this paper,we have carried out in-depth research on ADN's self-healing control two time system design,implementation of active self-healing adaptive dynamic Island technology and post failure self-healing capability evaluation.The main achievements are as follows:(1)In view of the characteristics of the stratified distribution of controllable resources in ADN,the multi agent system is used to make a comprehensive analysis and decision on the self-healing problem of the distribution network.The three layer multi agent system structure of ADN self healing analysis decision made up of decision layer,coordination layer and equipment layer is established.The technology will provide an intelligent analysis method and decision basis to realize the system in the normal state of operation and the recovery control under the condition of failure.(2)On the basis of the traditional load transfer recovery,a new method of dynamic isolated island division,which considers the more limited risk,is proposed.This method studies the optimal partition and adjustment scheme of isolated island from the whole fault recovery time.First,the CART decision tree is used to predict the power failure time.Then,the total load of the load is recovered as the objective function.After the DG priority index is used to identify the main power supply,the dynamic islanding is carried out during the blackout period.Aiming at the fluctuation of load and DG output,we define the risk index of island power overshoot,and establish chance constraint condition in mathematical model,so as to ensure the continuity and stability of island operation.In the whole failure recovery period,the island area can be dynamically adjusted with the output curve of load and DG,so as to realize the full use of DG and the maximum recovery of load.Through the comparison and analysis of the example,the rationality and superiority of the proposed optimization method is verified.(3)A method for evaluating self recovery capacity of active distribution network after failure is proposed,which takes account of the load and DG timing characteristics.The evaluation index system of self healing capacity after failure is established,and the method of self-healing ability evaluation is put forward.The self-healing ability evaluation index,establish the index recovery rate,recovery rate,self-healing control operation complexity,self-healing sustainable time coverage four quantitative,covering a range of load,the distribution network fault recovery after the speed and difficulty of operation,sustainable time etc..Then,based on the time series data of load and DG output,the total self-healing ability of different periods,branches and all day systems is quantitatively assessed through the proposed evaluation method,and the accurate location of ADN self healing weak period and weak branch is achieved.The advantages and effectiveness of the proposed method are verified by an example analysis.