Research On Configuration Optimization And Reliability Evaluation For Active Distribution Cyber Physical System

With the increasement of distributed generations and uncertain factors in the distribution network,it is difficult for the distribution network to meet the users’ demand for power supply reliability under the new situation.The wide application of communication technology has brought new vitality to the distribution network,and the active distribution network has become the next development direction of the distribution network.By making full use of the controllable parts in the active distribution network,the research work on the communication system that is helpful for the active management,control and service of the electrical side,which could further realize the goal of high operational reliability.Therefore,this thesis takes the characteristics of active distribution network into consideration,and achieves the goal of optimal reliability performance of active distribution network through the good coupling between the power system and the communication system.Then making an overall planning for the access of distributed generations,the setting of tie lines and corresponding communication system of the distribution network.The research work completed mainly includes the following aspects:(1)For most research of distribution network planning,the emergency handling of system operation failures is not considered.This thesis plans and designs the controllable resources involved in the fault handling strategy,such as distributed generations and tie lines.For the problem of unevenness after distributed generations accessed into the distribution network,the entropy of active power distribution based on the power flow tracking model is proposed to measure the power support effect of the distributed generations on the load node.The access optimization model of distributed generations is solved by particle swarm optimization algorithm.From the perspective of the topology of the distribution network,in order to solve the waste of power resources and communication resources caused by the existing contact line settings,the link entropy index is proposed to assess the importance of the tie lines in maintaining structural connectivity,and the setting plan of tie lines is planned to enhance the connectivity of the distribution network.The case study shows that reasonable planning of distributed generations and setting of tie lines have greatly improve the performance of the distribution network,and the effectiveness of the distribution network configuration optimization scheme is verified through complex network indicators.(2)This thesis proposes a control strategy that using distributed generations and tie lines to solve the problem of insufficient power supply when failures happened in the active distribution network,and established a corresponding communication system for controllable parts.The detailed process of constructing a communication system suitable for the active distribution network is proposed,and the modeling of the distribution cyber physical system is also based on this communication system.In order to analyze the influence of the coupling relationship between the power side and the communication side on the control function in the distribution network,this thesis paying more attention on the construction of the communication system suitable for the active distribution network.The case study shows that the coordination of the communication system can improve the power supply reliability of the distribution network.The scenario analysis proves the effectiveness of the control strategy.The reasonable access of distributed generations and the selection of important tie lines not only improve the system reliability,but also reduce the construction cost of the distribution cyber physical system.(3)Based on the active cyber physical system model,analyzing the influence of various factors of the power system and the communication system on the reliability of the distribution network power supply during the process of maintaining a reliable power supply to the load according to the handling strategy during the failure,which provides effective decision-making and technical support.Firstly,the model indicates that the realization of the control function is inseparable from the cooperation of the power system and the communication system;analyzing the output of distributed generations and conditions of tie-line operation conditions affected by the control function,then constructing a reliability evaluation model of the active distribution cyber physical system that considering the influence of the communication system.The results of the calculation example show that: the distribution network uses controllable resources according to the handling strategy with the help of communication technology to respond the failure.Various factors of the power and communication system have different influence on the power supply reliability of the distribution network.In addition,analyzing the influence of different factors on the reliability of distribution network power supply.The case study shows that when the cyber physical system recovers the power supply according to the control strategy with the help of the communication technology after the failure occurred in the distribution network,various factors of the power and communication system have different influence on the power supply reliability of the distribution network.The research work and results of this thesis are of great significance for achieving better operation of the distribution network and improving its reliability.