Research On DIFA System Based On Distributed Control

In recent years,with the development of power system,power supply reliability has been steadily improved.The loss and social impact caused by power outages are gradually reduced.However,compared with some developed countries,there is still much room for improvement.The distribution network,as an important part of power system,has direct impact on the reliability of power supply.At present,the research and development of distribution network in our country is slow,the flexibility is poor,and the coverage rate of distribution automation is relatively low.In general,the development of distribution network lags behind the transmission network seriously,which is the key link of restricting the development of power industry.Doing research on distribution network will promote the reform and development of distribution network and be of great significance to the improvement of power supply reliability.Feeder automation(FA)technology can realize fast fault isolation and power supply restoration,which can effectively reduce the outage time.Currently,according to the control mode,FA can be divided into:local FA,centralized FA and intelligent distributed feeder automation(DIFA).The local FA achieves automatic control with local information,and the system has the advantages of simple structure,rapid action.But it is difficult to achieve optimal control,and only applies to the relatively fixed network structure.Based on the communication network,centralized FA can obtain the measurement information of the whole area and realize the fault isolation and power supply recovery by specific algorithm.It achieves the optimization of control strategy,but the response speed is slow.FA technology is developing towards the direction of DIFA based on the distributed control.It overcomes the disadvantages of the two methods above,and realizes fast fault self-recovery by the information interaction within the region,which can not only improve the control performance,but also avoid the delay caused by the upload of information layer by layer.At present,there are already some researches and application on DIFA technology,but on the whole,no complete theoretical system exists,apply only to the hand-in-hand line and for the multi-contact network,some key problems remains unresolved.Based on the analysis above,this paper carries out the research on DIFA system.First of all,analyze the structure and working principle of the three FA systems,which lays the theoretical foundation for the discussion of DIFA.Secondly,propose the dynamic topology identification method based on distributed control,contact switch automatic judging method and fault recovery algorithm to solve the problems of STU autonomous topology identification and fault optimal restoration control in multi-contact distribution network.Finally,design the prototype to test the theory above,and the experimental results show that the proposed DIFA system can realize fast self-healing based on distributed control.The main innovation points of this paper are as follows:(1)The DIFA fault recovery algorithm of multi-contact distribution network is proposed.The method describes the feeder topology structure by multiway tree and two dimensional arrays.Based on the principle of load balancing,realize the restoration of all nodes from the power nodes layer by layer.The method enables multiple contact switches to participate in the power supply restoration process,and reasonably divides each power supply area,which make full use of the structural advantages of multi-contact distribution network.(2)The dynamic topology identification method based on distributed intelligence is proposed.In the method,the topology information is stored in distributed Smart Terminal Unit(STU).By the network,STU exchange information with each other to access the topology information stored in other terminal,and ultimately through the cascade to complete the topology structure recognition process.The method does not rely on the main station,and has the advantages of autonomy,flexible operation and fast generation.(3)Contact switch automatic judging method is proposed.By constructing the feeder topology of both sides of the target switch,and searching the closed power switch,realize the contact switch fast identification.And the updating of contact switch is triggered by three kinds of mode:initialization,event and timing,to ensure the reliability of the identification process.(4)Build the platform to test the developed DIFA system.Develop the STU prototype,and build the distribution network model by using RTDS simulation platform to test the proposed theory.Results show that the DIFA system can realize fast fault recovery of multi-contact distribution network,and has good application value.The paper studies the theory of DIFA system based on distributed control technology.Topology identification method guarantees the autonomous topology construction of STU,contact switch judging method ensures the dynamic updating of contact switch and the fault recovery algorithm based on the theories above realizes the reasonable division of power supply region.The research results in this paper can reduce the outage time and improve the reliability of power supply,which provides technical support for the popularization and application of DIFA in distribution network.