Distributed Fault Self-healing Technology With 5G Communication In Active Distribution Network

Due to the widespread and distributed access of new energy and the requirements for reliable and high-quality power supply,the research on distributed and fast fault self-healing in distribution network is particularly critical,which has the advantages of small burden,flexibility and speed.The rapid development of 5G wireless technology provides an excellent means of communication for distributed control.In 5G network,terminals installed in the power system exchange information with each other,so as to realize accurate fault location,rapid isolation and rapid power recovery.Under this background,the current technologies only apply 5G mechanically in a simple power system and do not form a systematic study.Therefore,in order to make full use of the advantages of 5G and better combine it with self-healing technology,this paper mainly conducts the following research based on engineering application:(1)Summarize the key technologies of 5G and analyze its adaptability as the communication medium.Firstly,the network structure of 5G and the key technologies of access network,bearer network and core network are briefly introduced.Then,aiming at several key indicators such as delay,transmission rate,reliability and security in the uRLLC slice,the adaptability is analyzed in the form of theory and test.Finally,under the premise of controlling reliability,the delay of distributed control with 5G is tested in different scenarios such as indoor,outdoor and with background traffic.Analysis results show the feasibility and adaptability of 5G.(2)Research on synchronization methods for distributed fault self-healing based on the fault information and 5G network.In distributed fault self-healing(DFSH)technology,both fault location and recovery processes require data synchronization.On the one hand,in order to improve the synchronization accuracy based on fault information,an accurate fault time detection method for distribution network based on the combination of voltage and current sudden-change and morphology is proposed.The data window is selected based on the sudden-change of phase current and voltage,and then these data are processed with multi-resolution morphological gradient operator.Considering the actual fault situation in distribution network,the structural elements with constant length and amplitude are selected to obtain the gradient signal highlighting the sudden-change of the waveform,and then the fault time is extracted from the extreme point position of the gradient signal.Simulation and data in field verify the detection accuracy of the method,which can achieve high-precision synchronization of both sides of one section and the whole fault line based on fault information.On the other hand,the synchronization method based on 5G network is studied,and a time service scheme based on 5G network is proposed using the time information involved in 5G standards.When 5G technology is mature,high-precision synchronization of the entire system can be achieved.(3)Research on the fast DFSH strategy for 5G communication.As the basis of this technology,a distributed information identification and storage method for distribution network topology layering and zoning is proposed.Aiming at the problem that the 5G communication delay is higher than that of industrial ethernet,the network topology is divided into layers and zones,and the distributed information query and storage strategy is proposed,which is applicable to the multi-branch and multi-connected distribution network,and can adapt to the changes of network operation status.As a key of this technology,a new differential criterion with amplitude and phase angle decoupling is proposed to better adapt to the active distribution network(ADN).Based on the obtained topology information,a distributed fast island detection and power supply recovery strategy is designed,which shortens the overall recovery time by reducing the number of information transmission.(4)Based on the proposed method and strategy,the DFSH function is implemented in a 5G communication terminal,and the RTDS is used for closed-loop testing.By simulating different situations,the performance of the terminal is tested,and the effectiveness of the proposed technology is verified.