Research On Intelligent Distributed Feeder Automation System For Urban Distribution Network

Cable lines are common in the urban distribution network, which contains both overhead lines and cable lines. Several contact switches has been one of the notable features in urban distribution network. Once trip-out accident occurs, the downstream loads of the fault region could be returned to normal power supply by contact lines, which have the advantages of flexibility and economics. Under the circumstances of more power supply instauration path of distribution network after the fault isolation, it also brings the problem of how to find out the optimal recovery path as soon as possible. Two types of feeder automation system are wide used in the present urban distribution network:One is feeder automation system which needs the coordination between automatic reclosing of the substation and section switches. But it only works when a fault occurs. And the fault-processing time has been pretty long since the fault treatment process has to be dealt with according to the strict protective principles. The other one is centralized feeder automation system, which relies on the real time supervision with communication network and the power distribution automation master station. With the development of communication technology and the intelligent power distribution terminal, intelligent distributed feeder automation system is bound to develop into a new operation mode of distribution automation system for its quick speed of fault handling and strong power of rapid restoration of non-fault section loads.As a solution, an intelligent distributed feeder automation system for urban distribution network is proposed in the paper. The system could identify the real-time distribution network topology automatically, and deal with the fault by smart terminal unit (STU).With the current and switch status information detected by the local and adjacent terminal, the system can quickly locate the fault zone. Even though it has to face the changes of operation mode at any time, it is easy to handle with the fault, without PT or power directional relay, without the cooperation and the synchronization of time. The main work is as follows.The structure and characteristics of ’hand in hand ’ring network and ’multi-sectioned and multi-contact’ ring network of urban distribution network are analyzed and summarized. And the wiring of both these two ring modes and a mode of fault handling methods are highlighted.The structure of intelligent distributed feeder automation system is proposed. The logic of fault location and isolation of different positions is elaborated. And the mechanism of opening the rapid reclosing of various switches, basing on intelligent distributed controlling, to achieve the recovery from the temporary fault is presented. Also, the paper introduces briefly the mechanism of recovery from permanent fault.The importance of the real-time distribution network topology recognition in intelligent distributed feeder automation system is analyzed. The network topology which containing the concept of static topology and dynamic topology is proposed. And the principle of real-time distribution network topology recognition by inquiring step by step with STUs of the feeder is described. Although the distribution network wiring pattern and the operation mode change constantly, the STU can achieve the update of real-time feeder topology through the real-time detection and update of the switch configuration information.Complying with the basic principles of the feeder power supply recovery after the fault isolation, the way of determining the optimal recovery path is proposed, which is confirmed by comparing the size between the load’s capacity waiting for the recovery and the contact feeder’s capacity. The fault restoration algorithm in the case of insufficient spare capacity and multi-contact lines is analyzed. And the mechanism of power supply recovery of the intelligent distributed feeder automation system’s application in cable lines, as an example, is described under the circumstance of multi-contact distribution network.In the end, the practical engineering application of the intelligent distributed feeder automation system in Zhongxin Knowledge City, Guangzhou, as an example, is simulated by the Matlab software for various possible faults arising in different positions of the distribution network. And the running condition of the system is analyzed, which verifies the effectiveness and feasibility of intelligent distributed feeder automation system.