Design And Implementation Of Remote Terminal Unit For Distributed Feeder Automation

With the rapid development of distributed renewable energy generation,more and more distributed generators are connected to the distribution networks.Power quality and power supply reliability of distribution network are facing many new challenges.Distribution networks with high efficiency and reliability will greatly improve its working condition.Feeder automation technology is the main part of distribution automation technology,which can be used to moniter a feeder,locate a fault,isolate fault area and resume power supply automatically.Intelligent distribution terminal unit is an equipment which dedicated in measurement,control,communication and protection of a distributed network.Distribution terminal units(DTU)form the basis of a feeder automation system.This dissertation designs and develops an intelligent distribution terminal unit which focus on the realization of distributed feeder automation.This DTU uses brand new distributed feeder automation strategy which is based on the wildly used centralized strategy.The main contents of this dissertation are as follows:(1)According to the industry standard,this dissertation puts forward a hardware design scheme of a distribution terminal unit.This distribution terminal unit includes main control module,AC acquisition module,DC acquisition module,switch state input/output module,power supply module and man-machine interface module.There are two main features of this device in hardware.Firstly,master chip uses dual core processor which consist of an ARM and a DSP core.This design get outstanding performance in terms of power consumption,performance and maintainability.Secondly,the terminal has an ethernet switch chip which allow the terminal directly connected to the ring network,which is suitable for distributed feeder automation application.(2)This dissertation proposes core software architecture of distribution terminal,its application software are baesd on Real Time Operating System(RTOS).This dissertation elaborates the realization process and flow of important software functions,such as IEC60870-5-101 and IEC60870-5-104 communication protocol,inter-kernel communication,human-machine interaction,management functions,real-time database,data compression,three section current protection,zero sequence current protection,PT wire disconnection protection,limit voltage protection,fault wave record,power quality index calculation.(3)Analysis of the fault current characteristics of active distribution network.Combined with the characteristics of distribution terminal this dissertation proposed a distributed fault localization algorithm for distribution networks,this method can be applied to all kinds of network topology with DG connection,isolate the fault area accurately and control the influence of power failure in a minimum range.The intelligent power distribution terminal unit has passed the type test and electromagnetic compatibility test of the experimental verification center of National ElectricPower Institute of science and technology.Compared with the similar products,the performance of the device meets the requirements of the industry,but also has lower hardware cost,stronger communication function and more convenient remote management and maintenance method.