Feeder Terminal Cpu Module Developed

Distribution Automation is an inevitable direction in the modernization progress of power system,because it can obviously improve the reliability and efficiency of distribution network,raise the quality of supplied power energy.Feeder Automation is a subset of Distribution Automation,which refers that in common condition breakers' status and feeders' current and voltage are tele-watched in the control center while breakers' breaking or closing operation can be manipulated by the center when in need,in fault situation it also aquires the fault infomation,decides and isolates the fault area,and resumes the power supplying of non-fault area.FTUs(Feeder Terminal Unit) are the core of Distribution Automation System,who are mainly in charge of both the remote data acquisition and communitcation with Master Station.FTUs are made up of CPU module,I/O module,power supply module,charger,storage battery,shell and all kinds of accessories.This paper is limited only to the development of CPU module,including the design of hardware circuit and the algorithm implement of software.The whole hardware circuit design was accomplished in Protel 99 SE, furthermore, the implement of MAX7128S inner logic was finished in Max Plus II V10.3.The high-powered Digital Signal Processor-TMS320F206 is used as Central Processing Unit,who can improve the data processing ability of the whole system. The simultaneously sampling A/D converter— MAX 125 is adopted to decrease the phase difference between voltage and current because of non-synchronous sampling. A piece of Complex Programmable Logic Device--MAX7128S is introduced to accomplish the task of Teleindication Input,Telecontrol Output and decorder,as can drastically simplify the circuit board design.Also,the author devises a frequency measuring circuit to track the fluctuation of power network frequency,accordingly adjusting the sampling interval of A/D convertors to guarantee the furthest even distributing of sampling values in a cycle.Software programming was completed in Code Composor 4.2,an Integrated Development Environment provided by Texas Instruments.Most programme was accomplished with ANSI C Language,except very little relating to CPU registers with assemble language.This paper introduces the embedded Real-Time OperatingSystem--uC/OS-II V2.52 as the base of whole software system.After uC/OS-II successfully transplanted into F206,the application software is devided into several tasks such as Task Telemetering, Task Teleindication, Task Communication and so on. In Task Protection,the author adopts FFT algorithm to improve the accuracy of fault detection,at the same time providing original data for harmonic analysis.In Task Communication DNP3.0 is introduced as the protocol between FTUs and Master Station,not only increasing sharply the dependability of data transmission but also ensuring strongly the compatibility with other company's products.The result of test shows that the operating speed and calculation precision in digital signal processing has been increased drastically by using F206.Moreover,the system Real Time performance,especially the response speed of higher priority tasks such as Task Teleindication and Task Protection, has been improved distinctly with the use of RTOS in FTU products.AIso, uC/OS-II being introduced as the basis of whole software not only facilitated the modulization design and increased the dependability of application software,but also reduced the developing time.And because of DNP3.0 being adopted as protocol, the architecture of whole Task Communication looks very clear,as also carrys out the modulization idea in designing software.