Arm7 Microprocessor-based Distance Protection

In the modern power network,the security and stability during power system's operating is required higher and more strictly,with the raising of the extra-high-pressure, high-capacity and long-distance power transmission line.Distance relay is the primary element of the transmission line protection,the performance characteristic of which has a direct and vital affect on the security and stability during power system's operating.For adapting to requirement for working stably in the modern extra-high-pressure power network,microprocessor-based distance relays are required higher and higher on not only hardware but software.On the base of generalizing the existing condition of microprocessor-based distance relays at the power transmission line,this subject analyzed the existing condition of the hardware of distance relays,compared 8-bit,16-bit SCM and 32-bit DSP protection scheme,and generalized there merits and demerits,then gave a scheme of relays based on ARM processor.This device used DEVICEARM2200 made by Zhouligong company to be the protective CPU,which mainly answered for controlling data acquisition,the sampled data processing,the protective function implementation,the human machine interface(HMI)and peripheral serial interface and Ethernet communication,and used other devices to be assistant to control sampling/holding,multi-path option switch and the I/O switching value.The subject realized the hardware design of the microprocessor-based protection scheme,and completed the designs of processor's peripheral circuits and sampling circuit.Analyzed the software-designed of the existing protection algorithms and function control in and abroad,this subject transplants real-time operating systemμC/OS-Ⅱto the protective device.Relative to hardware's fast development,the software's development is slowly,the present microprocessor protection generally uses the liner program of the assembly language.Although this design method has the code fining,carries out the efficiency higher merit in certain key operations,but the programmers want the overall planning memory arrangement,the data dispatch,the resource distribution and so on,so it causes the software development cycle to be long and difficult.Moreover,because the different programmers have the different thought customs and ways,it causes the software difficulty to exchange,transplant and maintenance.This subject unifies real-time operating systemμC/OS-Ⅱand the modulation hardware design,and constitutes one software and hardware number system platform. Besides maximum limit enhanced the efficiency of development and reduced the waste of resource,it may also enhance its performance with regarding the platform and optimizing the platform software and hardware resources.And it also meets the complex application need day by day.This subject attempts to realize the protection parallel processing with the duty way,it will not only enhance software's readability and the reliability greatly,but also provide the condition of the duty expansion.