Design Of MOA On-line Tester Based On Embedded System

Arrester is one of the most important apparatus in electrical equipment over voltage protection. The quality of its performance plays an important role in maintaining the safety of electrical equimment. MOA is a newly developed protector and has very good over voltage protection characteristics, which makes it is applied widely in power system. Hence, the on-line testing for MOA is of importance. By applying the MOA on-line testing technology, we can understand the performance condition of MOA at any time without unnecessary power-cut-off overhaul. Thus we can detect the abnormal phenomena and hidden accidents of MOA in time, take measure in advance to prevent the accident from getting worse and to avoid the economic loss resulted from the accident.This paper is based on study and application, the basic theory of MOA tester is introduced, the importance of estimating the performance of MOA by resistive current is analyzed and the method to getting resistive current by phase voltage and leakage current is presented. Based on above study, a MOA on-line tester which consists of phase voltage data collection unit, leakage current data collection unit, data transfer unit and data processing unit is developed. With the functions of real-time data collection, waveform dynamic display, current data storage and historical data inquire, it has a strong practicality in MOA on-line testing.This paper detaied introduces the related theory and implementation process of the embedded MOA on-line tester. The main works of this paper include:(1) Consult relevant literatures, to understand research status of on-line testing about MOA and embedded system, moreover, to make requirement analysis and feasibility analysis for this project.(2) Formulate the overall design scheme for this system. According to the relevant analysis principle of MOA on-line testing, the system is divided into three parts: data collection, data transfers and data process. Data collection part adopts CPLD and FPGA to control the AD conversion of MAX125 to fulfil the sampling signals of both voltage and current. The handheld terminal of data process part, based on Windows CE operation system, analyze and process the data received from data transfers with USB.(3) The system hardware circuit design. Including selection of hardware chips, circuit schematic design, PCB board design and custom-made, physical hardware to install and test.(4) The system software program design. The controllers of AD converter and ARM bus in data collection part is implemented, the program of setup USB connector and transfer data in S3C2440A is developed, the USB device driver under Windows CE operation system is worked out, the program of data collection in application software is designed.(5) Summarize this paper. Point out that the problems existing in the design and the next work.The application of this system will help to testing the status of MOA and the electric power system can run in the reliable state by inquire and analyse the historical data. Further more, we will add more functions of the handheld terminal to face the demand of building intelligent and powerful grid.