| Relay tester is a major equipment to debug and periodically inspect RelayProtection Device, the reliability of its performance parameters is important to ensurethe safe operation of the power system. Therefore, relay tester’s factory performanceindicators need to be debugged and tested regularly after use. The traditional testmethods needed many kinds of instruments and equipment, and the test process iscomplicated, heavy workload and inefficiency, thus, this paper designs andimplements a precision relay tester test system based on DSP technology and virtualinstrument technology to solve the aforementioned problems of the traditional testmethods. The main work includes:Hardware design of Test System, including the next-bit machine data acquisitionwith DSP as the core and processing unit, PC host computer network communicationinterface hardware design. Lower machine hardware design includes signalconditioning circuits, data acquisition and processing circuit, multi-channel switchingcircuit, the action time detection circuit, communications interface circuits. Dataacquisition and processing unit is designed with TMS320VC33digital signalprocessors and high-speed ADS8364A/D converter, using frequency trackingsynchronous sampling technology, to achieve Real-time detection of six-way voltage,six-way current, and action time and other performance parameters of tester.Software design of Test System, including next-bit machine data acquisition andprocessing software and PC computational analysis processing verification software.This paper made a systematic study on the detection methods of the performanceparameters of relay tester, expounded in detail measurement algorithms of voltageand current Valid Value, frequency, harmonics, other electrical parameter and actiontime; Proposed an improved frequency tracking sampling algorithm based on thewindowed interpolation FFT: it sampled the measured signal first with a certain fixedfrequency, and then used the windowed interpolation FFT algorithm to analyze thesignal and calculate the frequency, according to this calculated frequency which isclosed to the measured signal frequency, in accordance with the principle of simultaneous sampling to adjust the sampling frequency of the next sample, afterseveral cycle times, the measured frequency would be infinitely closed to the signalfrequency, thus achieved the tracking sampling of the signal frequency, and ultimatelyachieved the purpose of synchronous sampling and reducing synchronization errors.This paper focused on the lower software design methods, in order to make the papera complete and make the paper easier to read and understand, the PC software designwas also briefly described.According to the power industry standards, in the end, this paper made a testanalysis of the main performance of the Relay Tester test system. The test resultswere given, and the results were analyzed. The test results show that the systemindicators are at or above the power industry standard and has application value. |
