Research And Design Of On-line Monitoring Device Of MOA

Metal Oxide Arrester (MOA) is an important overvoltage protection device, which not only exerts a huge impact on the safe operation of electric equipment, but also influences economic benefits of the power system, especially, in terms of the economic benefits of high-voltage transmission system.With the rapid development of power industry, accordingly MOA has a more and more widely applications.In order to reduce power accident caused by MOA's aging, moisture and other factors. Usually the MOA monitors are used for on-line inspection to effectively prevent electrical accidents. Therefore, the research of online MOA monitor has a high social significance and a wild range of practical value.The paper introduces some currently popular methods of MOA monitor, and explains the advantages and disadvantages of the full current law, compensation method, frequency analysis method, the third harmonic resistive current method and dielectric loss method. Harmonic analysis is an ideal means of detectios because of its better noise immunity and stability. Therefore, the paper has in-depth studied the principle of harmonic analysis method, analysed the reasons and solutions of spectrum leakage and fence effect. After that, the paper presents dielectric loss means based on Hanning window interprolation FFT algorithms. The simulation results, brought by fundamental frequency, sampling point, the data length of truncation and the white noise, show that the harmonic analysis method with Hanning window interprolation FFT algorithms has high measurement accuracy,anti-interference characteristics and easy to achieve in the DSP.According the functional requirements of the mornitoring devices, a kind of On-line monitoring device of MOA structure, TMS320F2812 as processor, ADS8364 as analog data converters and STR-18 as communication module, is presented.The paper gives the general schematic of Hardware design, the main module flow chart of software design. At the same time, in order to improve the sampling data consistency and let the worker stay away from high voltage areas to reduce operational risk, the system uses wirelss communication. Finally, the paper completed the wireless communication debug and the menu desiged on LCD interface.