Study On On-line Monitoring System Of Capacitive Equipment For 220kV Liuxu Substation In Guangxi Hechi

The security, stability operation of capacitive equipment and metal oxide arrester (MOA) in substation is significant to power grid. So the study on capacitive equipment and the MOA on-line monitoring system has an important significance for the theory and engineering application. Aiming at the 220kV substation of Liuxu in Guangxi Hechi, this paper studys several key problems, such as: on-line monitoring technologies and methods for the dielectric loss of capacitor equipment and resistive leakage current of MOA, hardware and software design of the on-line monitoring system, as well as on-site installation, operation and so on.â‘ Aim at the problem of the inaccurate result caused by DFT algorithm used in the dielectric loss of electric capacitive equipment when the frequency of power grid is waving, the windowed interpolation algorithm, phase difference correcting method on discrete spectrum method and other DFT phase spectrum correction method were proposed in this paper. And the performance of the method is tested on-site and analyzed. The result indicates that the method has higher stability and accuracy.â‘¡The on-line monitoring of the MOA leakage current resistive component is achieved through harmonic analysis method. This method can not only accurately reflect the total leakage current and resistive current fundamental component, but also have a higher monitoring sensitivity than the conventional compensation method.â‘¢This paper chooses the suitable signal sensor, designs the signal enlarging circuit, filter circuit, frequency-following circuits and sample and hold circuit. Combining with software-controlled it selects A/D integrated data acquisition card of 12-bit high precise which simplify software programming and have higher flexibility and scalability.â‘£The on-site installation program of the 220kV substation of Liuxu in Guangxi Hechi is made, and the installation, commissioning and trial operation of the system are completed. The trial operation results of more than half a year show that the on-line monitoring system can effective monitor the capacitive dielectric loss of equipment and MOA resistive leakage current, and have high stability and accuracy.