Research On On-line Monitoring Of The Insulation Condition Of Capacitive Equipment

On-line monitoring technology is a real-time method which can not only monitor theinsulation condition but also get the characteristic parameters. Dielectric loss, capacitanceand leakage current are more sensitive parameters reflecting the defect. Among them,tan is an important parameter reflecting the insulation condition of capacitive devices, Inthis paper, the research object is transformer bushing.(1)Designed bipolar signal isolation circuit, a detailed analysis of the workingprinciple of the signal isolation circuit based on HCNR200. The actual proportion betweenoutput and input voltage remained at1.01.(2) In this paper, in order to increase the principles of software, using graphicalprogramming language-LabVIEW developed a real-time transformer bushing dielectricloss angle measurement software: Using wavelet filter out noise pollution and dielectricloss angle trend extraction; calculated current and voltage parameters for the gridfrequency fluctuations using windowed interpolation method effectively overcome theerrors due to the spectral leakage and picket fence effect caused by non-integer samplingcycle brings, collecting the mean of10measurement as the final output value; In order tohave a real-time recording and easy measurement history data query, the measurement datais saved to Access2010and Excel based on SQL.(3)For the assessment of insulation state, To improve the calculation of target inthe traditional grey target theory, in which method the approaching degree of every indexis consistent. In order to improve the precision of the traditional grey target theory,weighted grey target approaching degree calculation method is proposed.