Research On The Algorithm Of Dielectric Loss Measurement Based On Harmonic Analysis

With the rapid development of the national economy and society, the demand for the reliability of power supply becomes more and more high; Along with the national construction of strong smart grid planning formulation and implementation, the power industry has been highly valued by the research on the safety operation of power network and electrical equipment. High voltage electrical equipment with large dielectric capacitance is widely used in power system, its ability to run safely and reliably in the system directly affects the reliability of the power system, dielectric loss is particularly sensitive to changes in equipment insulation. So it has theoretical significance and practical value to carry out the research on the dielectric loss measurement of equipment insulation.Dielectric loss line detection is state detection, with real-time and enables continuous power supply. Therefore, this paper carried out research on the method of on-line detecting for the equipment insulation condition.Firstly, the paper theoretically analysised of the mechanism of barrier effect and leakage effects when use harmonic analysis in measuring the dielectric loss angle at the time of frequency fluctuations, proposed the use of windowing and spectrum correction method to improve, and it can effectively inhibit the barrier effect and the leakage effect on the measurement accuracy.Secondly, the paper analysised of the spectral characteristics of different windows function, proposed that applying Blackman Self-convolution weighted interpolation algorithm in measuring dielectric loss, and carried out simulation research, simulation results show that Blackman Self-convolution window can suppressed spectral leakage effectively, interpolation algorithm has higher correction accuracy, and the algorithm increased the measurement accuracy of dielectric loss.Finally, the paper applied all-phase FFT and phase correction method in the measurement of dielectric loss, solved the problem of strict requirements for initial position of the sampling of all phase FFT, and achieved a measure dielectric loss angle can start at any time; The analytical results show the algorithm in the realization of the process is not dependent on the window, the algorithm has good portability, simple and easy to implement, high precision measurement, and it has a higher practical value.