Inter-harmonic Detection And Processing Method

With the development of power system and power grid technology,a large number of nonlinear components into the power grid.Due to its own characteristics, the nonlinear components can feedback an irregular voltage and current waveform to the power grid.Irregular waves propagating in the power network are called harmonics.The definition of harmonic in power system is wide.The argument of the inter-harmonics is produced.The definition of the inter-harmonics is the voltage or current of the non integer fundamental frequency.The content of the inter harmonics increases with the increase of nonlinear loads in the power network, and it has a effect on people's life and production in some fields.For example, the inter-harmonic harm to the safety of power system.The use of various power equipment is influenced by the inter-harmonics.The flicker phenomenon of incandescent lamp has been produced by inter-harmonics.Scholars have carried out extensive research on the problem of inter-harmonics.By the definition of inter-harmonic can be seen in the frequency domain the inter-harmonic is random, which gives the detection of inter-harmonic challenges.Detection of inter harmonics is the premise of inter-harmonics governance.Accurate and real-time detection of inter-harmonics in order to achieve the optimal allocation of inter-harmonic compensation device.The characteristic of the inter harmonics is the frequency range is not sure, and the amplitude is small.The interaction of fundamental wave, harmonics and inter-harmonics in power system.In this paper, we first study the existing inter-harmonic correlation algorithm, and then use the non synchronous sampling to detect the frequency spectrum leakage.Previous studies on processing method of spectrum leakage is the weighted way to weaken.The innovative point of this algorithm is to detect the inter-harmonics by using the value of spectrum leakage and the characteristic of fundamental wave, harmonic and inter-harmonic.Spectrum analysis can be obtained by spectral analysis.The value of the main lobe and side lobe integer multiple points,The value of the fundamental and integer harmonics in the frequency point is zero.Inter-harmonics due to the spectral leakage phenomenon at this point will have the value to be taken out.Use of these data can be drawn between inter-harmonic amplitude, frequency and phase parameters, so as to achieve the purpose of inter-harmonic detection.In order to improve the resolution of the inter-harmonics without increasing the amount of computation.This paper based on improved Fast Fourier Transform.The principle of the three point method is to make use of three adjacent points in the discrete spectrum map to do simple operation, so as to obtain a new discrete spectrum to achieve the purpose of increasing the speed of attenuation.This algorithm and the three point method can be very good to combine, through the combination of improving the attenuation rate of FFT, thereby increasing the resolution of multiple inter harmonic.On the basis of the above work, the system simulation is carried out by using the scientific tool Matlab.It is proved that this method can eliminate the interference of fundamental wave and harmonic wave.Simulation results show that the system can effectively detect the correlation parameters of the inter-harmonics in the fundamental, harmonic and inter-harmonic systems.