Research On Harmonic Detection Technology Based On Improved Variational Mode Decomposition

With China’s strong support for clean energy,a large number of distributed power sources,such as wind power and photovoltaic,are connected to the national grid,which not only enriches the forms of power,but also makes the voltage components in the grid more complex,and the problem of harmonics becomes increasingly prominent.For equipment,harmonics will not only shorten its service cycle,but also affect the normal operation of high-precision equipment.For the power grid,harmonics can also lead to increased losses in the system.Therefore,improving the accuracy of harmonic detection is of great significance to the improvement of power grid harmonics.In order to improve the detection ability of harmonic signals,this dissertation mainly carries out research work in the following aspects:1.A variational mode decomposition harmonic detection method based on genetic particle swarm is proposed.Firstly,the genetic particle swarm optimization algorithm is used to calculate the optimal number of iterations,K.Then,the variational mode decomposition algorithm is used to decompose the signal into K IMF components.Finally,the amplitude and frequency of each IMF component are calculated to complete the harmonic detection.Fast Fourier transform(FFT),empirical mode decomposition(EMD)and genetic particle swarm(GPSO)based variational mode decomposition(VMD)algorithm were used to compare the simulation signals,and the effectiveness of the proposed VMD algorithm was verified.2.The hardware of the harmonic detection device based on the genetic particle swarm variational mode harmonic detection algorithm is designed,including the overall structure design of the hardware circuit,signal acquisition module,signal conditioning module,A/D sampling module,DSP minimum system,power supply module and peripheral module.3.The software programming of harmonic detection device based on genetic particle swarm optimization(GPSO)was completed,including the overall framework of the software,the main program design,the initialization program design and the interrupt program design of the GPSO and the VMD algorithm.4.The device of variational mode harmonic detection algorithm based on genetic particle swarm is verified experimentally.The experimental results show that there is little difference between the amplitude and the content of each harmonic measured by the designed harmonic detection device and the daily PQ3100,which proves that the software and hardware designed in this dissertation are effective.