Harmonic Detection And Suppression Of High Voltage DC Transmission System

In recent years,high voltage DC transmission technology has rapid development in our country.It helps to improve the current situation of China’s uneven distribution of resources.But in the process of DC transmission,system harmonics are inevitable. Therefore,the research on the detection and suppression of high voltage DC transmission system is always a hot research topic.Firstly,we analyzed some reasons for the harmonic generation of HVDC transmission system.And draw a conclusion that the maximum harmonic sources of DC transmission system is converter.And then,we research on the core component converter of HVDC transmission system.Research the harmonic characteristics at AC and DC side.The results show that the characteristic harmonics of AC side and DC side are k112 ? times and12 k times.It provides a theoretical basis for our next harmonic detection and harmonic suppression.Secondly,we have a theoretical study on the detection method of harmonics.Studied the Fourier transform,Wavelet transform and neural network algorithm.In view of the shortcomings of the algorithm, this paper puts forward the optimization of wavelet neural network algorithm.Prove the feasibility of the algorithm by MATLAB simulation experiment.Realizing the harmonic detection on HVDC transmission system.Thirdly, the converter control station select double closed-loop control system. It contains power and voltage outer loop and current inner loop control.And make a voltage limiting link in the power control system.When the system parameters fluctuated,this control system can ensure the system parameter fluctations to a minimum.This method can reduce the fluctuation of the harmonic system,achieveing the purpose of harmonic suppression.In the end.This paper studied the passive suppression of harmonics.Mainly studied the working principle and working mode of active filter and passive filter.Optimization of the passive filter parameters to reduce the construction cost of passive filter.It can also improve the filtering effect of passive filter.In this paper,the harmonics of HVDC transmission system selected the parallel hybrid filter to suppress the harmonics.And proved the filtering effect of hybrid filter by the MATLAB simulation.