The algorithm for the parameters of AC filters in HVDC transmission system

In conjunction with the reactive power exchange and AC voltage control, the issue of harmonic performance is one of the main power quality topics of high voltage direct current (HVDC) transmission projects. AC filters are widely used to restrain the AC side harmonics and to compensate for reactive power. The design of the AC filters has to satisfy the requirements of harmonic performance and reactive power compensation for the various operation modes. First of all the algorithm of the parameters of the single tuned filter are presented. Then during the process of designing double-tuned filter and triple tuned filter, two single tuned filters and three single tuned filters are designed to meet the need of reactive power compensation and the standard of harmonic restraint performance. With the parameters of two or three single tuned filters, formulae are given to calculate the parameters of double tuned filter and triple tuned filter. An example of designing a triple-tuned filter is offered. The impedance frequency characteristics of the three single tuned filters and the triple tuned filter are compared to show that the precision can meet the requirement of projects. Another way of double and triple tuned filter design, which is based on the analysis of circuits and impedance frequency characteristics of AC filters, is introduced. Two methods are compared to show both the advantage and the disadvantage of them.