Research On AC Filter Design Principle And Method For Multi-Circuit HVDC In The Same Converter Station

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. Multi-Circuit HVDC in the same converter station causes more difficulties of AC filter design.AC harmonics calculation is the base of AC filter design. Both performance calculation and rating calculation of ac filters need the ac harmonic result. This paper first studies the algorism of ac harmonic calculation, especially the effects of non-characteristic harmonics. In the end of this chapter the model of the multi-circuit HVDC projects is given.The following chapter has a thorough research on the parameter calculation of ac filters. 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 parameter for double-tuned filter and triple-tuned filter. At last performance calculation and rating calculation are made to verify the design of AC filters for meeting HVDC transmission projects' requirement. An example of designing a triple-tuned filter is given. The impedance frequency characteristics of the three single tuned filters and the triple tuned filter are compared to show that the difference between them is in the tolerance of projects. Another way of two and three tuned filter design, which is based on the analysis of circuits and impedance frequency characteristics of AC filter is introduced. Two methods are compared to show both the advantage and the disadvantage of them.In the last two chapters, for both performance and rating calculation of multi-circuit HVDC project ac filters, the paper describes the models and the calculation methods with examples.