Triple tuned harmonic filters-design principle and operating experience

The way an HVDC converter station is installed in an AC system will affect the power quality in that system. It is always one of the most important issues. In conjunction with the reactive power exchange and AC voltage control the issue of harmonic performance is one of the main power quality topics and will become increasingly important in the future. Thus, innovative solutions are needed to meet the increased demand for technical improvements in combination with competitive costs. The design of the AC filters has to satisfy the requirements of harmonic performance and reactive power compensation for the various operation modes and in the whole range of operation. Rigorous requirements on performance and reactive power exchange result in complex filter schemes with several different types and high component ratings. Taking these design aspects into account the use of triple tuned filters provides a significant optimization potential. This paper introduces first the design principle and further highlights the major technical features of this innovative AC filter concept. The experience gained during the commissioning tests and the subsequent commercial operation in the HVDC schemes 'EGAT-TNB 300 MW HVDC Interconnection' and Moyle Interconnector' are reported as well.