Active Power Filter for12-Pulse LCC Converter Employed in LCC-MMC Hybrid HVDC System

LCC (Line Commutated Converter) in HVDC (High Voltage Direct current) systems inject current harmonics in both DC transmission side and AC grids. Therefore, several techniques based on either passive and active filter have been proposed and applied to minimize the effect of these harmonics. This paper designs an SAPF (Shunt Active Power Filter) to compensate for the harmonics of an LCC converter. The control method was utilized based on SRF (Synchronous Reference Frame) theory to calculate reference currents based on dq transformation. This filter is used in a hybrid system consisting of a Twelve-pulse LCC and an MMC (Modular Multi Converter) (300 kV) HVDC system for reactive power reduction and harmonic current control compensation concurrently. A Control-Hardware-in-the-Loop (CHiL) platform is utilized to verify the validity of the proposed system.