Performance investigation of hybrid active filter during low load condition

A hybrid active filter with a new voltage synchronization control loop is proposed to improve the harmonic content of nonlinear active front end converters for mobile mining equipment. This hybrid filter topology utilizes the DC bus established by the AFE and provides load harmonics at the PCC. Unlike traditional hybrid active filters, this topology uses no real power or control loops to maintain a DC link as this is provided by the AFE. This paper investigates the hybrid active filters performance in two compensation modes, harmonic current only, and both harmonic current and reactive power injection. Necessary considerations for the medium voltage dc testbed topology, real power flow minimization, and the active filter control during worst case load harmonic currents are also discussed.