An Accurate DC-Link Voltage Determining Method of LC-Coupling Voltage Source Converter (VSC) Under High THD Operating Environment

$LC$ -coupling voltage source converters (VSCs) or called hybrid active power filters (HAPF), have been developed based on the L-coupling VSC or called active power filters (APF) in the power quality compensation field to save the operating and manufacturing costs of APF. In the HAPFs system, dc-link voltage is one of the critical design parameters to success compensate for the load. In previous research, a dc-link reference voltage is calculated as the root mean square (RMS) value of each order harmonics based on the fast Fourier transform (FFT) result of harmonic. However, under a high total harmonic distortion (THD) environment, this method may conclude a low dc-link reference value and result in a poor compensating result. This paper proposes a dc-link voltage references calculation method based on the compensating harmonic current slope and the load reactive current power to fulfill the compensating requirements. To verify the proposed method, a typical HAPF topology, and its control are introduced. And a comparative simulation based on all the above contents is provided to show that HAPF can fully compensate for the load harmonics and reactive power with the proposed calculation method.