Analytical Small-Signal Modelling of Diode-Rectifier based HVDC Link Based on Physical Switching Actions of Diodes

The diode-rectifier High-Voltage Direct-Current (HVDC) link provides a cost-effective energy transportation method for far-offshore wind farm. However, it relies on the grid-forming wind turbines to stabilize offshore grid. Herein, we establish an analytical small-signal model of diode-rectifier HVDC link, to provide theoretical bases for the offshore grid control. The proposed modeling approach utilizes the physical switching actions of diodes to relate the ac and dc variables of diode rectifier, which allows to fully preserve the dynamics of passive components at ac and dc sides, and meanwhile accurately captures frequency-coupling effects induced by the diodes’ nonlinear switching actions. The accuracy of the proposed small- signal model is validated by the frequency scanning in the electromagnetic transient (EMT) time-domain simulation.