Solution to the problem of low order harmonic resonance from HVDC converters

Abstract

The paper identifies a severe form of Low Order Harmonic Resonance problem in an HVdcfac system. It then seeks solutions to the problem by HVdc control means. This is achieved by a proper design of the Voltage Dependent Current Order Limiter (VDCOL), the Current Regulator and Timing Pulse generator. Supplementary control loops have also been introduced to result in a satisfactory performance as compared to that obtained with the use of uncharacteristic harmonic filter on the ac side. Robustness of a11 the options has been demonstrated through recovery performance of the dc link in response to 3-phase 5 cycle faults on both rectifier and inverter commutating buses.

Impact of a virtual resistor on the input admittance of a grid‐connected inverter

“…In a special case, for example, when a high‐voltage direct current (HVDC) transmission system is connected to nearby synchronous generator, instability may occur because of the interaction between power electronic devices and the synchronous generator. This instability can be eliminated by tuning the controller or by employing an alternative control scheme [1,2]. Another cause lies in the constant‐power operation of GCIs [3].…”