Study of Resonance Issues Between HVDC Link and Power System Components Using EMT Simulations

High Voltage Direct Current (HVDC) systems are increasingly popular in electric power grids. Control system of such devices can cause instabilities when interacting with other equipment in a power system. Depending on the control system dynamics, instability and resonance can occur in a wide range of frequencies (up to few kHz). Low and high frequency resonances have been registered in several power electronics based project. In this article, several realistic test cases where oscillations can occur between HVDC links and power system components are illustrated using electromagnetic transient (EMT) simulations. In order to analysis and identify the cause of such instabilities, this paper illustrates how to conduct a frequency domain analysis by means of EMT time domain simulation. As EMT-type models provided by the manufacturers are often inaccessible (or black-boxed), the method presented considers black-boxed HVDC link model.