Impacts of AC Cable to the Risks of Multi-frequency Oscillations of Cable-Connected VSC

Multi-frequency oscillation is a new type of oscillation issue in the power system caused by control interactions of renewable converters and power electronic devices. This paper investigates the impacts of cable parameters to multi-frequency oscillations of voltage source converter (VSC) connected through AC cable. The analysis is based on small-signal sequence impedance models. Due to cable capacitance, the frequency of impedance resonance of cable is much lower than that of transmission line, which raises the risks of oscillation. Also it is found that cable of lower rated voltage has higher risks of multi-frequency oscillations. The theoretical study is demonstrated by time-domain simulations based on PSCAD.