Oscillation Suppression Method in Multi-VSC System Based on Parameter Optimization

Voltage source converters (VSCs) connecting to the power grid and interacting with it may cause system oscillations. One significant reason for the oscillations is the mismatch of control parameters in VSCs. Therefore, parameter optimization is an important method to suppress system oscillations. However, the existing parameter optimization methods have failed to provide quantified values for parameter optimization. To solve this issue, a stability evaluation function based on double Gerschgorin discs is proposed in this article to quantitatively evaluate the stability of the multi-VSC system. Then, based on the stability evaluation function, a parameter sensitivity method is proposed to identify the key parameters that cause system oscillations. Finally, the corresponding parameter optimization method is used to obtain the quantified parameter optimization values through iterative calculations, which provides targeted guidance and suggestions for suppressing system oscillation. The parameter optimization method is validated based on the simulation results of a three-VSC system with differentiated control parameters.

I. Introduction

In recent years, new energy generation has developed rapidly. The voltage source converter (VSC) is widely used at the interface of new energy integration into the power grid because of its efficient and flexible characteristics. However, the interaction between VSCs and the power grid can precipitate wideband oscillations ranging from a few Hz to several kHz. Such oscillations pose a significant risk to the secure and consistent operation of the power grid [1]. Effectively curtailing these wideband oscillations, emanating from the integration of VSCs, is imperative for ensuring the reliability of the system.