| Abstract |
Power electronics have been widely used in the transmission systems due to its capability to control the power flows as well as the voltages and currents. However, in the renewable energy transmission system, the weak-grid will make the VSCs work under nonlinear domain, where their behavior are quite different from the linear case. What's more, the interconnected VSCs are sometimes used to ensure more robust and flexible power transmission, leading to a multi-machine system, where the predominant nonlinear oscillations should be studied to suggest more information in designing the parameters of the system. This paper proposed a methodology to offer analytical results to predict nonlinear interaction for both oscillation amplitude and frequency-shift while avoiding numerical simulation of huge computational burden. Based on Normal Form theory, this methodology can be applied to large-scale power system that exhibits behavior of N coupled second-order oscillators. The nonlinear indices are then proposed to quantify the parameter impact on the nonlinear system dynamics. |
