Analysis Method for Supraharmonics of Voltage Source Converters with Dual Dynamic Phasors

This paper proposes a dual dynamic phasor analysis method for the supraharmonics (SHs) in voltage source converters (VSCs). With double Fourier transformation, a periodical signal with two different frequencies can be presented in frequency domain. Pulse width modulation (PWM) with modulation signals and carrier signals can be depicted as dual dynamic phasors (DDPs) defined by the double Fourier transformation. DDPs can be also transformed into dual dynamic phasor sequence components (DDPSCs) by symmetrical component method. With DDPs and DDPSCs, an analysis model of VSC can be developed as a state space equation, which can describe the switching dynamics and the SH interactions between ac and dc side. Simulations in different situations are applied to verify the correctness of the analysis model and some interesting findings are given in the paper.