Multi‐scale transient modelling and simulation for distribution network‐interactive CHB multilevel converters

Wave Function and Multiscale Modeling of MMC-HVdc System for Wide-Frequency Transient Simulation

“…Assuming the modulation in Appendix B generates the reference with the magnitude M (t) and phase angle ∆θ dy (t), which present low-frequency dynamics. As the NLM in [24], ω c t dn (t) = ∆θ dy (t) + ∆θ actn (t) in which ∆θ actn is the angle distance between the two SM WPFs. Using trigonometric decomposition and adding the terminal voltages of all N SMs on the upper arm, i.e.…”

“…3, the current injected into the individual capacitor is decoupled with the dc and ac parts, and furthermore the capacitor voltage can be decomposed into different frequency components. As a consequence, for the simplicity, the companion model of the dc component is given in (24), whereas a frequency-adaptive companion model of other ac frequency parts is obtained as in (25).…”

“…3 are established, and then the holistic MMC-HVDC electrical system model is resolved numerically using the nodal analysis method. Then, by calculating the MMC arm currents and using (24) and (25), the voltages of all individual capacitors are calculated at current time-step. The modeling details of the MMC electrical parts can be found in Section III.…”

“…Cooperated with the arm current, the correspond current injected into the capacitors are updated. According to (24) and ( 25), the capacitor voltages are updated for constructing the controlled voltage sources.…”

“…The wide-frequency transient phenomena in PE-dominated power systems created a demand for more general models and more comprehensive studies. In the preliminary work [24], the describing function-based multi-scale model for lowvoltage cascaded H-bridge (CHB) converter was developed, but the function is still piecewise and the influence of dccircuit quantities on the modeling is not considered. This paper provides the reader more generalized methodology.…”