Generalized switching function model of modular multilevel converter

Abstract

This paper presents a generalized switching function model of the modular multilevel converter (MMC) that can be used instead of MMC electromagnetic transient simulation model for full-scale simulations of high-voltage dc (HVDC) and flexible ac transmission systems (FACTS). The proposed method is computationally more efficient and numerically stable than its electromagnetic transient simulation counterpart, and it is applicable for wide range of studies, including ac and dc network faults. The proposed switching function model is packaged in a graphical form to suit various simulation platforms such as Simulink and PSCAD. The validity of the presented model is confirmed using simulation and its scalability has been demonstrated on MMC with 301 cells per arm, considering power reversal during normal operation and dc short circuit fault

Modelovanje I Simulacija Modularnog Pretvarača Sa Više Nivoa (Mmc) U Realnom Vremenu Koristeći Prekidačku Funkciju

“…Submoduli su uključeni ili isključeni u zavisnosti od prekidačke funkcije, koja određuje stanje svakog submodula. U svakom submodulu nalazi se jedan DC kondenzator, koji je napunjen sa naponom: [4] Matematički model izlaznog napona 0 za fazu a može se predstaviti preko gornje ili preko donje grane u kolu. Ako se predstavi preko gornje grane dobija se izraz (2), a ako preko donje grane izraz (3):…”

Modeling of MMC for Fast and Accurate Simulation of Electromagnetic Transients: A Review

“…The continuous variant of EIM has been validated against laboratory prototypes in [110,126]. Similarly, the switching function and average models have been validated against detailed models or EIM in the literature [19,20,100,101,106,107].…”

“…Such models for MMC are presented in [97][98][99][100]. The works in [97][98][99] utilize the state-space formulation, which is computationally intensive and not suitable for fault studies in an HVDC system, while [100] proposes a generalized switching function model that utilizes the binary function to model the individual operation of submodules with high computational efficiency. The references in [101][102][103][104] extend this modeling approach to allow inherent incorporation of the blocked state of the converter.…”

“…The prime motivation for the selection of PSCAD/EMTDC as the choice of simulation software is its wide use in industry and academia [18,38,49,100,123] for the simulation of the HVDC grid system. However, constrained by the restriction on the maximum number of nodes (200) of the educational license of PSCAD/EMTDC, the maximum number of submodules per arm in these simulations is restricted to 14.…”

Steady-state performance of state-of-the-art modular multilevel and alternate arm converters with DC fault-blocking capability

“…For example, it is cumbersome to account for the effect of complex Capacitor Balancing Algorithms (CBAs) in average models. This is due to the fact that CBAs affect the average switching frequency per switching device (switching loss), arm energy balance and inter-arm dynamics, and hence, average models are unable to reproduce such effects [9,10].…”