Alternate arm modular multilevel converter energy balancing via overlap onset control

Abstract

This study introduces a novel method called overlap onset control (OOC) to balance and maintain alternate arm modular multilevel converter (AAC) submodule capacitor voltages at their desired value. OOC performs zero-current switching and controls the timing of AAC commutation to regulate submodule voltages while retaining output voltage quality. The study uses steady-state converter models to develop the mathematical foundations behind the proposed capacitor voltage regulation method and then presents electromagnetic transient simulation results in PSCAD/EMTDC to demonstrate OOC's ability to extend the AAC operating range.

Keywords

• EMTP
• power system simulation
• power system CAD
• zero current switching
• HVDC power convertors
• voltage control
• switching convertors
• power capacitors
• overlap onset control
• AAC commutation
• output voltage quality
• steady-state converter models
• capacitor voltage regulation method
• AAC operating range
• alternate arm modular multilevel converter
• OOCs
• energy balancing
• submodule voltage regulation
• zero-current switching controls
• electromagnetic transient simulation
• PSCAD-EMTDC