Multi-module Bi-directional Buck-Boost Inverter-based HVDC Back-to-Back Transmission System

Offshore wind energy is now seen as a key contributor to the renewable energy future. HVDC technology is among the chief technologies enabling widespread use of offshore wind. This paper proposes a new configuration, namely, Multimodule Buck-Boost Inverter (MBBI) for HVDC transmission applications. The MBBI consists of several simple buck-boost converters that can be easily assembled for high-voltage and high-power applications. The paper shows that the MBBI has a fast response and pure sinusoidal output which minimizes/eliminates the requirements for supplementary AC filters and offers an inherent suppression to the common mode voltages. MBBI also provides complete blocking capability of AC side contributions during DC side faults. The paper discusses the system architecture, voltage and current ratings of its semiconductor devices, and the required controllers. The performance of the proposed system is tested using a simulation study during normal as well as abnormal operating conditions. The simulation results prove the advantages offered by this proposed system.