Hybrid AC Transmission System with Back-to-Back Converter Configuration and MTDC Operation Considering PV Energy Integration

MMC-based back-to-back (B2B) converters are promising for hybrid AC/DC transmission systems when integrating large scale PV sources. This paper proposes a novel configuration for hybrid AC transmission systems with B2B converters and multi-terminal direct current (MTDC) operation which facilitates the integration of PV energy and enhances the system stability and reliability. This is achieved by an advanced interconnection with two operation modes: 1-A bi-directional power flow via AC connections, and 2- Direct active power injection to the MTDC from PV source. Conventional outer, inner and capacitor voltage balancing control systems are utilized in this study for regulating the currents and voltages of B2B converter. Also, The Perturb and observe (P and O) technique is implemented for obtaining maximum power point tracking (MPPT) of the PV generation considering a dc-dc boost converter. The efficacy of this proposed configuration is verified through time-domain simulations carried out by MATLAB/SIMULINK.