Abstract
A novel modular Transformerless, Self-balanced, Static Synchronous Series Compensator (TSB-SSSC) capable of delivering ultra-high current, with the objective of dynamically balancing the impedance of the transmission power grid, is proposed. Balancing transmission lines is crucial in power optimization and delivery because it increases the power transfer capability without building new power lines. The transformerless SSSC needs to support and control the line current from a few hundred to several thousand amperes. This paper presents how the ultra-high current architecture of the TSB-SSSC is achieved by operating multiple converters with self-balancing capabilities in parallel. The mechanism of self-balancing is based on the intrinsic physics of the capacitor and is enabled by a passive network of capacitor equalizers that keep the capacitor voltage equal during switching disconnection. The second self-balancing system consists of an inductive component that balances possible differences among delay switching caused by the aging of the multiple IGBTs from the different converters that form the SSSC. This work presents the analytical set of equations that describes the system and a complete set of simulations where the effectiveness of self-balancing paralleling topology is shown.