Abstract:

Firstly, a novel STATCOM based on AC-AC converter is introduced in this paper, which lack of DC link energy storage and is more reliable and cost-effective. Push-pull forward AC converter is used for the study, and the working principle, compensation characteristics, control strategy is studied. Insolated high frequency ac-ac converter is introduced intonovel STATCOM, as a result, electrical isolationbetween grid-side and the compensation capacitor is implemented and compensation capacity is increased. Direct current control scheme which based on single-phase reactive current detection methods have been proposed in this paper. Compared with present control mode which based on orthogonal decomposition module and dqcoordinate transformation, the scheme proposed has less calculation amount and simple structure, and it is easy to achieve. Finally, the simulation was carry out to verify above theoretical analysis and the proposed direct current control scheme. The simulation results show thatnovel STATCOM based on insolated high frequency AC-AC convertercan compensate reactive current real time and dynamically. The system is stablewell, closed-loop can adjust the compensator quickly without static error.

Key words: AC-AC converter, push-pull forward, STATCOM, direct current control scheme