An Approach to Regulating the DC-Link Voltage of a Voltage-Source BTB System During Power Line Faults.

A voltage-source back-to-back system for the purpose of achieving power flow control and/or line-frequency change in transmission systems has the attractive features of reliable and continuous operation, even during power line faults. However, an over- voltage appearing across the dc link during the faults should be limited to as low a value as possible because it does affect the power device ratings. This paper proposes a dc-link voltage regulator for effectively suppressing the overvoltage during power line faults. This regulator is characterized by compensating for a time delay inherent in each current controller, and for a power flow imbalance occurring during power line faults. The validity of the proposed regulator is confirmed by theory and computer simulation. [ABSTRACT FROM AUTHOR]