Fast extraction of positive-sequence current from harmonically corrupted three-phase currents for TCR compensator control systems

The authors discuss a practical scheme for extracting the magnitude of the positive-sequence component from harmonically corrupted three-phase currents found in modern energy systems. The scheme is cost-effective, fast, and simple in design, with the novel combination of software processing and digital and analog circuits. The scheme has been successfully applied to a microprocessor-based thyristor-controlled reactor (TCR) control system and is suitable for similar real-time applications that already include one or more processing units. It is demonstrated that the scheme is adequately fast for the TCR control system because the extraction delay is typically less than half a cycle. The scheme is especially suitable for microprocessor-based control systems because the averaging function can be advantageously performed by software.<>