Operation and Control of HV D-C Transmission

The special requirements on control of inverters for HV (high-voltage) d-c transmission have led to a special control system, which is described. Co-operation between regulators at each end of the transmission is necessary in reducing the consequences of disturbances in the converters. Also described are the switching and blocking of valve groups and how to accomplish this without using circuit breakers. The type of protective system is discussed in a general way.