Description

Abstract

For high-voltage direct-current (HVDC) transmission, the strength of the ac system is important for normal operation. High voltage DC transmission is a high power electronics technology used in electric power systems. It is an efficient, economic and flexible method to transmit large amounts of electrical power over long distances by overhead transmission lines or underground/submarine cables. The HVDC transmission based on voltage source converters (VSC) is a comparatively new technology, where the valves are built by IGBTs (Insulated Gate Bipolar Transistors) and PWM Pulse Width Modulation) is used to create the desired voltage waveform Compared to conventional line commutated HVDC systems. By using the recently proposed power-synchronization control, the short-circuit capacities of the ac systems are no longer the limiting factors, but rather the load angles. In addition, the paper proposes a control structure particularly designed for weak-ac-system inter connections. This should be compared to previous results for VSC based HVDC using vector current control.