Modeling and control of a high voltage direct current power transmission system based on active voltage source converters

A non-linear strategy for a high voltage direct current power transmission system (HVDC) based on voltage-source-converters is proposed. Specifically, a point-to-point monopole link between two three-phase systems which may operate at different frequencies is analyzed. Based on the dq model of the open loop system, the expressions which define its operating points are obtained. These expressions allow the analysis of the operating regions of the system. After the open loop analysis, a control strategy is proposed based on the input-output linearization method. The control strategy allows dc voltage and active power flow regulation as well as decoupled manipulation of the reactive power flows in both ac sides. The control system is tested through computational simulation considering a carrier based PWM technique for the commutation of the switches.