Frequency control capability of VSC-HVDC transmission system

摘要

High voltage direct current (HVDC) systems have been used as an effective solution to transmit power over long distances. Performance of HVDC systems has significantly improved with the emergence of voltage source converter based HVDC (VSC-HVDC). Increased controllability provides independent control of active and reactive power which facilitates controlling of voltage and frequency. This paper investigates the frequency control capability of VSC-HVDC to determine the improvement extent that VSC HVDC systems provide for the frequency recovery and system inertia. Two frequency control strategies using dc voltage and active power outer loops are investigated. The analysis is carried out using a time domain simulator, where the tie line in the Kundur test system is replaced by VSC-HVDC. Simulation results have shown that frequency control capability of VSC-HVDC dramatically improves the frequency performance, especially in isolated power systems.