Frequency Regulation Technique in AC-DC Network using Converter Current Modulation in VSC-HVDC System

摘要

In order to meet existing and future load growth, capacity addition by economical RE generation and replacement of hydrocarbon-driven or fossil fuel-based alternators are the major trend in power system development worldwide. In effect, there is gradual decrease in system inertia. The intermittency and variability of RE-sources being a well-established phenomenon creates not only load-generation balancing issues in real time scale, but leads to system operational problems like wide frequency fluctuations, high rate of change of frequency, etc. This makes the power system very much prone to serious frequency insecurities. For secure operation of integrated EHVAC-HVDC hybrid power system, frequency regulation concept is embedded inside converter control systems and a telecommunication-independent active power frequency droop-based Converter Current Modulation technique using IGBT-based VSC HVDC system is proposed in this paper, which offers support to maintain stable frequency near nominal value in an interconnected power system during generation loss, load-switching or a fault in the system, avoiding any frequency dip. The proposed VSC-HVDC control scheme has been simulated by MATLAB/Simulink tool and performance of the controller is demonstrated to validate the superiority of the proposed scheme over the conventional vector current control scheme used in VSC-HVDC system.