A new frequency control method to enhance fault ride-through capability of VSC-HVDC systems supplying industrial plants

Abstract

Voltage sags is one of the most important issue of power quality, which can disrupt industrial process and impose huge costs on industrial plants. For improving disturbance ride-through capability of voltage source converter based on high voltage direct current (VSC-HVDC) supplying industrial plant, an auxiliary frequency controller is proposed to control output voltage frequency at inverter station. Since industrial loads are more sensitive to voltage drops compared to frequency deviations, output voltage frequency is slightly deceased based on DC-link voltage changes during disturbances in proposed control scheme in order to prevent voltage collapse and provide desirable voltage quality for industrial plants; hence, the continuity of industrial process will be ensured. The case study is a part of a real industrial plant and variations of DC-link voltage, AC buses voltages, induction motors speed, and performance of adjustable speed drive are investigated when the proposed method is used during faults. In proposed method, voltage drop across industrial plant during a severe fault is less than other methods and dynamic performance of system is improved. The case study is simulated under balanced three-phase fault, double line-to-ground fault, and single line-to-ground fault in PSCAD/EMTDC, and results verify the validity of the proposed control scheme. © 2022