Comparison Between Synchronous Condenser And Static Var Compensator On Voltage Stability Of HVDC System

This thesis presents a comprehensive comparison between Synchronous Condenser(SC) and Static Var Compensator(SVC) on voltage stability in HVDC system.Both devices have different dynamic performance and operating principles.SC’s unique ability to contribute short-circuit power and system inertia make it more prominent device.This thesis also addresses about the influence of SVC and SC on voltage stability of HVDC system after voltage drop fault of sending end and receiving end,during voltage sag of the short circuit fault at different line location etc.50%,80%,100% of line length,and overvoltage of sending-end caused by DC Bi-polar block fault.The voltage of AC-DC systems,current of AC-DC systems;reactive power compensated and active power of HVDC for both SC and SVC have been compared under different faults.During voltage faults when voltage drop is less than 20%SVC can recover the system up to 0.95p.u.which is similar to SC.But during severe voltage drops like 48%,performance of SVC drop significantly and reactive power reduce from 270 to 180Mvar,SVC only recover 10% more voltage.SC can recover voltage to 90% even in severe faults and reactive power rises up to 900Mvar for severe voltage drops.During short circuit fault location from 100% to 50% of line length away from bus,SC reactive power has increased by 530Mvar but Vrms drop from 0.97 to 0.74p.u.But SV’s reactive power reduced from 230 to 80Mvar and Vrms drop to 0.52p.u.During DC Bi-polar block fault SVC and SC can recover the Vrms to 1.27p.u.But reactive power absorbed by SVC is double of SC’s.The CIGRE benchmark model for HVDC control studies has been used in this thesis.The results can provide theory basis for the operation of SC and SVC connected to HVDC system.