Transient Voltage Support Technology Based on Flexible DC Traction Power Supply Systems

In the super-large urban load center area, motor loads, represented by air conditioning compressors have been increasing annually, posing a severe challenge to power system transient stability. Thanks to the rapid development of flexible DC traction power supply systems (FDTPSSs) in recent years, a new way for transient voltage support has emerged. Through the active and reactive power decoupling control of the voltage source converter (VSC) in FDTPSSs, this paper leverages its redundant reactive power capacity to compensate reactive power swiftly and support transient voltage for the power grid. The proposed transient voltage support scheme adopts variable droop voltage control, where droop gain of the Q-V controller is adaptively adjusted based on the current maximum reactive capacity of each VSC so that more reactive power can be exerted for voltage support. The proposed strategy has been validated in MATLAB/PSAT based on the Beijing Metro Line 13A.