Fault ride-through control system for alternating-current excitation power supply

Abstract

The invention provides a fault ride-through control system for an alternating-current excitation power supply. When a point of common coupling (PCC) voltage drops slightly, a three-phase electronic switch K1 is switched on, K2 is switched off, a current inner loop in a double-loop control strategy adopts a method combining proportional integral resonant control and variable damper control, and a PCC voltage valid value outer loop output serves as a given value of current inner loop current. When the PCC voltage drops deeply, the three-phase electronic switch K1 is switched off, K2 is switchedon, direct-current voltage output loops of a machine-side converter (MC) and a grid-side converter (GC) adopt a proportional integral resonant control method, and a current inner loop adopts a proportional integral resonant control method. Through adoption of the control system, rotor overcurrent of a doubly fed induction generator (DFIG) caused by a PCC voltage dropping fault is restrained; ripple voltage on a direct-current side of the alternating-current excitation power supply caused by a PCC voltage asymmetrical dropping fault can be reduced; and the alternating-current size current resonant content is lowered.

Description

technical field [0001] The invention relates to an AC excitation power supply for a doubly-fed wind turbine, in particular to an AC excitation power fault ride-through control system. Background technique [0002] The fault ride-through capability of doubly-fed wind turbines is limited by the capacity of the AC excitation power supply. It is sensitive to the fault of the common connection point voltage. Protection measures need to be taken to suppress the overcurrent of the DFIG rotor side of the doubly-fed generator and protect the AC excitation power supply. The control technology of improved AC excitation power supply, such as proportional resonance control technology, dual dq-PI rotor current control technology, voltage-based power compensation method, control method using active damper, etc., can suppress the overcurrent of AC excitation power supply and improve Operating capability of DFIG during common connection point PCC voltage drop fault. [0003] The rotor crowb...

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Problems solved by technology

[0010] 3. Only install three-phase electronic switches between the stator side and the rotor side of the doubly-fed generator DFIG and the AC side of the machine-side converter and the grid-side converter, which will cause the doubly-fed generator when the common connection point voltage fails The frequent start and stop of DFIG is not conducive to the control of doubly-fed generator DFIG, and at the same time, it does not consider the control method of AC excitation power supply when the common connection point PCC voltage drops asymmetrically.

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