Control method and control system for grid-side converter

Abstract

The invention provides a control method and a control system for a grid-side converter. The method includes: when a modulation ratio is at a first set section, a direct-current bus voltage reference value is limited in a direct-current limit range, when the modulation ratio is at a second set section, the sum of a voltage increment and the direct-current bus voltage reference value is limited in the direct-current limit range; the limited voltage is used as a given value of direct-current bus voltage; the modulation ratio is obtained according to reference voltage and the direct-current bus voltage of a vector pulse width modulation unit. The modulation ratio can reflect voltage values of a power grid, when the modulation ratio is at the first set section, power grid voltage is normal, when the modulation ratio is at the second set section, the power grid voltage is in transient increase, so that the given value of the direct-current voltage is increased, saturation of the modulation ratio is restrained, controllability of the grid-side converter is increased, stable grid-connected operation of the grid-side converter during transient voltage increase is guaranteed, and high-voltage ride through capability of the converter is increased.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a control method and system for a grid-side converter. Background technique [0002] Converters include machine-side converters and grid-side converters, etc. The machine-side converters, namely rectifiers, are connected to generators, the grid-side converters, namely inverters, are connected to the grid side, and the machine-side converters The converter and the grid-side converter are connected to a DC bus for rectification and inverter control. During the working stage of the converter, when the grid voltage rises transiently, the control margin of the DC side decreases, resulting in the risk of runaway of the grid-side converter. If the grid-side converter loses control, it will easily lead to overvoltage or overcurrent on the DC side , so that the converter cannot be stably connected to the grid, and even fails to be disconnected from the grid. And as the installed capacit...

AI Technical Summary

Problems solved by technology

During the working stage of the converter, when the grid voltage rises transiently, the control margin of the DC side decreases, resulting in the risk of runaway of the grid-side converter. If the grid-side converter loses control, it will easily lead to overvoltage or overcurrent on the DC side , so that the converter cannot run stably on the grid, and even fails to be disconnected from the grid

And with the continuous increase of the installed capacity of generators, the frequency of grid voltage transient rise will increase, and the serious impact of the resulting batch failure of converters on the grid will become increasingly prominent

Images