Converter synchronous stability control method under fault condition

Abstract

The invention discloses a synchronous and stable control method for a converter under a fault condition, and relates to control on a grid-connected converter during a low-voltage crossing fault period. Firstly, active and reactive current reference quantities of the converter are obtained according to the voltage drop depth; the invention further provides a dynamic voltage feedback control method, the deviation between the q-axis voltage reference quantity of the grid-connected point and the actual q-axis voltage component of the grid-connected point is introduced into the active current reference quantity through a proportional-integral controller, and the active and reactive current reference values during the fault period are determined by comparing the current reference value with the withstand current of the converter. According to the method, on the basis of considering the operation performance and capacity constraint of the converter, the residual capacity of the converter in the fault period is fully utilized, the grid-connected synchronization capability of the converter in the low-voltage ride-through period is improved to the maximum extent, and the synchronous instability risk of the grid-connected converter in the fault period is reduced.

Description

technical field [0001] The invention belongs to the technical field of converter fault ride-through control, and relates to a converter synchronous stability control method under fault conditions Background technique [0002] With the increase in the scale of new energy access, the relationship between new energy and the power grid has become more and more close, and the interaction between the two has become increasingly complex. The new energy power generation system mainly uses the converter as the power interface to connect to the power grid. The access of large-scale power electronic converters has changed the dynamic characteristics of the power grid, and the related dynamic problems have gradually emerged. [0003] In addition, the converter passively tracks the change of the grid voltage phase through the phase-locked loop, and provides a reference coordinate system for its own control loop to achieve different control objectives. The existing fault ride-through con...

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Problems solved by technology

[0004] However, with the increase of large-scale new energy access and transmission distance, the equivalent impedance of the grid increases, and the grid becomes weaker. The input of the phase-locked loop is used to estimate the frequency and phase angle of the grid, which further intensifies the interaction between the grid-connected converter and the grid, and increases the risk of synchronous instability of the grid-connected converter during a fault

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