Self-adaptive phase-locked loop structure, grid-connected system and structure changing method

Abstract

The invention discloses a self-adaptive phase-locked loop structure, a grid-connected system and a structure changing method, and the structure comprises a PI regulator which is used for the zero static error tracking of a DC component under a synchronous coordinate system, and is configured to comprise a gain regulator Kp and an integral regulator Ki / s; the control module is used for generating an equivalent damping coefficient D according to the power angle delta, the power grid voltage Vg and the grid-connected current Ig of the converter, and judging a symbol of the equivalent damping coefficient D; when the equivalent damping coefficient D is greater than or equal to 0, a first control signal is generated to act on the PI regulator, so that the gain regulator Kp and the integral regulator Ki / s are both in a working state, and the phase-locked loop is of a second-order structure; when the equivalent damping coefficient D is smaller than 0, a second control signal is generated to act on the PI regulator, so that the gain regulator Kp is in a working state, the integral regulator Ki / s is in a closed state, and the phase-locked loop is of a first-order structure. According to the invention, the transient synchronization stability of the phase-locked loop can be improved when the disturbance is too large while accurate trajectory tracking is realized.

Description

technical field [0001] The invention relates to an adaptive phase-locked loop structure, a grid-connected system and a method for changing the structure. Background technique [0002] In order to achieve "carbon peaking and carbon neutrality", the number of wind and solar power sources is rapidly increasing, and the proportion of new energy power sources in the power system is increasing. As the grid-connected interface of wind and solar power, whether the converter can restore synchronization after a short-circuit or disconnection of the power grid has become a research hotspot. Because the grid-tracking grid-connected converter controls the synchronous operation of the converter through the grid-connected point voltage, the response speed is fast, and it is widely used. [0003] The core control link of the grid tracking converter is the phase-locked loop. The phase-locked loop obtains the phase-locked angle by detecting the voltage at the grid-connected point, and uses t...

AI Technical Summary

Problems solved by technology

[0004] Due to the large number of grid-connected wind and solar power sources, for the safe and reliable operation of the grid, the converter cannot be directly locked arbitrarily

If the method of adjusting the parameters of the phase-locked loop is used, the parameters need to be re-adjusted in the face of different faults. The process is cumbersome, and even the appropriate parameters cannot be found for adjustment, resulting in the failure of the system phase-locked loop.

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