Phase self-tracking grid-connected pre-synchronization control method without phase-locked loop

Abstract

The invention discloses a phase self-tracking grid-connected pre-synchronization control method without a phase-locked loop. The steps include: step 1) obtaining the electrical angle θ of the modulated wave through the active power loop in the virtual synchronous generator or droop control; step 2 ) Compensate the electrical angle of the modulated wave, step 3) adjust the phase and amplitude of the output voltage of the grid-connected inverter to make it the same as the phase and amplitude of the grid voltage, step 4) close the three-phase grid-connected contactor, Step 5) Disconnect the phase and amplitude pre-synchronization control to adjust the grid-connected inverter, and that's it. The method of the present invention adopts the phase self-tracking grid-connected pre-synchronization control without a phase-locked loop, and the θ used in the dq-axis rotating coordinate system is the output phase angle θ of the virtual synchronous generator or the drooping control active power loop, thereby eliminating the need for The grid voltage is phase-locked, which simplifies the algorithm.

Description

technical field [0001] The invention belongs to the technical field of grid-connected pre-synchronization control, and relates to a phase self-tracking grid-connected pre-synchronization control method without a phase-locked loop. Background technique [0002] In recent years, energy and environmental issues have become a huge challenge for the development of human society. New energy sources have been widely used, and more and more distributed power sources have begun to be connected to the grid. These new energies are connected to the grid through grid-connected inverters, which can stably transmit power to the grid when the grid voltage is normal. In the event of a grid failure or power outage, the inverter is disconnected from the grid, continues to supply uninterrupted power to nearby critical loads in an independent operation mode, and can be connected to the grid again when the grid is restored. Therefore, grid-connected smooth switching technology has always been a ...

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Problems solved by technology

[0007] The purpose of the present invention is to provide a phase-locked-loop self-tracking grid-connected pre-synchronization control method, which solves the problem that the inverter output voltage and grid voltage phase Inconsistency, the traditional control algorithm is relatively cumbersome, which increases the problem of system instability

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