A phase-locked loop control method for single-phase grid-connected microgrid based on repetitive control

Abstract

The invention relates to a micro-grid single-phase grid-connection phase-locked loop control method based on repetition control. The method comprises the steps of collecting single-phase network voltage signals ug, establishing an orthogonal coordinate system by adopting a secondary generalized integrator, and establishing a micro-grid single-phase grid-connection phase-locked loop based on the repetition control according to a modified instantaneous reactive power theory. The micro-grid single-phase grid-connection phase-locked loop control method based on the repetition control has the advantages that the tracking precision of a system can be improved greatly after the repetition control of several periods, and the quality of the system is improved. The method is suitable for tracking periodic input signals, can also restrain periodic interference, the micro-grid single-phase grid-connection phase-locked loop control method based on the repetition control is established according to the modified instantaneous reactive power theory, the problems that the phase-locked loop is delayed and is poor in dynamic performance are solved, the control performance of the system is further improved, the robustness of the system is enhanced, and the phase locking precision is improved.

Description

technical field [0001] The invention belongs to the technical field of micro-grids, and relates to a micro-grid single-phase grid-connected phase-locked loop control method based on repetitive control. Background technique [0002] Phase-Locked Loop (PLL for short) technology refers to a closed-loop control system that can automatically track the frequency and phase of the input signal. It is widely used in power grid frequency adjustment, power system automation, radar technology and other high-tech fields. It also plays a very important role in photovoltaic power generation systems. [0003] In the grid-connected inverter control link, the DC power generated by the photovoltaic array is converted into AC power, and the grid-connected current needs to meet the conditions of the same frequency and phase as the grid-connected current and grid voltage. Therefore, phase-locked loop technology is used to adjust the phase difference is essential. [0004] The implementation of ...

AI Technical Summary

Problems solved by technology

The former can only detect two zero-crossing points of the voltage in one power frequency cycle, thus limiting the speed of the phase-locked loop, and when the grid voltage fluctuates and distorts, it cannot accurately capture the zero-crossing points, thus affecting the phase-locked loop. accuracy; the latter is widely used due to its simple software phase-locking structure and fast dynamic response. However, the algorithm has a large delay, which affects the accuracy of phase-locking

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