Method of realizing single-phase phase-locked loop by software

Abstract

The present invention relates to a method for realizing single-phase phase-locked loop by adopting software, comprising the following steps of: constituting an input signal in an alpha-beta coordinate system with a standard signal as a reference (1); carrying out PI adjustment through the output of dq0 conversion q axle component based on the instantaneous reactive power theory, carrying out frequency correction through the output of the PI adjustment step, using an output signal of the frequency correction step as a reference, and carrying out phase correction through using the integration step (2); designing a low pass filter and ensuring the speed and the accuracy of the tracking of the phase-locked loop (3); speeding up the calculation by adopting 16 bit fixed point TMS320C2812DSP programming (4). The method adopts closed-loop control, which is high in stability and quick in tracking speed, with the transient response time less than 0.04s and wide frequency range of the locked phase between about 45 and 55Hz, is not interfered by the harmonic waves and the twinkling fluctuation of the system voltage or current, can accurately and quickly track the fundamental wave frequency and the phase information of the voltage and current in an electric power system, and provides system synchronous frequency signals for active filters and dynamic voltage adjustors, etc.

Description

technical field [0001] The invention relates to a method for realizing a phase-locked loop, in particular to a method for realizing a single-phase phase-locked loop by using software. Background technique [0002] In the prior art, analog phase-locked loop and digital phase-locked loop technologies are usually used to obtain information on the phase and frequency of the fundamental wave of the system. [0003] Both are implemented in hardware. The problems existing in the analog phase-locked loop are: DC zero drift, device saturation, loss of lock, etc.; while the digital phase-locked loop also has higher requirements on the device, although the real-time performance of the phase-locked loop can be guaranteed by adopting digital circuit design, But there are difficulties in designing low-pass filters. [0004] However, both methods rely on the zero-crossing comparison method, and the voltage and current waveforms in the actual power system still have harmonic interference,...

AI Technical Summary

Problems solved by technology

The problems existing in the analog phase-locked loop are: DC zero drift, device saturation, loss of lock, etc.; while the digital phase-locked loop also has higher requirements on the device, although the real-time performance of the phase-locked loop can be guaranteed by adopting digital circuit design, However, it is difficult to design a low-pass filter

This method uses multiple low-pass filters and arctangent functions; however, when the DSP program is running, calling these functions will reduce the program running time and affect the tracking speed of the phase-locked loop.

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