Non-delayed single-phase phase-locked loop second harmonic filtering method

Abstract

The invention relates to a non-delayed single-phase phase-locked loop second harmonic filtering method which comprises the following steps: an orthogonal vector generation module enables input single-phase signals to be orthogonal signals in a virtual mode; a Park conversion module carries out Park conversion based on a phase-locked loop phase angle on the orthogonal signals output by the orthogonal vector generation module, and converts the orthogonal signals into direct current components; two series-connected differentiators are used for carrying out secondary derivation on the direct current components output by the Park conversion module, and enable the signals after secondary derivation to pass a proportioner, the output results of the proportioner and the direct current components output by the Park conversion module are summated through a first summing unit, and in the direct current components are eliminated; the direct current components after elimination of the second harmonics pass through the proportioner, a second summing unit and an integrator in sequence, and then the phase-locked loop phase angle is output. Compared with the prior art, the non-delayed single-phase phase-locked loop second harmonic filtering method has the advantages of being simple in design and good in real-time performance and dynamic performance.

Description

technical field [0001] The invention relates to a single-phase phase-locked loop in a distributed power generation system, in particular to a second-harmonic filtering method of a single-phase phase-locked loop without delay. Background technique [0002] In recent years, distributed power generation systems such as wind power and photovoltaics have received more and more attention in the search for ways to overcome the world's energy crisis. As the core of energy conversion and control in the distributed generation system and the interface with the distribution network, the performance of the single-phase grid-connected inverter directly affects and determines the quality of the entire grid-connected system. The phase, frequency and amplitude of the grid voltage are the key information for grid-connected synchronization, and the single-phase phase-locked loop (Phase Locked Loop, PLL) plays a pivotal role. figure 1 The general model of the traditional single-phase PLL is sh...

AI Technical Summary

Problems solved by technology

[0003] 1. In the traditional method, the cutoff frequency of the filter must be designed very low, which increases the difficulty of filter design and is difficult to realize;

[0004] 2. Due to the delay characteristic of the filter in the traditional technology, it will become longer and longer as the cut-off frequency becomes smaller, which will affect the dynamic response performance of the entire system

[0005] In view of the above reasons, the traditional method of eliminating the double frequency component in the phase-locked loop increases the difficulty of system design and affects the dynamic performance of the entire system, which is not suitable for the use of the entire system

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