Small signal impedance modeling method for second-order generalized integrator-phase locked loop (SOGI-PLL)

Abstract

The invention relates to a small signal impedance modeling method for a second-order generalized integrator-phase locked loop (SOGI-PLL). The modeling method comprises six steps: 1, a DC component mu<dq> (t) under a rotating coordinate system is calculated, power grid voltage different from a base wave frequency and a phase angle small interference signal are injected respectively under a rectangular coordinate system, and the relationship between input power grid voltage under a stationary coordinate system and an output small signal under the rotating coordinate system is analyzed; 2, a transfer function for an imaginary axis output disturbance component and a phase angle disturbance component under the rotating coordinate system is built; 3, a transfer function for a power grid voltage disturbance component and a phase angle disturbance component under the stationary coordinate system is built; 4, a transfer function for a reference current disturbance component and a phase angle disturbance component is built; 5, a transfer function for a reference current disturbance component and a power grid voltage disturbance component under the stationary coordinate system is built; and 6, a complete single-phase SOGI-PLL impedance model is built. The modeling method provided by the invention has the advantages of simple and convenient calculation, and accurate modeling.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a small-signal impedance modeling method of a generalized second-order integral phase-locked loop. Background technique [0002] Phase-locked loop technology is a phase-locked loop, which is a grid synchronization technology. Today, when new energy is widely connected to the grid, the key technology to ensure the safe and stable operation of new energy access to the grid is grid synchronization technology, and phase-locked loop technology It is widely used in business. [0003] At present, there are some power quality problems whether it is distributed power generation or large-scale power stations integrated into the grid. Impedance analysis method is an effective method to effectively solve harmonic interference and system voltage stability. The most critical and difficult technology of the impedance analysis method is the impedance modeling technology of the frequency convert...

AI Technical Summary

Problems solved by technology

Recently, the small-signal impedance modeling technology of PLL has been studied at home and abroad. In the current small-signal impedance modeling method, a small interference signal is generally used at the AC side grid voltage, and then according to the specific parameters and topology of the PLL Deriving and calculating the small-signal impedance model of the PLL, and this method is currently only applied to the simplest 1 / 4 cycle delay single-phase phase-locked loop, and has not been applied to the more complex generalized second-order integral phase-locked loop

The main disadvantage of this method is that when establishing the impedance model of the PLL, it is necessary to apply the harmonic linearization method to separate the disturbance. A large number of Fourier transforms are required, and there is a problem of convolution, and the calculation is more complicated.

In addition, this method does not consider the influence of the single-phase phase-locked loop quadrature signal generation link on the PLL impedance during the PLL impedance modeling process, but simply assumes a signal lagging behind the grid voltage by 90° as the quadrature signal of the phase-locked loop signal, and cannot truly reflect the complete impedance characteristics of a single-phase phase-locked loop

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