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Frequency coupling modeling method of single-phase lcl grid-connected inverter considering phase-locked loop

A technology of inverters and phase-locked loops, applied in the field of frequency coupling modeling of single-phase LCL grid-connected inverters, can solve problems such as inability to construct input signals, asymmetric input signals, etc., and is conducive to popularization and application , high model accuracy and clear physical meaning

Active Publication Date: 2021-05-25
HUNAN UNIV
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Problems solved by technology

In fact, it is impossible to construct a set of input signals that are strictly orthogonal using any algorithm. Therefore, for a single-phase system, its input signals are asymmetrical

Method used

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  • Frequency coupling modeling method of single-phase lcl grid-connected inverter considering phase-locked loop
  • Frequency coupling modeling method of single-phase lcl grid-connected inverter considering phase-locked loop
  • Frequency coupling modeling method of single-phase lcl grid-connected inverter considering phase-locked loop

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Embodiment Construction

[0025] figure 1 It is the circuit topology diagram of single-phase photovoltaic grid-connected system. Among them: the main circuit is composed of a boost circuit, a single-phase full-bridge inverter and an LCL filter; the single-phase full-bridge inverter uses the synchronous reference system theory to control the active and reactive power of the system through the PI controller in the dq coordinate system. power current, the transfer function of the controller is

[0026]

[0027] where k p is the proportional coefficient, k i is the integral coefficient.

[0028] figure 1 Medium, L g is the grid side inductance; L 1 and L 2 are the LCL filter inductors on the inverter side and grid side respectively; R 1 and R 2 L respectively 1 and L 2 parasitic parameters; C f Is the LCL filter capacitor; R d is the damping resistance; L g is the grid inductance; u inv is the midpoint voltage of the inverter bridge arm; u s is the inverter output voltage; i s is the in...

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Abstract

The invention discloses a frequency coupling modeling method of a single-phase LCL grid-connected inverter considering a phase-locked loop. The harmonic linearization method is used to obtain the modulation signal of the inverter considering the output phase angle deviation of the phase-locked loop. Frequency-domain expression; then according to the main circuit topology and modulation signal frequency-domain expression, the frequency coupling impedance model of single-phase grid-connected inverter is established, which solves the problem of accurate modeling of single-phase grid-connected inverter impedance. Based on this model, the system stability and the influence of various system parameters on the degree of frequency coupling can be analyzed. It can be seen from the built model that the frequency coupling phenomenon mainly occurs at low frequencies, and the coupling current components generated at high frequencies are almost negligible. The invention provides a theoretical basis for the stability analysis of the new energy grid-connected system.

Description

technical field [0001] The invention relates to the field of renewable energy power generation systems, in particular to a frequency coupling modeling method of a single-phase LCL grid-connected inverter considering a phase-locked loop. Background technique [0002] New energy power generation devices such as wind energy and solar energy need to be connected to the grid through power electronic converters, that is, grid-connected inverters. However, the connection of power electronic inverter devices with high penetration rate to the grid will have an impact on the stability of the system. The premise of stability analysis is to establish an accurate system model. [0003] Scholar Sun Jian proposed to use the method of harmonic linearization to establish the impedance model of a single three-phase LC type grid-connected inverter. This method not only takes into account the inverter parameters and control strategy, but also takes into account the frequency domain The impact ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
CPCH02J3/38H02J2203/20
Inventor 陈燕东王伊伍文华周乐明杨苓谢志为谭文娟谢璐
Owner HUNAN UNIV
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