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Small signal impedance modeling method for single-phase grid-connected inverter considering phase-locked loop

A modeling method and small-signal model technology, applied in the direction of single-network parallel feeding arrangement, AC network circuit, circuit device, etc., to achieve the effect of high model accuracy, clear physical meaning and simple expression

Active Publication Date: 2018-12-07
HUNAN UNIV
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  • Application Information

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Problems solved by technology

However, there is no relevant literature using the harmonic linearization method to model single-phase phase-locked loops and single-phase LCL grid-connected inverter systems.

Method used

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  • Small signal impedance modeling method for single-phase grid-connected inverter considering phase-locked loop
  • Small signal impedance modeling method for single-phase grid-connected inverter considering phase-locked loop
  • Small signal impedance modeling method for single-phase grid-connected inverter considering phase-locked loop

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Embodiment Construction

[0041] 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

[0042]

[0043] where k p is the proportional coefficient, ki is the integral coefficient.

[0044] 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 The parasitic parameters; C 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 inv...

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Abstract

The invention discloses a small signal impedance modeling method for a single-phase grid-connected inverter considering a phase-locked loop, which constructs a small signal impedance model of the grid-connected inverter containing a single-phase phase-locked loop by using harmonic linearization, and solves a problem of accurate modeling for broadband impedance of the single-phase grid-connected inverter. Influences imposed on the system stability by power grid impedance and the bandwidth of the phase-locked loop can be analyzed based on the model. When the power grid impedance is small, the influences imposed on the system stability by the phase-locked loop can be neglected; and when the power grid is weak, the phase margin of the system will gradually decrease or even become unstable along the increase in bandwidth of the phase-locked loop. The invention provides a model and method for small disturbance stability analysis for power grid access of the single-phase grid-connected inverter, and facilitates the popularization and application of the single-phase inverter grid-connected system.

Description

technical field [0001] The invention relates to the field of renewable energy power generation systems, in particular to a single-phase grid-connected inverter small-signal impedance modeling method 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. The grid-connected inverter is the core device of the grid-connected power generation system, and its topology, control strategy and parameters will directly affect the power quality of the grid-connected current and the stability of the system. As the most commonly used inverter topology, the LCL voltage source grid-connected inverter has become a research hotspot of scholars at home and abroad. [0003] In the grid-connected system, a phase-locked loop is required to lock the phase and frequency of the grid voltage as the current reference ...

Claims

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Application Information

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IPC IPC(8): H02J3/38
CPCH02J3/38H02J2203/20
Inventor 陈燕东王伊伍文华谢志为罗安
Owner HUNAN UNIV
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