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Non-isolated photovoltaic inverter leakage current suppression method and system

A photovoltaic inverter and leakage current technology, applied in photovoltaic power generation, photovoltaic modules, AC power input conversion to DC power output, etc., can solve problems such as feedback variable failure and system instability, and achieve system stability and control Accurate performance, suppression of common mode resonance current and leakage current effect

Active Publication Date: 2021-08-20
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the time-delay problem of the active damping method makes the feedback variable invalid in the unstable region, and even causes the system to be unstable

Method used

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  • Non-isolated photovoltaic inverter leakage current suppression method and system
  • Non-isolated photovoltaic inverter leakage current suppression method and system
  • Non-isolated photovoltaic inverter leakage current suppression method and system

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Embodiment 1

[0050] According to an embodiment of the present invention, a second-order time-domain passive control method for suppressing leakage current and common-mode resonance current of a non-isolated three-level photovoltaic inverter is disclosed, and an improved LC filter is revealed from the perspective of frequency domain The internal mechanism and reason of suppressing high-frequency leakage current and generating common-mode resonance current, established a mathematical model of common-mode resonance current, proved that the common-mode resonance current system is passive, and designed a second-order time-domain passive controller, It also proves the global asymptotic stability of the system, which is the first application of passive control theory in the second-order time-domain system in the field of inverter control; the common-mode resonance current and leakage current are suppressed, and the output current waveform of the inverter side is realized The sinusoidalization of ,...

Embodiment 2

[0195] According to an embodiment of the present invention, a non-isolated photovoltaic inverter leakage current suppression system is disclosed, including:

[0196] A module for obtaining the grid voltage and grid phase, and converting the sampling value of the inverter side current into a DC component through coordinate transformation;

[0197] A module for obtaining the DC component of the output voltage by using the first-order passive controller, and obtaining the three-phase modulation wave and the zero-sequence injection component through coordinate inverse transformation;

[0198] It is used to sum the three-phase output current on the inverter side to obtain the common-mode resonant current, and make a difference with its reference value. The second-order time-domain passive controller is used to suppress the common-mode resonant current. After the second-order time-domain passive The output variable after the controller is injected into the three-phase modulation wav...

Embodiment 3

[0202] In one or more embodiments, a terminal device is disclosed, including a server, the server includes a memory, a processor, and a computer program stored on the memory and operable on the processor, and the processor executes the The program implements the non-isolated photovoltaic inverter leakage current suppression method in the first embodiment. For the sake of brevity, details are not repeated here.

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PUM

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Abstract

The invention discloses a non-isolated photovoltaic inverter leakage current suppression method and system. The method comprises the steps: obtaining a power grid voltage and a power grid phase, and converting a sampling value of an inverter side current into a direct current component through coordinate transformation; using a first-order passive controller to obtain an output voltage direct current component, and acquiring a three-phase modulation wave and a zero-sequence injection component through coordinate inverse transformation; and summing a three-phase output current at an inverter side to obtain a common-mode resonance current, enabling the common-mode resonance current to be subtracted from a reference value, using a second-order time-domain passive controller for inhibiting the common-mode resonance current, and injecting an output variable passing through the second-order time-domain passive controller into a three-phase modulation wave to serve as an input variable of a carrier modulation strategy. According to the invention, the common-mode resonance current and the leakage current are successfully suppressed, outstanding steady-state and transient performance is shown, and sinusoidal waveform of the output current at the inverter side and stability of the system are realized.

Description

technical field [0001] The invention relates to the technical field of non-isolated photovoltaic inverters, in particular to a non-isolated photovoltaic inverter leakage current suppression method and system. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] In recent years, as the core equipment for energy conversion and control, inverters have been widely used in photovoltaic power generation systems, power transmission fields, and medium and high voltage large-capacity AC speed regulation fields. Compared with two-level inverters, three-level inverters are widely used in photovoltaic power generation systems due to their higher output waveform quality, smaller filter size, lower voltage stress on switching devices, and higher conversion efficiency. [0004] In actual engineering, a key problem that needs to be solved urgently for the non...

Claims

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Application Information

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IPC IPC(8): H02M1/32H02M1/12H02M7/483H02M7/487H02S40/32
CPCH02M1/32H02M1/12H02M1/126H02M7/483H02M7/487H02S40/32Y02E10/56
Inventor 张承慧姜英邢相洋李晓艳
Owner SHANDONG UNIV
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