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: 2022-06-03
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

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] According to an embodiment of the present invention, a non-isolated three-level photovoltaic inverter is disclosed to suppress leakage current and common mode

[0056] Two carriers of the same phase are used in the carrier modulation scheme.

[0059]

[0062]

[0064]

[0066]

[0068]

[0069]

[0072]

[0073] According to formula (7), the inverter common-mode equivalent circuit using a traditional LC filter is shown in Figure 2(a). For capacitive element

[0075]

[0077]

[0079]

[0081]

[0083] According to equations (7) and (11), the inverter common-mode equivalent circuit using the improved LC filter is shown in Figure 2(b). with figure

[0084] To better compare the ability of the two circuits to suppress leakage current, they were analyzed in the frequency domain. traditional LC filter

[0085]

[0086]

[0087] Its corresponding Bode diagram is shown in Figure 3, and the conclusions obtained are as follows.

[0090]

[0092] G

[0093]

[0097]

[0099]

[0100]...

Embodiment 2

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

[0199] For collecting the DC side capacitor voltage, the proportional controller is used to control the balance of the DC side midpoint voltage, and output it.

Embodiment 3

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PUM

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Abstract

The invention discloses a non-isolated photovoltaic inverter leakage current suppression method and system, comprising: obtaining grid voltage and grid phase, converting the sampling value of the inverter side current into a DC component through coordinate transformation; The source controller obtains the DC component of the output voltage, and obtains the three-phase modulation wave and zero-sequence injection component through coordinate inverse transformation; the three-phase output current of the inverter side is summed to obtain the common-mode resonant current, and it is compared with its reference value. The first-order time-domain passive controller suppresses the common-mode resonant current, and the output variable after passing through the second-order time-domain passive controller is injected into the three-phase modulation wave as the input variable of the carrier modulation strategy. The invention successfully suppresses common-mode resonance current and leakage current, exhibits outstanding steady-state and transient performance, and realizes sinusoidalization of the output current waveform of the inverter side and system stability.

Description

Method and system for suppressing leakage current of non-isolated photovoltaic inverter technical field The present invention relates to the technical field of non-isolated photovoltaic inverters, especially a leakage current of non-isolated photovoltaic inverters Suppression method and system. Background technique The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art information. technique. In recent years, as the core equipment for energy conversion and control, inverters have been widely used in photovoltaic power generation systems, power The field of force transmission and the field of medium and high-voltage large-capacity AC speed regulation, etc. Compared with the two-level inverter, the three-level inverter Higher waveform quality, smaller filter size, lower voltage stress of switching devices, and higher conversion efficiency are widely used in photovoltaics Pow...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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