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Method for judging fault of photovoltaic grid connection inverter

A technology for inverters and photovoltaics, applied in the field of judging photovoltaic grid-connected inverter faults, can solve problems such as reliability problems, inability to reflect inverter open circuit faults, and overcurrent protection failure to operate, etc., to achieve clear judgment methods and easy actions reliable effect

Inactive Publication Date: 2014-12-03
STATE GRID CORP OF CHINA +1
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AI Technical Summary

Problems solved by technology

Due to the fragility of the power switch tube and the complexity of control, the inverter has become the weakest link in the system that is most prone to failure, and its reliability problems have always existed
However, in some cases, an open circuit fault occurs inside the inverter, and the DC component on the DC side is less than the protection setting value, and the overcurrent protection shown in formula (4) cannot operate, resulting in the overcurrent protection installed on the DC side not reflecting Inverter internal open circuit fault

Method used

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  • Method for judging fault of photovoltaic grid connection inverter
  • Method for judging fault of photovoltaic grid connection inverter
  • Method for judging fault of photovoltaic grid connection inverter

Examples

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Embodiment 1

[0045] detection as attached figure 1 The structure diagram of the grid-connected system of the photovoltaic grid is shown, where PV is the photovoltaic power supply, i DG is the output current of photovoltaic power supply, i c1 is the capacitive current on the DC side, C dc is the DC side capacitance, u dc is the DC side voltage, i dc is the DC side current, VT 1 - 6 For power switching elements 1-6, VD 1 - 6 For freewheeling diodes 1-6, i a - c is the AC side current, L 1 , L 2 are the left and right inductors in the LCL filter on the AC side, V a - c is the capacitor voltage on the AC side, U a - c is the system voltage, C d is the capacitor in the LCL filter, R d is the damping resistor of the LCL filter. The protection range shown by the dotted line in the figure is the circuit range required to be protected by the detection method of this embodiment.

[0046] attached diagram 2-1 , 2-2 and 2-3 show the attached figure 1 The VT1 circuit shown in the ...

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Abstract

The invention relates to a method for judging a fault of a photovoltaic grid connection inverter. The method includes the following steps: acquiring current data at a DC side; according to a formula, calculating a scale factor K based on harmonic waves; according to a formula, calculating a set threshold T(h); if K<T(h), judging that a fault does not happen in the photovoltaic grid connection inverter; and if K>T(h), judging that a fault happens in the photovoltaic grid connection inverter. The invention proposes a judgment method of a self-adaptive protection scheme based on the scale factor K of the harmonic waves on the basis of the prior inverter protection. The method is adaptive to judgment of fault types of different inverters and is free from effects of external environment change so that judgment is accuracy.

Description

technical field [0001] The invention relates to a method for judging the failure of a photovoltaic grid-connected inverter. Background technique [0002] In the distributed power supply, the voltage source inverter is the core and most important device of the whole system. Due to the fragility of the power switch tube and the complexity of the control, the inverter becomes the weak link most prone to failure in the system, and its reliability problem has always existed. Existing inverter protection mainly includes: overcurrent protection, overvoltage protection, undervoltage protection, temperature protection, etc. These protection principles are relatively simple and do not make full use of the fault characteristics of the inverter. At present, there are relatively few researches on inverter protection. In "Single current sensor technique in the DC link of three-phase PWM-VS inverters: a review and a novel solution", Blaabjerg F et al. described the method of installing ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/42
Inventor 赵杰王硕刘国平黄朝晖方永毅史文丽王敬引山春凤杨建华武剑宋静刘卉陈元元程慧琳杨华李吉昌马乐王清亮陈子来沈洋王小丹李佳琪肖莹米超曹培
Owner STATE GRID CORP OF CHINA
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