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A fault detection method, fault detection circuit and inverter

A detection circuit and fault detection technology, applied in the direction of measuring electrical variables, converting irreversible DC power input to AC power output, instruments, etc., can solve the problem of automatically entering the standby state, the inverter cannot be connected to the grid, and the inverter Problems such as not being able to be connected to the grid normally, to achieve the effects of easy promotion and application, increased hardware costs, and simple and reliable logic

Active Publication Date: 2018-04-10
SUNGROW POWER SUPPLY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] When the DC bus voltage detected by the DC bus voltage detection circuit is too high or too low, the inverter cannot be connected to the grid normally.
For example: when the DC bus voltage detection circuit fails and the detected DC bus voltage is lower than the actual value, the inverter will automatically enter the standby state due to the low input voltage; at this time, if the DC bus voltage detection circuit cannot be detected in time Faults will cause the inverter to fail to run in parallel with the grid for a long time

Method used

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  • A fault detection method, fault detection circuit and inverter
  • A fault detection method, fault detection circuit and inverter
  • A fault detection method, fault detection circuit and inverter

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Embodiment 1

[0038] see figure 2 , Embodiment 1 of the present invention discloses a fault detection method to detect in real time whether the DC bus voltage detection circuit in the inverter fails, including:

[0039] Step 201: After the inverter under test enters the standby state, control the bus pre-charging circuit to pre-charge the DC bus;

[0040] Step 202: After the pre-charging is completed, control the AC relay to pull in, so that the inverter under test enters an uncontrollable rectification state;

[0041] The AC relay is connected between the AC side of the inverter to be tested and the grid, that is figure 1 The switch K is marked in the middle. After the AC relay is closed, the inverter under test enters the uncontrollable rectification state. At this time, the grid energy will be output to the DC bus through the uncontrollable rectification circuit inside the inverter under test. Before closing the AC relay, the DC Bus pre-charging, because: from the working principle o...

Embodiment 2

[0049] In addition to the DC bus voltage, the monitoring nodes of the running state of the inverter also include inverter voltage, grid voltage, etc., still refer to figure 1 , the inverter detects the DC bus voltage at point A, the inverter voltage at point B, and the grid voltage at point C in real time through the internal DC bus voltage detection circuit, inverter voltage detection circuit, and grid voltage detection circuit. , the measured voltages output by the DC bus voltage detection circuit, the inverter voltage detection circuit and the grid voltage detection circuit are respectively V1, V2 and V3.

[0050] Since the theoretical value of the DC bus voltage needs to be calculated based on the current grid voltage, to ensure the reliability of the fault detection process of the DC bus voltage detection circuit, the reliability of the grid voltage detection circuit must first be ensured. For this, see image 3 , Embodiment 3 of the present invention discloses yet anoth...

Embodiment 3

[0062] In a power station, multiple grid-connected inverters are connected in parallel to the grid through the same transformer, and the grid voltage information output by each inverter is collected in real time for comparison and analysis. If the information is quite different from other inverters, the grid voltage detection circuit in the few inverters must be faulty. Based on this, see Figure 4 , this embodiment 4 discloses yet another fault detection method, so as to realize the fault detection of the DC bus voltage detection circuit only when the power grid voltage detection circuit is guaranteed to be free of faults, so as to ensure the accuracy of the fault detection result of the DC bus voltage detection circuit Accurately, the method includes (for ease of description, the measured value voltages output by the DC bus voltage detection circuit and the grid voltage detection circuit in the inverter to be tested are respectively V1 and V3):

[0063] Step 401: After the ...

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PUM

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Abstract

The invention discloses a fault detection method, a fault detection circuit and an inverter. The method includes the following steps that after the inverter to be tested gets into a standby state, a bus precharging circuit is controlled to precharge a direct-current bus; after precharging is completed, an alternating-current relay is controlled to be closed, so that the inverter to be tested works in an uncontrollable rectification state; a measurement value output by a direct-current bus voltage detection circuit in the inverter to be tested is read; whether the difference between the measurement value output by the direct-current bus voltage detection circuit and a theoretical value is larger than a first threshold value is judged, if yes, a direct-current bus voltage detection circuit fault is reported, and therefore whether the direct-current bus voltage detection circuit in the inverter breaks down is detected in real time.

Description

technical field [0001] The invention relates to the technical field of fault detection, and more specifically, to a fault detection method, a fault detection circuit and an inverter. Background technique [0002] see figure 1 , in the photovoltaic grid-connected power generation system, in order to ensure the normal grid-connected operation of the inverter, it is necessary to use the DC bus voltage detection circuit in the inverter to detect the DC bus voltage at point A in real time. [0003] When the DC bus voltage detected by the DC bus voltage detection circuit is too high or too low, the inverter cannot be connected to the grid normally. For example: when the DC bus voltage detection circuit fails and the detected DC bus voltage is lower than the actual value, the inverter will automatically enter the standby state due to the low input voltage; at this time, if the DC bus voltage detection circuit cannot be detected in time Faults will cause the inverter to fail to ru...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R35/00H02J3/38H02M7/48
CPCY02B70/10
Inventor 倪华代尚方俞雁飞杨宗军
Owner SUNGROW POWER SUPPLY CO LTD