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Balance compensation device of low-voltage power grid

A technology of balance compensation and low-voltage power grid, applied in the field of electric power, can solve the problems of three-phase unbalance of low-voltage power grid, and achieve the effect of solving the problem of three-phase unbalance.

Inactive Publication Date: 2015-04-29
STATE GRID CORP OF CHINA +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In view of this, the application provides a balance compensation device for the low-voltage power grid, which is used to compensate the zero-sequence current to solve the three-phase unbalance problem of the low-voltage power grid

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  • Balance compensation device of low-voltage power grid
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  • Balance compensation device of low-voltage power grid

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Embodiment 1

[0027] figure 1 A structural diagram of a balance compensation device for a low-voltage power grid provided in an embodiment of the present application.

[0028] Such as figure 1 As shown, the balance compensation device provided by this embodiment includes a meander transformer 10 , a single-phase inverter 20 , a zero-sequence current detection circuit 40 and an inverter controller 30 .

[0029] The 10 three-phase input terminals of the meander transformer are connected to the three-phase phases of the low-voltage power grid 100. Since its impedance to the positive sequence current and the negative sequence current is very large, it will not affect its current, but its impedance to the zero sequence current is very large. Small, and basically 0, so zero-sequence current can flow easily.

[0030] One end of the output end of the single-phase inverter 20 is connected to the neutral line of the meander transformer 10 , and the other end is respectively connected to the neutral...

Embodiment 2

[0065] Figure 5 A structural diagram of a balance compensation device for a low-voltage power grid provided in another embodiment of the present application.

[0066] Such as Figure 5 As shown, the balance compensation device provided in this embodiment is based on the previous embodiment with the addition of a protection circuit 50 .

[0067] Because the output power of the single-phase inverter of this device has a certain limit, when the output current is too large, it will cause irreversible damage to the device. Fault, so the compensation current must be limited to protect the device. The protection circuit is used to cut off the connection between the meander transformer 10 and the low-voltage grid when the zero-sequence current exceeds the preset limit current, so as to protect the device. By examining the parameters of each component, the limit current of the device is preferably 60 amps.

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Abstract

The invention provides a balance compensation device of a low-voltage power grid. The balance compensation device comprises a zigzag transformer, a single-phase inverter, a zero sequence current detecting circuit and an inverter controller, wherein the zigzag transformer is connected to the three phases of the low-voltage power grid, one end of the output end of the single-phase inverter is connected with the neutral line of the zigzag transformer, the zero sequence current detecting circuit is used for detecting the currents of the neutral line of the zigzag transformer and the currents of the neutral line of the low-voltage power grid, the inverter controller controls the single-phase inverter according to the detecting results of the zero sequence current detecting circuit, and the other end of the output end of the single-phase inverter is used for being connected with the neutral line of the low-voltage power grid. By the balance compensation device, zero sequence currents form a loop among the zigzag transformer, the single-phase inverter and a load, the currents of the neutral line of the low-voltage power grid is allowed to drop to zero, compensation of the zero sequence currents of the low-voltage power grid is completed, and the three-phase unbalance problem of the low-voltage power grid is solved.

Description

technical field [0001] The present application relates to the field of electric power technology, and more specifically, relates to a balance compensation device for a low-voltage power grid. Background technique [0002] my country's distribution network adopts a three-phase four-wire distribution transformer power supply mode, and the transformer capacity is less than 100kVA, which accounts for about half of the total number of transformers in the world. Because the distribution is basically done manually, it is easy to cause low-voltage single-phase loads in the distribution network to fail. These factors inevitably lead to the unbalanced three-phase problem of the low-voltage power grid. [0003] Unbalanced three-phase will lead to neutral line overload, overheating, and electromagnetic interference, affect the supply voltage waveform, insulation layer damage, reduce power factor, reduce the service life of transformers and electrical equipment and other problems. Conte...

Claims

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Application Information

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IPC IPC(8): H02J3/26H02H7/122
CPCY02E40/50H02J3/26H02H7/122H02H7/1225H02H7/1227
Inventor 董细炉徐永阳章忠郑健睿张育华方淼江李琼
Owner STATE GRID CORP OF CHINA
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