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Intelligent PT harmonic elimination and phase selection method and device

A harmonic elimination and phase selection technology, applied in the direction of circuit devices, emergency protection circuit devices, emergency protection circuit devices for limiting overcurrent/overvoltage, etc., can solve the problem of increasing the number of fault trips and power outages Ground fault judgment and protection, equipment and personal threats, etc., to achieve the effect of benefiting the reliability of power supply, the safety of power supply, and the simple and reliable measurement and control

Active Publication Date: 2016-02-24
ZHANGJIAKOU POWER SUPPLY COMPANY OF STATE GRID JINBEI ELECTRIC POWER COMPANY +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the operation mode of resistive grounding also has certain disadvantages: 1) When a single-phase grounding occurs, a large grounding current may generate high contact voltage and step voltage, which poses a threat to equipment and people, and damages the surrounding communication lines. 2) The single-phase grounding protection action trips, which increases the number of fault trips and power outage time, and reduces the reliability of power supply; The power supply capacity makes the operation more complicated; 4) It cannot judge and protect the high-resistance ground fault

Method used

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  • Intelligent PT harmonic elimination and phase selection method and device
  • Intelligent PT harmonic elimination and phase selection method and device
  • Intelligent PT harmonic elimination and phase selection method and device

Examples

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example 1

[0032] When a feeder instantaneous single-phase ground fault occurs on the busbar where the device is located, the microcomputer measurement and control device immediately selects the single-phase ground fault phase and fault line from the changes of three-phase voltage, zero-sequence voltage and feeder current, and checks whether there is a continuous fault If there is no record, it is a new fault. The program records the fault phase, fault line and fault occurrence time, gives an alarm and returns to re-judgment; after returning to re-judgment several times, the fault disappears, and its duration is shorter than the permanent fault If the value is set, the device will determine that the fault is an instantaneous ground fault, and the protection will only be used as an alarm for phase selection and line selection.

example 2

[0034]When a feeder permanent single-phase ground fault occurs on the busbar where the device is located, the microcomputer measurement and control device immediately selects the single-phase ground fault phase and fault line from the changes of three-phase voltage, zero-sequence voltage and feeder current, and checks whether there is a continuous fault. If there is no fault record, it is a new fault. The program records the fault phase, fault line and fault occurrence time, gives an alarm and returns to re-judgment; after returning to re-judgment several times, the fault still exists, and its duration is longer than permanent If the fault setting value is set, the device determines that the fault is a permanent ground fault, and the protection not only performs phase selection and line selection alarm, but also drives the trip box corresponding to the output terminal of the selected fault line to cut off the ground fault line.

example 3

[0036] Due to voltage disturbances such as single-phase grounding faults on the busbar where the device is located, the ferromagnetic resonance of the voltage transformer is excited. The microcomputer measurement and control device immediately judges the occurrence of resonance from the changes in the three-phase voltage, zero-sequence voltage and frequency, and drives and connects to the opening of the voltage transformer. The solid-state relay of the triangle is closed instantaneously, consuming resonance energy to achieve harmonic elimination.

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Abstract

The invention provides an intelligent PT harmonic elimination and phase selection method and device. A three-phase five-pole voltage transformer PT is adopted to acquire voltage data in a power grid, and sampling of three-phase bus voltage and zero-sequence voltage is performed by a voltage sampling module when zero-sequence voltage occurs; sampling of zero-sequence current of all feeder lines is performed by a current sampling module, all sampling values are inputted to a single-chip microcomputer, the amplitude and the phase of all phases of voltage and zero-sequence voltage are calculated and judged by the single-chip microcomputer, fault phases and fault lines are selected, faults are classified into instantaneous faults or permanent faults according to duration of single-phase earth faults, and only alarming is actuated for protection as for the instantaneous single-phase earth faults so that reliability of power supply can be guaranteed; and tripping is actuated for protection apart from alarming as for the permanent single-phase earth faults so that safety of power supply can be guaranteed.

Description

technical field [0001] The invention relates to the field of power grid safety, especially a method and device for phase selection of harmonic elimination, in particular to a method and device for intelligently identifying and protecting single-phase grounding faults by eliminating resonance in a neutral point non-effectively grounded power grid. Background technique [0002] In the neutral point non-effectively grounded power grid, resonance and single-phase grounding are the main fault forms in the operation of the power grid, which affect the safe operation of the power grid. [0003] There are many energy storage components in the power system. When the system is in operation or fails, the series connection of nonlinear inductive components containing iron core components such as transformers and transformers with the capacitance in the system may cause ferromagnetic resonance, which poses a threat to the safe operation of the power system. harm. In the indirect groundi...

Claims

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Application Information

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IPC IPC(8): H02H9/08
CPCH02H9/08
Inventor 张平董潇涛孙嘉宁周毅段振坤夏博
Owner ZHANGJIAKOU POWER SUPPLY COMPANY OF STATE GRID JINBEI ELECTRIC POWER COMPANY
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