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Selection method of 110 kV power distribution network neutral resistor

A neutral point grounding, distribution network technology, applied in emergency protection circuit devices, electrical components, circuit devices, etc. for limiting overcurrent/overvoltage, can solve the problem of inability to meet sensitive load power supply requirements and user economic losses , product quality decline and other problems, to achieve the effect of improving the quality of system power supply

Inactive Publication Date: 2014-03-19
STATE GRID CORP OF CHINA +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In recent years, with the extensive use of sensitive loads such as frequency conversion speed control equipment and various automatic production lines controlled by computers, voltage sag has become an important power quality problem, and several cycles of voltage sag will affect some enterprises. The normal operation of electrical equipment leads to a decline in product quality, disorder or interruption of the production line, and frequent voltage sags cause huge economic losses to users.
The 110kV system adopts the neutral point direct grounding method, which can no longer meet the power supply requirements of sensitive loads

Method used

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  • Selection method of 110 kV power distribution network neutral resistor
  • Selection method of 110 kV power distribution network neutral resistor
  • Selection method of 110 kV power distribution network neutral resistor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] For E-type transformers (Y 0 / Y-12, Y / Y-12), the windings on both sides are star-connected, and at least one side of the neutral point is not grounded, the zero-sequence current and zero-sequence voltage cannot pass through the transformer, and the positive-sequence and negative-sequence voltage When the vector passes through the E-type transformer, the phase does not change, so the sequence component relationship between the high and low voltage sides is shown in formula (1):

[0026] U m ( 1 ) · U m ( 2 ...

Embodiment 2

[0072] for F 1 type transformer (Y 0 / △-11, Y / △-11), when the zero-sequence current flows through the star side, the zero-sequence induced electromotive force will be generated in each phase winding of the delta side, and provide a path for the zero-sequence current, because the zero-sequence current three-phase The magnitude and phase are the same, and the zero-sequence current and voltage components still cannot propagate to the outside of the triangle side. At the same time, the positive sequence and negative sequence components will also undergo phase changes after passing through the transformer. The sequence component relationship between the high and low pressure sides is shown in formula (19):

[0073]

[0074] In the same way, F 1 The transfer matrix of the phase voltage and line voltage of the type transformer is:

[0075] T F 1 - P = T ...

Embodiment 3

[0084] Because in the general distribution network, the step-down transformer has both F 1 Type wiring, and E-type wiring, comprehensively considered, the constraints that must be satisfied to determine the neutral point resistance of the 110kV resistance-grounded distribution network are:

[0085] k=R 0 / X 1 ≥11 (23)

[0086] According to the requirements of 2.1 of DL / T620-1997 "Overvoltage Protection and Insulation Coordination of AC Electrical Installations", the system design of high resistance grounding should comply with R 0 ≤X CO guidelines to limit transient overvoltages due to arcing ground faults. R 0 is the equivalent zero-sequence resistance of the system, X CO is the distributed capacitive reactance per phase of the system, and for low resistance grounded systems, the criterion for limiting transient overvoltage is R 0 / X 0 ≥2, where X 0 is the equivalent zero-sequence inductive reactance of the system.

[0087] Then the neutral point grounding resistanc...

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Abstract

The invention discloses a selection method of a 110 kV power distribution network neutral resistor. The method comprises: eliminating a first constraint condition of a load side voltage temporary drop / temporary rise caused by a single-phase grounding fault: R0>=11X1; and limiting a second constraint condition of system transient overvoltage: R0<=Xco and a third constraint condition: R0>=2X0.

Description

technical field [0001] The invention relates to a selection method of a grounding resistance, in particular to a selection method of a distribution network neutral point grounding resistance. Background technique [0002] my country's 110kV distribution network generally operates in the way of direct grounding of the neutral point. When a single-phase grounding short circuit occurs in this system, the three-phase voltage on the load side is obviously asymmetrical, and the voltage sag is serious. In recent years, with the extensive use of sensitive loads such as frequency conversion speed control equipment and various automatic production lines controlled by computers, voltage sag has become an important power quality problem, and several cycles of voltage sag will affect some enterprises. The normal operation of electrical equipment leads to a decline in product quality, disorder or interruption of the production line, and frequent voltage sags cause huge economic losses to ...

Claims

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Application Information

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IPC IPC(8): H02H9/08H02H9/04
Inventor 冯光亮吕艳萍张博曾国何晓章李俊贺攀
Owner STATE GRID CORP OF CHINA