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Capacitive switching control method for inhibiting zero sequence and negative sequence current of distribution transformer

A distribution transformer and negative-sequence current technology, which is applied in the field of power systems, can solve problems such as prone to overcompensation and failure to consider the influence of distribution transformer governance effects

Active Publication Date: 2013-02-13
四川得丰电气有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The above method does not consider the influence of the actual device capacity on the treatment effect of distribution transformers, which is prone to problems such as overcompensation

Method used

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  • Capacitive switching control method for inhibiting zero sequence and negative sequence current of distribution transformer

Examples

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Embodiment 1

[0031] Example 1 figure 1 , A capacitive switching control system that suppresses the zero-sequence and negative-sequence currents of distribution transformers. It consists of a voltage transformer 11, a current transformer 12, a front-end processing circuit 13, a central processing unit 14, a capacitor adjustment cabinet 15, and GPRS communication The module 16 and the upper computer 17 are composed of the voltage transformer 11 and the current transformer 12 of the power quality acquisition unit to collect the voltage, current and neutral current signals of the transformer during operation, and transmit the collected signals to the central processing unit 14, the central processing unit 14 Calculate the voltage, current, and power factor based on the collected signals, and consider the harm of over-compensation to the distribution transformer, calculate the effective capacitance adjustment, obtain the control signal of the capacitance adjustment cabinet 15 and control the actio...

Embodiment 2

[0032] Example 2, suppose that the three-phase voltage on the low-voltage side of the distribution transformer at this time is = = =220V, the phase difference is 120 degrees, the three-phase current and power factor are respectively =11.9A, =23.2A, =10.3A, =0.92, =0.96, =0.73, the load is inductive, the reference capacity of the capacitor adjustment cabinet is 1kvar, and the adjustment range of the phase-to-phase and phase-to-ground reactive power adjustment is 0kvar to 7kvar.

[0033] According to formula (1), the three-phase active power on the load side is:

[0034] =2.4kw, =4.9kw, =1.7kw;

[0035] According to formula (2), the inductive reactive power on the load side is:

[0036] =-1.0kvar, =-1.4kvar, =-1.5kvar;

[0037] At this time, the negative sequence current is 5.1A, and the zero sequence current is 3.7A. According to the formula (3), the reactive power adjustments that should be compensated between the phases and the corresponding ground after preliminary opti...

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Abstract

The invention relates to a capacitive switching control method for inhibiting zero sequence and negative sequence current of a distribution transformer. An electric power quality acquisition unit acquires a three-phase voltage current and neutral current signals; a central processing unit calculates voltage, current and power factor parameters according to the acquired signals, and determines an actual switching amount; a capacitor is switched by the control of an intelligent combination switch; current load state and capacity regulation conditions are transmitted to an upper computer through a GPRS (General Packet Radio Service) module; and background software realizes the functions of data recording, analysis and the like. According to the method provided by the invention, the influence of overcompensation on a distribution transformer can be considered according to the acquired electric power quality signals, so that the capacitor can be reasonably regulated, thereby effectively inhibiting zero sequence and negative sequence current of the distribution transformer and improving the electric power quality of the distribution transformer.

Description

Technical field [0001] The invention belongs to the field of power systems, and particularly relates to a capacitive switching control method for suppressing the zero sequence and negative sequence current of a distribution transformer. Background technique [0002] A large number of three-phase four-wire connections are used in my country’s urban and rural distribution networks, and there are a large number of single-phase loads. The long-term three-phase unbalanced operation of distribution transformers reduces the power quality of users’ electricity, increases transformer losses, and increases transformer winding temperature. High, even burned the winding. If there is a large zero or negative sequence current in the line, the temperature of the metal parts of the transformer will increase, and in severe cases, it will even cause a transformer accident. In addition, too high zero or negative sequence current will reduce the power supply quality of the distribution transformer. ...

Claims

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Application Information

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IPC IPC(8): H02J3/00H02J3/18
CPCY02E40/30
Inventor 张占龙赵晖何为雷剪张家铭郭民怿
Owner 四川得丰电气有限公司
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