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Three-phase unbalance control method and phase commutation system

A three-phase, balanced technology, applied in the field of commutation systems, can solve the problems of distribution transformer operating temperature rise, distribution transformer output reduction, power conversion efficiency drop, etc., to improve the quality of power supply voltage and reduce dynamic unbalance degree of effect

Active Publication Date: 2019-11-08
NANJING INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The unbalanced three-phase load will cause a series of impacts on the distribution station area, mainly including: 1) the output of the distribution transformer is reduced, and the power conversion efficiency is greatly reduced; 2) the loss of the distribution transformer and the line is greatly increased; 3 ) lead to a serious decline in the quality of the power supply voltage of the heavy-duty phase in the distribution station area; 4) the zero-sequence current of the distribution transformer is greatly increased, and the eddy current loss caused increases the operating temperature of the distribution transformer, endangering its safety and life
However, reactive power compensation devices have problems such as difficult calculations, switching oscillations, and harmonic amplification.
The commutator generally uses a combination of relays and power electronic devices, which has problems such as no clear mechanical breakpoint, large additional loss, and vulnerability to lightning strikes and other factors, which will cause great economic losses and safety hazards to users' lives and industrial production.
Another problem with these governance measures is the high cost

Method used

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  • Three-phase unbalance control method and phase commutation system
  • Three-phase unbalance control method and phase commutation system
  • Three-phase unbalance control method and phase commutation system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] In this method embodiment, step S1 includes the steps of:

[0057] S11, measure the active power P of each phase of the three-phase system A ,P B ,P C ;

[0058] S12, calculate the three-phase average power P of the three-phase system aver :

[0059] P aver =(P A +P B +P C ) / 3

[0060] S13, calculate the active power unbalance degree ε of the three-phase system P :

[0061]

[0062] Step S2 comprises the following steps:

[0063] S21, define the active power unbalance threshold of the three-phase system, judge whether the active power unbalance of the current three-phase system meets the threshold, if it is satisfied, then do not perform commutation switching operation, if not, go to step S22;

[0064] S22, calculate the difference ΔP between the active power of the three phases A, B, and C and the average power of the three phases respectively A , ΔP B , ΔP C :

[0065] ΔP A =P A -P aver

[0066] ΔP B =P B -P aver

[0067] ΔP C =P C -P ave...

Embodiment 2

[0076] Such as figure 1 As shown, the corresponding method steps of the specific steps of this embodiment are as follows:

[0077] First, calculate the unbalance degree of the three-phase system according to the active power and positive or negative of the load in the three-phase system: that is, the three-phase unbalance is defined by the active power and positive or negative of the load. Measure the active power P of each phase separately A ,P B ,P C , The power can be divided into positive and negative, the active power generated by the power supply is negative, and the active power consumed by the load is positive. To meet the three-phase load balance, that is, the active power and attributes of each phase load are the same.

[0078] Define the unbalance degree of active work as

[0079]

[0080] Where: P aver =(P A +P B +P C ) / 3, namely P aver is the average value of the three-phase active power.

[0081] The definition of load unbalance based on active powe...

Embodiment 3

[0095] refer to figure 2 and image 3 As shown, the three-phase unbalanced commutation system of the present invention is specifically as follows: a proper amount of low-voltage load automatic phase-commutation devices are reasonably arranged in the distribution station area, and a low-voltage load automatic phase-commutation terminal controller is added. The terminal controller is realized by computer, which obtains the real-time active power and phase sequence real-time data of the three-phase load on the low-voltage side of the distribution transformer in the three-phase line from the existing three-phase line monitoring system (that is, the monitoring module and the computer terminal in the figure) , so that according to the obtained data, the unbalanced three-phase load on the low-voltage side of the distribution transformer can be monitored in real time. The phase real-time power data is analyzed, judged and optimized, and the optimal commutation control command is iss...

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Abstract

The invention disclose a three-phase unbalance management method and commutation system based on active power unbalanced automatic phase change control strategy which comprises the following steps: first, the imbalance degree of the three-phase system is calculated based on the load capacity and the positive and negative load in the three-phase system; whether commutation is switched and phase identification of the loading switching is needed to match the required change commutation capacity; at last the accessed phase is selected and accessed to correspondent with the to be switched phase, and then a phase-change switch which is adaptable to the load capacity and the change phase capacity is accessed, and the load is switched, so that three-phase active power tends to balance. The three-phase unbalance management method and commutation system based on active power unbalanced automatic phase change control strategy governs the three-phase unbalance phenomenon, the three-phase unbalance degree is reduced obviously, and the quality of the providing electricity is improved.

Description

technical field [0001] The invention relates to the technical field of three-phase unbalance control in electric power systems, in particular to a three-phase unbalance control method and a phase-commutation system based on an active power unbalance automatic phase-commutation control strategy. Background technique [0002] The three-phase imbalance of the power system is mainly caused by the asymmetry of the three-phase load and the unbalanced distribution of a large number of single-phase loads in the three-phase system. The unbalanced three-phase load will cause a series of impacts on the distribution station area, mainly including: 1) the output of the distribution transformer is reduced, and the power conversion efficiency is greatly reduced; 2) the loss of the distribution transformer and the line is greatly increased; 3 ) lead to a serious decline in the quality of the power supply voltage of the heavy-duty phase in the distribution station area; 4) the zero-sequence ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/26
CPCH02J3/26Y02E40/50
Inventor 郝思鹏储婷丁哲
Owner NANJING INST OF TECH
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