Method and device for obtaining three-phase power flow of power distribution network with ungrounded transformers

Patent metadata

Field	Value
Publication number	US-9625929-B2
Application number	US-201414292022-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	Jan 10, 2014
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A method for obtaining a three-phase power flow of a power distribution network and a device for obtaining a three-phase power flow of a power distribution network are provided. The method includes steps of: selecting a three-phase power transformer in the power distribution network and configuring a secondary side of the three-phase power transformer with an ungrounded neutral connection, such that the three-phase power transformer satisfies a preset voltage-current relationship; adding a constraint condition to the preset voltage-current relationship to correct a three-phase admittance matrix of the three-phase power transformer; and applying the three-phase admittance matrix to a preset algorithm to obtain a three-phase power flow of the power distribution network.

First claim

What is claimed is:

1. A method for obtaining a three-phase power flow of a power distribution network, comprising steps of:
selecting a three-phase power transformer in the power distribution network, and configuring a secondary side of the three-phase power transformer with an ungrounded neutral connection, such that the three-phase power transformer satisfies a preset voltage-current relationship;
adding a constraint condition to the preset voltage-current relationship to correct a three-phase admittance matrix of the three-phase power transformer; and
applying the three-phase admittance matrix to a preset algorithm to obtain the three-phase power flow of the power distribution network.

2. The method according to claim 1 , wherein the preset voltage-current relationship of the three-phase power transformer is expressed according to formula (1),

[

I
p

I
s

]

=

[

Y
pp

Y

p
⁢

⁢
s

Y
sp

Y
ss

]

⁡

[

U
p

U
s

]

(
1
)

where U p represents a primary voltage vector of the three-phase power transformer, I p represents a primary current vector of the three-phase power transformer, U s represents a secondary voltage vector of the three-phase power transformer, I s represents a secondary current vector of the three-phase power transformer,

Y
=

[

Y
pp

Y

p
⁢

⁢
s

Y
sp

Y
ss

]

represents the three-phase admittance matrix of the three-phase Y phase power transformer, Y pp represents a self-admittance sub-matrix at the primary side, Y ss represents a self-admittance sub-matrix at the secondary side, Y ps represents a mutual admittance sub-matrix from the primary side to the secondary side, Y sp represents a mutual admittance sub-matrix from the secondary side to the primary side, Y sp =Y ps T , “T” represents a transposition calculation of a matrix.

3. The method according to claim 2 , wherein
the constraint condition is expressed according to formula (2),
U sa +U sb +U sc =3 U 0   (2)

where U sa , U sb and U sc represent secondary voltages on phases a, b and c respectively, U 0 represents a zero-sequence voltage at the secondary side;
wherein the voltage-current relationship with the constraint condition is expressed according to formula (3),

[

I
p

I
s
′

]

=

[

Y
pp

Y

p
⁢

⁢
s

′

Assignees

• Univ Tsinghua
• Guizhou Power Grid Information & Telecommunication Co Ltd

Inventors

• Wu Wenchuan
• Zhang Boming
• Zou Qing
• Sun Hongbin
• Li Fei
• Guo Qinglai
• Liu Yi
• Gao Yajing
• Miao Hongjia
• Ji Yuan

Classifications

• G01R31/62

  Testing of transformers · CPC title

• G01R19/2513 Primary

  Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging · CPC title

• G05F1/66 Primary

  Regulating electric power · CPC title

• G01R27/02

  Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant (by measuring phase angle only G01R25/00) · CPC title

• G01R31/027

  Physics · mapped topic