CN108459233A - A kind of main transformer gets higher equivalent circuit and the recognition methods of two-phase disconnection fault - Google Patents
A kind of main transformer gets higher equivalent circuit and the recognition methods of two-phase disconnection fault Download PDFInfo
- Publication number
- CN108459233A CN108459233A CN201810257387.7A CN201810257387A CN108459233A CN 108459233 A CN108459233 A CN 108459233A CN 201810257387 A CN201810257387 A CN 201810257387A CN 108459233 A CN108459233 A CN 108459233A
- Authority
- CN
- China
- Prior art keywords
- sequence
- impedance
- pressure side
- equivalent
- busbares
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000000819 phase cycle Methods 0.000 claims abstract description 41
- 230000007935 neutral effect Effects 0.000 claims abstract description 24
- 238000003032 molecular docking Methods 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000007405 data analysis Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Supply And Distribution Of Alternating Current (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The present invention provides the equivalent circuit that a kind of main transformer gets higher two-phase disconnection fault, is formed by circuit equivalent with 220kV busbares, 110kV busbares, the normal main transformers of multiple 220kV and 220kV failure main transformers, and failure neutral point of main transformer is grounded.Specifically include the positive sequence network, negative sequence network and zero-sequence network mutually concatenated；Positive sequence network include positive sequence equivalent busbar and each main transformer height, in and low-pressure side positive sequence impedance；Negative sequence network includes the equivalent busbar of negative phase-sequence and each main transformer height, medium voltage side negative sequence impedance；Zero-sequence network includes the height of the equivalent busbar of zero sequence and the main transformer of neutral ground, medium voltage side negative sequence impedance；Wherein, there is equal in magnitude, the identical electric current in direction on the on high-tension side positive and negative, zero sequence impedance of failure main transformer simultaneously, and have equal in magnitude, the identical electric current in direction simultaneously on the negative of medium voltage side, zero sequence impedance.Implement the present invention, 220kV main transformers can be solved get higher two-phase broken string to lead to main transformer process experience caused by trip event is insufficient, less efficient simultaneously.
Description
Technical field
The present invention relates to electric system T ＆ D Technology field more particularly to a kind of main transformer get higher two-phase disconnection fault etc.
Imitate circuit and recognition methods.
Background technology
No. 3 main transformers of certain 220kV substation in 2017 get higher power transmission after switch maintenance work, in transmission process, first
Conjunction get higher it is without exception when switch, but close become in switch after, there is zero sequence mistake in No. 3 main transformers and running No. 1 main transformer medium voltage side
II section of stream is protected while the phenomenon that acts, to cause No. 3 and No. 1 two main transformers while trip.Staff is analysing in depth
After fault waveform and fault current amplitudes, the reason of confirming the event, gets higher BC two-phases broken string for No. 3 main transformers.
However, there is no document to get higher two-phase broken string to 220kV main transformers at present carries out theoretical research, and scene lacks broken string
The process experience of failure so that the analysis time of the event is very long, and power supply can not be replied immediately soon so as to cause this two main transformers, to supplying
Electric reliability and the safe and stable operation ability of power grid cause large effect.
Therefore, there is an urgent need for equivalent circuit and recognition methods that a kind of main transformer gets higher two-phase disconnection fault, 220kV master can be solved
Getting higher two-phase broken string leads to problems such as process experience caused by main transformer while trip event insufficient, less efficient.
Invention content
Technical problem to be solved of the embodiment of the present invention is, provides a kind of main transformer and gets higher the equivalent of two-phase disconnection fault
Circuit and recognition methods, can solve 220kV main transformers and get higher two-phase broken string to lead to main transformer processing caused by trip event simultaneously
The problems such as lacking experience, be less efficient.
In order to solve the above-mentioned technical problem, an embodiment of the present invention provides a kind of main transformers to get higher the equivalent of two-phase disconnection fault
Circuit, and by 220kV busbares, 110kV busbares and normal main transformers of multiple 220kV between in parallel and one
220kV failure main transformers are formed by circuit equivalent, and the 220kV failures neutral point of main transformer is grounded；
The equivalent circuit that the main transformer gets higher two-phase disconnection fault includes the positive sequence network mutually concatenated, negative sequence network and zero sequence net
Network；Wherein,
The positive sequence network includes the positive sequence equivalent busbar and its corresponding equivalent power supply, substitutional resistance of the 220kV busbares, institute
State the positive sequence equivalent busbar and its corresponding duty value and the normal main transformers of the multiple 220kV and described of 110kV busbares
The corresponding high-pressure side positive sequence impedance of 220kV failure main transformers, medium voltage side positive sequence impedance and low-pressure side positive sequence impedance；Wherein, institute
The equivalent power supply for stating 220kV busbares is serially connected in the positive sequence equivalent of the 220kV busbares by the substitutional resistance of the 220kV busbares
On the input terminal of busbar；The duty value of the 110kV busbares is serially connected in the output of the positive sequence equivalent busbar of the 110kV busbares
On end；The normal main transformers of each 220kV by one end of corresponding high-pressure side positive sequence impedance, medium voltage side positive sequence impedance one
End and one end of low-pressure side positive sequence impedance are docking together, and also access the other end of corresponding high-pressure side positive sequence impedance
The output end of the positive sequence equivalent busbar of the 220kV busbares, and also by the other end of corresponding medium voltage side positive sequence impedance
Access the input terminal of the positive sequence equivalent busbar of the 110kV busbares；The 220kV failures main transformer is by its corresponding high-pressure side positive sequence
One end of one end of impedance, one end of medium voltage side positive sequence impedance and low-pressure side positive sequence impedance is docking together, also that its is corresponding
The other end of medium voltage side positive sequence impedance accesses the input terminal of the positive sequence equivalent busbar of the 110kV busbares, also by its corresponding height
The other end of pressure side positive sequence impedance accesses one end of the negative sequence network；The output of the positive sequence equivalent busbar of the 220kV busbares
One end of the zero-sequence network is also accessed at end；
The negative sequence network includes the equivalent busbar of negative phase-sequence of the equivalent busbar of negative phase-sequence of the 220kV busbares, the 110kV busbares,
And the multiple normal main transformers of 220kV and the corresponding high-pressure side negative sequence impedance of the 220kV failures main transformer and medium voltage side
Negative sequence impedance；Wherein, the normal main transformers of each 220kV bear one end of corresponding high-pressure side negative sequence impedance and medium voltage side
One end of sequence impedance mutually concatenates, and the other end of corresponding high-pressure side negative sequence impedance is also accessed the 220kV busbares
The equivalent busbar of negative phase-sequence, and the other end of corresponding medium voltage side negative sequence impedance is also accessed to the negative phase-sequence of the 110kV busbares
Equivalent busbar；The 220kV failures main transformer is by the one of one end of its corresponding high-pressure side negative sequence impedance and medium voltage side negative sequence impedance
End mutually concatenates, and the other end of its corresponding medium voltage side negative sequence impedance is also accessed to the equivalent busbar of negative phase-sequence of the 110kV busbares, also
The other end of its corresponding high-pressure side negative sequence impedance is accessed to the other end of the zero-sequence network；The negative phase-sequence of the 220kV busbares
Equivalent busbar is also connected with the other end of the high-pressure side positive sequence impedance of 220kV failures main transformer in the positive sequence network；
The zero-sequence network include the equivalent busbar of zero sequence of the 220kV busbares, the 110kV busbares the equivalent busbar of zero sequence,
The corresponding high-pressure side zero sequence impedance of 220kV main transformers of neutral ground among the multiple normal main transformers of 220kV and middle pressure
The high-pressure side zero sequence impedance and medium voltage side zero sequence impedance of side zero sequence impedance and the 220kV failures main transformer；Wherein, in each
Property point ground connection the normal main transformers of 220kV by the one of one end of corresponding high-pressure side zero sequence impedance and medium voltage side zero sequence impedance
End mutually concatenates, and the other end of corresponding high-pressure side zero sequence impedance is also accessed to the equivalent mother of zero sequence of the 220kV busbares
Line, and the other end of corresponding medium voltage side zero sequence impedance is also accessed to the equivalent busbar of zero sequence of the 110kV busbares；Institute
It states 220kV failures main transformer mutually to concatenate one end of one end of its corresponding high-pressure side zero sequence impedance and medium voltage side zero sequence impedance, also
The other end of its corresponding medium voltage side zero sequence impedance is accessed to the equivalent busbar of zero sequence of the 110kV busbares, it is also that its is corresponding
The other end of high-pressure side zero sequence impedance accesses the output end of the positive sequence equivalent busbar of 220kV busbares in the positive sequence network；It is described
The equivalent busbar of zero sequence of 220kV busbares also in the negative sequence network high-pressure side negative sequence impedance of 220kV failures main transformer it is another
End is connected；
Wherein, same on the high-pressure side positive sequence impedance of the 220kV failures main transformer, high-pressure side negative sequence impedance and high-pressure side zero sequence impedance
When have equal in magnitude, the identical electric current in direction；
Wherein, there is equal in magnitude, side simultaneously on the medium voltage side negative sequence impedance of the 220kV failures main transformer and medium voltage side zero sequence impedance
To identical electric current.
Wherein, the voltage of the positive sequence equivalent busbar of the 220kV busbares, the equivalent busbar of negative phase-sequence and the equivalent busbar of zero sequence is homogeneous
Deng.
Wherein, the voltage of the positive sequence equivalent busbar of the 110kV busbares, the equivalent busbar of negative phase-sequence and the equivalent busbar of zero sequence is homogeneous
Deng.
Wherein, the normal main transformers of the multiple 220kV and the corresponding low-pressure side positive sequence impedance of the 220kV failures main transformer
Above while there is equal in magnitude, the identical electric current in direction.
The embodiment of the present invention additionally provides the recognition methods that a kind of main transformer gets higher two-phase disconnection fault, in main transformer above-mentioned
It gets higher and is realized on the equivalent circuit of two-phase disconnection fault, the method includes：
Step S1, from the equivalent circuit, obtain positive sequence network on flow through 220kV failure main transformers high-pressure side positive sequence impedance,
The electric current of medium voltage side positive sequence impedance and low-pressure side positive sequence impedance flows through the high-pressure side negative phase-sequence of 220kV failure main transformers on negative sequence network
Flowed through on the electric current and zero-sequence network of impedance and medium voltage side negative sequence impedance 220kV failure main transformers high-pressure side zero sequence impedance and in
Press the electric current of side zero sequence impedance；
Step S2, when high-pressure side positive sequence impedance, high-pressure side negative sequence impedance and the high-pressure side zero for detecting the 220kV failures main transformer
There is equal in magnitude, the identical electric current in direction simultaneously in sequence impedance, and detects the medium voltage side negative phase-sequence of the 220kV failures main transformer
Have simultaneously in impedance and medium voltage side zero sequence impedance it is equal in magnitude, when the identical electric current in direction, it is determined that the 220kV failures main transformer
It gets higher and two-phase disconnection fault occurs.
Implement the embodiment of the present invention, has the advantages that：
In embodiments of the present invention, since the main transformer circuit of practical paired running is transformed into equivalent circuit, and to equivalent circuit
The electric current of middle failure main transformer is differentiated quickly to determine the two-phase disconnection fault of failure main transformer, so as to solve 220kV master
Getting higher two-phase broken string leads to problems such as process experience caused by main transformer while trip event insufficient, less efficient.
Description of the drawings
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technology description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention, for those of ordinary skill in the art, without having to pay creative labor, according to
These attached drawings obtain other attached drawings and still fall within scope of the invention.
Fig. 1 is the practical circuit diagram of single 220kV main transformers provided in an embodiment of the present invention；Wherein, a is neutral ground
220kV main transformers；B is the 220kV main transformers of isolated neutral；
Fig. 2 is the equivalent circuit of a in Fig. 1；
Fig. 3 is the equivalent circuit of b in Fig. 1；
Fig. 4 is the practical circuit diagram that main transformer provided in an embodiment of the present invention gets higher two-phase disconnection fault；
Fig. 5 is the equivalent circuit diagram that main transformer provided in an embodiment of the present invention gets higher two-phase disconnection fault；
Fig. 6 is the application scenario diagram for the equivalent circuit that main transformer provided in an embodiment of the present invention gets higher two-phase disconnection fault；
Fig. 7 is the flow chart for the recognition methods that main transformer provided in an embodiment of the present invention gets higher two-phase disconnection fault.
Specific implementation mode
To make the object, technical solutions and advantages of the present invention clearer, the present invention is made into one below in conjunction with attached drawing
Step ground detailed description.
Inventor has found, by converting actual circuit to equivalent circuit, and analyzes equivalent circuit, can be quick
The problems of analysis actual circuit, advantageously reduce the complexity of data analysis, improve analysis efficiency, be physical fault
Processing provides effective ensure.
As shown in Figure 1, in the research that 220kV main transformers get higher two-phase broken string, 220kV main transformers can be divided into neutral ground
220kV main transformers（As shown in a in Fig. 1）With the 220kV main transformers of isolated neutral（As shown in b in Fig. 1）.
At this point, as shown in Fig. 2, the 220kV main transformers of neutral ground shown in a in Fig. 1 are transformed into including positive sequence, negative phase-sequence
And the equivalent circuit of zero sequence.Wherein, ZH（1）、ZH（2）、ZH（0）Respectively the 220kV main transformers of neutral ground is electric in positive sequence equivalent
High-pressure side impedance in road, negative phase-sequence equivalent circuit and zero sequence equivalent circuit；ZM（1）、ZM（2）、ZM（0）Respectively neutral ground
The medium voltage side impedance in positive sequence equivalent circuit, negative phase-sequence equivalent circuit and zero sequence equivalent circuit of 220kV main transformers；ZL（1）、ZL（2）、
ZL（0）Respectively the 220kV main transformers of neutral ground in positive sequence equivalent circuit, negative phase-sequence equivalent circuit and zero sequence equivalent circuit
Low-pressure side impedance.
As shown in figure 3, being transformed into the 220kV main transformers of isolated neutral shown in b in Fig. 1 including positive sequence and negative phase-sequence
Equivalent circuit.Due to the earth-free operation of neutral point of main transformer, zero-sequence current circulation cannot be formed, i.e. only positive sequence equivalent circuit and negative
Sequence equivalent circuit.Wherein, ZH（1）、ZH（2）Respectively the 220kV main transformers of isolated neutral in positive sequence equivalent circuit, negative phase-sequence etc.
Imitate the high-pressure side impedance in circuit；ZM（1）、ZM（2）Respectively the 220kV main transformers of isolated neutral in positive sequence equivalent circuit, negative
Medium voltage side impedance in sequence equivalent circuit；ZL（1）、ZL（2）Respectively the 220kV main transformers of isolated neutral is electric in positive sequence equivalent
Low-pressure side impedance in road, negative phase-sequence equivalent circuit.
It can be seen that two-phase broken string event can be got higher to 220kV main transformers according to above-mentioned 220kV main transformers equivalent transformation process
Barrier circuit carries out equivalent transformation to determine the authenticity of failure.As shown in figure 4, the main transformer get higher two-phase disconnection fault circuit by
220kV busbares, 110kV busbares and the normal main transformers of multiple 220kV between in parallel（Such as 220kV main transformers #1, #
2 ..., #N）With a 220kV failure main transformer（Such as 220kV main transformers #N+1）It is formed, and 220kV failure neutral point of main transformer is grounded.It answers
When explanation, 220kV main transformers #1 ~ #N+1 is previously obtained preliminary judgement, but the two-phase broken string event of 220kV failure main transformers #N+1
Barrier is also undetermined.
Therefore, the equivalent circuit that a kind of main transformer gets higher two-phase disconnection fault is inventor provided, can be directed to shown in Fig. 4
Main transformer gets higher two-phase disconnection fault circuit, and quick failure judgement main transformer is the possibility of two-phase disconnection fault.
As shown in figure 5, in the embodiment of the present invention, a kind of main transformer that inventor provides gets higher the equivalent of two-phase disconnection fault
Circuit specifically includes：Positive sequence network A, negative sequence network B and the zero-sequence network C mutually concatenated；Wherein,
Positive sequence network A includes the positive sequence equivalent busbar A1 and its corresponding equivalent power supply Es, substitutional resistance of the 220kV busbares
The positive sequence equivalent busbar A2 of Zs, the 110kV busbar and its normal main transformer #1 ~ #N of corresponding duty value Zp and multiple 220kV and
The corresponding high-pressure side positive sequence impedance Z of 220kV failure main transformers #N+1H（1）, medium voltage side positive sequence impedance ZM（1）And low-pressure side positive sequence resistance
Anti- ZL（1）；Wherein, the equivalent power supply Es of 220kV busbares is being serially connected in 220kV busbares just by the substitutional resistance Zs of 220kV busbares
On the input terminal of the equivalent busbar A1 of sequence；The duty value Zp of 110kV busbares is serially connected in the positive sequence equivalent busbar A2's of 110kV busbares
On output end；The normal main transformer #1 ~ #N of each 220kV are by corresponding high-pressure side positive sequence impedance ZH（1）One end, middle pressure
Side positive sequence impedance ZM（1）One end and low-pressure side positive sequence impedance ZL（1）One end be docking together, also by corresponding high pressure
Side positive sequence impedance ZH（1）Other end access 220kV busbares positive sequence equivalent busbar A1 output end, and also will respectively correspond to
Medium voltage side positive sequence impedance ZM（1）The other end access 110kV busbares positive sequence equivalent busbar A2 input terminal；220kV failure masters
Become #N+1 by its corresponding high-pressure side positive sequence impedance ZH（1）One end, medium voltage side positive sequence impedance ZM（1）One end and low-pressure side positive sequence
Impedance ZL（1）One end be docking together, also by its corresponding medium voltage side positive sequence impedance ZM（1）Other end access 110kV busbares
The input terminal of positive sequence equivalent busbar A2, also by its corresponding high-pressure side positive sequence impedance ZH（1）Other end access negative sequence network B
One end；The output end of the positive sequence equivalent busbar A1 of 220kV busbares also accesses one end of zero-sequence network C；
Negative sequence network B includes the equivalent busbar B2 of negative phase-sequence of equivalent busbar B1,110kV busbar of negative phase-sequence of 220kV busbares and multiple
The corresponding high-pressure side negative sequence impedance Z of 220kV normal main transformer #1 ~ #N and 220kV failure main transformers #N+1H（2）And medium voltage side negative phase-sequence
Impedance ZM（2）；Wherein, the normal main transformer #1 ~ #N of each 220kV are by corresponding high-pressure side negative sequence impedance ZH（2）One end and
Medium voltage side negative sequence impedance ZM（2）One end mutually concatenate, also by corresponding high-pressure side negative sequence impedance ZH（2）The other end access
The equivalent busbar B1 of negative phase-sequence of 220kV busbares, and also by corresponding medium voltage side negative sequence impedance ZM（2）The other end access
The equivalent busbar B2 of negative phase-sequence of 110kV busbares；220kV failure main transformer #N+1 are by its corresponding high-pressure side negative sequence impedance ZH（2）One
End and medium voltage side negative sequence impedance ZM（2）One end mutually concatenate, also by its corresponding medium voltage side negative sequence impedance ZM（2）The other end access
The equivalent busbar B2 of negative phase-sequence of 110kV busbares, also by its corresponding high-pressure side negative sequence impedance ZH（2）Other end access zero-sequence network C
The other end；The equivalent busbar B1 of negative phase-sequence of 220kV busbares also with the high-pressure side of 220kV failures main transformer #N+1 in positive sequence network A just
Sequence impedance ZH（1）The other end be connected；
Zero-sequence network C includes the equivalent busbar C2 of zero sequence, multiple of equivalent busbar C1,110kV busbar of zero sequence of 220kV busbares
220kV main transformers #K ~ #K+L of neutral ground among the normal main transformer #1 ~ #N of 220kV（K+L<N）Corresponding high-pressure side zero sequence
Impedance ZH（0）And medium voltage side zero sequence impedance ZM（0）And the high-pressure side zero sequence impedance Z of 220kV failure main transformers #N+1H（0）And medium voltage side
Zero sequence impedance ZM（0）；Wherein, the normal main transformer #K ~ #K+L of the 220kV of each neutral ground are by corresponding high-pressure side
Zero sequence impedance ZH（0）One end and medium voltage side zero sequence impedance ZM（0）One end mutually concatenate, also by corresponding high-pressure side zero sequence
Impedance ZH（0）The other end access 220kV busbares the equivalent busbar C1 of zero sequence, and also by corresponding medium voltage side zero sequence hinder
Anti- ZM（0）The other end access 110kV busbares the equivalent busbar C2 of zero sequence；220kV failure main transformer #N+1 are by its corresponding high-pressure side
Zero sequence impedance ZH（0）One end and medium voltage side zero sequence impedance ZM（0）One end mutually concatenate, also by its corresponding medium voltage side zero sequence impedance
ZM（0）The other end access 110kV busbares the equivalent busbar C2 of zero sequence, also by its corresponding high-pressure side zero sequence impedance ZH（0）It is another
Terminate the output end of the positive sequence equivalent busbar A1 of 220kV busbares in positive sequence network A；The equivalent busbar C1 of zero sequence of 220kV busbares
Also with the high-pressure side negative sequence impedance Z of 220kV failures main transformer #N+1 in negative sequence network BH（2）The other end be connected；
Wherein, the high-pressure side positive sequence impedance Z of 220kV failures main transformer #N+1H（1）, high-pressure side negative sequence impedance ZH（2）And high-pressure side zero sequence
Impedance ZH（0）Above while there is equal in magnitude, the identical electric current in direction；For example, high-pressure side positive sequence impedance ZH（1）Electric current I11, high pressure
Side negative sequence impedance ZH（2）Electric current I21, high-pressure side zero sequence impedance ZH（0）Electric current I01Equal in magnitude, direction is identical；
Wherein, the medium voltage side negative sequence impedance Z of 220kV failures main transformer #N+1M（2）And medium voltage side zero sequence impedance ZM（0）Above while having big
It is small equal, the identical electric current in direction, for example, medium voltage side negative sequence impedance ZM（2）Electric current I22, medium voltage side zero sequence impedance ZM（0）Electricity
Flow I02Equal in magnitude, direction is identical.
It should be noted that since power grid does not have negative phase-sequence load so that main transformer low-pressure side winding will not in equivalent circuit
Negative-sequence current is generated, and main transformer low-pressure side is delta connection, main transformer low-pressure side line current there will not be in equivalent circuit
Zero-sequence current, therefore the low-pressure side of 220kV failure main transformers #N+1 is not in negative-sequence current and zero-sequence current.K, L, N are just
Integer.
It is understood that once detecting the high-pressure side positive sequence impedance Z of 220kV failure main transformers #N+1H（1）, high-pressure side it is negative
Sequence impedance ZH（2）And high-pressure side zero sequence impedance ZH（0）Above while there are equal in magnitude, the identical electric current in direction, and 220kV failure masters
Become the medium voltage side negative sequence impedance Z of #N+1M（2）And medium voltage side zero sequence impedance ZM（0）Equal in magnitude, the identical electric current in direction is gone up while having,
It will then judge that the failure that 220kV failure main transformers #N+1 occurs is two-phase disconnection fault.
In embodiments of the present invention, the positive sequence equivalent busbar A1 of 220kV busbares, the equivalent busbar B1 of negative phase-sequence and the equivalent mother of zero sequence
The voltage of line C 1 is equal, and is all 220kV.
In embodiments of the present invention, the positive sequence equivalent busbar A2 of 110kV busbares, the equivalent busbar B2 of negative phase-sequence and the equivalent mother of zero sequence
The voltage of line C2 is equal, and is all 110kV.
In embodiments of the present invention, the normal main transformer #1 ~ #N of multiple 220kV and 220kV failure main transformers #N+1 are corresponding
Low-pressure side positive sequence impedance ZL（1）Above while there is equal in magnitude, the identical electric current in direction, because power grid occurs disconnection fault and will not lead
Equipment damage is caused, normal power supply can be kept, several seconds time is only maintained to transformer tripping from disconnection fault occurs at this time, in the time
The workload demand of user is constant.It should be noted that due to the normal main transformer #1 ~ #N of multiple 220kV and 220kV failure main transformers #N+1
Corresponding low-pressure side positive sequence impedance ZL（1）Above while there is equal in magnitude, the identical electric current in direction, and workload demand is constant simultaneously
For constant, then the normal main transformer #1 ~ #N of multiple 220kV in Fig. 5 and the corresponding low-pressure side positive sequences of 220kV failure main transformers #N+1
Impedance ZL（1）It can be omitted.
As shown in fig. 6, getting higher the application scenarios of the equivalent circuit diagram of two-phase disconnection fault to the main transformer in inventive embodiments
It is described further, it is specific as follows：
Fig. 6 is the equivalent circuit of the actual circuit of 4 220kV main transformers；Wherein, #1 ~ #3 is normal main transformer, and #4 is failure main transformer,
And the main transformer that #1 and #4 is neutral ground, #2 ~ #3 are the main transformer of isolated neutral；Equivalent power supply ESFlow into positive sequence circuit A
In load current be denoted as IHf；The sides #1-#4 main transformer 10kV load current is denoted as ILf1、ILf2、ILf3、I01；IMfFor 110kV busbares
Duty value electric current；I1、I2、I0Positive sequence, negative phase-sequence and zero-sequence current respectively in sequence net circuit.
At this point, the high-pressure side positive sequence impedance Z of #4 failure main transformersH（1）Electric current I11, high-pressure side negative sequence impedance ZH（2）Electric current
I21, high-pressure side zero sequence impedance ZH（0）Electric current I01Equal in magnitude, direction is identical, and medium voltage side negative sequence impedance ZM（2）Electric current I22、
Medium voltage side zero sequence impedance ZM（0）Electric current I02Equal in magnitude, direction is identical.
The voltage equation and ohmic law of equation for listing each node obtain the zero-sequence current formula of zero sequence circuit（1）It is as follows：
（1）
Assuming that I before broken stringHf=1200A, it is concluded that；
At this point, the zero-sequence current that the 281A of gained is surveyed when getting higher two-phase disconnection fault with #4 failure main transformers is not much different, to
Demonstrate the correctness of equivalent circuit.
As shown in fig. 7, in the embodiment of the present invention, a kind of main transformer provided gets higher the recognition methods of two-phase disconnection fault,
It realizes on the equivalent circuit that main transformer above-mentioned gets higher two-phase disconnection fault, the method includes：
Step S1, from the equivalent circuit, obtain positive sequence network on flow through 220kV failure main transformers high-pressure side positive sequence impedance,
The electric current of medium voltage side positive sequence impedance and low-pressure side positive sequence impedance flows through the high-pressure side negative phase-sequence of 220kV failure main transformers on negative sequence network
Flowed through on the electric current and zero-sequence network of impedance and medium voltage side negative sequence impedance 220kV failure main transformers high-pressure side zero sequence impedance and in
Press the electric current of side zero sequence impedance；
Step S2, when high-pressure side positive sequence impedance, high-pressure side negative sequence impedance and the high-pressure side zero for detecting the 220kV failures main transformer
There is equal in magnitude, the identical electric current in direction simultaneously in sequence impedance, and detects the medium voltage side negative phase-sequence of the 220kV failures main transformer
Have simultaneously in impedance and medium voltage side zero sequence impedance it is equal in magnitude, when the identical electric current in direction, it is determined that the 220kV failures main transformer
It gets higher and two-phase disconnection fault occurs.
Implement the embodiment of the present invention, has the advantages that：
In embodiments of the present invention, since the main transformer circuit of practical paired running is transformed into equivalent circuit, and to equivalent circuit
The electric current of middle failure main transformer is differentiated quickly to determine the two-phase disconnection fault of failure main transformer, so as to solve 220kV master
Getting higher two-phase broken string leads to problems such as process experience caused by main transformer while trip event insufficient, less efficient.
One of ordinary skill in the art will appreciate that implement the method for the above embodiments be can be with
Relevant hardware is instructed to complete by program, the program can be stored in a computer read/write memory medium,
The storage medium, such as ROM/RAM, disk, CD.
The above disclosure is only the preferred embodiments of the present invention, cannot limit the right model of the present invention with this certainly
It encloses, therefore equivalent changes made in accordance with the claims of the present invention, is still within the scope of the present invention.
Claims (5)
1. a kind of main transformer gets higher the equivalent circuit of two-phase disconnection fault, which is characterized in that its with by 220kV busbares, 110kV busbares
And the normal main transformers of multiple 220kV and a 220kV failure main transformer between in parallel is formed by circuit equivalent, and
The 220kV failures neutral point of main transformer ground connection；
The equivalent circuit that the main transformer gets higher two-phase disconnection fault includes the positive sequence network mutually concatenated, negative sequence network and zero sequence net
Network；Wherein,
The positive sequence network includes the positive sequence equivalent busbar and its corresponding equivalent power supply, substitutional resistance of the 220kV busbares, institute
State the positive sequence equivalent busbar and its corresponding duty value and the normal main transformers of the multiple 220kV and described of 110kV busbares
The corresponding high-pressure side positive sequence impedance of 220kV failure main transformers, medium voltage side positive sequence impedance and low-pressure side positive sequence impedance；Wherein, institute
The equivalent power supply for stating 220kV busbares is serially connected in the positive sequence equivalent of the 220kV busbares by the substitutional resistance of the 220kV busbares
On the input terminal of busbar；The duty value of the 110kV busbares is serially connected in the output of the positive sequence equivalent busbar of the 110kV busbares
On end；The normal main transformers of each 220kV by one end of corresponding high-pressure side positive sequence impedance, medium voltage side positive sequence impedance one
End and one end of low-pressure side positive sequence impedance are docking together, and also access the other end of corresponding high-pressure side positive sequence impedance
The output end of the positive sequence equivalent busbar of the 220kV busbares, and also by the other end of corresponding medium voltage side positive sequence impedance
Access the input terminal of the positive sequence equivalent busbar of the 110kV busbares；The 220kV failures main transformer is by its corresponding high-pressure side positive sequence
One end of one end of impedance, one end of medium voltage side positive sequence impedance and low-pressure side positive sequence impedance is docking together, also that its is corresponding
The other end of medium voltage side positive sequence impedance accesses the input terminal of the positive sequence equivalent busbar of the 110kV busbares, also by its corresponding height
The other end of pressure side positive sequence impedance accesses one end of the negative sequence network；The output of the positive sequence equivalent busbar of the 220kV busbares
One end of the zero-sequence network is also accessed at end；
The negative sequence network includes the equivalent busbar of negative phase-sequence of the equivalent busbar of negative phase-sequence of the 220kV busbares, the 110kV busbares,
And the multiple normal main transformers of 220kV and the corresponding high-pressure side negative sequence impedance of the 220kV failures main transformer and medium voltage side
Negative sequence impedance；Wherein, the normal main transformers of each 220kV bear one end of corresponding high-pressure side negative sequence impedance and medium voltage side
One end of sequence impedance mutually concatenates, and the other end of corresponding high-pressure side negative sequence impedance is also accessed the 220kV busbares
The equivalent busbar of negative phase-sequence, and the other end of corresponding medium voltage side negative sequence impedance is also accessed to the negative phase-sequence of the 110kV busbares
Equivalent busbar；The 220kV failures main transformer is by the one of one end of its corresponding high-pressure side negative sequence impedance and medium voltage side negative sequence impedance
End mutually concatenates, and the other end of its corresponding medium voltage side negative sequence impedance is also accessed to the equivalent busbar of negative phase-sequence of the 110kV busbares, also
The other end of its corresponding high-pressure side negative sequence impedance is accessed to the other end of the zero-sequence network；The negative phase-sequence of the 220kV busbares
Equivalent busbar is also connected with the other end of the high-pressure side positive sequence impedance of 220kV failures main transformer in the positive sequence network；
The zero-sequence network include the equivalent busbar of zero sequence of the 220kV busbares, the 110kV busbares the equivalent busbar of zero sequence,
The corresponding high-pressure side zero sequence impedance of 220kV main transformers of neutral ground among the multiple normal main transformers of 220kV and middle pressure
The high-pressure side zero sequence impedance and medium voltage side zero sequence impedance of side zero sequence impedance and the 220kV failures main transformer；Wherein, in each
Property point ground connection the normal main transformers of 220kV by the one of one end of corresponding high-pressure side zero sequence impedance and medium voltage side zero sequence impedance
End mutually concatenates, and the other end of corresponding high-pressure side zero sequence impedance is also accessed to the equivalent mother of zero sequence of the 220kV busbares
Line, and the other end of corresponding medium voltage side zero sequence impedance is also accessed to the equivalent busbar of zero sequence of the 110kV busbares；Institute
It states 220kV failures main transformer mutually to concatenate one end of one end of its corresponding high-pressure side zero sequence impedance and medium voltage side zero sequence impedance, also
The other end of its corresponding medium voltage side zero sequence impedance is accessed to the equivalent busbar of zero sequence of the 110kV busbares, it is also that its is corresponding
The other end of high-pressure side zero sequence impedance accesses the output end of the positive sequence equivalent busbar of 220kV busbares in the positive sequence network；It is described
The equivalent busbar of zero sequence of 220kV busbares also in the negative sequence network high-pressure side negative sequence impedance of 220kV failures main transformer it is another
End is connected；
Wherein, same on the high-pressure side positive sequence impedance of the 220kV failures main transformer, high-pressure side negative sequence impedance and high-pressure side zero sequence impedance
When have equal in magnitude, the identical electric current in direction；
Wherein, there is equal in magnitude, side simultaneously on the medium voltage side negative sequence impedance of the 220kV failures main transformer and medium voltage side zero sequence impedance
To identical electric current.
2. main transformer as described in claim 1 gets higher the equivalent circuit of two-phase disconnection fault, which is characterized in that the 220kV is female
The voltage of the equivalent busbar of the positive sequence equivalent busbar of line, negative phase-sequence and the equivalent busbar of zero sequence is equal.
3. main transformer as claimed in claim 2 gets higher the equivalent circuit of two-phase disconnection fault, which is characterized in that the 110kV is female
The voltage of the equivalent busbar of the positive sequence equivalent busbar of line, negative phase-sequence and the equivalent busbar of zero sequence is equal.
4. main transformer as claimed in claim 3 gets higher the equivalent circuit of two-phase disconnection fault, which is characterized in that the multiple
There is equal in magnitude, direction simultaneously on the normal main transformers of 220kV and the corresponding low-pressure side positive sequence impedance of the 220kV failures main transformer
Identical electric current.
5. a kind of main transformer gets higher the recognition methods of two-phase disconnection fault, which is characterized in that it is in any one of such as claim 1-4
The main transformer gets higher and is realized on the equivalent circuit of two-phase disconnection fault, the method includes：
Step S1, from the equivalent circuit, obtain positive sequence network on flow through 220kV failure main transformers high-pressure side positive sequence impedance,
The electric current of medium voltage side positive sequence impedance and low-pressure side positive sequence impedance flows through the high-pressure side negative phase-sequence of 220kV failure main transformers on negative sequence network
Flowed through on the electric current and zero-sequence network of impedance and medium voltage side negative sequence impedance 220kV failure main transformers high-pressure side zero sequence impedance and in
Press the electric current of side zero sequence impedance；
Step S2, when high-pressure side positive sequence impedance, high-pressure side negative sequence impedance and the high-pressure side zero for detecting the 220kV failures main transformer
There is equal in magnitude, the identical electric current in direction simultaneously in sequence impedance, and detects the medium voltage side negative phase-sequence of the 220kV failures main transformer
Have simultaneously in impedance and medium voltage side zero sequence impedance it is equal in magnitude, when the identical electric current in direction, it is determined that the 220kV failures main transformer
It gets higher and two-phase disconnection fault occurs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810257387.7A CN108459233B (en) | 2018-03-27 | 2018-03-27 | Equivalent circuit of main transformer high-voltage two-phase disconnection fault and identification method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810257387.7A CN108459233B (en) | 2018-03-27 | 2018-03-27 | Equivalent circuit of main transformer high-voltage two-phase disconnection fault and identification method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108459233A true CN108459233A (en) | 2018-08-28 |
| CN108459233B CN108459233B (en) | 2024-01-19 |
Family
ID=63237626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810257387.7A Active CN108459233B (en) | 2018-03-27 | 2018-03-27 | Equivalent circuit of main transformer high-voltage two-phase disconnection fault and identification method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108459233B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112234577A (en) * | 2020-10-21 | 2021-01-15 | 南方电网科学研究院有限责任公司 | Single-phase line break fault processing method, device and medium |
Citations (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3362597D1 (en) * | 1982-07-12 | 1986-04-24 | Merlin Gerin | Two-phase differential circuit breaker |
| JPS61266971A (en) * | 1985-05-22 | 1986-11-26 | Masaji Nakajima | Improvement of detection system for wire breaking trouble |
| JPH0487177A (en) * | 1990-07-26 | 1992-03-19 | Fuji Denki Shisutetsuku Kk | Severance sensing method for delta wiring three-phase load electric heater |
| RU2066511C1 (en) * | 1992-07-16 | 1996-09-10 | Юрий Яковлевич Лямец | Remote method for protection and automatic control of electric power transmission line |
| JPH0932913A (en) * | 1995-07-19 | 1997-02-07 | Toyota Motor Corp | Control device for automatic transmission |
| US6525543B1 (en) * | 2000-10-20 | 2003-02-25 | Schweitzer Engineering Laboratories | Fault type selection system for identifying faults in an electric power system |
| CN2796219Y (en) * | 2005-01-25 | 2006-07-12 | 辽宁省电力有限公司辽阳供电公司 | Self adaptive main changing, mothed connection and liaison line spare self projection device |
| CN101557101A (en) * | 2008-10-14 | 2009-10-14 | 吴宏斌 | Relay protection method for eliminating failure in transformer dead zone |
| WO2012059136A1 (en) * | 2010-11-05 | 2012-05-10 | Siemens Aktiengesellschaft | Monitoring a power supply line supplied at one end for earth faults |
| CN102937687A (en) * | 2012-10-26 | 2013-02-20 | 杨万钟 | Method for distinguishing disconnection fault and grounding fault during grounding of neutral point through small resistor |
| CN103311909A (en) * | 2013-05-19 | 2013-09-18 | 国家电网公司 | Method for realizing voltage protection of single-phase earth fault of line by using positive sequence break variable and zero sequence component |
| CN103308823A (en) * | 2013-05-23 | 2013-09-18 | 国家电网公司 | Method for locating single-phase disconnection non-ground fault of power distribution network |
| CN103887771A (en) * | 2014-04-23 | 2014-06-25 | 国家电网公司 | Method for identifying fault branches on basis of zero and negative sequence integrated current |
| CN104198884A (en) * | 2014-08-06 | 2014-12-10 | 国网山东省电力公司 | Differential principle based large-scale power grid intelligent trouble diagnosis method |
| CN104730410A (en) * | 2015-03-16 | 2015-06-24 | 王金泽 | Distribution line breakage monitoring method and device based on voltage and current vectors |
| CN104777397A (en) * | 2015-04-16 | 2015-07-15 | 王金泽 | Distribution line single-phase break line judgment and positioning method based on line voltage vector criterion |
| CN105891680A (en) * | 2016-06-16 | 2016-08-24 | 国网山东省电力公司滨州供电公司 | 10kV distribution line multiphase disconnection fault determination method based on three-phase voltage and current |
| CN106300254A (en) * | 2016-10-13 | 2017-01-04 | 国家电网公司 | A kind of relay protecting method identifying the single-phase or biphase broken string of circuit |
| CN106505524A (en) * | 2016-12-01 | 2017-03-15 | 国网浙江省电力公司电力科学研究院 | A kind of power plant non-whole phase protection method |
| CN106980067A (en) * | 2017-04-11 | 2017-07-25 | 国网河南省电力公司电力科学研究院 | The broken string recognition methods compared based on residual voltage differential values |
-
2018
- 2018-03-27 CN CN201810257387.7A patent/CN108459233B/en active Active
Patent Citations (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3362597D1 (en) * | 1982-07-12 | 1986-04-24 | Merlin Gerin | Two-phase differential circuit breaker |
| JPS61266971A (en) * | 1985-05-22 | 1986-11-26 | Masaji Nakajima | Improvement of detection system for wire breaking trouble |
| JPH0487177A (en) * | 1990-07-26 | 1992-03-19 | Fuji Denki Shisutetsuku Kk | Severance sensing method for delta wiring three-phase load electric heater |
| RU2066511C1 (en) * | 1992-07-16 | 1996-09-10 | Юрий Яковлевич Лямец | Remote method for protection and automatic control of electric power transmission line |
| JPH0932913A (en) * | 1995-07-19 | 1997-02-07 | Toyota Motor Corp | Control device for automatic transmission |
| US6525543B1 (en) * | 2000-10-20 | 2003-02-25 | Schweitzer Engineering Laboratories | Fault type selection system for identifying faults in an electric power system |
| CN2796219Y (en) * | 2005-01-25 | 2006-07-12 | 辽宁省电力有限公司辽阳供电公司 | Self adaptive main changing, mothed connection and liaison line spare self projection device |
| CN101557101A (en) * | 2008-10-14 | 2009-10-14 | 吴宏斌 | Relay protection method for eliminating failure in transformer dead zone |
| US20130221976A1 (en) * | 2010-11-05 | 2013-08-29 | Siemens Aktiengesellschaft | Monitoring a power supply line supplied at one end for ground faults |
| WO2012059136A1 (en) * | 2010-11-05 | 2012-05-10 | Siemens Aktiengesellschaft | Monitoring a power supply line supplied at one end for earth faults |
| CN102937687A (en) * | 2012-10-26 | 2013-02-20 | 杨万钟 | Method for distinguishing disconnection fault and grounding fault during grounding of neutral point through small resistor |
| CN103311909A (en) * | 2013-05-19 | 2013-09-18 | 国家电网公司 | Method for realizing voltage protection of single-phase earth fault of line by using positive sequence break variable and zero sequence component |
| CN103308823A (en) * | 2013-05-23 | 2013-09-18 | 国家电网公司 | Method for locating single-phase disconnection non-ground fault of power distribution network |
| CN103887771A (en) * | 2014-04-23 | 2014-06-25 | 国家电网公司 | Method for identifying fault branches on basis of zero and negative sequence integrated current |
| CN104198884A (en) * | 2014-08-06 | 2014-12-10 | 国网山东省电力公司 | Differential principle based large-scale power grid intelligent trouble diagnosis method |
| CN104730410A (en) * | 2015-03-16 | 2015-06-24 | 王金泽 | Distribution line breakage monitoring method and device based on voltage and current vectors |
| CN104777397A (en) * | 2015-04-16 | 2015-07-15 | 王金泽 | Distribution line single-phase break line judgment and positioning method based on line voltage vector criterion |
| CN105891680A (en) * | 2016-06-16 | 2016-08-24 | 国网山东省电力公司滨州供电公司 | 10kV distribution line multiphase disconnection fault determination method based on three-phase voltage and current |
| CN106300254A (en) * | 2016-10-13 | 2017-01-04 | 国家电网公司 | A kind of relay protecting method identifying the single-phase or biphase broken string of circuit |
| CN106505524A (en) * | 2016-12-01 | 2017-03-15 | 国网浙江省电力公司电力科学研究院 | A kind of power plant non-whole phase protection method |
| CN106980067A (en) * | 2017-04-11 | 2017-07-25 | 国网河南省电力公司电力科学研究院 | The broken string recognition methods compared based on residual voltage differential values |
Non-Patent Citations (5)
| Title |
|---|
| 刘小宝;潘书燕;宋艳;: "一起220kV变压器差动保护动作行为分析", 水电自动化与大坝监测, no. 04 * |
| 张芜: "电力系统非全相运行时相序电流和相序电压的关系", 继电器, no. 11 * |
| 郭碧媛;张丰;罗松;: "220kV主变110kV侧零序过流保护跳闸整定的改进", 电力系统保护与控制, no. 20 * |
| 高超;郑小革;刘晓;: "电力系统单相缺相故障分析及异常处置防范措施", 湖南电力, no. 01 * |
| 黄权;: "浅谈集控运行主变故障的判断及检查", 科技视界, no. 05 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112234577A (en) * | 2020-10-21 | 2021-01-15 | 南方电网科学研究院有限责任公司 | Single-phase line break fault processing method, device and medium |
| CN112234577B (en) * | 2020-10-21 | 2023-04-28 | 南方电网科学研究院有限责任公司 | Single-phase disconnection fault processing method, device and medium |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108459233B (en) | 2024-01-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zou et al. | A fast protection scheme for VSC based multi-terminal DC grid | |
| CN102854437B (en) | Fault line selection method of low current grounding system using time-frequency atom decomposition theory | |
| CN103163430A (en) | Resonant grounding system fault line selection method by combining complex wavelets with ANN (artificial neural network) | |
| CN106353564B (en) | The Power System Shortcuts electric current acquisition methods of meter and V/X Connection Traction Transformer | |
| CN106908697A (en) | A kind of synthetic power-frequency and the distribution network fault line selection method in transient reactive power direction | |
| CN111211574A (en) | Method for calculating bipolar fault current on direct current side of multi-terminal direct current power grid based on half-bridge type MMC | |
| CN109001592A (en) | A kind of resonant earthed system fault line selection method for single-phase-to-ground fault based on transient | |
| CN112485590A (en) | Power distribution network single-phase line-breaking fault identification method | |
| CN211528583U (en) | Portable insulation monitoring device | |
| CN110165644B (en) | New energy station pilot protection method based on transient current time-frequency characteristics | |
| Lee et al. | New fault detection method for low voltage DC microgrid with renewable energy sources | |
| CN108459233A (en) | A kind of main transformer gets higher equivalent circuit and the recognition methods of two-phase disconnection fault | |
| CN103414175A (en) | Short-circuit fault current limiter | |
| CN105762845B (en) | ± 10kV flexible direct current power distribution network incoming transport power grid modes determine method | |
| CN112415426A (en) | Single-phase earth fault detection method, system, terminal and readable storage medium of small-resistance earth system | |
| Fan et al. | Three-phase fault direction identification method for outgoing transmission line of DFIG-based wind farms | |
| CN116937808A (en) | Fault isolation method and device for low-voltage distribution network, electronic equipment and storage medium | |
| CN113608069A (en) | Direct-current power distribution network ground fault identification method and system of MMC injected detection signal | |
| CN109861188B (en) | Grounding protection method and system based on centralized new energy grid-connected mode | |
| CN105510731A (en) | Parallel resonance detection alarming method and system for medium-voltage side power grid of power transformer | |
| CN203616369U (en) | Special riser transformer for low voltage energization | |
| Zhang et al. | A non-unit line protection scheme for MMC-MTDC grids based on aerial-mode voltage traveling waves | |
| CN217931874U (en) | Distribution network ground fault and insulation resistance recognition device | |
| CN216252533U (en) | System power supply circuit | |
| CN103675386B (en) | Upflow transformer for low-voltage energization |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |