CN109861169A - One kind differentiating series transformer overvoltage method based on difference stream quintuple harmonics - Google Patents
One kind differentiating series transformer overvoltage method based on difference stream quintuple harmonics Download PDFInfo
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Abstract
The invention discloses one kind to differentiate series transformer overvoltage method based on difference stream quintuple harmonics, comprising the following steps: S1 calculates the rated current of high-voltage winding and low pressure winding；S2 calculates the coefficient of balance of high-voltage winding and low pressure winding according to the rated current of high-voltage winding and low pressure winding；S3 calculates segregated phase differential current according to the coefficient of balance of the electric current and high-voltage winding of high-voltage winding and low pressure winding and low pressure winding；S4 calculates difference stream quintuple harmonics content according to segregated phase differential current；S5 judges whether series transformer occurs overvoltage according to difference stream quintuple harmonics content.The present invention is not necessarily to install PT at winding both ends, directly differentiates overvoltage by calculating difference stream quintuple harmonics, saves transforming plant primary material and method is simple and effective.
Description
Technical field
Present invention relates particularly to a kind of overvoltage protections of Unified Power Flow control series transformer more particularly to one kind to be based on
Difference stream quintuple harmonics differentiates series transformer overvoltage method, belongs to Relay Protection Technology in Power System field.
Background technique
Modern power systems are quickly grown, and grid structure is increasingly complicated.Trend is uneven, voltage support is insufficient, short circuit current
The problems such as excessive, is interweaved, and brings new challenge to operation of power networks control.Meanwhile it is defeated to increase by new transmission line of electricity is built
Send capacity more and more difficult, trend, which is unevenly distributed, has become an important factor for restricting electric network transportation ability.Unified Power Flow control
Device (UPFC) processed, can be multiple to AC transmission system electrical as function flexible AC transmission equipment of new generation the most comprehensive
Amount realizes that independent, fast and accurately control and dynamic compensate, and can either realize the accurate control of trend, improves route and conveys function
The rate limit；And the voltage for the dynamic support correlation substation that can be handled up by fast reactive improves system voltage stability；Simultaneously also
System damping can be improved, improve system dynamic characteristic.
Rationally installing THE UPFC has great importance to the development of China Power Grids, and series transformer is UPFC
Very important component part in system.But presently relevant research focuses mostly in control strategy, output performance and system application side
In formula, overall plan, protection zone division and inverter equipment protection are also concentrated mainly on to the research of protection, lacked to string
Join the research of transformer body protection.
Series transformer characteristic and the method for operation determine that its protection is very different compared with mature shunt transformer, string
It is individually designed to join tranformer protection needs.Series transformer is connected in high-tension line since itself voltage rating is lower, is
The case where end voltage increases is easy to appear in the case where system failure or control system exception.Therefore, it is excessively electric winding need to be arranged in device
Pressure protection.Actually winding voltage can not be measured directly, can be by measuring winding both end voltage, and the difference of the two is exactly winding electricity
Pressure.But it needs to install PT at winding both ends, and two PT measurement voltage vectors make the difference can PT broken string erroneous judgement overvoltage
Problem, the solution that there is no at present.
Summary of the invention
It is an object of the invention to overcome deficiency in the prior art, provide a kind of based on difference stream quintuple harmonics differentiation string
Join transformer overvoltage method, without installing PT at winding both ends, overvoltage directly differentiated by the poor stream quintuple harmonics of calculating,
It saves transforming plant primary material and method is simple and effective, while solving the technical issues of PT broken string erroneous judgement overvoltage.
Differentiate that series transformer is excessively electric based on difference stream quintuple harmonics in order to solve the above technical problems, the present invention provides one kind
Pressure method, characterized in that the following steps are included:
S1 calculates the rated current of high-voltage winding and low pressure winding；
S2 calculates the coefficient of balance of high-voltage winding and low pressure winding according to the rated current of high-voltage winding and low pressure winding；
S3 is calculated according to the coefficient of balance of the electric current and high-voltage winding of high-voltage winding and low pressure winding and low pressure winding
Segregated phase differential current；
S4 calculates difference stream quintuple harmonics content according to segregated phase differential current；
S5 judges whether series transformer occurs overvoltage according to difference stream quintuple harmonics content.
Further, in S1, the rated current for calculating high-voltage winding and low pressure winding includes:
High-voltage winding rated current calculation formula are as follows:
Low pressure winding rated current calculation formula are as follows:
In formula: Ie.hFor high-voltage winding rated current, Ie.lFor low pressure winding rated current, S is the specified appearance of series transformer
Amount, UhFor high-voltage winding voltage rating, na.hFor high-voltage winding CT no-load voltage ratio, UlFor low pressure winding voltage rating, na.lFor low pressure winding
CT no-load voltage ratio.
Further, in S2, high-voltage winding and low pressure winding are calculated according to the rated current of high-voltage winding and low pressure winding
Coefficient of balance include:
High-voltage winding coefficient of balance khAre as follows:
Low pressure winding coefficient of balance klAre as follows:
Further, in S3, according to the flat of the electric current and high-voltage winding of high-voltage winding and low pressure winding and low pressure winding
The coefficient that weighs calculates the process of segregated phase differential current are as follows:
Note flows through high-voltage winding electric current and isFlowing through low pressure winding electric current is
Since high-voltage winding and low pressure winding one are the wiring of Y type, one is the wiring of Δ type, and the phase of the two line current is not
Together, 30 ° of the advanced low pressure winding of high-voltage winding need to be to secondary current phase adjustment when calculating differential difference stream；
It is as follows for high-voltage winding electric current adjustment formula:
Wherein,For high-voltage winding a phase current value adjusted,For high-voltage winding b phase current value adjusted,For high-voltage winding c phase current value adjusted；
It is as follows for low pressure winding electric current adjustment formula:
Wherein,For low pressure winding a phase current value adjusted,For low pressure winding b phase current value adjusted,For low pressure winding c phase current value adjusted；
Segregated phase differential current calculation formula is as follows:
Wherein,It differs and flows for a,It differs and flows for b,It differs and flows for c.
Further, in S4, calculating difference stream quintuple harmonics content includes:
The real part a of the fundamental current of abc segregated phase differential current is calculated first1ωiAnd imaginary part b1ωi, calculation formula are as follows:
In formula, T is the period of fundametal compoment, and t is the time, and ω is fundamental wave sample frequency, IdiFor difference current.
Then the real part a of the quintuple harmonics electric current of abc segregated phase differential current is calculated5ωiAnd imaginary part b5ωi, calculation formula are as follows:
Both last amplitude is divided by, and difference stream quintuple harmonics content I is obtaineddi5ω:
Further, judge whether series transformer occurs overvoltage process according to difference stream quintuple harmonics content are as follows: if poor
Flow quintuple harmonics content Ida5ω,Idb5ω,Idc5ω, there is in three-phase any one entry value to be greater than 35%, be then determined as that series transformer is sent out
Raw overvoltage.
Compared with prior art, the beneficial effects obtained by the present invention are as follows being: the invention proposes use difference stream quintuple harmonics
Content differentiates the new criterion of series transformer overvoltage, overcomes when existing voltage vector makes the difference method PT broken string and judges by accident not
Foot.The method of the present invention can convenient and efficient identification series transformer overvoltage, for series transformer protect engineering practice optimization
Provide beneficial theoretical supplement.
Detailed description of the invention
Fig. 1 is the structure chart of series transformer；
Fig. 2 is the wiring schematic diagram of series transformer；
Fig. 3 is the schematic diagram of transformer overexcitation time-harmonic wave electric current；
Fig. 4 is the measuring point arrangement schematic diagram of series transformer；
Fig. 5 is to judge whether series transformer occurs the criterion schematic diagram of overvoltage.
Specific embodiment
The invention will be further described below in conjunction with the accompanying drawings.Following embodiment is only used for clearly illustrating the present invention
Technical solution, and not intended to limit the protection scope of the present invention.
The harmonic wave of one book of Large-scale machine set relay protection theoretical basis and nearest pertinent literature to the exciting current of transformer
Characteristic has carried out experimental research and analysis.The transformer parameter that uses is tested as (60MVA, 78kV, crystal grain electric appliance silicon steel sheet),
The characteristics of surveying out transformer overexcitation time-harmonic wave electric current, as shown in Figure 3.From figure 3, it can be seen that exciting current quintuple harmonics
Electric current be changed significantly, for overvoltage in 115%-120%, quintuple harmonics electric current reaches maximum value, is fundamental current
55%, when overvoltage is bigger, I5/I1(quintuple harmonics content) significantly reduces again, when overvoltage is 140%, I5/I1About
35%, when voltage is lower than 105% or is higher than 140%, I5/I1> 35%.It therefore can be humorous by five times in calculating exciting current
The content of wave differentiates overvoltage, when quintuple harmonics is greater than 35%, then it is assumed that series transformer is in overvoltage condition, and issues phase
Answer alarm signal.It should be pointed out that series transformer is in serious overexcitation state at this time when voltage is greater than 140%,
First and second current difference increases, and differential protection will act, standby of the differential protection as overvoltage protection at this time, therefore not examine herein
Consider the case where voltage is greater than 140%.
Series transformer structural schematic diagram is as shown in Figure 1, specifically wiring schematic diagram is as shown in Fig. 2, it can be seen that high
Press side winding using opening Y pattern, the two ends substring of every phase joins line attachment；Low-pressure side winding is yn pattern, connects the change of current
Device, Neutral Grounding through Resistance in Electrical；It balances winding and uses triangle pattern, bringing onto load, winding head and the tail terminal do not draw balance winding
Out, wherein a phase terminal is directly grounded remaining two phase terminal through arrester ground.
By the above introduction about the construction it is found that series transformer is substantially still transformer, the harmonic characterisitic of exciting current with
Shunt transformer is consistent, therefore can differentiate overvoltage using exciting current quintuple harmonics characteristic.
One kind of the invention is based on difference stream quintuple harmonics and differentiates series transformer overvoltage method, including following procedure:
Step 1: calculating the rated current of high-voltage winding and low pressure winding.
High-voltage winding rated current calculation formula are as follows:
Low pressure winding rated current calculation formula are as follows:
In formula: Ie.hFor high-voltage winding rated current, Ie.lFor low pressure winding rated current, S is the specified appearance of series transformer
Amount, UhFor high-voltage winding voltage rating, na.hFor high-voltage winding CT no-load voltage ratio, UlFor low pressure winding voltage rating, na.lFor low pressure winding
CT no-load voltage ratio.
Step 2: calculating the coefficient of balance of high-voltage winding and low pressure winding.
The principle of compositionality of transformer differential protection is also based on Kirchhoff's first law, i.e.,
In formula:For the vector sum of each winding current of transformer, due to low pressure winding voltage rating and CT no-load voltage ratio and high pressure
The difference of winding, high-voltage winding is different from low pressure winding CT secondary current when actual motion.If transformer differential CT secondary current
Difference, then the size of current for flowing into each phase difference element from high and low pressure winding is not also identical, to be unable to satisfy?
In protection equipment for transformer, refers to one and the electric current that two differ in size is converted to the conversion system for acting on identical electric current
Number, is referred to as coefficient of balance for the coefficient.
The voltage class and CT no-load voltage ratio of series transformer high and low pressure winding coefficient of balance and each winding are all related, and relationship is such as
Under:
High-voltage winding coefficient of balance khAre as follows:
Low pressure winding coefficient of balance klAre as follows:
Step 3: calculating segregated phase differential current.
Series-transformer implement body measuring point arrangement is as shown in figure 4, description measuring point arrangement is in order to which clear scheme is from series-transformer
Device where measurement high-voltage winding and low pressure winding electric current.In figure, TA1 is net side TA (TA, that is, CT, current transformer),
High-voltage winding electric current is flowed through for acquiring, TA2 is converter valve side TA, flows through low pressure winding electric current for acquiring, shows in figure
For TV1 the and TV2 script series transformer both end voltage mutual inductor (TV, that is, PT, voltage transformer) of dotted line, the two vector is done
Difference can be used for overvoltage protection, can be without configuration in this programme.
Note flows through high-voltage winding electric current and isFlowing through low pressure winding electric current isThis
The upper surface of variable is a little expressed as vector, this is professional universal expression method.Winding is balanced due to non-loaded, is only used for improving electricity
EMF waveform, electric current are negligible.
Since high-voltage winding and low pressure winding one are the wiring of Y type, one is the wiring of Δ type, and the phase of the two line current is not
Together, 30 ° of the advanced low pressure winding of high-voltage winding need to be to secondary current phase adjustment when calculating differential difference stream.In the present invention using by
High-voltage winding carries out phase adjustment to low pressure winding.
It is as follows for high-voltage winding electric current adjustment formula:
High-voltage winding biphase current subtract each other two-by-two again divided by radical sign 3 by way of the secondary three-phase of high-voltage winding may be implemented
Electric current is 30 ° mobile to lag direction, and high-voltage winding and low pressure winding current phase are completely the same at this time, therefore complete phase tune
It is whole, multiplied by previously mentioned coefficient of balance kh, conversion can be completed.
Wherein,For high-voltage winding a phase current value adjusted,For high-voltage winding b phase current value adjusted,For high-voltage winding c phase current value adjusted.
For low pressure winding electric current, do not need to carry out phase adjustment, it is only necessary to multiplied by coefficient of balance klConversion can be completed,
It is as follows that low pressure winding electric current adjusts formula:
Wherein,For low pressure winding a phase current value adjusted,For low pressure winding b phase current value adjusted,For low pressure winding c phase current value adjusted.
Segregated phase differential current calculation formula is as follows:
Wherein,It differs and flows for a,It differs and flows for b,It differs and flows for c.
That is segregated phase differential currentIt is adjusted through phase and coefficient of balance for high-voltage winding and low pressure winding
The absolute value of current vector sum.Poor stream is the abbreviation of difference current herein.
Step 4: calculating difference stream quintuple harmonics content.
The real part a of the fundamental current of abc segregated phase differential current is calculated first1ωiAnd imaginary part b1ωi, calculation formula are as follows:
In formula, T is the period of fundametal compoment, and t is the time, and ω is fundamental wave sample frequency, IdiFor difference current.
Then the real part a of the quintuple harmonics electric current of abc segregated phase differential current is calculated5ωiAnd imaginary part b5ωi, calculation formula are as follows:
Both last amplitude is divided by, and difference stream quintuple harmonics content I is obtaineddi5ω:
In practical applications, discrete Fourier can be used and calculate every cycle differential fundamental wave amplitude and quintuple harmonics amplitude:
In formula, N is every cycle sampling number, is set as 48 in the embodiment of the present invention.
Step 5: judging whether series transformer occurs overvoltage according to difference stream quintuple harmonics content.
It is shown in Figure 5, judge whether series transformer occurs the criterion of overvoltage according to difference stream quintuple harmonics content are as follows:
If difference stream quintuple harmonics content Ida5ω,Idb5ω,Idc5ω, there is in three any one value to be greater than 35%, be then determined as series-transformer
Overvoltage occurs for device, and issues corresponding alarm.
The invention proposes using difference stream quintuple harmonics content to differentiate the new criterion of series transformer overvoltage, overcome
Existing voltage vector makes the difference the deficiency of erroneous judgement when method PT breaks.The method of the present invention being capable of convenient and efficient identification series transformer mistake
Voltage protects the optimization of engineering practice to provide beneficial theoretical supplement for series transformer.
It should be understood by those skilled in the art that, embodiments herein can provide as method, system or computer program
Product.Therefore, complete hardware embodiment, complete software embodiment or reality combining software and hardware aspects can be used in the application
Apply the form of example.Moreover, it wherein includes the computer of computer usable program code that the application, which can be used in one or more,
The computer program implemented in usable storage medium (including but not limited to magnetic disk storage, CD-ROM, optical memory etc.) produces
The form of product.
The application is referring to method, the process of equipment (system) and computer program product according to the embodiment of the present application
Figure and/or block diagram describe.It should be understood that every one stream in flowchart and/or the block diagram can be realized by computer program instructions
The combination of process and/or box in journey and/or box and flowchart and/or the block diagram.It can provide these computer programs
Instruct the processor of general purpose computer, special purpose computer, Embedded Processor or other programmable data processing devices to produce
A raw machine, so that being generated by the instruction that computer or the processor of other programmable data processing devices execute for real
The device for the function of being specified in present one or more flows of the flowchart and/or one or more blocks of the block diagram.
These computer program instructions, which may also be stored in, is able to guide computer or other programmable data processing devices with spy
Determine in the computer-readable memory that mode works, so that it includes referring to that instruction stored in the computer readable memory, which generates,
Enable the manufacture of device, the command device realize in one box of one or more flows of the flowchart and/or block diagram or
The function of being specified in multiple boxes.
These computer program instructions also can be loaded onto a computer or other programmable data processing device, so that counting
Series of operation steps are executed on calculation machine or other programmable devices to generate computer implemented processing, thus in computer or
The instruction executed on other programmable devices is provided for realizing in one or more flows of the flowchart and/or block diagram one
The step of function of being specified in a box or multiple boxes.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, without departing from the technical principles of the invention, several improvement and deformations can also be made, these improvement and deformations
Also it should be regarded as protection scope of the present invention.
Claims (6)
1. one kind differentiates series transformer overvoltage method based on difference stream quintuple harmonics, characterized in that the following steps are included:
S1 calculates the rated current of high-voltage winding and low pressure winding；
S2 calculates the coefficient of balance of high-voltage winding and low pressure winding according to the rated current of high-voltage winding and low pressure winding；
S3 calculates three-phase according to the coefficient of balance of the electric current and high-voltage winding of high-voltage winding and low pressure winding and low pressure winding
Difference stream；
S4 calculates difference stream quintuple harmonics content according to segregated phase differential current；
S5 judges whether series transformer occurs overvoltage according to difference stream quintuple harmonics content.
2. according to claim 1 a kind of based on difference stream quintuple harmonics differentiation series transformer overvoltage method, feature
It is that in S1, the rated current for calculating high-voltage winding and low pressure winding includes:
High-voltage winding rated current calculation formula are as follows:
Low pressure winding rated current calculation formula are as follows:
In formula: Ie.hFor high-voltage winding rated current, Ie.lFor low pressure winding rated current, S is series transformer rated capacity, Uh
For high-voltage winding voltage rating, na.hFor high-voltage winding CT no-load voltage ratio, UlFor low pressure winding voltage rating, na.lFor low pressure winding CT change
Than.
3. it is according to claim 2 it is a kind of series transformer overvoltage method is differentiated based on difference stream quintuple harmonics, in S2, root
Include: according to the coefficient of balance that the rated current of high-voltage winding and low pressure winding calculates high-voltage winding and low pressure winding
High-voltage winding coefficient of balance khAre as follows:
Low pressure winding coefficient of balance klAre as follows:
4. it is according to claim 1 it is a kind of series transformer overvoltage method is differentiated based on difference stream quintuple harmonics, in S3, root
The process of segregated phase differential current is calculated according to the electric current and high-voltage winding of high-voltage winding and low pressure winding and the coefficient of balance of low pressure winding
Are as follows:
Note flows through high-voltage winding electric current and isFlowing through low pressure winding electric current is
Since high-voltage winding and low pressure winding one are the wiring of Y type, one is the wiring of Δ type, the advanced low pressure winding of high-voltage winding
30 °,
It is as follows for high-voltage winding electric current adjustment formula:
Wherein,For high-voltage winding a phase current value adjusted,For high-voltage winding b phase current value adjusted,For
High-voltage winding c phase current value adjusted；khFor high-voltage winding coefficient of balance；
It is as follows for low pressure winding electric current adjustment formula:
Wherein,For low pressure winding a phase current value adjusted,For low pressure winding b phase current value adjusted,For
Low pressure winding c phase current value adjusted；klFor low pressure winding coefficient of balance；
Segregated phase differential current calculation formula is as follows:
Wherein,It differs and flows for a,It differs and flows for b,It differs and flows for c.
5. it is according to claim 4 it is a kind of series transformer overvoltage method is differentiated based on difference stream quintuple harmonics, in S4, meter
Calculating difference stream quintuple harmonics content includes:
The real part a of the fundamental current of abc segregated phase differential current is calculated first1ωiAnd imaginary part b1ωi, calculation formula are as follows:
In formula, T is the period of fundametal compoment, and t is the time, and ω is fundamental wave sample frequency, IdiFor difference current.
Then the real part a of the quintuple harmonics electric current of abc segregated phase differential current is calculated5ωiAnd imaginary part b5ωi, calculation formula are as follows:
Both last amplitude is divided by, and difference stream quintuple harmonics content I is obtaineddi5ω:
。
6. it is according to claim 1 a kind of based on difference stream quintuple harmonics differentiation series transformer overvoltage method, according to difference
Stream quintuple harmonics content judges whether series transformer occurs the process of overvoltage are as follows: if difference stream quintuple harmonics content Ida5ω,
Idb5ω,Idc5ω, there is in three-phase any one entry value to be greater than 35%, be then determined as that overvoltage occurs for series transformer.
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| CN201910211526.7A CN109861169A (en) | 2019-03-20 | 2019-03-20 | One kind differentiating series transformer overvoltage method based on difference stream quintuple harmonics |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108183463A (en) * | 2017-12-29 | 2018-06-19 | 长园深瑞继保自动化有限公司 | The method of intelligent substation transformer ratio differential protection faulty action preventing |
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2019
- 2019-03-20 CN CN201910211526.7A patent/CN109861169A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108183463A (en) * | 2017-12-29 | 2018-06-19 | 长园深瑞继保自动化有限公司 | The method of intelligent substation transformer ratio differential protection faulty action preventing |
Non-Patent Citations (2)
| Title |
|---|
| 张晨星: "PST1200U型变压器差动保护装置辅助调试软件的开发", 《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》 * |
| 王维俭等: "《大型机组继电保护理论基础》", 30 September 1989, 水利电力出版社 * |
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