CN1078829A - Differential protecting technology for impedance matching banlance transformer - Google Patents
Differential protecting technology for impedance matching banlance transformer Download PDFInfo
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- CN1078829A CN1078829A CN 92106936 CN92106936A CN1078829A CN 1078829 A CN1078829 A CN 1078829A CN 92106936 CN92106936 CN 92106936 CN 92106936 A CN92106936 A CN 92106936A CN 1078829 A CN1078829 A CN 1078829A
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Abstract
A kind of Protection Technology of electrifing railway supply transformer.Derived the in theory size and the phase relation of each electric current of balanced impedance matching transformer high and low pressure side.As long as choose three groups of current transformer 1LH, 2LH and the 3LH of suitable no-load voltage ratio, can guarantee transformer when normal operation and external fault, differential relay reliably is failure to actuate, and when internal fault took place, differential relay can sensitive action excision short trouble.
Description
A kind of Protection Technology of electrifing railway supply transformer.
Balanced impedance matching transformer low pressure side joint electric railway uplink and downlink two phase loads, the two-phase load current changes with the ruuning situation of train; High pressure side joint three-phase electrical power system.Its great advantage is: under the various situations of low-pressure side two-phase asymmetric load, transformer high-voltage side three-phase current has higher symmetry, has reduced negative-sequence current, and negative-sequence current has improved the quality of power supply of system to the influence of electric power system.Owing on this transformer device structure, make step down side biphase current I
αAnd I
βPhase difference be 90 ° of electrical degrees, and C phase current and I
αAnd I
βThe phase difference of electric current changes between 0 °～90 ° and 90 °～180 °; High voltage side current and low-pressure side current and phase difference change between 0 °～90 ° with the variation of train operating mode.Therefore, brought difficulty for the realization of balanced impedance matching transformer differential protection.
The objective of the invention is to study the Changing Pattern of the high and low pressure side electric current of above-mentioned balancing transformer, derive the relation between each phase current.And study a kind of desirable differential protection mode of connection circuit and the computational methods of differential protection short circuit current, to satisfy the needs of such transformer differential protection.
Derived the theoretically magnitude relationship of each phase current of balanced impedance matching transformer high and low pressure side of the present invention has worked out the differential protection mode of connection of the balancing transformer shown in accompanying drawing 1 and accompanying drawing 2 and the computational methods of short circuit current on this basis.
Establishing balanced impedance matching transformer 3(no-load voltage ratio in accompanying drawing 1 is K) high-pressure side A, B, C three-phase current be I
A, I
B, I
CAmong-the Tu 9,10,11; Low-pressure side two-phase load current is I
α, I
βAmong-the Tu 7,8, with I
αSize and the phase relation of deriving each phase current for reference vector are as follows:
By following formula (4) and (6) as seen: I
A-I
CWith I
α-I
βSame-phase; By formula (2) and (5) as seen :-I
BWith I
α+ I
βSame-phase.High and low pressure side as if three groups of current transformers of suitable no-load voltage ratio being inserted transformers 3 then can guarantee above-mentioned two groups of electric current numerically equals or close.This has satisfied the requirement of differential protection butted line mode just.Based on this thought be connected to same specification in the high-pressure side of accompanying drawing 1, with one group of current transformer 1LH-figure of no-load voltage ratio in its no-load voltage ratio of 4(be n
L1), it is n with its no-load voltage ratio of 2(among one group of current transformer 3LH-figure of no-load voltage ratio that low-pressure side is connected to same specification
L3) and 2LH-figure in the 1(no-load voltage ratio be n
L2).Like this, the secondary side current (I of 1LH
A-I
C)/n
L1Among-the Tu 13 with the secondary side current (I of low-pressure side 2LH
α-I
β)/n
L215 equal and opposite in direction phase places are identical among the-Tu, are among the differential knee-joint differential relay 1CJ-figure 5 with this two electric current.Secondary side current-I of 1LH
B/ n
L1Among-the Tu 12 with the secondary side current (I of low-pressure side 3LH
α+ I
β)/n
L314 equal and opposite in direction phase places are identical among the-Tu, are among the differential knee-joint differential relay 2CJ-figure 6 with this two electric current.
The low-pressure side C that further discovers transformer 3 relatively electric current always equals (I
α-I
β), therefore also can be only with on the current transformer 2LH access C phase terminal, can obtain (I at the secondary side of 2LH
α-I
β)/n
L2, obtain the differential protection mode of connection shown in the accompanying drawing 2 thus.The mode of connection shown in the accompanying drawing 2 is than the economy but effect is identical more of the mode of connection shown in the accompanying drawing 1.Which kind of mode of connection the user can determine to select for use according to on-site actual situations.
The transformer differential protection mode of connection of the present invention, in normal operation with when external fault takes place, identical big or small close of the current phase of two differential arms, the electric current of inflow differential relay is the unsymmetrical current of current transformer only, differential relay is failure to actuate.When various internal short circuit fault took place transformer, differential relay flowed into two sub-values of short circuit current, and differential relay moves delicately, excised short trouble, had realized the purpose of reliably protecting transformer.
The transformation ratio selection of transformer high and low side current transformer 1LH, 2LH, 3LH is as follows in the above-mentioned differential protection circuit:
(1) at first by the no-load voltage ratio n that selects high voltage side current instrument transformer 1LH greater than the principle of rated current
L1;
(2) press n
L3/ n
L1=
K determines the calculating no-load voltage ratio n of current transformer 3LH
L3, again by selecting actual no-load voltage ratio n near calculating the no-load voltage ratio principle
L3;
(3) press n
L2/ n
L1=K determines the calculating no-load voltage ratio n of current transformer 2LH
L2, again by selecting actual no-load voltage ratio near the principle of calculating no-load voltage ratio;
Because the short-time overload operation often appears in electric railway, the calculating of 2LH also can be by selecting actual no-load voltage ratio n greater than the principle of calculating no-load voltage ratio
L2Thus, the current transformer (n that do not match
L2/ n
L1≠ the unsymmetrical current that K) produces can take measures to eliminate its influence by differential relay.
The differential protection calculation of short-circuit current:
1. when differential protection was adjusted operating current, the external fault maximum short circuit current calculated (α, c, β three-phase shortcircuit)
1. low-pressure side calculation of short-circuit current
In the formula: Ea is that high-pressure side A phase electromotive force is torn the electromotive force that is incorporated into the corresponding a phase winding of low-pressure side open;
Impedance for system's maximum operational mode
Tear the value that is incorporated into low-pressure side open;
Z
' IFor the value that is incorporated into low-pressure side is torn in the impedance of transformer high-voltage side winding open;
Z
IBe step down side ac phase and bc phase winding impedance mutually.
2. high-pressure side calculation of short-circuit current
K is the ratio of transformer high-low pressure phase winding in the formula
2. when verification differential protection sensitivity coefficient, the calculating (α, β two alternate short circuits) of the minimum short circuit current of power transformer interior fault
1. the minimum short circuit current of low-pressure side
In the formula
Be system's minimum operational mode impedance
Tear the value of calculating low-pressure side open, other symbol implication is the same.
2. high-pressure side short circuit current
The mode of connection of the present invention and short-circuit current calculation method have been carried out comprehensive dynamic simulation test, and content comprises:
The dynamic simulation test in 1. various normal whens operation;
Dynamic simulation test during 2. various external fault;
Dynamic simulation test during 3. various internal fault;
Dynamic simulation test when 4. various commutations insert power supply.
The dynamic simulation test result of projects has all obtained ideal results, proves that fully the protection mode of connection principle of being invented is correct, and Theoretical Calculation conforms to the actual tests result, and it is convenient to implement, few, the good economy performance of used element.When power supply adopted various commutations to insert transformer, the differential protection mode of connection need not change, and can satisfy all requirements of differential protection.
The short positive mode computational methods of the transformer differential protection mode of connection of the present invention can be used for the wiring and the calculating of adjusting of the differential protection of power system of electric railway balanced impedance matching transformer.
Description of drawings
In the accompanying drawing 1
1-low-pressure side current transformer 2LH, its no-load voltage ratio is n
L2;
2-low-pressure side current transformer 3LH, no-load voltage ratio is n
L3;
3-balanced impedance matching transformer high-low pressure winding, its high-pressure side phase winding is K with the ratio of the low-pressure side triangle phase winding number of turn;
4-high voltage side current instrument transformer 1LH, no-load voltage ratio is n
L1;
5,6-differential relay 1CJ, 2CJ;
7,8-step down side electric current I
β, I
α;
9,10,11-transformer high-voltage side three-phase current I
A, I
B, I
C;
12, secondary side current-I of 13-instrument transformer 1LH
B/ n
L1, (I
A-I
C)/n
L1;
Secondary side current (the I of 14-instrument transformer 3LH
α+ I
β)/n
L3
Secondary side current (the I of 15-instrument transformer 2LH
α-I
β) n
L2;
16, the electric current I of 17-differential relay 1CJ, 2CJ
J1, I
J2
In the accompanying drawing 2
1-low-pressure side current transformer 2LH, its no-load voltage ratio is n
L2;
2-low-pressure side current transformer 3LH; No-load voltage ratio is n
L3;
3-balanced impedance matching transformer winding, no-load voltage ratio are K;
4-high voltage side current instrument transformer 1LH, no-load voltage ratio is n
L1;
5,6-differential relay 1CJ, 2CJ;
7,8,9-step down side three-phase current I
α, I
C=(I
α-I
β), I
β;
10,11,12-transformer high-voltage side three-phase current I
A, I
B, I
C
13, the secondary side current (I of 14-instrument transformer 1LH
B/ n
L1), (I
A-I
C)/n
L1;
Secondary side current (the I of 15-instrument transformer 3LH
α+ I
β)/n
L3;
Secondary side current (the I of 16-instrument transformer 2LH
α-I
β)/n
L2;
17,18-differential relay electric current I
J1, I
J2
Implementation example
1) model of protected impedance matching transformer and parameter
Model SFY-20000/110-GY
Rated capacity 2000KVA
High-pressure side rated voltage 110KV ± 2 * 2.5%
Low-pressure side rated voltage 27.5KV
High-pressure side rated primary current 104.975A
Low-pressure side rated primary current 363.636A
The ratio K=2.828 of high pressure phase winding and low pressure triangle phase winding
2) adopt the differential protection mode of connection, choice of equipment and points for attention shown in Figure 2
1. determine the no-load voltage ratio n of 1LH
L1
A rated current I
A=105A
Choose n
L2=50/5 model: LCWD-110 150/5
2. determine the no-load voltage ratio n of 2LH
L2
Calculate and change n
L2=Kn
L1=423/5
Actual change: n
L2400/5 model: select ∠ RD-35 400/5
Also can select actual change: n
L2=600/5, model is selected LRD-35 600/5
3. determine the no-load voltage ratio n of 3LH
L3
Calculate no-load voltage ratio: n
L3=
Kn
L1＝734.996/5
Choose actual no-load voltage ratio: n
L3=750/5 model LRD-35 750/5
Claims (4)
1, a kind of Protection Technology of electrifing railway supply transformer is characterized in balanced impedance matching transformer low-pressure side electric current I
αBe parameter vector, the pass of deriving each phase current of transformer high and low pressure side is:
The differential protection mode of connection of balancing transformer and the computational methods of differential protection short circuit current have been worked out on this basis; in the differential protection mode of connection of being studied; the high and low pressure side of transformer is connected to current transformer 1LH, 2LH, the 3LH of suitable no-load voltage ratio, makes the secondary side current (I of transformer high-voltage side current transformer
A-I
C)/n
L1And the secondary side current (I of 2LH
α-I
2)/n
L3Equal and opposite in direction part mutually is identical, makes (I
B/ n
L1) and 3LH secondary current (I
α+ I
β)/n
L3The equal and opposite in direction phase place is identical, with (I
A-I
C)/n
L1With (I
α-I
β)/n
L2For differential knee-joint differential relay 1CJ, with (I
B/ n
L1) and (I
α+ I
β)/n
L3For differential knee-joint differential relay 2CJ constitutes differential protection.
2,, it is characterized in that the differential arm electric current of low-pressure side (I according to the Protection Technology of the described supply transformer of claim I
α-I
β)/n
L2Both can be mutually and β two current transformers acquisitions mutually by α, also can be by obtaining in the current transformer 2LH access step down side C phase terminal.
3, according to the described supply transformer Protection Technology of claim I, it is characterized in that current transformer 1LH, 2LH, the variation selection principle of 3LH is as follows:
(1) at first by the no-load voltage ratio n that selects high voltage side current instrument transformer 1LH greater than the principle of rated current
L1;
(2) by (n
L2)/(n
L1)=K determines the calculating no-load voltage ratio n of current transformer 2LH
L2, again by near or select actual no-load voltage ratio n greater than the principle of calculating no-load voltage ratio
L2; (3) by (n
L3)/(n
L1)=
K determines the calculating no-load voltage ratio n of current transformer 3LH
L3, again by selecting actual specific n near the principle of calculating no-load voltage ratio
L3
4, according to the described supply transformer Protection Technology of claim I, it is characterized in that being calculated as of differential protection short circuit current:
(1) maximum short circuit current calculates when α, c, β three-phase shortcircuit:
(a) low-pressure side short circuit current
(b) high-pressure side short circuit current
(2) α, the calculating of the minimum short circuit current of β line to line fault:
(a) the minimum short circuit current of low-pressure side
(b) high-pressure side short circuit current
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92106936 CN1078829A (en) | 1992-05-22 | 1992-05-22 | Differential protecting technology for impedance matching banlance transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92106936 CN1078829A (en) | 1992-05-22 | 1992-05-22 | Differential protecting technology for impedance matching banlance transformer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1078829A true CN1078829A (en) | 1993-11-24 |
Family
ID=4942560
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 92106936 Pending CN1078829A (en) | 1992-05-22 | 1992-05-22 | Differential protecting technology for impedance matching banlance transformer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1078829A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100424955C (en) * | 2002-08-26 | 2008-10-08 | 南京南瑞继保电气有限公司 | Variable slope differential ratio protection method |
| CN101764392B (en) * | 2010-01-11 | 2012-04-11 | 山东大学 | Multi-lateral current magnitude voltage magnitude based transformer relay protecting method |
| CN103795030A (en) * | 2014-01-15 | 2014-05-14 | 山东大学 | Transformer relay protection method based on longitudinal branch connection conductance |
| CN105259467A (en) * | 2015-11-18 | 2016-01-20 | 南京国电南自电网自动化有限公司 | Single-phase fault analysis method considering star-triangle transformation |
| CN114264901A (en) * | 2021-12-07 | 2022-04-01 | 广东电网有限责任公司 | Balance current simulation method and related device during transformer out-of-area fault |
-
1992
- 1992-05-22 CN CN 92106936 patent/CN1078829A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100424955C (en) * | 2002-08-26 | 2008-10-08 | 南京南瑞继保电气有限公司 | Variable slope differential ratio protection method |
| CN101764392B (en) * | 2010-01-11 | 2012-04-11 | 山东大学 | Multi-lateral current magnitude voltage magnitude based transformer relay protecting method |
| CN103795030A (en) * | 2014-01-15 | 2014-05-14 | 山东大学 | Transformer relay protection method based on longitudinal branch connection conductance |
| CN103795030B (en) * | 2014-01-15 | 2016-10-26 | 山东大学 | A kind of connect the transformer relay protecting method of conductance based on vertical propping up |
| CN105259467A (en) * | 2015-11-18 | 2016-01-20 | 南京国电南自电网自动化有限公司 | Single-phase fault analysis method considering star-triangle transformation |
| CN114264901A (en) * | 2021-12-07 | 2022-04-01 | 广东电网有限责任公司 | Balance current simulation method and related device during transformer out-of-area fault |
| CN114264901B (en) * | 2021-12-07 | 2023-08-22 | 广东电网有限责任公司 | Balanced current simulation method and related device for transformer out-of-zone faults |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C01 | Deemed withdrawal of patent application (patent law 1993) | ||
| WD01 | Invention patent application deemed withdrawn after publication |