CN103401226B - Substation area differential protection method for intelligent substation - Google Patents
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Abstract
The invention discloses a substation area differential protection method for an intelligent substation, which comprises a big differential protection mode taking the substation as the principal thing, and more than two small differential protection modes taking the substations as the principal things; the big differential protection mode serves as a starting element, any one small differential protection mode serves as an action element; when the two conditions are satisfied simultaneously, the differential protection outputs action; the small differential protection modes are still failure selecting elements; the range of the big differential protection mode is delimitated by high voltage side current of each transformer and all outlet current on the medium voltage side generating line and the low voltage side generating line, of the substation, (not comprising buscouple and segment); the ranges of the small differential protection modes are delimitated by corresponding high voltage side current of the transformer, and all corresponding outlet current on the generating lines connected with main change medium voltage side and low voltage side, (not comprising buscouple and segment). The method not only can thoroughly protect the substation, but also can close the failure transformer in a targeted manner, is small in influence range for the electricity using user, and is particularly suitable for the substation provided with two or more than two transformers to use.
Description
Technical field
The invention belongs to the relay protection automatic field of power engineering, for improving the safe and reliable of Operation of Electric Systems
Property, particularly to a kind of substation area differential protection method for intelligent substation.
Background technology
Transformer station (Substation) is that some electric devices are combined, and in order to voltage of transformation, accepts and distributes electricity
The flow direction of electric power, can be controlled and adjust the electric power facility of voltage.In power system, transformer station is the assembly of transmission and disttrbution
Point.Transformer station mainly comprises as feed line (inlet wire, outlet) and bus, disconnecting switch, earthed switch, chopper, power transformer
Device (main transformer), voltage transformer TV(PT), current transformer TA (CT), discharging rod.Transformer station can be divided mainly into: hinge power transformation
Stand, one-end substation；Primary substation, step-down substation；The transformer station of power system, industrial and mineral transformer station, railroad substation
(27.5kV, 50Hz)；The voltages such as 1000kV, 750kV, 500kV, 330kV, 220kV, 110kV, 66kV, 35kV, 10kV, 6.3kV
The transformer station of grade；10kV switching station；Box-type substation.
At present, the most commonly used Fibre Optical Communication Technology of transformer station, synchronization accuracy disclosure satisfy that the requirement of protection, at a high speed
The network technology of development meet day by day increase to network capacity and the demand of safe and reliable performance, IEC61850 marks
Accurate complexity and the technology realization also efficiently solving original system integration and share of information, these advanced technologies
The information sharing that application is intelligent substation is laid a good foundation, and also research, enforcement for territory, station differential protection provide probability.
Utilize the feature that intelligent substation internal information can be shared flexibly, overall as protected object using transformer station, utilize input of entirely standing,
Export the voltage of each element, current information and the information centralized decision-making such as device action, state, complete the information of territory, station differential protection
Gather, it is achieved complete centralized differential back-up protection function of standing.
At present, in Power System in China, on intelligent substation differential protecting method, it is all to use whole station protected mode.
It is to say, when differential protecting method judges to break down, the breaker actuation of whole transformer station can be controlled, thus plays guarantor
Protect the purpose of transformer station.Such as, China Patent No. be 200910025578.1 patent of invention disclosed in a kind of sampling value difference
The phasor differential protecting method of current start, this guard method combines sampling value difference and the differential advantage of phasor, has
Higher anti-interference and reliability, but remain and reach to protect transformer station by the way of controlling the input of whole station or output
Purpose.This guard method, although serve the effect protecting whole transformer station, but also have impact on whole transformer station and cover
In the range of power supply, can not control targetedly in transformer station certain or some break down the duty of transformator.
Summary of the invention
The technical problem to be solved in the present invention is can to protect transformer station for above-mentioned not enough offer one comprehensively, can have again
Closing fault transformator pointedly, the substation area differential protection method for intelligent substation little to customer impact scope.
For solving above-mentioned technical problem, it is the poorest that this substation area differential protection method for intelligent substation includes based on transformer station
Moving protected mode and the plural little differential protection pattern based on each transformator, big differential protection pattern is for starting unit
Part, arbitrary little differential protection pattern is action element, when above-mentioned two condition meets simultaneously, differential protection outlet action, little
Differential protection pattern or fault selection element.
This substation area differential protection method for intelligent substation is to realize can protecting change by double differential protected mode comprehensively
Power station, again can closing fault transformator targetedly, little to customer impact scope.
It is differential that double differential protected mode is primarily referred to as including two sets in this substation area differential protection method for intelligent substation
Protected mode, the biggest differential protection pattern and little differential protection pattern.For convenience of narration, it is the poorest big differential protection pattern to be referred to as
Or big differential mode formula, little differential protection pattern is referred to as little difference or little differential mode formula.The protection domain of differential mode formula is based on transformer station greatly,
The most whole transformer station is all the protection object protection protection domain of big differential mode formula, and the quantity of the biggest differential mode formula only has one
Set.The protection object of little differential mode formula or protection domain are the single transformer in transformer station and relevant device thereof.Transformer station has
Several transformators just have a few set little differential mode formula, often overlap little differential mode formula and only protect transformator corresponding thereto and relevant device thereof.
In this substation area differential protection method for intelligent substation, big differential mode formula is as starting element, in order to distinguish event inside and outside district of transformer station
Barrier.And little differential mode formula is i.e. action element, also it is that fault selects element.
The work process of this double differential protected mode is: under normal operating mode, when big differential mode formula and a certain little differential mode formula
When being satisfied by criterion, the high-pressure side chopper of tripping little differential mode formula correspondence transformator, medium voltage side include the branch road of this little differential mode formula in
Chopper, medium voltage side bus bus, low-pressure side chopper and low-pressure side bus section switch.If the biggest differential mode formula is full
Foot operating criterion, all elements of tripping medium voltage side after time delay.From said process, when transformer station breaks down, start
Element meets, and big differential mode formula starts.When arbitrary transformator breaks down, the little poor Modal action corresponding with this transformator, this
Double differential protected mode outlet action.After the protected mode outlet action of this double differential, select the little differential mode formula of this action as event
Barrier selects element, and control its corresponding high-pressure side chopper of transformator, medium voltage side include in this little differential mode formula branch breaker,
Medium voltage side bus bus, low-pressure side chopper and low-pressure side bus section switch.So, transformer station breaks down
Time, this substation area differential protection method for intelligent substation can criterion breaks down exactly transformator, and only cut off this transformator
Input and output circuit, will not cut off the input and output circuit of whole transformer station, so, in same transformer station other do not occur therefore
The operation of the transformator of barrier is by unaffected, it is ensured that the functional reliability of transformer station and the stability of power supply.
As a kind of implementation, big differential protection model domain be defined in each high voltage side of transformer electric current of transformer station,
On medium voltage side and low-pressure side bus all go out line current (not including mother, segmentation), it is right that little differential protection model domain is defined in
Answer on transformator high voltage side current, corresponding main transformer medium voltage side and the connected bus of low-pressure side all go out line current (include mother, divide
Section).
Each high voltage side of transformer electric current in the coverage of big differential protection pattern is defined in transformer station, medium voltage side and
On low-pressure side bus all go out line current (not including mother, segmentation), it is simply that the protection domain of big differential protection pattern is set
Each high voltage side of transformer, medium voltage side and low-pressure side in transformer station, the namely high-pressure side of bed rearrangement transformer station, medium voltage side and low
Pressure side.Big differential protection pattern can be according to electric current in each high voltage side of transformer, medium voltage side and low-pressure side in being set in transformer station
The current signal that transformer feeds back carries out the criterion of starting element.Relative, by the coverage of little differential protection pattern
Be defined on corresponding high voltage side of transformer electric current, corresponding main transformer medium voltage side and the connected bus of low-pressure side all go out line current (wrap
Include mother, segmentation), it is simply that in the protection domain of little differential protection pattern is set in transformer station centered by corresponding transformator, with
The corresponding high-pressure side of transformator, medium voltage side and low-pressure side are the scope on border, namely by being arranged on corresponding transformer high-voltage
The current signal that side, medium voltage side and low-pressure side current transformer feed back carries out the criterion of operation condition.By the poorest and little difference
Range set after, when being broken down by great Cha criterion transformer station, this little difference can be excised according to the criterion of little difference corresponding
The transformator broken down, solves the drawback a whole set of transformer station cut off in traditional protection mode, effectively prevent because of one
Platform transformer fault and the operation of other transformators in affecting same transformer station, improve the power supply reliability of transformer station.
This patent also includes
Step 1, data select and process
Defining two main transformers, main transformer is high, medium voltage side is double bus scheme, and main transformer low-pressure side is single mother partition wiring；Definition
Territory differential protection protection domain of standing is two main transformers+medium voltage side outlet+low-voltage side outlet；For realizing territory, station differential protection function,
Protection needs the ac analog data got as follows
Current sampling data is
Main transformer high-pressure side CT, main transformer medium voltage side CT, medium voltage side bus outlet CT, medium voltage side mother CT, low-pressure side bus go out
Line CT and low-pressure side segmentation CT current sampling data；Above-mentioned current sampling data is differential for constituting each of station territory differential protection
Element；
Voltage sample data are
Two sections of busbar voltages of main transformer medium voltage side, two sections of busbar voltages of main transformer low-pressure side；
Step 2, the data of big poor element select
Big poor element is as starting element or fault initiating element, in order to distinguish territory, station protection internal fault external fault；The poorest
Protection domain is two main transformers+medium voltage side bus+low-pressure side bus；The data constituting big differential protection pattern are:
High voltage side current: use two main transformer high-pressure side CT to gather the vector of electric current；
Medium voltage side electric current: use the medium voltage side bus each branch road CT without main transformer branch road and mother to gather the vector of electric current
With；
Low-pressure side electric current: use the low-pressure side bus each branch road CT without main transformer branch road and segmentation to gather the vector of electric current
With；
Step 3, the data of little poor element select
Little poor element is used as fault and selects element, the part that protection domain is every main transformer+correspondence of each little poor element
Medium voltage side bus and low-pressure side bus；
The data constituting each little poor element differential protection are:
High voltage side current: use this main transformer high-pressure side CT to gather electric current；
Medium voltage side electric current: a certain section of the medium voltage side using this main transformer to connect does not contains each branch road of bus and the mother of this main transformer branch road
Connection CT gathers the vector of electric current；
Low-pressure side electric current: a certain section of the low-pressure side using this main transformer to connect does not contains each branch road of bus of this main transformer branch road and divides
Section CT gathers the vector of electric current；
Step 4, data calculate
For choosing of medium voltage side current sampling data, special logic is used to realize, the connection of real-time tracking main transformer branch road
State, specifically connects bus according to main transformer branch road and determines that the outlet CT of this little poor element included in by needs；Mother branch road is fixing to be included in
Two little poor elements；The polarity of device mother CT arranges with I female connection branch road, when counting II female corresponding little poor element, fixing
Corresponding sampled data is negated；
The computing formula of the little spill current of medium voltage side is as follows:
Wherein," the little spill current of medium voltage side " for the little poor element of 1#；" medium voltage side little difference electricity for the little poor element of 2#
Stream ",For the branch current of medium voltage side in the range of little poor element protection,=1,2,3 natural numbers such as grade；In formula, the little difference of medium voltage side
Calculating of electric current introduces the little poor i.e. jth of element associated coefficient of middle pressure bus each branch road 1# not containing main transformer branch road containing mother branch road
The coefficient of association of element poor element little to 1#, the coefficient of association of the little poor element associated coefficient of 2# i.e. jth element poor element little to 2#；
The calculating of electric current is all carried out according to primary current value；
Low-pressure side bus uses single mother partition main wiring mode, and on bus, all branch roads are fixing connects, can be according to scene
The branch road CT that each little poor element needs to count is preset in physical cabling, and wherein segmentation CT is fixing counts two little poor elements；Segmentation
The polarity of CT connects branch road with I mother, and when counting II female corresponding little poor element, the fixing sampled data by correspondence negates；Stand territory
Differential protection is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert；
Step 5, elimination transformer station each side current amplitude phase difference
Utilizing digital method to compensate no-load voltage ratio and phase place, transformer station's each side sense of current with sensing transformator is all
Positive direction, each side CT secondary current phase place is adjusted by software, uses the conversion regime of Y → △, and Y enters horizontal phasing control in side；For
The transformator of Y/Y/ △-12-11 or the transformator of Y/Y/Y-12-12, Y side conversion formula is
For the transformator of Y/Y/ △-12-1, Y side conversion formula is
Electric current before not changing for Y side,For each phase current after correction；
Step 6, percentage differential action calculate
Low definite value:
High-set setting:
For difference current,For differential protection starting current definite value,For stalling current, S is ratio brake coefficient,For the reference current of differential protection, on the basis of the rated current of high-pressure side, each side sense of current with sensing transformator is all
Positive direction；
(1) differential for both sides
It is respectively the electric current of Current Transformer Secondary side, transformator high and low pressure side；
(2) differential for three sides and above several side
In formula: 3≤k≤4,It is respectively the electric current of Current Transformer Secondary side, transformer station each side；
Step 7, excitation surge current criterion
Excitation surge current criterion mainly includes second harmonic mode and waveform comparison mode, and can be selected by control word；When
" secondary harmonic brake " control word is adjusted when being 1, uses second harmonic mode locking, adjusts when being 0, uses waveform comparison mode
Locking.
Step 8, waveform comparison criterion
Difference current or the degree of asymmetry of phase current calculating waveform can be automatically selected according to the different operating modes of transformer station, calculate
Go out the waveform degree of asymmetry of excitation surge current, it determines equation is as follows
In formula:For the asymmetric angle value of difference current sampled point,Symmetry for corresponding difference current sampled point
Value, K is a certain fixed coefficient；If certain phase difference current meets above formula, locking this phase differential protection.
Described big differential protection pattern is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert.
Described little differential protection pattern is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert.
Percentage differential, also known as ratio brake differential protection, does not operationally take into account that CT saturation and current transformer transient state
The situation that characteristic is inconsistent, can strengthen the general of this substation area differential protection method for intelligent substation after therefore arranging percentage differential
Property or interference free performance.Increment is differential not to be affected by properly functioning load current, it is also possible to solve the circle that transformator is slight
Between fault and high resistance earthing fault, be favorably improved operational reliability.Configuration fast differential over current protection, can be with snap action, tripping
Each side chopper, is particularly suitable for quickly excising the internal fault that transformer station is serious.Difference current Threshold Crossing Alert arranges time delay exactly
Protection, so can filter the current signal of some instantaneous mutations, contributes to reducing the probability of misoperation, improves reliable
Property.
In sum, adopt substation area differential protection method for intelligent substation in this way, transformer station can be protected comprehensively,
Again can closing fault transformator targetedly, little to electricity consumption customer impact scope, be particularly suitable for being provided with two and above transformation
The transformer station of device uses.
Accompanying drawing explanation
In conjunction with accompanying drawing, the present invention is described in further detail:
Fig. 1 is the electrical schematic diagram of transformer station in the present invention；
Fig. 2 is protection domain schematic diagram the poorest in the present invention；
Fig. 3 is the protection domain schematic diagram of first little difference in the present invention；
Fig. 4 is the protection domain schematic diagram of second little difference in the present invention；
Fig. 5 is the performance chart of percentage differential；
Fig. 6 is biased differential protection logic chart；
Fig. 7 is increment differential protection act performance plot；
Fig. 8 is increment differential relay protective scheme figure；
Fig. 9 is fast differential over current protection logic chart；
Figure 10 difference current out-of-limit relay protective scheme figure.
Detailed description of the invention
As it is shown in figure 1, this substation area differential protection method for intelligent substation includes the big differential protection mould based on transformer station
Formula and based on the plural little differential protection pattern of each transformator, big differential protection pattern is starting element, Ren Yi little
Differential protection pattern is action element, when above-mentioned two condition meets simultaneously, and differential protection outlet action, little differential protection mould
Formula or fault selection element.Two set differential protection patterns are included, i.e. in this substation area differential protection method for intelligent substation
Big differential protection pattern and little differential protection pattern.For convenience of narration, big differential protection pattern is referred to as the poorest or big differential mode formula,
Little differential protection pattern is referred to as little difference or little differential mode formula.The protection domain of big differential mode formula is based on transformer station, say, that whole
Individual transformer station is all the protection object protection protection domain of big differential mode formula, and the quantity of the biggest differential mode formula only has a set of.Little differential mode
The protection object of formula or protection domain are the single transformer in transformer station and relevant device thereof.Transformer station has several transformators
Just there is a few set little differential mode formula, often overlap little differential mode formula and only protect transformator corresponding thereto and relevant device thereof.Become in this intelligence
In the differential protecting method of territory, station, power station, big differential mode formula is as starting element, in order to distinguish transformer station's internal fault external fault.And little differential mode
Formula is i.e. action element, is also that fault selects element.
The protection process of this substation area differential protection method for intelligent substation is: under normal operating mode, when big differential mode formula and
When a certain little differential mode formula is satisfied by criterion, the high-pressure side chopper of tripping little differential mode formula correspondence transformator, medium voltage side are included in little
The branch breaker of differential mode formula, medium voltage side bus bus, low-pressure side chopper and low-pressure side bus section switch.If
The biggest differential mode formula meets operating criterion, all elements of tripping medium voltage side after time delay.From said process, when transformer station occurs
During fault, starting element meets, and big differential mode formula starts.When arbitrary transformator breaks down, the little difference corresponding with this transformator
Modal action, the protected mode outlet action of this double differential.After the protected mode outlet action of this double differential, select the little difference of this action
Pattern selects element as fault, and control its corresponding high-pressure side chopper of transformator, medium voltage side includes this little differential mode formula in
Branch breaker, medium voltage side bus bus, low-pressure side chopper and low-pressure side bus section switch.So, power transformation
Time breaking down in station, this substation area differential protection method for intelligent substation can criterion breaks down exactly transformator, and only cut
The input and output circuit of this transformator disconnected, will not cut off the input and output circuit of whole transformer station, so, in same transformer station its
The operation of the transformator that he does not breaks down is by unaffected, it is ensured that the functional reliability of transformer station and the stability of power supply.
As a kind of implementation, big differential protection model domain be defined in each high voltage side of transformer electric current of transformer station,
On medium voltage side and low-pressure side bus all go out line current, do not include that mother, segmentation, little differential protection model domain are defined in correspondence
On high voltage side of transformer electric current, corresponding main transformer medium voltage side and the connected bus of low-pressure side all go out line current, including mother, divide
Section.
Each high voltage side of transformer electric current in the coverage of big differential protection pattern is defined in transformer station, medium voltage side and
On low-pressure side bus all go out line current, do not include mother, segmentation, it is simply that be set in by the protection domain of big differential protection pattern
Each high voltage side of transformer, medium voltage side and low-pressure side, the namely high-pressure side of bed rearrangement transformer station, medium voltage side and low pressure in transformer station
Side.Big differential protection pattern can be mutual according to electric current in each high voltage side of transformer, medium voltage side and low-pressure side in being set in transformer station
The current signal that sensor feeds back carries out the criterion of starting element.Relative, by coverage circle of little differential protection pattern
On corresponding high voltage side of transformer electric current, corresponding main transformer medium voltage side and the connected bus of low-pressure side all go out line current, including
Mother, segmentation, it is simply that in the protection domain of little differential protection pattern is set in transformer station centered by corresponding transformator, with correspondence
The high-pressure side of transformator, medium voltage side and low-pressure side are the scope on border, namely by be arranged on corresponding high voltage side of transformer, in
The current signal that pressure side and low-pressure side current transformer feed back carries out the criterion of operation condition.Scope by the poorest and little difference
After setting, when being broken down by great Cha criterion transformer station, generation corresponding to this little difference can be excised according to the criterion of little difference therefore
The transformator of barrier, solves the drawback a whole set of transformer station cut off in traditional protection mode, effectively prevent because of a transformation
Device fault and the operation of other transformators in affecting same transformer station, improve the power supply reliability of transformer station.
For convenience of narration, just this substation area differential protection method for intelligent substation, territory differential protecting method of referred to as standing, or
Referred to as territory, station differential protection.Territory differential protection of standing all uses electronic current mutual inductor to realize, as whole based on transformer station
The centralized back-up protection of individual transformer station, can reflect the phase fault within bus and single-phase earthing fault, also can reflect
Phase fault, high-pressure side and the medium voltage side single-phase earthing fault of transformator (abbreviation main transformer) inside and shorted-turn fault.
Territory differential protection of standing, based on Differential Protection Principles of Transformer, arranges the big difference of transformer station and each the little difference of transformator.The poorest by
On each main transformer high voltage side current of transformer station, medium voltage side and low-pressure side bus all go out line current constitute (do not include mother, point
Section), little difference by this TV station main transformer high voltage side current, medium voltage side and the connected bus of low-pressure side this TV station main transformer all go out line current structure
Become (including mother, segmentation).The poorest as starting element, in order to distinguish transformer station's internal fault external fault, little difference is that fault selects unit
Part.Territory differential protection of standing is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert.
1, data select and process
As it is shown in figure 1, identify Substation Bus Arrangement figure in figure, containing two main transformers, main transformer is high, medium voltage side is that double-bus connects
Line, main transformer low-pressure side is single mother partition wiring.Definition station territory differential protection protection domain is two main transformers+medium voltage side outlet+low
Pressure side outlet.For realizing territory, station differential protection function, protection needs the ac analog data got as follows:
Current sampling data:
Main transformer high-pressure side CT(CT11, CT21), main transformer medium voltage side CT(CT12, CT22), medium voltage side bus outlet CT
(CT202, ┄, CT20m), medium voltage side mother CT(CT201), low-pressure side bus outlet CT(CT302, ┄, CT30n) and low-pressure side
Segmentation CT(CT301) current sampling data；Above-mentioned current sampling data is for constituting each difference element of territory, station differential protection.
Voltage sample data:
Two sections of busbar voltages of main transformer medium voltage side, two sections of busbar voltages of main transformer low-pressure side.Obtain voltage data and be mainly used in reality
Defencive function in existing charging process.
The data of big poor element select
Big poor element is as starting element or fault initiating element, in order to distinguish territory, station protection internal fault external fault.Such as Fig. 2 institute
Showing, the poorest protection domain is two main transformers+medium voltage side bus+low-pressure side bus.The data constituting big differential protection pattern are:
High voltage side current: use two main transformer high-pressure sides CT(CT11, CT21) gather electric current vector；
Medium voltage side electric current: use the medium voltage side bus each branch road CT without main transformer branch road and mother to gather the vector of electric current
With；
Low-pressure side electric current: use the low-pressure side bus each branch road CT without main transformer branch road and segmentation to gather the vector of electric current
With.
The data of little poor element select
Little poor element is used as fault and selects element.As shown in Figure 3, Figure 4, the protection domain of each little poor element is every master
Change+corresponding part medium voltage side bus and low-pressure side bus.
Figure is medium voltage side " fuzzy protection domain " in the range of dashed box, is primarily due to main transformer medium voltage side outlet and uses double-bus
The mode of connection, this mode of connection determines all connection branch roads on bus and can switch in running, and this is just
Determine each little poor element protection scope not fix, dynamically change according to the change of actual operating.Each
The electric current that little poor element is chosen changes also with the change of bus running manner.
The data constituting each little poor element differential protection are:
High voltage side current: use this main transformer high-pressure side CT(such as CT11) gather electric current；
Medium voltage side electric current: a certain section of the medium voltage side using this main transformer to connect does not contains each branch road of bus and the mother of this main transformer branch road
Connection CT gathers the vector of electric current；
Low-pressure side electric current: a certain section of the low-pressure side using this main transformer to connect does not contains each branch road of bus of this main transformer branch road and divides
Section CT gathers the vector of electric current；
For choosing of medium voltage side current sampling data, special logic is used to realize: the connection of real-time tracking main transformer branch road
State, specifically connects bus according to main transformer branch road and determines that the outlet CT of this little poor element included in by needs；It should be noted that mother is propped up
Road is fixing includes two little poor elements in.The polarity of device mother CT arranges with I female connection branch road, when counting II female corresponding little difference unit
During part, the fixing sampled data by correspondence negates；
The computing formula of the little spill current of medium voltage side is as follows:
(3-3-1)
(3-3-2)
Wherein," the little spill current of medium voltage side " for the little poor element of 1#；" medium voltage side little difference electricity for the little poor element of 2#
Stream ",For the branch current of medium voltage side in the range of little poor element protection,=1,2,3 natural numbers such as grade；In formula, medium voltage side little difference electricity
Calculating of stream introduces the middle pressure bus each branch road 1# little poor element associated coefficient i.e. jth unit not containing main transformer branch road containing mother branch road
The coefficient of association of part poor element little to 1#, the coefficient of association of the little poor element associated coefficient of 2# i.e. jth element poor element little to 2#；Electricity
The calculating of stream is all carried out according to primary current value.
Low-pressure side bus uses single mother partition main wiring mode, and on bus, all branch roads are fixing connects, can be according to scene
The branch road CT that each little poor element needs to count is preset in physical cabling, and wherein segmentation CT is fixing counts two little poor elements；Segmentation
The polarity of CT connects branch road with I mother, and when counting II female corresponding little poor element, the fixing sampled data by correspondence negates；
Territory differential protection of standing is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert.
Owing to transformator joint group is different and the difference of each side CT no-load voltage ratio, transformer station's each side current amplitude phase place is the most different,
Differential protection first has to eliminate these impacts.Need to utilize digital method that no-load voltage ratio and phase place are compensated, transformer station's each side electricity
The direction of stream is all with sensing transformator as positive direction, and each side CT secondary current phase place is adjusted by software, uses the conversion side of Y → △
Formula, i.e. Y enters horizontal phasing control in side.For transformator or the transformator of Y/Y/Y-12-12 of Y/Y/ △-12-11, Y side conversion public affairs
Formula is as follows:
(3-2-1)
For the transformator of Y/Y/ △-12-1, Y side conversion formula is as follows:
(3-2-2)
Electric current before not changing for Y side,For each phase current after correction.△ side electricity
Flow not corner.
Following description is based on eliminating on the basis of transformer station's each side current amplitude phase difference.
Ratio brake differential protection operation equation comprises low definite value and high-set setting two parts, and low definite value operation equation is by excitation
Shoving and the locking of CT exception, high-set setting operation equation is not by the locking that excitation surge current and CT are abnormal.Ratio brake differential protection
Do not consider the situation that CT is saturated and CT transient characterisitics are inconsistent.
In conjunction with Fig. 5, Fig. 6, illustratively percentage differential operation equation
Low definite value:
(3-2-3)
High-set setting:
(3-2-4)
For difference current,For differential protection starting current definite value,For stalling current, S is ratio brake coefficient,For the reference current (generally on the basis of the rated current of high-pressure side) of differential protection, each side sense of current is all to point to transformation
Device is positive direction.
(1) differential for both sides
(3-2-5)
(3-2-6)
It is respectively the electric current of Current Transformer Secondary side, transformator high and low pressure side.
(2) differential for three sides and above several side
(3-2-7)
(3-2-8)
In formula: 3≤k≤4,It is respectively the electric current of Current Transformer Secondary side, transformer station each side.
In the present embodiment, it is additionally provided with excitation surge current criterion, mainly includes second harmonic mode and waveform comparison mode, and
Can be selected by control word.When " secondary harmonic brake " control word adjust be 1 time, use second harmonic mode locking, adjusting is 0
Time, use waveform comparison mode locking.
Second harmonic criterion mode, also known as second harmonic criterion mode, is described in detail by second harmonic mode below.
During transformator air-drop, three phase excitation often has a phase to contain substantial amounts of second harmonic in shoving.But, each side of territory differential protection of standing
Electric current horizontal phasing control to be entered, the electric current after phase place adjusts is no longer real excitation surge current, the secondary harmonic component in electric current
Also can change.Current calculation secondary harmonic component can be automatically selected, as empty at transformator according to the different operating modes of transformer station
Carry the Current calculation secondary harmonic component before using phase place to adjust when closing a floodgate, therefore, calculate the secondary harmonic component of excitation surge current
More true, performance is relatively reliable.Transformator, when properly functioning, use the secondary harmonic component in difference current to identify and encourages
Magnetic shoves.Discriminant equation is as follows:
In formula:For the second harmonic in difference current,For the first-harmonic in difference current,For second harmonic system
Number.
If certain phase difference current meets above formula, simultaneously locking three-phase differential protection.
While using second harmonic "or" locking, the fault during air-drop main transformer is identified, puts into by phase in short-term
Comprehensive open criterion, can correctly identify excitation surge current, can open differential guarantor to fast and reliable when dropping failure transformer again
Protect, improve the speed of action of differential protection when dropping transformator in fault.
Waveform comparison criterion
Difference current or the degree of asymmetry of phase current calculating waveform can be automatically selected according to the different operating modes of transformer station, calculate
The waveform degree of asymmetry going out excitation surge current is more true, and protective value is relatively reliable.Discriminant equation is as follows:
In formula:For the asymmetric angle value of difference current sampled point,Symmetry for corresponding difference current sampled point
Angle value, K is a certain fixed coefficient.If certain phase difference current meets above formula, locking this phase differential protection.
As shown in Figure 7, Figure 8, increment is differential not to be affected by properly functioning load current, has more differential than vertical difference higher
Sensitivity, owing to the choosing of stalling current of vertical poor differential protection includes normal load current, in transformer station occur weak therefore
During barrier, vertical difference differential protection is big due to stalling current, possible deferred action or be failure to actuate.Increment is differential mainly solves transformator
Slight turn-to-turn fault and high resistance earthing fault.
Operation equation
(3-2-9)
(3-2-10)
Wherein:；
ForMiddle amplitude maximum person；
。
Owing to territory, station differential protection needs to identify the excitation surge current running status of transformator, occur seriously when transformer station is internal
During fault, it is impossible to enough quickly excise fault, power system is stablized and brings serious harm, so configuration fast differential over current protection,
It is used for the internal fault that quickly excision transformer station is serious.
As it is shown in figure 9, fast differential over current protection is instantaneous when arbitrary phase difference current electric current is more than differential quick-break current ration
Action, tripping each side chopper.
As shown in Figure 10, put into when differential protection and arbitrary phase difference current is fixed more than 0.5 times of differential protection starting current
During value, time delay 5s report difference current gets over limited signal.
Owing to our station territory differential protection uses the poorest+little differential mode formula, the wavy trajectory of this territory differential protection of therefore standing is: just
Often under the method for operation, when the poorest and the little difference of correspondence are satisfied by criterion, jump element correspondence main transformer of deserting high-pressure side chopper,
It is female that medium voltage side includes this branch breaker of little poor element, medium voltage side bus bus, low-pressure side chopper and low-pressure side in
Line section switch；If the biggest difference meets operating criterion, all elements of tripping medium voltage side after time delay.
Claims (3)
1. a substation area differential protection method for intelligent substation, is characterized in that: include the big differential protection mould based on transformer station
Formula and based on the plural little differential protection pattern of each transformator, big differential protection pattern is starting element, is called for short big
Difference element, arbitrary little differential protection pattern is action element, is called for short little poor element, when big differential protection pattern and little differential protection
When pattern meets simultaneously, differential protection outlet action, little differential protection pattern or fault selection element；Big differential protection pattern
Scope is defined in the institute not including mother and segmentation on each high voltage side of transformer electric current of transformer station, medium voltage side and low-pressure side bus
There are line current, little differential protection model domain to be defined in corresponding high voltage side of transformer electric current, corresponding transformator medium voltage side and low
On pressure side connected bus all include mother and segmentation go out line current；Also include
Step 1, data select and process
Defining two main transformers, main transformer is high, medium voltage side is double bus scheme, and main transformer low-pressure side is single mother partition wiring；Territory, definition station
Differential protection protection domain is two main transformers+medium voltage side outlet+low-voltage side outlet；For realizing territory, station differential protection function, protection
Need the ac analog data got as follows
Current sampling data is
Main transformer high-pressure side CT, main transformer medium voltage side CT, medium voltage side bus outlet CT, medium voltage side mother CT, low-pressure side bus outlet CT
With low-pressure side segmentation CT current sampling data；Above-mentioned current sampling data is for constituting each differential unit of territory, station differential protection
Part；
Voltage sample data are
Two sections of busbar voltages of main transformer medium voltage side, two sections of busbar voltages of main transformer low-pressure side；
Step 2, the data of big poor element select
Big poor element is as starting element, in order to distinguish territory, station protection internal fault external fault；The protection domain of big poor element is two
Main transformer+medium voltage side bus+low-pressure side bus；The data constituting big differential protection pattern are:
High voltage side current: use two main transformer high-pressure side CT to gather the vector of electric current；
Medium voltage side electric current: use the medium voltage side bus each branch road CT without main transformer branch road and mother to gather the vector of electric current；
Low-pressure side electric current: use the low-pressure side bus each branch road CT without main transformer branch road and segmentation to gather the vector of electric current；
Step 3, the data of little poor element select
Little poor element is used as fault and selects element, presses in the part that protection domain is every main transformer+correspondence of each little poor element
Side bus and low-pressure side bus；
The data constituting each little poor element differential protection are:
High voltage side current: use this main transformer high-pressure side CT to gather electric current；
Medium voltage side electric current: a certain section of the medium voltage side using this main transformer to connect does not contains each branch road of bus and mother CT of this main transformer branch road
Gather the vector of electric current；
Low-pressure side electric current: a certain section of the low-pressure side using this main transformer to connect does not contains each branch road of bus and the segmentation CT of this main transformer branch road
Gather the vector of electric current；
Step 4, data calculate
For choosing of medium voltage side current sampling data, special logic is used to realize, the connection status of real-time tracking main transformer branch road,
Specifically connect bus according to main transformer branch road and determine that the outlet CT of this little poor element included in by needs；Mother branch road is fixing include in two little
Difference element；The polarity of device mother CT arranges with I female connection branch road, when counting II female corresponding little poor element, fixing by correspondence
Sampled data negate；
The computing formula of the little spill current of medium voltage side is as follows:
Wherein," the little spill current of medium voltage side " for the little poor element of 1#；For " the little spill current of medium voltage side " of the little poor element of 2#,For the branch current of medium voltage side in the range of little poor element protection,=1,2,3 natural numbers such as grade；In formula, the little spill current of medium voltage side
Calculate and introduce the middle pressure bus not containing main transformer branch road containing mother branch road, the little poor element associated coefficient of each branch road 1#I.e. jth
The coefficient of association of element poor element little to 1#, the little poor element associated coefficient of 2#The i.e. association of jth element poor element little to 2#
Coefficient；The calculating of electric current is all carried out according to primary current value；
Low-pressure side bus uses single mother partition main wiring mode, and on bus, all branch roads are fixing connects, can be according to on-the-spot actual
The branch road CT that each little poor element needs to count is preset in wiring, and wherein segmentation CT is fixing counts two little poor elements；Segmentation CT's
Polarity connects branch road with I mother, and when counting II female corresponding little poor element, the fixing sampled data by correspondence negates；Territory of standing is differential
Protection is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert；
Step 5, elimination transformer station each side current amplitude phase difference
Utilizing digital method to compensate no-load voltage ratio and phase place, transformer station's each side sense of current is all to point to transformator as pros
To, each side CT secondary current phase place is adjusted by software, uses the conversion regime of Y → △, and Y enters horizontal phasing control in side；For Y/Y/
The transformator of △-12-11 or the transformator of Y/Y/Y-12-12, Y side conversion formula is
For the transformator of Y/Y/ △-12-1, Y side conversion formula is
Electric current before not changing for Y side,For each phase current after correction；
Step 6, percentage differential action calculate
Low definite value:
High-set setting:
For difference current,For differential protection starting current definite value,For stalling current, S is ratio brake coefficient,For
The reference current of differential protection, on the basis of the rated current of high-pressure side, each side sense of current is all to point to transformator as pros
To；
(1) differential for both sides
It is respectively the electric current of Current Transformer Secondary side, transformator high and low pressure side；
(2) differential for three sides and above several side
In formula: 3≤k≤4,It is respectively the electric current of Current Transformer Secondary side, transformer station each side；
Step 7, excitation surge current criterion
Excitation surge current criterion mainly includes second harmonic mode and waveform comparison mode, and can be selected by control word；When " secondary
Harmonic braking " control word adjusts when being 1, uses second harmonic mode locking, and adjust when being 0, use waveform comparison mode locking；
Step 8, waveform comparison criterion
Difference current or the degree of asymmetry of phase current calculating waveform can be automatically selected according to the different operating modes of transformer station, calculate and encourage
The waveform degree of asymmetry that magnetic shoves, it determines equation is as follows
In formula:For the asymmetric angle value of difference current sampled point,For the symmetrical angle value of corresponding difference current sampled point,
K is a certain fixed coefficient；If certain phase difference current meets above formula, locking this phase differential protection.
2. substation area differential protection method for intelligent substation as claimed in claim 1, is characterized in that: described big differential protection pattern
It is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert.
3. substation area differential protection method for intelligent substation as claimed in claim 1 or 2, is characterized in that: described little differential protection
Pattern is made up of percentage differential, increment quick-break differential, differential, difference current Threshold Crossing Alert.
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| CN103779843B (en) * | 2014-03-01 | 2016-04-20 | 华北电力大学 | Based on territory, station protection system and the guard method thereof of differential flexible overlapping subregion |
| CN104319735B (en) * | 2014-09-30 | 2018-02-02 | 许继集团有限公司 | A kind of excitation flow recognition method of auto-transformer longitudinal difference protection |
| CN104868451B (en) * | 2015-04-10 | 2016-02-03 | 国网山东省电力公司 | Realize GIS fault precisely to excise and the bus protection algorithm of automatic recovery of power supply |
| CN105510731B (en) * | 2015-11-26 | 2018-04-20 | 国网辽宁省电力有限公司大连供电公司 | Power transformer medium voltage side power grid parallel resonance detects alarm method and system |
| CN106300262B (en) * | 2016-08-26 | 2019-02-05 | 大唐黄岛发电有限责任公司 | A kind of 220kV grade transformer protection method for substation's remote power-feeding |
| CN106300288B (en) * | 2016-08-27 | 2018-12-04 | 许继集团有限公司 | A kind of station domain differential protecting method and device |
| CN106549367B (en) * | 2016-10-20 | 2019-03-19 | 许继集团有限公司 | A kind of differential protection method for bus and device for mother CT exception |
| CN108173240B (en) * | 2017-12-19 | 2019-06-28 | 华中科技大学 | A kind of transformer excitation flow recognition method and system based on compound time difference method |
| CN108181528B (en) * | 2017-12-31 | 2020-07-31 | 中国能源建设集团华东电力试验研究院有限公司 | High-voltage cable differential protection checking system in no-load state |
| CN109066319A (en) * | 2018-09-20 | 2018-12-21 | 深圳供电规划设计院有限公司 | A kind of substation low-voltage side wiring construction |
| CN111060739B (en) * | 2020-02-14 | 2021-10-12 | 东方电子股份有限公司 | Fault type identification method based on differential current and fault characteristic quantity |
| CN112003250B (en) * | 2020-07-30 | 2023-08-18 | 中国电力科学研究院有限公司 | Direct-current line differential protection method and system for extra-high voltage direct-current system |
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