CN108551162A - A kind of neutral grounding mode conversion equipment - Google Patents
A kind of neutral grounding mode conversion equipment Download PDFInfo
- Publication number
- CN108551162A CN108551162A CN201810703656.8A CN201810703656A CN108551162A CN 108551162 A CN108551162 A CN 108551162A CN 201810703656 A CN201810703656 A CN 201810703656A CN 108551162 A CN108551162 A CN 108551162A
- Authority
- CN
- China
- Prior art keywords
- neutral
- mode
- power grid
- conversion equipment
- neutral grounding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/08—Limitation or suppression of earth fault currents, e.g. Petersen coil
Abstract
The invention discloses a kind of neutral grounding mode conversion equipments, it is characterized in that controllable impedance is arranged between the neutral point and ground of power grid, the impedance value of controllable impedance is adjusted according to the open delta voltage and/or three phase-to-ground voltages of voltage transformer in power grid, and does not change the symmetry of power grid three-phase voltage；Adjustment controllable impedance makes power grid be in high current earthing mode in normal operating condition；Small current neutral grounding mode is converted under singlephase earth fault state or is converted to high current earthing mode；Realize the mutual conversion of neutral grounding mode of the power grid under normal and singlephase earth fault two states.The present invention has taken into account high current ground connection and the advantages of small current neutral grounding, the shortcomings that abandoning different earthing modes so that power grid internal overvoltage is low, and trip-out rate is low, power supply reliability is high.
Description
Technical field
The present invention relates to power equipments, more specifically provide neutral grounding mode conversion equipment for transmission and distribution network,
Realize the mutual conversion of power grid two or more neutral grounding mode.
Background technology
Electric connecting mode between three-phase ac power system neutral and the earth, referred to as neutral point of electric network ground connection side
Formula.Neutral grounding mode is related to the security reliability and economy of power grid；Directly affect system equipment dielectric level simultaneously
Selection, overvoltage level and the means of relay protection, communication interference etc..In general, Power Network Neutral namely becomes
Electricity in transformer voltage neutral point earthing modes at different levels.
Neutral point effective grounding, that is, heavy current grounding system：China 110kV and the above power grid generally use high current to be grounded
Mode, i.e. neutral point effective grounding mode in actual motion, to reduce single-phase-to-ground current, can also be such that some transformers use
Earth-free mode, in neutral point effective grounding mode, neutral point potential is fixed as ground potential, and single-phase earthing event is occurring
When barrier, the raising of non-faulting phase voltage does not exceed 1.4 times of operation phase voltages；Transient overvoltage level is relatively low；Fault current is very
Greatly, earth leakage protective can act rapidly in tripping, cut off failure, it is shorter that system equipment bears the overvoltage time.Therefore, high current connects
Ground system can be such that the apparatus insulated requirement level of whole system reduces, to which cost be greatly reduced；In the prior art, neutral point has
It imitates there are two types of earthing modes：One is being directly grounded, another kind is through low resistance grounding.The advantages of neutral point effective grounding mode
It is to be, internal overvoltage is low, localization of fault is easy, can cut off faulty line rapidly；The disadvantage is that：It is cut off because it is rapid
Faulty line interruptedly supplying power causes trip-out rate high, and power supply reliability is low；Also, earth current is big, and ground potential rises higher, increasing
Big touch voltage and step voltage is big；Increase the interference to information system；Increase the counterattack of low-voltage net.
Neutral non-effective grounding, that is, small current neutral grounding system：For the power distribution network of 6~35kV, low current is usually used
Earthing mode, i.e. neutral non-effective grounding mode.Neutral non-effective grounding mode can be divided mainly into：It is earth-free, through extinguishing arc
Resistance or high resistance ground during coil is grounded and passes through.The advantages of neutral non-effective grounding is：Singlephase earth fault stable state power current
It is small；Lightning stroke insulation flashover transient fault can be removed automatically, without tripping；Can single-phase earthing operation, improve power grid and uninterruptedly supply
Electricity improves power supply reliability；Earth current is small, reduces the raising of ground potential, reduces step voltage, reduces to information system
The interference of system reduces the counterattack etc. to low-voltage net；The disadvantage is that：Internal overvoltage is high, big to weak isolating breakdown probability；Therefore
Barrier point is difficult to position, can be with 100% accurate route selection without any line selection apparatus.
Different neutral grounding modes respectively has advantage and disadvantage, and the advantages of high current earthing mode is small current neutral grounding mode
The shortcomings that, the advantages of the shortcomings that high current earthing mode is small current neutral grounding mode.
On the other hand, the network system of 110kV, 220kV above, since voltage is very high, neutral point is generally adopted
With direct grounding way, but since relay protection setting configures and prevent the requirement of communication interference etc., in order to limit list
Phase short circuit current, wherein there is some transformers to use isolated neutral mode.Under this method of operation, due to lightning stroke, list
Phase ground short circuit failure etc. can cause neutral point overvoltage, and transformer is graded insulation mostly, therefore overvoltage is to neutrality
The insulation of point causes very big threat, and the treatment measures of current this harm are to install gap additional between the neutral point and ground of transformer
In parallel with arrester, gap breakdown voltage dispersion value is very big, and gap breakdown itself results in neutral point voltage and drops suddenly, this electricity
The steep drop of pressure equally causes to impact to transformer neutral point insulation.
Invention content
The present invention is to provide a kind of Power Network Neutral to avoid above-mentioned existing deficiencies in the technology
Conversion equipment, to which high current ground connection can be taken into account and the advantages of small current neutral grounding, the shortcomings that abandoning different earthing modes so that
Power grid internal overvoltage is low, and trip-out rate is low, power supply reliability is high.
Another goal of the invention of the present invention is to overcome solidly earthed neutral system isolated neutral transformer
The shortcomings that neutral point insulation gap and protection of arrester, provides overvoltage level low-voltage and changes smooth neutral point insulation protection
Device.
The present invention is to solve technical problem to adopt the following technical scheme that：
The characteristics of neutral grounding mode conversion equipment of the present invention is：The neutral grounding mode conversion equipment is in electricity
Controllable impedance is set between the neutral point and ground of net, and the impedance value of the controllable impedance is according to voltage transformer in the power grid
Open delta voltage and/or three phase-to-ground voltages are adjusted, and do not change the symmetry of the three-phase voltage of the power grid；
By adjusting the controllable impedance, it is in high current earthing mode in normal operating condition to make the power grid；It is described
Power grid is converted to small current neutral grounding mode under singlephase earth fault state or is converted to high current earthing mode；Realize the electricity
The mutual conversion of neutral grounding mode of the net under normal and singlephase earth fault two states；
The power grid refers in high current earthing mode in normal operating condition：The power grid is in normal operating condition
When, the resistance characteristic of controllable impedance is the resistance characteristic under high current earthing mode；And single-phase earthing occurs in the power grid
It is in high current in neutral grounding mode into small current neutral grounding mode or the transfer process of high current earthing mode when failure
The earth current that the controllable impedance of earthing mode is generated in fault point is not more than 50 amperes.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：The adjustment of the controllable impedance makes the electricity
The zero sequence impedance of net and the ratio of positive sequence impedance are not less than 0.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：The adjustment of the controllable impedance makes the electricity
The attenuation coefficient of net and the ratio of intrinsic frequency are not less than 0.2.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：Singlephase earth fault occurs in the power grid
When, control the controllable impedance power make fault point earth current be not more than the power grid single-phase earthing when fault point permit
Permitted the maximum current value flowed through.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：For the power grid of not physical neutral, make
Neutral point of electric network is established with grounding transformer, controls the power of the grounding transformer to limit the controllable impedance in fault point
The earth current of formation.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：It is required for after singlephase earth fault occurs
The power grid for cutting off faulty line immediately, is arranged the neutral grounding mode conversion equipment, so that the power grid is normally being transported
It is in high current earthing mode when row state；When singlephase earth fault occurs, and postpone T1 milliseconds：If failure vanishes, power grid
Restore normal operating condition, then the neutral grounding mode conversion equipment continues as being in high current earthing mode；If failure according to
So exist, then the neutral grounding mode conversion equipment is converted to the high current ground connection side that neutral point is grounded through low values of resistors
Formula, to cut off faulty line, after excision faulty line, power system restoration normal operating condition, the neutral grounding mode
Conversion equipment be converted to be arranged in high current earthing mode the high current earthing mode fault point earth current be 100~
1000 amperes, T1 values are 30-10000 milliseconds.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：It is required for after singlephase earth fault occurs
The T2 times cut off the power grid of faulty line in limited time, and the neutral grounding mode conversion equipment is arranged, so that the power grid exists
It is in high current earthing mode when normal operating condition；When singlephase earth fault occurs, and postpone T2 seconds：If failure vanishes,
Power system restoration normal operating condition, then the neutral grounding mode conversion equipment continue as be in high current earthing mode；If therefore
Barrier still remains, then the neutral grounding mode conversion equipment is converted to the low current that neutral point is grounded through medium resistance device and connects
Ground mode by line selection device for low current locating bad lines, and cuts off faulty line, is cutting off faulty line, power system restoration just
After normal operating status, the neutral grounding mode conversion equipment is converted in high current earthing mode, and the low current is arranged
The fault point earth current of earthing mode is 10~100 amperes, and T2 values are 1~8000 second.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：It is required for after singlephase earth fault occurs
Continuous service is no more than 2 hours power grids, the neutral grounding mode conversion equipment is arranged, so that the power grid is normal
It is in high current earthing mode when operating status；Neutral point is converted to when singlephase earth fault occurs to be grounded through high resistance resistor,
Or the small current neutral grounding mode of neutral by arc extinction coil grounding or isolated neutral, fault point earth current are not more than
50A；If 2 hour internal faults disappear, power system restoration normal operating condition, the neutral grounding mode conversion equipment conversion
To be in high current earthing mode.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：Continue after meeting generation singlephase earth fault
Under conditions of operation is no more than 2 hours, for the neutral grounding mode for having been converted into small current neutral grounding mode under malfunction
Conversion equipment, any time by the neutral grounding mode conversion equipment be converted to neutral point be grounded through medium resistance device it is small
Current earthing mode, and by line selection device for low current locating bad lines, to cut off faulty line, fault point earth current is
10~100 amperes；After cutting off faulty line power system restoration normal operating condition, the neutral grounding mode conversion equipment turns
It is in high current earthing mode to be changed to.
The characteristics of neutral grounding mode conversion equipment of the present invention, lies also in：In in solidly earthed neutral system
Property the earth-free transformer of point, the controllable impedance is arranged between the neutral point and ground of the isolated neutral transformer, electricity
Net in normal and failure operation state in medium resistance device or the earthing mode of high resistance resistor, with limit system fluctuation,
The overvoltage of transformer neutral point caused by lightning stroke and singlephase earth fault, the isolated neutral transformer refers to 110kV
Above isolated neutral transformer.
Compared with the prior art, the present invention has the beneficial effect that：
1, present invention firstly provides the conversion of neutral grounding mode, provide a kind of neutral grounding mode conversion equipment and
Method, the shortcomings that taking into account high current ground connection and abandon their various earthing modes the advantages of small current neutral grounding so that in power grid
Portion's overvoltage is low, and trip-out rate is low, power supply reliability is high, overcome power grid only there are one neutral grounding mode it is inconvertible lack
Point；
2, the present invention is in high current earthing mode in normal operating condition, and the resistance characteristic of controllable impedance connects for high current
Resistance characteristic under ground mode provides channel of releasing for the residual charge of system fluctuation and lightning stroke, thus resonance does not occur for power grid,
And switching manipulation overvoltage is low；
3, the adjustment of controllable impedance of the present invention is so that the zero sequence impedance of power grid and the ratio of positive sequence impedance are not less than 0, it is ensured that
Zero sequence impedance and the ratio of positive sequence impedance are less than without falling into (- 20, -1) region so that it is guaranteed that power grid is mutually grounded power-frequency overvoltage
1.1 times of line voltage；
4, the adjustment of controllable impedance of the present invention is so that the attenuation coefficient of the power grid and the ratio of intrinsic frequency are not less than
0.2, the resonance overvoltage and transient overvoltage of system are not more than 2.5 times of phase voltage；
5, it requires to cut off the power grid of faulty line immediately after the singlephase earth fault of the invention for generation, has ensured power grid wink
Between failure do not trip, improve power supply reliability, overcome the high disadvantage of the power supply reliability of heavy current grounding system；
6, the present invention after singlephase earth fault generation, can select to require adaptation with it according to the power grid of different requirements
Neutral grounding mode operation under malfunction cuts off faulty line or delay excision faulty line or continuous service 2 at once
Faulty line is cut off after hour；
7, the present invention be the isolated neutral transformer being directly grounded in power grid neutral point insulation provide it is a kind of newly
Protected mode, overvoltage level is low and voltage change is smooth, and performance is far superior to existing gap discharge protection, overcomes gap
The shortcomings that+protection of arrester voltage drops suddenly.
Description of the drawings
Fig. 1 neutral points are in high current and arc suppression coil, resistance-grounded system transfer principle figure；
Fig. 2 neutral points are in high current and grounding through arc transfer principle figure；
Fig. 3 neutral points are in high current and resistance-grounded system transfer principle figure；
The power that Fig. 4 D.C. magnetic biasings control controllable impedance realizes neutral point in high current and resistance-grounded system transfer principle
Figure；
Fig. 5 D.C. magnetic biasings control grounding transformer power and realize neutral point in high current and resistance-grounded system transfer principle
Figure；
Fig. 6 D.C. magnetic biasings control grounding transformer power and realize neutral point in high current and resistance-grounded system transfer principle
Figure；
Perfect the voltage of phase when Fig. 7 single-phase earthings；
The relationship of Fig. 8 resonance overvoltages multiple and circuit parameter.
Figure label：1 is in the controllable impedance of high current earthing mode, 11 single-phase transformers, 12 adjustable resistors, 2 extinguishing arcs
Coil, 3 resistors, K1, K2, K3 are single-phase switch, and K is threephase switch, and P is D.C. magnetic biasing device, and J is grounding transformer, three
Mutually electricity is A, B, C, and O is neutral point of electric network.
Specific implementation mode
Neutral grounding mode conversion equipment is that controllable impedance is arranged between the neutral point and ground of power grid in the present embodiment,
The impedance value of controllable impedance is adjusted according to the open delta voltage and/or three phase-to-ground voltages of voltage transformer in power grid,
And do not change the symmetry of power grid three-phase voltage.
By adjusting controllable impedance, it is in high current earthing mode in normal operating condition to make power grid；Power grid connects single-phase
Small current neutral grounding mode is converted under earth fault state or is converted to high current earthing mode；Realize power grid normal and single-phase connect
The mutual conversion of neutral grounding mode under earth fault two states.
Neutral grounding mode is related to the security reliability of power grid, economy；System equipment insulation water is directly affected simultaneously
Flat selection, overvoltage level and the means of relay protection, communication interference etc..The neutral grounding mode of the previous power grid of mesh only has
A kind of earthing mode, no matter normal operation or failure neutral grounding mode are the same.
Different neutral grounding modes respectively has advantage and disadvantage, and the advantages of high current earthing mode is small current neutral grounding mode
The shortcomings that, the advantages of the shortcomings that high current earthing mode is small current neutral grounding mode.
Present invention firstly provides the conversion of neutral grounding mode, a kind of neutral grounding mode conversion equipment and side are provided
Method, the shortcomings that taking into account high current ground connection and abandon their various earthing modes the advantages of small current neutral grounding so that inside power grid
Overvoltage is low, and trip-out rate is low, power supply reliability is high, overcomes the inconvertible disadvantage of neutral grounding mode.
If Fig. 1, K1 are closed controllable impedance and put into neutral point of electric network, when systems are functioning properly, switch K2 and K3, which are in, to be beaten
Open position is only in the controllable impedance 1 of high current earthing mode, and controllable impedance is the controllable resistance in high current earthing mode at this time
Anti- 1, when single-phase earthing occurs for power grid, if singlephase earth fault occurs, closure switch K2 puts into arc suppression coil 2, and adjusting can
Resistor 12 is adjusted so that 11 nonoverload of single-phase transformer, power grid are converted to small current neutral grounding mode and run, controllable impedance is at this time
It is in parallel with arc suppression coil 2 in the controllable impedance 1 of high current earthing mode；When singlephase earth fault continues 30 minutes, intermediate value is put into
Resistor 3 cuts off faulty line by small current line selection locating bad lines, and it is in high current that controllable impedance, which is controllable impedance, at this time
The parallel connection of the controllable impedance 1, arc suppression coil 2 and medium resistance device 3 of earthing mode；The normal shape of power system restoration after excision faulty line
State, neutral grounding mode conversion equipment turn on the switch K2 and K3, and power grid is made to be run in high current earthing mode.
Power grid refers in high current earthing mode in normal operating condition：Power grid is controllable to hinder in normal operating condition
Anti- resistance characteristic is the resistance characteristic under high current earthing mode；And when singlephase earth fault occurs for power grid, in neutrality
Point earthing mode is into small current neutral grounding mode or the transfer process of high current earthing mode, in the controllable of high current earthing mode
The earth current that impedance is generated in fault point is not more than 50 amperes.
If the controllable impedance 1 in high current earthing mode in Fig. 1 is made of single-phase transformer 11 and controllable resistor 12, become
Depressor 11 is 10000V/400V, and setting capacity is 3kVA；Controllable resistor 12 is made as 0.02 Ω in normal operation time control, single-phase
Earth fault time control is made as 60 Ω or more, ensures 11 nonoverload of single-phase transformer；Controllable resistor 12 is equivalent when power grid normal operation
It is the value that 12.5 ohm of ground connection are equivalent to low-resistance resistor to system primary side neutral resistor, therefore is in high current system performance；
When singlephase earth fault occurs for power grid, controllable resistor 12 is transformed into from 0.02 Ω in 60 Ω above procedure, due to transformer 11
The limitation of capacity, fault point generate electric current 5A hereinafter, therefore be in high current earthing mode controllable impedance 1 power grid just
Often it is in high current grounding resistance characteristic when operation, the larger earth current without providing high current ground connection.Simultaneously in big electricity
The controllable impedance 1 of earthing mode is flowed in neutral grounding mode transfer process, and fault point earth current will not be caused excessive.
In specific implementation, the adjustment of controllable impedance is so that the zero sequence impedance of power grid and the ratio of positive sequence impedance are not less than 0.Such as
Fig. 7 is the voltage pattern that single-phase earthing perfects phase, k=Xo/X1(zero sequence impedance/positive sequence impedance) is such as fallen between (- 20, -1), single
Phase earth fault will produce very high power-frequency overvoltage, and k values are higher closer to -2 power-frequency overvoltage values, and work occurs in when k=-2
Frequency resonance, each point voltage tends to be infinitely great on circuit.It as k ＞ 0, then never falls between (- 20, -1), therefore will not occur
Single-phase earthing resonance, so that it is guaranteed that power grid is mutually grounded 1.1 times that power-frequency overvoltage is less than line voltage.
In specific implementation, the adjustment of controllable impedance is so that the attenuation coefficient of power grid and the ratio of intrinsic frequency are not less than 0.2.
Such as the relationship of Fig. 8 resonance overvoltages multiple and circuit parameter, as attenuation coefficient and the intrinsic frequency, that is, μ/ω of power grid0﹥ 0.2, then
Power grid occurs overvoltage multiple when resonance and is no more than 2.5 times.
The present invention is in high current earthing mode in normal operating condition, and the resistance characteristic of controllable impedance is grounded for high current
Resistance characteristic under mode provides channel of releasing for the residual charge of system fluctuation and lightning stroke, thus resonance does not occur for power grid, and
Switching manipulation overvoltage is low.
When singlephase earth fault occurs for power grid, the power for controlling controllable impedance makes the earth current of fault point be not more than
The maximum current value that fault point allows to flow through when power grid single-phase earthing.Controllable impedance as in Fig. 1~4 being in high current earthing mode
1, the electric current generated in fault point in the controllable impedance 1 of high current earthing mode by the power limit of equipment transformer 11；Figure
5, in 6 it is the electric current generated in fault point by controlling the power limit control impedance 1 of grounding transformer J, the ground connection transformation in Fig. 5
Device J is the Y type modes of connection, and the grounding transformer J in Fig. 6 is the open delta type mode of connection, and grounding transformer J is simultaneous in Fig. 5,6
The function of single-phase transformer 11 is cared for.
For the power grid of not physical neutral, neutral point of electric network is established using grounding transformer, controls grounding transformer
Power to limit the earth current that controllable impedance is formed in fault point.The medium voltage side winding of medium voltage network is often delta connection side
Formula, because without physical neutral, it is necessary to which artificial establishes artificial neutral point using grounding transformer J.It is to pass through in Fig. 5,6
The electric current that the power limit control impedance 1 of control grounding transformer J is generated in fault point.
For the power grid for requiring to cut off faulty line after singlephase earth fault occurs immediately, such as Fig. 3, resistor 3 is low
Be worth resistor, neutral grounding mode conversion equipment be set, by adjusting in the controllable impedance 1 of high current earthing mode so that
Power grid is in high current earthing mode in normal operating condition.When singlephase earth fault occurs, and postpone T1 milliseconds such as
Postpone 200ms：The purpose for postponing 200ms after singlephase earth fault is tripping caused by escaping the instant earthings failures such as lightning stroke, only
It is that permanent fault just cuts off faulty line, if failure vanishes power system restoration normal operating condition, neutral grounding mode
Conversion equipment continues as being in high current earthing mode；If failure still remains, failure is permanent fault, then neutral ground side
Formula conversion equipment closure switch K3 is converted to the high current earthing mode that neutral point is grounded through low values of resistors, to cut off failure
Circuit, after cutting off faulty line power system restoration normal operating condition, neutral grounding mode conversion equipment is converted in big electricity
Earthing mode is flowed, the fault point earth current of setting high current earthing mode is 100~1000 amperes, overcomes high current ground connection
The high defect of system trip rate, improves system power supply reliance security, and T1 values are 30-10000 milliseconds.
For requiring to prescribe a time limit after singlephase earth fault occurs, the T2 times cut off the power grid of faulty line, such as Fig. 3, resistor
3 be medium resistance device, neutral grounding mode conversion equipment is arranged, by adjusting in the controllable impedance 1 of high current earthing mode
So that power grid is in high current earthing mode in normal operating condition.When singlephase earth fault occurs, and postpone T2 seconds：
If failure vanishes power system restoration normal operating condition, neutral grounding mode conversion equipment continues as being in high current ground connection side
Formula；If failure still remains, such as half an hour or a hour in limited time, the neutral ground if singlephase earth fault disappears
It is in high current earthing mode that mode conversion equipment, which is automatically restored to neutral point, if failure does not disappear combination switch K3, then neutral point
Earthing mode conversion equipment is converted to the small current neutral grounding mode that neutral point is grounded through medium resistance device, not only escapes lightning stroke in this way
Equal instant earthings failure, and to exit faulty line or load avoids loss from stopping time, such as the power supply of steel-making blast furnace
Load then by line selection device for low current locating bad lines, and cuts off faulty line, in excision faulty line power system restoration
After normal operating condition, neutral grounding mode conversion equipment is opened K3 and is converted in high current earthing mode, and low current is arranged
The fault point earth current of earthing mode be 10~100 amperes, it is sufficient to make 100% route selection of small current line selection, by T2 values be 1~
8000 seconds.Such as Fig. 5,6, adjustment resistor 12 is low values of resistors under power grid normal operating condition, and controllable impedance is by controlled power
Grounding transformer J and adjustable resistor 12 form；The power of grounding transformer J is controlled by D.C. magnetic biasing device P so that electricity
It is run in high current earthing mode under net normal operating condition；When singlephase earth fault occurs, by controlling grounding transformer J
Power and adjustable resistor 12 resistance value, can make power grid be converted to medium resistance device ground connection small current neutral grounding mode,
Power grid can be made to be converted to the small current neutral grounding mode of high resistance resistor ground connection, power grid can be made to be converted to low values of resistors ground connection
High current earthing mode.
With reference to Fig. 3 neutral ground is realized again by the resistance value of the power and adjustable resistor 12 of single-phase transformer 11
Mode conversion equipment makes power grid or is run in high current earthing mode, or is the high current earthing mode of low values of resistors ground connection
Operation, or run for the small current neutral grounding mode of medium resistance device ground connection, or be the small current neutral grounding side of high resistance resistor ground connection
Formula is run.
For the power grid for requiring continuous service to be no more than 2 hours after singlephase earth fault occurs, such as Fig. 2,5,6, setting
Neutral grounding mode conversion equipment, by adjusting in the controllable impedance 1 of high current earthing mode so that power grid is normally being transported
It is in high current earthing mode when row state；Neutral point is converted to when singlephase earth fault occurs to be grounded through high resistance resistor, or
The small current neutral grounding mode of neutral by arc extinction coil grounding or isolated neutral, Fig. 2 are converted into the ground connection of arc suppression coil 2,
Fig. 5,6 are to be converted into high resistance resistor 3 by the capacity and controllable resistor 12 of control grounding transformer J to be grounded, in being converted to
Property the earth-free mode of point run need system capacitive current be less than national regulations, fault point earth current be not more than 50A；If 2
After a hour internal fault disappearance power system restoration normal operating condition, then neutral grounding mode conversion equipment is converted in high current
Earthing mode.
Meet occur singlephase earth fault after continuous service be no more than 2 hours under conditions of, under malfunction
Be converted to the neutral grounding mode conversion equipment of small current neutral grounding mode, any time is by neutral grounding mode conversion equipment
Be converted to the small current neutral grounding mode that neutral point is grounded through medium resistance device, and by line selection device for low current locating bad lines,
To cut off faulty line, fault point earth current is 10~100 amperes；In excision faulty line power system restoration normal operation shape
After state, neutral grounding mode conversion equipment is converted in high current earthing mode.
Such as Fig. 4, the output power of single-phase transformer 11 is regulated and controled by D.C. magnetic biasing P, and coordinates the regulation and control of resistance 12.It is single-phase
The no-load voltage ratio of transformer is 10000V/400V, and regulation and control D.C. magnetic biasing P makes the output power of single-phase transformer in 3kVA, and regulation and control can
The resistance value for controlling resistance 12 is 0.02 Ω so that power grid is from high current earthing mode；When singlephase earth fault occurs for power grid, first
Adjustment controllable resistor 12 be 0.44 Ω, in half an hour singlephase earth fault disappearance neutral grounding mode conversion equipment continue be in
High current earthing mode；If failure still remains, regulation and control D.C. magnetic biasing P makes the output power of single-phase transformer in 120kVA,
Power grid is converted to medium resistance device earthing mode, and controllable impedance generates the electric current of 20A in fault point, and line selection device for low current is accurate
Locating bad lines, and faulty line power system restoration normal operation is cut off, neutral grounding mode is converted after cutting off faulty line
Device is converted in high current earthing mode.Neutral point low value can certainly be converted to when singlephase earth fault occurs for power grid
Resistance-grounded system mode, after singlephase earth fault occurs, then delay 200ms regulates and controls D.C. magnetic biasing P and makes single-phase transformer
For output power in 2500kVA, power grid is converted to low values of resistors high current earthing mode, and controllable impedance generates about in fault point
The electric current of 500A, microcomputer complex protection quickly cut off faulty line.
Two different form of grounding transformer in Fig. 5,6 regulates and controls the output work of grounding transformer J by D.C. magnetic biasing P
Rate, and coordinate the regulation and control of resistance 12.The voltage of grounding transformer is 10kV, and regulation and control D.C. magnetic biasing P so that grounding transformer J's is defeated
Go out power in 3kVA, the resistance value 12 for regulating and controlling controllable resistor is 12 Ω so that power grid is from high current earthing mode；When power grid occurs
When singlephase earth fault, it is 230 Ω first to adjust controllable resistor 12, and D.C. magnetic biasing P is regulated and controled after half an hour and makes single-phase transformer
Output power in 120kVA, power grid is converted to medium resistance device earthing mode, and controllable impedance generates the electricity of 20A in fault point
Stream, faulty line is accurately positioned in line selection device for low current, and cuts off faulty line.Power grid can certainly be worked as, single-phase earthing occurs
Neutral point low values of resistors earthing mode is converted to when failure, after singlephase earth fault occurs, then delay 100ms is adjusted first
Resistance is that controllable resistor is 28 ohm, and regulation and control D.C. magnetic biasing P makes the output power of grounding transformer J in 1150kVA, and power grid turns
It is changed to low values of resistors high current earthing mode, controllable impedance generates the electric current of about 200A in fault point, and microcomputer complex protection is quickly cut
Except faulty line.
There are some transformers to use isolated neutral mode in the network system of 110kV, 220kV above.
Under this method of operation, since lightning stroke, single-phase grounding fault etc. can cause neutral point overvoltage, and transformer is most
It is graded insulation, therefore overvoltage causes very big threat to the insulation of neutral point, it is necessary to which protective device, which is arranged, to it prevents accident
Occur.
For the isolated neutral transformer in solidly earthed neutral system, controllable impedance setting does not connect in neutral point
Between the neutral point and ground of ground transformer, such as Fig. 1, the controllable impedance 1 in high current earthing mode in figure is connected on neutral point not
Between the neutral point and ground of the transformer of ground connection, the power setting of single-phase transformer 11 is 1kVA, and the two of single-phase transformer 11
Secondary side voltage is 230V, and controllable resistor is set as 53 ohm, and power grid is in medium resistance device in normal and failure operation state
Or the earthing mode of high resistance resistor, to limit system fluctuation, lightning stroke and singlephase earth fault caused by transformer neutral point
Overvoltage, isolated neutral transformer refer to the isolated neutral transformer of 110kV or more.Controllable impedance can also be set
It sets and is integrated in inside transformer and transformer, it is user-friendly, improve security reliability.Overcome the neutrality in transformer
The shortcomings that putting protection in parallel with arrester with installation gap between ground：Gap breakdown voltage dispersion value is very big, and gap breakdown sheet
Body results in neutral point voltage and drops suddenly, and drop equally causes to impact voltage to transformer neutral point insulation suddenly.
Claims (10)
1. a kind of neutral grounding mode conversion equipment, it is characterized in that：The neutral grounding mode conversion equipment is in power grid
Neutral point and ground between controllable impedance is set, the impedance value of the controllable impedance is opened according to voltage transformer in the power grid
Mouth triangular voltages and/or three phase-to-ground voltages are adjusted, and do not change the symmetry of the three-phase voltage of the power grid；
By adjusting the controllable impedance, it is in high current earthing mode in normal operating condition to make the power grid；The power grid
Small current neutral grounding mode is converted under singlephase earth fault state or is converted to high current earthing mode；Realize that the power grid exists
The mutual conversion of neutral grounding modes normal and under singlephase earth fault two states；
The power grid refers in high current earthing mode in normal operating condition：The power grid, can in normal operating condition
The resistance characteristic for controlling impedance is the resistance characteristic under high current earthing mode；And singlephase earth fault occurs in the power grid
When, in neutral grounding mode into small current neutral grounding mode or the transfer process of high current earthing mode, it is grounded in high current
The earth current that the controllable impedance of mode is generated in fault point is not more than 50 amperes.
2. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：The adjustment of the controllable impedance makes
The ratio of the zero sequence impedance and positive sequence impedance that obtain the power grid is not less than 0.
3. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：The adjustment of the controllable impedance makes
The ratio of the attenuation coefficient and intrinsic frequency that obtain the power grid is not less than 0.2.
4. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：Single-phase connect occurs in the power grid
When earth fault, control the controllable impedance power make fault point earth current be not more than the power grid single-phase earthing when therefore
The maximum current value that barrier point allows to flow through.
5. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：For not physical neutral
Power grid establishes neutral point of electric network using grounding transformer, controls the power of the grounding transformer to limit the controllable impedance
In the earth current that fault point is formed.
6. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：For in generation single-phase earthing event
The power grid for requiring to cut off faulty line after barrier immediately, is arranged the neutral grounding mode conversion equipment, so that the power grid
It is in high current earthing mode in normal operating condition.
When singlephase earth fault occurs, and postpone T1 milliseconds：If failure vanishes, power system restoration normal operating condition, institute
It states neutral grounding mode conversion equipment and continues as being in high current earthing mode；If failure still remains, the neutral point connects
Ground mode conversion equipment is converted to the high current earthing mode that neutral point is grounded through low values of resistors, to cut off faulty line,
After excision faulty line, power system restoration normal operating condition, the neutral grounding mode conversion equipment is converted in big electricity
Earthing mode is flowed, the fault point earth current that the high current earthing mode is arranged is 100~1000 amperes, and T1 values are 30-
10000 milliseconds.
7. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：For in generation single-phase earthing event
T2 times that require to prescribe a time limit after barrier cut off the power grid of faulty line, the neutral grounding mode conversion equipment are arranged, so that institute
It is in high current earthing mode in normal operating condition to state power grid.
When singlephase earth fault occurs, and postpone T2 seconds：It is described if failure vanishes, power system restoration normal operating condition
Neutral grounding mode conversion equipment continues as being in high current earthing mode；If failure still remains, the neutral ground
Mode conversion equipment is converted to the small current neutral grounding mode that neutral point is grounded through medium resistance device, is positioned by line selection device for low current
Faulty line, and faulty line is cut off, after excision faulty line, power system restoration normal operating condition, the neutral ground
Mode conversion equipment be converted to be arranged in high current earthing mode the small current neutral grounding mode fault point earth current be 10
~100 amperes, T2 values are 1~8000 second.
8. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：For in generation single-phase earthing event
It requires continuous service to be no more than 2 hours power grids after barrier, the neutral grounding mode conversion equipment is set, so that the electricity
Net is in high current earthing mode in normal operating condition；Neutral point is converted to through high value resistor when singlephase earth fault occurs
Device is grounded or the small current neutral grounding mode of neutral by arc extinction coil grounding or isolated neutral, and fault point earth current is not
More than 50A；If 2 hour internal faults disappear, power system restoration normal operating condition, the neutral grounding mode conversion equipment
It is in high current earthing mode to be converted to.
9. neutral grounding mode conversion equipment according to claim 7, it is characterized in that：Single-phase earthing event occurs meeting
Under conditions of continuous service is no more than 2 hours after barrier, for the neutral point for having been converted into small current neutral grounding mode under malfunction
The neutral grounding mode conversion equipment is converted to neutral point through medium resistance device by earthing mode conversion equipment, any time
The small current neutral grounding mode of ground connection, and by line selection device for low current locating bad lines, to cut off faulty line, fault point connects
Earth-current is 10~100 amperes；After cutting off faulty line power system restoration normal operating condition, the neutral grounding mode turns
Changing device is converted in high current earthing mode.
10. neutral grounding mode conversion equipment according to claim 1, it is characterized in that：For neutral-point solid ground
Isolated neutral transformer in system, the controllable impedance be arranged neutral point in the isolated neutral transformer with
Between ground, power grid is in the earthing mode of medium resistance device or high resistance resistor in normal and failure operation state, with limitation
The overvoltage of transformer neutral point caused by system fluctuation, lightning stroke and singlephase earth fault, the isolated neutral transformer
It refer to the isolated neutral transformer of 110kV or more.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810703656.8A CN108551162A (en) | 2018-06-30 | 2018-06-30 | A kind of neutral grounding mode conversion equipment |
| CN201811198902.5A CN109245068A (en) | 2018-06-30 | 2018-10-15 | A kind of neutral grounding mode conversion equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810703656.8A CN108551162A (en) | 2018-06-30 | 2018-06-30 | A kind of neutral grounding mode conversion equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108551162A true CN108551162A (en) | 2018-09-18 |
Family
ID=63493283
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810703656.8A Pending CN108551162A (en) | 2018-06-30 | 2018-06-30 | A kind of neutral grounding mode conversion equipment |
| CN201811198902.5A Pending CN109245068A (en) | 2018-06-30 | 2018-10-15 | A kind of neutral grounding mode conversion equipment |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811198902.5A Pending CN109245068A (en) | 2018-06-30 | 2018-10-15 | A kind of neutral grounding mode conversion equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN108551162A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112103934A (en) * | 2020-08-19 | 2020-12-18 | 许继电气股份有限公司 | Resistor switching device and method in low-current line selection parallel connection |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110783923B (en) * | 2019-11-26 | 2021-10-29 | 广东电网有限责任公司广州供电局 | Transformer substation main transformer neutral point connection processing method and system |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101183788A (en) * | 2007-12-11 | 2008-05-21 | 广州智光电气股份有限公司 | Power network controlled reactance and small resistor combination type earthing device |
| KR20130026691A (en) * | 2011-09-06 | 2013-03-14 | 한국전력공사 | Device and method for grounding the neutral |
| CN102545171A (en) * | 2011-12-22 | 2012-07-04 | 江苏宏安变压器有限公司 | Multi-winding adjustable reactor and single phase grounding fault clearing method thereof |
| CN203180519U (en) * | 2013-02-28 | 2013-09-04 | 嘉兴电力局 | Neutral point grounding switch equipment set for 20kV power grid |
| CN103208788B (en) * | 2013-03-08 | 2015-11-04 | 李景禄 | Intelligent Dynamic power network neutral point earthing method and the complete sets of equipment |
| CN208923822U (en) * | 2018-06-30 | 2019-05-31 | 张安斌 | A kind of neutral grounding mode conversion equipment |
-
2018
- 2018-06-30 CN CN201810703656.8A patent/CN108551162A/en active Pending
- 2018-10-15 CN CN201811198902.5A patent/CN109245068A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112103934A (en) * | 2020-08-19 | 2020-12-18 | 许继电气股份有限公司 | Resistor switching device and method in low-current line selection parallel connection |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109245068A (en) | 2019-01-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10148080B2 (en) | Single-phase-to-earth fault processing device and method for neutral non-effectively grounded distribution network | |
| CN101950958B (en) | Capacitance-adjusting type arc suppression coil complete device and operation mod of same | |
| CN106908693A (en) | A kind of arc suppression coil earthing system single-phase grounding selecting method of high-accuracy | |
| CN103280782B (en) | The relay protecting method of failure in transformer dead zone excision | |
| CN106655120A (en) | Intelligent ground protection method and system for neutral point of power distribution network | |
| CN102545171A (en) | Multi-winding adjustable reactor and single phase grounding fault clearing method thereof | |
| CN107332211B (en) | A kind of capacitance-resistance type transformer DC magnetic bias inhibition device | |
| CN108879645A (en) | A kind of arc suppression coil and pro-active intervention arc-extinction device paired running device and method | |
| CN109713648A (en) | Quickly cut off the relay protecting method of imperfect internal bridge dead-zone fault | |
| CN207801474U (en) | Power network neutral point offset-type resistance converts earthing or grounding means | |
| CN108551162A (en) | A kind of neutral grounding mode conversion equipment | |
| CN104065056A (en) | Process control method of 10 kV power grid ground fault | |
| CN208923822U (en) | A kind of neutral grounding mode conversion equipment | |
| CN204651919U (en) | A kind of 10kV neutral point of electric network joint grounding device | |
| CN107147099B (en) | Arc grounding over-voltage suppressing method and system | |
| CN103236687B (en) | Short-time controllable reactor compensation method | |
| CN108879646A (en) | A method of singlephase earth fault is solved based on phased arc suppression coil | |
| CN103560501A (en) | Controlled type small-resistor arc extinction device and method | |
| CN1136638C (en) | Total-state compensating arc-extinguishing coil automatic tuning device | |
| CN103490384B (en) | Multi-generator ship intermediate voltage electric power system protection method and device | |
| CN203883464U (en) | Controllable small-resistor arc-extinguishing device | |
| CN107317309A (en) | A kind of earthing mode Collaborative Control conversion method and system based on GOOSE | |
| CN112666421A (en) | Fault area isolation method based on compensation damping type active intervention arc suppression device | |
| CN207184030U (en) | The small base station distribution box for preventing switch trip that there is self-recovering function | |
| CN214479610U (en) | Flexible complete grounding system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20180918 |