CN106253255A - A kind of generator neutral point high induction reactance grounding device - Google Patents
A kind of generator neutral point high induction reactance grounding device Download PDFInfo
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- CN106253255A CN106253255A CN201510310760.7A CN201510310760A CN106253255A CN 106253255 A CN106253255 A CN 106253255A CN 201510310760 A CN201510310760 A CN 201510310760A CN 106253255 A CN106253255 A CN 106253255A
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Abstract
The invention discloses a kind of generator neutral point high induction reactance grounding device, it is by compositions such as shell, grounding transformer, secondary reactor, secondary resistor, primary current transformer, secondary current transformer, disconnecting switch, electric controling elements.Secondary reactor and secondary capacitor in parallel are connected to the secondary side of grounding transformer, utilize the impedance transformation function of transformator, are allowed to conversion and arrive grounding transformer primary side, are equivalent to high induction reactance.Grounding transformer primary side is connected between generator neutral point and ground, becomes high induction reactance grounding device.This device selects suitable secondary reactor and secondary resistor, can reach to limit large-scale hydroelectric generator time singlephase earth fault occurs, meeting under conditions of generator neutral point displacement voltage is not more than 10% specified phase voltage, current in the fault point is being limited in the purpose within 15A.In the configuration of one-phase ground protection, still can use high grounding simultaneously, select instantaneous tripping.Thus use this device can effectively reduce the risk of generator stator core scaling loss, improve the reliability of generator operation.
Description
Technical field
The present invention relates to generator neutral point grounding device, further relate to a kind of large-scale hydroelectric generator neutral point high induction reactance grounding device.When electromotor generation singlephase earth fault, apparatus of the present invention can effectively reduce earth fault electric current, within being limited in 15A and limit electromotor and perfect the overvoltage multiple of phase below 2.6 times of specified phase voltages.Apparatus of the present invention good looking appearance, internal structure are compact, easy to use, safe and reliable to operation, the relatively simple feature of protective relaying device.Can be widely used in large-scale hydroelectric generator earth neutral system, be also applied for other when needing to limit singlephase earth fault, current in the fault point reaches desired value, perfects phase overvoltage less than in the power system of 2.6 times.
Background technology
Generator neutral point high induction reactance grounding device is the code regulation according to relevant national standard and large-scale hydraulic power plant generator neutral point ground connection and a kind of product of market demand research and development.At present in big-and-middle-sized hydraulic power plant, generator neutral point grounding device generally uses two ways, a kind of grounding transformer ground connection (high resistance ground) for generator neutral point band secondary resistor.Another kind is that generator neutral point is through reactor (arc suppression coil) ground connection.When both modes all can effectively limit generation singlephase earth fault, electromotor perfects the overvoltage multiple of phase.The difference of both modes is, selects the first grounding device mode, and when singlephase earth fault occurs in generator, earth-fault current is more than electromotor three-phase ground capacitance electric current (generally √ 2 times), and electromotor can instantaneous tripping.This earthing mode is less than the generator operation still safety of 15 ~ 20A for single-phase earth fault current.But, 20-30A is typically larger than for super-huge hydroelectric generator three-phase ground capacitance electric current, some earth-fault currents even can be more than 45A.Under such conditions, even if ground protection correct operation tripping operation electromotor, it is likely to burn out generator stator core, expands earth fault scope, even develop into phase fault, cause great economic loss.Select the second pattern, due to neutral reactor electric current and electromotor capacitive earth current phase 180 °, therefore can effectively reduce electromotor earth-fault current, it is not necessary to electromotor instantaneous tripping.This earthing mode has the operating experience of long period to be also safe for general middle-size and small-size hydroelectric generator.But, for some electromotor, the most large-scale super-huge hydroelectric generator, can be because trouble point earth current contain abundant three, five time and higher harmonic current with arc suppression coil Coil Compensation during very big (20 ~ 30A the is the biggest) singlephase earth fault of electricity generator stator coil capacitive earth current, in the case of many, trouble point earth current can not be up to state standards the numerical value (1.5-3A) that (code) specifies.Grounding through arc also results in neutral point displacement voltage when electromotor normally works and raises, and can exceed that the requirement that the degree of unbalancedness of national regulations is less than 10%.Simultaneously because the change of generator operating condition resonance likely occurs and compensates bad, affect electromotor normal safe and run.In a word, for large-scale super-huge hydroelectric generator, both earthing modes have its weak point, carry out risk to engine health operating band.
Generator neutral point high induction reactance grounding device of the present invention is provided simultaneously with the advantage of above two grounding device mode, turn avoid the deficiency of two kinds of earthing modes.When occur singlephase earth fault time, can restriction perfect phase overvoltage multiple in the reasonable scope on the basis of, within earth-fault current is limited in 15A.Can guarantee that neutral point displacement voltage when electromotor normally works is in allowed band.The requirement of relay protection instantaneous tripping can also be realized.If earth-fault current is less than 15A, electromotor one-phase ground protection again can correct operation, tripped in 0.4 second electromotor put into degaussing switch, then the degree of generator stator core scaling loss can alleviate significantly, just can protect the safe operation of electromotor.
Summary of the invention
It is an object of the invention to there are provided a kind of generator neutral point grounding device, refering in particular to is a kind of compact conformation, simple to operate, operation maintenance convenient generator neutral point high induction reactance grounding device.
For achieving the above object, the present invention uses techniques below measure:
A kind of generator neutral point high induction reactance grounding device, it is made up of grounding transformer, secondary reactor, secondary resistor, first and second current transformer, disconnecting switch and some electric controling elements, shell etc..It is characterized in that: grounding transformer, secondary reactor, secondary resistor, first and second current transformer, disconnecting switch and electric controling element are arranged in a shell closed, generator neutral point lead-in wire is connected to head end terminal of grounding transformer coil, by tail end terminal ground of grounding transformer coil.Secondary reactor and secondary capacitor in parallel are connected on the secondary terminals of grounding transformer.Secondary reactor and current transformer are arranged in the lower section of secondary resistor.
Grounding transformer is the single-phase all-insulation transformer of dry type, and its insulation uses epoxy casting pattern.Make material selection high-quality silicon steel sheet and the copper wires in enough cross sections, so that the total losses of grounding transformer are less than 1.5% rated capacity.Grounding transformer selects low short-circuit impedance type of design, short-circuit impedance percentage ratio≤3%.Other parameters meet the GB requirement to dry-type power transformer.
Secondary reactor is that dry type is single-phase, full-shield hollow-core construction, and Foil winding (14) selected by coil, determines its sectional area according to the size of rated thermal current, and during to ensure normally to work, coil temperature rise is less than 60K.Coil is outer equipped with stalloy shielding iron core (15), is contained among an aluminum radome (16), is fixed on the lower section of secondary resistor together with coil after fastening.The inductance value of secondary reactor is calculated by electromotor three-phase ground capacitance electric current and the earth-fault current value required for requiring, it is contemplated that on-the-spot actual condition and convenient adjust, and secondary reactor should arrange and minimum be not less than 5 taps.
Secondary resistor is dry type single-phase lamellar gridiron structure, and resistor disc material is nichrome.Using hot-face insulation to support between resistor disc (17) and sheet, all union joints are all adopted same material and are welded.Secondary resistor uses reciprocating meander configuration to be arranged symmetrically with, and noninductive method makes, and inductance value own is minimum, does not interferes with calculating and the compensation effect of secondary reactor.The resistance value of secondary resistor is calculated by the earth-fault current value required for electromotor three-phase ground capacitance electric current and protection regulatory requirements, it is contemplated that on-the-spot actual condition and convenient adjust, and secondary resistor should arrange and minimum be not less than 5 taps.
Within all components and parts of generator neutral point high resistance grounding device are all contained in a shell closed, shell lands installations, possesses excellent outward appearance and mechanical strength, leaves enough heat-dissipating spaces in the cabinet of overall dimensions consideration simultaneously.
Accompanying drawing explanation
Fig. 1 is a kind of generator neutral point high induction reactance grounding device electrical schematic diagram.
Fig. 2 is a kind of generator neutral point high induction reactance grounding device outline drawing.
Fig. 3 is a kind of generator neutral point high induction reactance grounding device cut-away view.
Fig. 4 is secondary reactor schematic diagram.
Fig. 5 is secondary resistor structure schematic diagram.
Wherein: input terminal (1), disconnecting switch (2), grounding transformer (3), head end terminal (4), tail end terminal (5), primary current transformer (6), secondary current transformer (7), secondary reactor (8), secondary resistor (9), shell (10), grounding transformer secondary terminals (11) (12), a ground terminal (13), secondary reactor Foil winding (14), shielding iron core (15), aluminum radome (16), secondary resistor sheet (17).
Detailed description of the invention
Below in conjunction with the accompanying drawings the present invention is described in further detail:
A kind of generator neutral point high induction reactance grounding device, it is by input terminal (1), disconnecting switch (2), grounding transformer (3), head end terminal (4), tail end terminal (5), primary current transformer (6), secondary current transformer (7), secondary reactor (8), secondary resistor (9), shell (10), grounding transformer secondary terminals (11) (12), ground terminal (13) forms, it is characterized in that: generator neutral point is connected on the input terminal (1) of this device through cable or connection row (line), a head end terminal (4) of grounding transformer (3) is accessed by disconnecting switch (2), receive on shell (10) through tail end terminal (6) of grounding transformer and primary current transformer (7) again.Shell (10) is provided with Special grounding terminal (13) and is connected with grounded screen.This completes the wiring of a second part of this device.
Secondary terminals (11) first line of a couplet of grounding transformer (3) is connected to each line bank of secondary reactor (8) and secondary resistor (9), and meanwhile, secondary terminals (11) is also connected ground connection with copper bar with shell (10).The secondary terminals (12) of grounding transformer (3) is by, after secondary current transformer (7), being connected with another line bank each of secondary reactor (8) and secondary resistor (9).So secondary reactor (8) and secondary resistor (9) is just connected in the secondary side of grounding transformer (3) in parallel.
The induction reactance of the secondary reactor (8) that grounding transformer (3) secondary side couples and the resistance of secondary resistor (9), converted by no-load voltage ratio, be transformed into grounding transformer (3) primary side, become high induction reactance, reach the requirement of high induction reactance ground connection.The resistance value of the secondary resistor (9) changed and the induction reactance value of secondary reactor (8); can be achieved with the ground connection induction reactance of different numerical value; fault current when realizing electromotor singlephase earth fault is design load (demanding party's required value); restriction perfects phase overvoltage, it is provided that the purpose of relay protection trip signal.
Claims (10)
1. a generator neutral point high induction reactance grounding device, internal structure: input terminal (1), disconnecting switch (2), grounding transformer (3), head end terminal (4), tail end terminal (5), primary current transformer (6), secondary current transformer (7), secondary reactor (8), secondary resistor (9), shell (10), grounding transformer secondary terminals (11) (12), a ground terminal (13) etc. form, it is characterised in that:
Head end terminal (4) of grounding transformer (3) is connected on generator neutral point by disconnecting switch (2), input terminal (1), and a tail end terminal (5) is by primary current transformer (6) ground connection.
2. No. two reactors (8) and secondary resistor (9) are connected in parallel on the secondary terminals (11) (12) of grounding transformer (3).
3. secondary terminals (11) connects the earthing of casing by copper bar.
4. grounding transformer (3) is short-circuit impedance percentage ratio≤3%, the dry type epoxy cast transformer of total equivalence loss≤1.5% rated capacity.
5. No. two reactors (8) are full-shield air-core reactors, and coil is Foil winding (14), and coil is externally provided with stalloy shielding iron core (15).
6. silicon sheet core is externally provided with aluminum radome (16).
7. No. two resistors (9) are nichrome lamellar walled structure, and all connection positions are the welding of identical material resistance, and resistor disc (17) uses reciprocating being arranged symmetrically with, and noninductive method makes.
8. the resistance value of the inductance value secondary resistor of No. two reactors obtains after being calculated by the single-phase earth fault current value of electromotor three-phase ground capacitance electric current and requirement.
9. the grounding transformer (3) in generator neutral point high induction reactance grounding device, secondary reactor (8), secondary resistor (9), primary current transformer (6), secondary current transformer (7), disconnecting switch (2), within electric controling element etc. is all contained in a shell closed.
10. shell sizes is typically 1600x1250x2100mm3Or 2200x1400x2100mm3。
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| CN201510310760.7A CN106253255A (en) | 2015-06-09 | 2015-06-09 | A kind of generator neutral point high induction reactance grounding device |
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| CN201510310760.7A CN106253255A (en) | 2015-06-09 | 2015-06-09 | A kind of generator neutral point high induction reactance grounding device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108270208A (en) * | 2016-12-30 | 2018-07-10 | 安徽新在线科技股份有限公司 | A kind of generator neutral point is grounded nonlinear resistance device |
| CN108512211A (en) * | 2018-05-25 | 2018-09-07 | 长江勘测规划设计研究有限责任公司 | Combine cabinet style impedance type gigantic generating units neutral earthing devices |
| CN108899885A (en) * | 2018-05-25 | 2018-11-27 | 长江勘测规划设计研究有限责任公司 | Huge water wheel generator group impedance parameter automatic optimizing method |
| CN112366746A (en) * | 2020-10-22 | 2021-02-12 | 四川水利职业技术学院 | Method for preventing large neutral line current of built low-voltage water turbine generator set |
-
2015
- 2015-06-09 CN CN201510310760.7A patent/CN106253255A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108270208A (en) * | 2016-12-30 | 2018-07-10 | 安徽新在线科技股份有限公司 | A kind of generator neutral point is grounded nonlinear resistance device |
| CN108512211A (en) * | 2018-05-25 | 2018-09-07 | 长江勘测规划设计研究有限责任公司 | Combine cabinet style impedance type gigantic generating units neutral earthing devices |
| CN108899885A (en) * | 2018-05-25 | 2018-11-27 | 长江勘测规划设计研究有限责任公司 | Huge water wheel generator group impedance parameter automatic optimizing method |
| CN108899885B (en) * | 2018-05-25 | 2019-10-08 | 长江勘测规划设计研究有限责任公司 | Huge water wheel generator group impedance parameter automatic optimizing method |
| CN108512211B (en) * | 2018-05-25 | 2023-06-27 | 长江勘测规划设计研究有限责任公司 | Neutral point grounding device of combined cabinet type impedance type giant generator set |
| CN112366746A (en) * | 2020-10-22 | 2021-02-12 | 四川水利职业技术学院 | Method for preventing large neutral line current of built low-voltage water turbine generator set |
| CN112366746B (en) * | 2020-10-22 | 2023-07-21 | 四川水利职业技术学院 | Method for preventing neutral line current of built low-voltage hydroelectric generating set from being too high |
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Application publication date: 20161221 |