CN207542953U - A kind of generator neutral point earthing or grounding means - Google Patents
A kind of generator neutral point earthing or grounding means Download PDFInfo
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- CN207542953U CN207542953U CN201721579020.4U CN201721579020U CN207542953U CN 207542953 U CN207542953 U CN 207542953U CN 201721579020 U CN201721579020 U CN 201721579020U CN 207542953 U CN207542953 U CN 207542953U
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Abstract
The utility model provides a kind of generator neutral point earthing or grounding means, equipped with single-phase earthing transformer, ground resistance, earthing reactance, controls switching device, capacitor, control platform, current transformer, voltage transformer entirely；The current transformer, voltage transformer are connected to generator outlet, the single-phase earthing high voltage side of transformer is connected between generator neutral point and grounded screen, the ground resistance, earthing reactance are connected in parallel to single-phase earthing step down side, and the capacitor is connected in parallel to single-phase earthing step down side by controlling the H bridges of switch composition entirely；Control platform is according to the collected voltage of voltage transformer and current transformer, the current signal of generator outlet, by the way that the drive signal of full control switching device is calculated, so as to change capacitor equivalent to the equivalent capacitance value of single-phase earthing Circuit Fault on Secondary Transformer.The utility model can effectively reduce generator unit stator unbalanced earth fault capacitance current, and can guarantee protection equipment for generator action message.
Description
Technical field
The utility model is related to a kind of generator neutral point earthing or grounding means.
Background technology
Since generator and generator terminal equipment are there are direct-to-ground capacitance, when singlephase earth fault occurs for generator unit stator winding,
Electric arc caused by flowing through the generator voltage system capacitive earth current of trouble point will burn stator core or even can be further
Develop phase fault, cause generator failure.According to statistics, generator singlephase earth fault is the most important class of generator failure
Type.For limitation fault ground electric arc, prevent earth fault from expanding, effective protection generator and generator terminal equipment, generator neutral point
Generally use is grounded through arc suppression coil or through high resistant mode.Two methods are each advantageous, since ground arc is in capacitive, through extinguishing arc
Coil ground connection can effectively reduce ground-fault arc electric current, and electric arc self-extinguish can be made to momentary type singlephase earth fault, improve
Generator operational reliability, this mode are suitable for Pump for Medium and Small Power Generating Set.Generator is chosen suitably through high resistance ground by calculating
Resistance value can make earth fault resistor current component be more than capacitance current component, overvoltage peak value caused by making earth fault
In the range of 2.6 times of generator specified phase voltage, while it can ensure generator protection system action message, to ensure that unit is pacified
Entirely, this mode is suitable for high-rating generator.
However, as generator capacity further increases, particularly large-sized water turbine generator, generator unit stator single-phase earthing
Capacitance current is more than IEEE C37.101-2006《Generator protection for earthing directive/guide》Specified in generator unit stator single-phase earthing
Current limit value 25A, at this time if be still grounded using neutral point through high resistant mode, event after generator stator single-phase earthing fault
Barrier point stator winding will be burnt, and generator is caused to damage.For such case, there is document proposition can be in high grounding
The parallel reactance of grounding transformer secondary side or increase grounding transformer impedance, to reduce trouble point capacitance current component, this side
It is to combine by undercompensation through arc suppression coil and through two kinds of earthing modes of high resistant in method principle, capacitance current should be reduced, again
Ensure protection system action message, but since generator unit stator capacitance current is only estimated value, in practice capacitance current and event
Barrier point and method of operation relationship are larger, can not accurately choose suitable reactance or transformer impedance, therefore still can not effectively limit
Earth current.
Utility model content
The technical problems to be solved in the utility model is：In view of the above problems, power generation can effectively be reduced by providing
Machine stator unbalanced earth fault capacitance current, and can guarantee the generator neutral point earthing or grounding means of protection equipment for generator action message.
For this purpose, the utility model uses following technical scheme：
A kind of generator neutral point earthing or grounding means, it is characterised in that it is equipped with single-phase earthing transformer, ground resistance, ground connection
Switching device, capacitor, control platform, current transformer, voltage transformer are controlled in reactance entirely；The current transformer, voltage are mutual
Sensor is connected to generator outlet, and the single-phase earthing high voltage side of transformer is connected between generator neutral point and grounded screen, described
Ground resistance, earthing reactance are connected in parallel to single-phase earthing step down side, and the capacitor by controlling the H bridges of switch composition simultaneously entirely
It is coupled to single-phase earthing step down side；
Control platform according to the collected voltage of voltage transformer and current transformer, the current signal of generator outlet,
By the way that the drive signal of full control switching device is calculated, so as to change capacitor equivalent to single-phase earthing Circuit Fault on Secondary Transformer
Equivalent capacitance value.
Further, the control platform is a kind of signal system using digital signal processors such as DSP or FPGA as core
System.
It is described it is full control switching device can be insulated gate bipolar transistor IGBT or gate electrode capable of switching off type thyristor GTO or
Integrated gate commutated thyristor IGCT.
The utility model will have following advantageous effect：
It, can be by adjusting the driving of full-controlled device 1. according to the method for operation of generator and the difference of single-line to ground fault point
Signal, quick response realization compensate trouble point earthing capacitance current, ground arc are greatly reduced, stator winding is generated
Harm.
2. inductive current caused by the earthing reactance of single-phase earthing Circuit Fault on Secondary Transformer will be more than generator maximum stator
1.35 times of unbalanced earth fault capacitance current, you can realize overcompensation.
It, can be quickly in dynamic regulation 3. single-phase earthing Circuit Fault on Secondary Transformer has the H bridges and capacitor of full-controlled device composition
The inductive current that property point device is sent out.
4. ground resistance will provide enough resistor currents, that is, it can guarantee that the resonance overvoltage that earth fault generates is less than hair
In the range of 2.6 times of machine phase voltages, inhibit failure propagation, while can guarantee that enough electric currents make protection equipment for generator reliable again
Action ensures unit safety.
5. it can effectively reduce single-phase earthing transformer capacity so that heavy-duty generator single-phase earthing transformer capacity is selected
It selects in the reasonable scope.
Description of the drawings
Fig. 1 is the circuit diagram of the utility model generator neutral point earthing or grounding means.
Specific embodiment
The utility model is described in further detail with reference to the accompanying drawings and embodiments：
With reference to Fig. 1, the generator neutral point earthing or grounding means that this embodiment is related to has single-phase earthing transformer 1, ground connection
Resistance 2, earthing reactance 3, IGBT4, capacitor 5, control platform 6, current transformer 7, voltage transformer 8 etc..The electric current is mutual
Sensor 7, voltage transformer 8 are connected to generator outlet, and 1 high-pressure side of single-phase earthing transformer is connected to generator neutral point with connecing
Between earth mat, the ground resistance 2, earthing reactance 3 are connected in parallel to 1 low-pressure side of single-phase earthing transformer.The capacitor 5 is by exhausted
The H bridges that edge grid bipolar transistor (IGBT) 4 forms are connected in parallel to 1 low-pressure side of single-phase earthing transformer.
Drawing reference numeral 91 is generator A phases circuit direct-to-ground capacitance；Drawing reference numeral 92 is generator B phases circuit direct-to-ground capacitance；
Drawing reference numeral 93 is generator C phases circuit direct-to-ground capacitance.
The control platform is a kind of signal system using digital signal processor DSP as core, generated control letter
Number insulated gate bipolar transistor (IGBT) 4 is sent to by optical fiber, 4 conducting of control insulated gate bipolar transistor (IGBT) and
Shutdown.
The control platform connects simultaneously with the voltage transformer 7 of each phase and current transformer 8, acquisition generator outlet end
Corresponding voltage, current signal.
Its parameter selecting step is as follows：
1. it is determined according to generator specified phase voltage Ug=11550V and single-phase earthing transformer rated voltage (220V) single
The no-load voltage ratio n=52.5 of phase grounding transformer 1；
2. according to generator unit stator side direct-to-ground capacitance value CgThe inductance value L of earthing reactance 3 is calculated in=4 μ Fn=
0.7mH, the inductive current I that earthing reactance 3 is provided during stator side singlephase earth faultLn=70.5A is about that generator maximum is determined
Sub- side capacitive earth current Igc1.35 times of=52.2A.
3. according to generator unit stator side direct-to-ground capacitance value Cg=4 μ F select the capacitance C of capacitor 5n=n2Cg/ 3=
3675μF。
4. ground resistance 2Rn=110Ln=0.077 Ω, to ensure earth point short circuit current electricity after stator single-phase earthing fault
It hinders component and is more than capacitive component.
5. after the operation of generator No Load Start, control platform system is according to the collected voltage signal Ug in generator outlet end
With current signal Ig and the phase difference of the twoCapacitance current after single-phase short circuit can be calculatedAnd further
To the inductive current I for going out earthing reactance offerLnWith IgcDifference (ILn-Igc), the driving that full-controlled device is obtained according to this difference is believed
Number.
6. the full-controlled device drive signal sent out according to control platform 6, to control capacitance current caused by capacitor 5
With (ILn-Igc) equal, you can the capacitance current of Single-phase Ground Connection Failure is reduced to zero or so.
Above description is not limitation of the utility model, and the utility model is also not limited to the example above, this technology neck
The those of ordinary skill in domain, in the scope of the utility model, the variation made changes addition or replacement, should all belong to this practicality
Novel protection domain.
Claims (3)
1. a kind of generator neutral point earthing or grounding means, it is characterised in that it is equipped with single-phase earthing transformer, ground resistance, ground connection electricity
Resist, control switching device, capacitor, control platform, current transformer, voltage transformer entirely；The current transformer, mutual induction of voltage
Device is connected to generator outlet, and the single-phase earthing high voltage side of transformer is connected between generator neutral point and grounded screen, described to connect
Ground resistance, earthing reactance are connected in parallel to single-phase earthing step down side, and the capacitor is in parallel by the H bridges for controlling switch composition entirely
To single-phase earthing step down side；
Control platform passes through according to the collected voltage of voltage transformer and current transformer, the current signal of generator outlet
The drive signal of full control switching device is calculated, it is equivalent to single-phase earthing Circuit Fault on Secondary Transformer so as to change capacitor equivalent
Capacitance.
2. a kind of generator neutral point earthing or grounding means as described in claim 1, it is characterised in that the control platform is a kind of
Using digital signal processor as the signal system of core.
3. a kind of generator neutral point earthing or grounding means as described in claim 1, it is characterised in that the full control switching device can
To be insulated gate bipolar transistor IGBT or gate electrode capable of switching off type thyristor GTO or integrated gate commutated thyristor IGCT.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721579020.4U CN207542953U (en) | 2017-11-23 | 2017-11-23 | A kind of generator neutral point earthing or grounding means |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201721579020.4U CN207542953U (en) | 2017-11-23 | 2017-11-23 | A kind of generator neutral point earthing or grounding means |
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| CN207542953U true CN207542953U (en) | 2018-06-26 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947493A (en) * | 2017-11-23 | 2018-04-20 | 中国电建集团华东勘测设计研究院有限公司 | A kind of generator neutral point earthing or grounding means and parameter selection method |
| CN110247377A (en) * | 2019-04-30 | 2019-09-17 | 云南电网有限责任公司电力科学研究院 | A kind of power distribution network intelligence low resistance grounding device and its control method |
-
2017
- 2017-11-23 CN CN201721579020.4U patent/CN207542953U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947493A (en) * | 2017-11-23 | 2018-04-20 | 中国电建集团华东勘测设计研究院有限公司 | A kind of generator neutral point earthing or grounding means and parameter selection method |
| CN107947493B (en) * | 2017-11-23 | 2023-06-23 | 中国电建集团华东勘测设计研究院有限公司 | Neutral point grounding device of generator and parameter selection method |
| CN110247377A (en) * | 2019-04-30 | 2019-09-17 | 云南电网有限责任公司电力科学研究院 | A kind of power distribution network intelligence low resistance grounding device and its control method |
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