CN104078936B - Injection type stator ground protection method adapting to pump storage group variable frequency starting - Google Patents
Injection type stator ground protection method adapting to pump storage group variable frequency starting Download PDFInfo
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Abstract
The invention discloses an injection type stator ground protection method adapting to pump storage group variable frequency starting. The method is characterized in that in the site, a phase angle shifting angle between low-frequency injected voltage and current phase quantities is actually measured under two modes of back-to-back starting and SFC starting from a static state to a rating state; a running station of a current unit is determined according to the closing/opening state of auxiliary contacts of switches and a received running station state sent by a monitoring system; according to the actually-measured positive sequence voltage and the running station of the unit, phase angle correction is performed on a low-frequency injected current signal; a protecting device uses the low-frequency injected voltage and the corrected low-frequency injected current as the calculation input amount, and further conventional injection type stator ground protection is adopted to perform protective calculation and protection logic distinguishing. According to the method, core calculation of an original protective resistance criterion and a zero-sequence current criterion is not changed, and the method is easy to achieve.
Description
Technical field
The present invention relates to field of power, relate more specifically to the injected type stator earth fault of pump-storage generator
Relay protecting method.
Background technology
High-rating generator neutral point typically adopts high resistance grounding mode, and relatively conventional mode is to become through single phase distribution
Depressor is grounded；High voltage side of transformer one end sending and receiving generator neutral point, the other end is grounded；The jumbo electricity of transformer low voltage side joint
Resistance, this resistance is converted to high-pressure side, is equivalent to the resistance that hundreds of ohm is to several kilohms.This single phase distribution transformer is again
Referred to as neutral grounded transformer (neutral grounding transformer), referred to as ngt.
When there is singlephase earth fault in generator unit stator winding it is possible to fault current destroys generator stator core,
It is also possible to cause the voltage-to-ground of non-faulting phase to raise.Because once high-rating generator stator core is destroyed, during maintenance
Between all long, the economic loss of compressor emergency shutdown is very huge.Therefore, high-rating generator requires the 100% of installing no dead band to determine
Sub- ground protection, wherein, injected type stator ground protection is widely used.
The ultimate principle of injected type stator ground protection is: low-frequency voltage is added in ngt low-pressure side and bears by low frequency power supply system
Carry on resistance, by ngt, low-frequency voltage signal is injected in generator unit stator winding zero sequence loop over the ground, generator unit stator
In the case of winding insulation is normal, the electric current of injection is capacitance current；After there is earth fault, resistive in injection current
Electric current.The low-frequency voltage of detection injection, low-frequency current signal, by phasor calculation, obtain the transition resistance of earth fault；Protection
Logic is collectively formed by resistance criterion and zero sequence current criterion, and protection device detects earth fault transition resistance (hereinafter referred to as
" transition resistance ") less than definite value, Stator ground fault to resistance in judgement；It is fixed that protection device detects that zero-sequence current value exceedes
Value, is equally judged to Stator ground fault.Because voltage and current measurement link has intrinsic phase angle difference, ngt is not preferable change simultaneously
Depressor, the low frequency signal of injection can produce certain pressure drop, therefore injected type stator ground protection in use, leading on ngt
Frequently with phase angle compensation, impedance-compensated, to eliminate these impacts.Introduction with regard to injected type stator ground protection refers to " big
The analysis of generator power transformer interior fault and relay protection " (Wang Weijian etc. writes, China Electric Power Publishing House, 2006) the
Three chapters.
Electromotor static, generate electricity two kinds of operating modes under, phase angle after the compensation between protector measuring injecting voltage electric current,
Assume to be respectively θ0And θ1.Ideally, θ0And θ1Equal.During actual application, the low frequency signal due to injection compares
Little, the signal change of disease of ngt summation current transformer (ct) measurement links has certain non-linear, so θ0And θ1Unequal, have a small amount of
Deviation, this deviation directly affects the accuracy of transition resistance measurement.
For improving transition resistance certainty of measurement, conventional way has two kinds:
(1) method one.Under static operating mode, phase angle compensation definite value θ is determined by actual measurementset；Respectively electromotor static, send out
Under electric two kinds of operating modes, survey θ0And θ1；Artificial adjustment definite value θset, it is changed into θ 'set, θ can be made1It is changed into θ '1.If θ '1=θ0, then protect
Demonstrate,prove and under generating operation mode, had higher certainty of measurement.Or artificial adjustment definite value θset, it is changed into θ 'set, make θ '1Between θ0、θ1It
Between, abandon higher certainty of measurement under generating operation mode it is ensured that having similar certainty of measurement under static two kinds of operating modes with generating.
(2) method two.Article " the injected type stator ground protection method based on segmentation phase angle compensation " (" modern electric ",
1st phase in 2014) disclosed in method.First survey the impact result to phase angle shift for the triple harmonic current, using measured data as
Definite value record is in protection device；During generator operation, the size of actual measurement triple harmonic current, segmentation benefit is carried out according to definite value
Repay.
For method one, be primarily present two problems: (1) it cannot be guaranteed that static, the two kinds of operating modes that generate electricity reach simultaneously higher
Certainty of measurement；(2) for pump-storage generator it is impossible to also reach higher certainty of measurement during ensureing variable frequency starting, this
It is because:
, there is back-to-back startup, sfc start operating performance in pump-storage generator.Different Starting mode, generator unit stator winding
External equipment is different, and in running change in voltage larger it is therefore desirable to phase angle compensation amount can variant, with one
Phase angle compensation is inadequate.The back-to-back startup of pump-storage generator is as variable-frequency power sources a unit, voltage by little by
Gradual change is big, frequency gradually becomes work frequency by little, during this, power supply output is added on startup unit stator winding, makes
This generating unit speed is gradually increasing；It is by rest frequency changer (static frequency converter, letter that sfc starts
Claim sfc) power frequency supply is transformed into variable-frequency power sources, the output of this power supply is added on startup unit stator winding, so that this unit is turned
Speed is gradually increasing.
For method two, the problem being primarily present is: the data that (1) surveys is relatively more, and the calculating of segmented compensation slightly dislikes multiple
Miscellaneous；(2) equally can not solve the problems, such as to be also required for preferable certainty of measurement during pump-storage generator variable frequency starting.
Content of the invention
The purpose of the present invention is: a kind of injected type stator ground protection method is proposed, on the basis of original guard method,
Increase work condition judging and linear compensation means, make this protection also can reach higher transition in pump-storage generator variable frequency starting
The certainty of measurement of resistance.
For reaching above-mentioned purpose, the present invention adopts the technical scheme that: adapts to the injection of pump-storage generator variable frequency starting
Formula earthing protection method for stator, is characterized in that, comprises the steps:
In operating condition under back-to-back startup mode, and operating condition is under sfc Starting mode, records respectively from quiet
Only arrive rated condition, the angle of the phase angle shift between the voltage x current phasor of low frequency injection；
Protection device is according to the state of each switch auxiliary contact closure/disconnection, and the monitoring system receiving is brought
Operating condition, determine the operating condition of current unit；
Protection device according to determined by unit operation operating mode, select the angle of corresponding described phase angle shift, and tie
Close the electromotor positive sequence voltage size of actual measurement, phase angle correction is carried out to low frequency injection current signal.
In such scheme, the angle surveying phase angle shift under operating condition is for back-to-back startup mode refers specifically to: by drawing water
Accumulation of energy unit back-to-back running mode connects primary equipment, and wherein two units, all in resting state, are not added with excitation；Put into
The low frequency of dragged unit is supply-injected；Protector measuring calculates low frequency injecting voltage now and electric current, record both it
Between phase angle bePump-storage generator back-to-back startup, runs to rated condition；Protector measuring calculates now low
Frequency injecting voltage and electric current, record phase angle between the two is It is the angle of phase angle shift.
In such scheme, the angle surveying phase angle shift under operating condition is for sfc Starting mode refers specifically to: by water-storage
The unit sfc method of operation connects primary equipment, and unit is not added with excitation, and sfc does not have voltage output yet；Put into dragged unit
Low frequency is supply-injected；Protector measuring calculates low frequency injecting voltage and electric current now, and record phase angle between the two isPump-storage generator sfc starts, and runs to rated condition；Protector measuring calculate low frequency injecting voltage now and
Electric current, record phase angle between the two is It is the angle of phase angle shift.
In such scheme, described phase angle that low frequency injection current signal is carried out corrects by equation below calculating:
Wherein,It is low frequency injection current,It isResult after correction,It is the phase angle of correction, u1It is protection dress
Put the electromotor positive sequence voltage of survey calculation, ubaseIt is reference voltage, be definite value.
In such scheme, described ubaseValue be specified phase voltage.
The invention has the beneficial effects as follows: amended injected type stator ground protection is adapted to pump-storage generator and leans against
The back of the body starts, sfc startup optimization operating mode.Determine the phase of low frequency injecting voltage current signal in the case of two kinds of startup optimization by actual measurement
Angle offset, is automatically performed the compensation of phase angle shift it is ensured that being grounded transition by work condition judging and actual measurement positive sequence voltage size
Resistance measurement has higher certainty of measurement under different operating conditions.Compare the method that triple-frequency harmonics compensates phase angle, the present invention
Measured data is less；Phase angle compensation is carried out according to positive sequence voltage size, there is no the data of multiple segmentations, compensation calculation is simpler
Single.Do not change resistance criterion, the core calculations of zero sequence current criterion of original injected type stator ground protection, it is easy to accomplish.
Brief description
Fig. 1 is an application operating mode of the present invention, the wiring diagram of pump-storage generator back-to-back startup,
Fig. 2 is an application operating mode of the present invention, the wiring diagram that pump-storage generator sfc starts,
Fig. 3 is the calculation processes schematic diagram of the present invention.
Specific embodiment
Below with reference to drawings and the specific embodiments, technical scheme is described in detail.
Pump-storage generator is dynamoelectric machine (m/g), both can work as motor running it is also possible to work as generator operation.
The m/g of one 250mw, rated voltage 15.75kv, rated power factor 0.98/0.9 (rated power factor during motor running
For 0.98, during generator operation, rated power factor is 0.9)；Main transformer rated capacity 300mva, rated voltage no-load voltage ratio
500kv/15.75kv, the yd-11 mode of connection, short-circuit impedance 16%；Neutral grounded transformer ngt, rated capacity 90kva, volume
Determine voltage change ratio 15.75kv/500v；Ngt low-pressure side load resistance 0.839 ω.
Pump-storage generator back-to-back startup is as shown in Figure 1.In Fig. 1:
M/g: dynamoelectric machine.
Gcb1, gcb2: be respectively #1 machine, the generator outlet chopper of #2 machine.
Psw1, psw2: be respectively #1 machine, the commutation disconnecting switch of #2 machine.
T1, t2: be respectively #1 machine, the main transformer of #2 machine.
Nsw1, nsw2: be respectively #1 machine, the neutral ground disconnecting switch of #2 machine.
Ngt1, ngt2: be respectively #1 machine, the neutral grounded transformer of #2 machine.
Rn1, rn2: be respectively #1 machine, the neutral grounded transformer low-pressure side load resistance of #2 machine.
Ssw1, ssw2: be respectively #1 machine, the startup phase-change switch of #2 machine.
The low frequency of us:#1 machine is supply-injected.
The current transformer that the injected type stator ground protection of ct:#1 machine is used.
un、in: the voltage of protection device, current input signal.
#1 machine is motor running, is trailing unit；#2 machine is generator operation, is the variable-frequency power sources dragging；The back of the body
In backrest start-up course, phase-change switch psw1, psw2 of two units disconnect, the output of #2 machine through outlet breaker gcb2,
Start phase-change switch ssw2, deliver to the startup phase-change switch ssw1 of #1 machine along startup bus, be connected on the stator winding of #1 machine.Work(
Rate conveying direction is dashed lines and shown in the direction of arrow.#2 machine exports frequency conversion voltage, voltage by little become larger, frequency is by little
Gradually become work frequency, make #1 generating unit speed gradually rise up to rated speed.Here it is Back To Back Startup Procedure.This is back-to-back
In start-up course, the nsw2 of #2 machine disconnects, and the nsw1 of #1 machine closes it is ensured that being applied to the injection low frequency of #2 machine neutral point low-pressure side
Power supply (in figure is omitted and is not drawn into) is isolated, does not affect the injected type stator ground protection of #1 machine.
Pump-storage generator sfc starts as shown in Figure 2.In Fig. 2:
Sfc: rest frequency changer (static frequency converter).
The input power bus of bus: rest frequency changer.
The output chopper of cb: rest frequency changer.
The output disconnecting switch of psw: rest frequency changer.
The same Fig. 1 of remaining symbol implication.
#1 machine is motor running, is trailing unit.Sfc exports variable-frequency power sources, through chopper cb, disconnecting switch
Psw, delivers to the startup phase-change switch ssw1 of #1 machine, is connected on the stator winding of #1 machine along startup bus.Power conveying direction is such as
Shown in figure dotted line and the direction of arrow.Sfc export frequency conversion voltage, voltage by little become larger, frequency gradually becomes power frequency by little
Frequency, makes #1 generating unit speed gradually rise up to rated speed.Here it is sfc start-up course.
Case study on implementation of the present invention provides the injected type stator ground protection method adapting to pump-storage generator variable frequency starting, bag
Include following steps:
Step one: connect primary equipment by pump-storage generator back-to-back running mode, wherein two m/g are all in quiet
Only state, is not added with excitation；The low frequency putting into dragged unit is supply-injected, the us in such as Fig. 1；Protector measuring electricity now
Pressure un, electric current inThe phasor of corresponding low frequency Injection SignalRecord phase angle between the two is
Step 2: pump-storage generator back-to-back startup, runs to rated condition；Protector measuring voltage now
un, electric current inThe phasor of corresponding low frequency Injection SignalRecord phase angle between the two is
Step 3: connect primary equipment by the pump-storage generator sfc method of operation, wherein m/g, sfc are all in static
State, m/g is not added with excitation, and sfc does not have voltage output；The low frequency putting into dragged unit is supply-injected, the us in such as Fig. 2；Protect
Protection unit measurement voltage u nown, electric current inThe phasor of corresponding low frequency Injection SignalRecord is between the two
Phase angle be
Step 4: pump-storage generator sfc starts, and runs to rated condition；Protector measuring voltage u nown, electricity
Stream inThe phasor of corresponding low frequency Injection SignalRecord phase angle between the two is
Further, referring to the drawings 3, complete step 5 and step 6, realize adapting to pump-storage generator variable frequency starting
Generator injected type stator ground protection.
In Fig. 3:
A: the status information of each switch auxiliary contact closure/disconnection.
The operating condition that b: monitoring system is brought.
Step 5: during injected type stator ground protection commencement of commercial operation, according to the method for operation, adjust correction by equation below
Low frequency injection current phasor:
Wherein,It is the result after correcting,It is the phase angle of correction, u1Be protector measuring calculate electromotor just
Sequence voltage, ubaseIt is reference voltage, be a definite value, take electromotor specified phase voltage.
Protection device receives state (the input a) in Fig. 3, and reception monitoring of each switch auxiliary contact closure/disconnection
(the input b) in Fig. 3 determines that current unit is in " back-to-back startup ", " sfc startup " to the operation operating condition that system is brought
Or " other " operating mode.
Step 6: the resistance criterion of injected type stator ground protection adopts voltageWith the electric current after correctionAs meter
The input quantity calculated, remaining computational methods is constant, and relay protective scheme is constant.The zero-sequence current computational methods of injected type stator ground protection
Constant, relay protective scheme is constant.
Claims (5)
1. adapt to the injected type stator ground protection method of pump-storage generator variable frequency starting, it is characterized in that, comprise the steps:
In operating condition under back-to-back startup mode, and operating condition is under sfc Starting mode, record respectively from static to
Rated condition, the angle of the phase angle shift between the voltage x current phasor of low frequency injection；
Protection device is according to the state of each switch auxiliary contact closure/disconnection, and the fortune that the monitoring system receiving is brought
Row operating mode, determines the operating condition of current unit；
Protection device according to determined by unit operation operating mode, select the angle of corresponding described phase angle shift, and combine real
The electromotor positive sequence voltage size surveyed, carries out phase angle correction to low frequency injection current signal.
2. the injected type stator ground protection method adapting to pump-storage generator variable frequency starting as claimed in claim 1, it is special
Levy and be, the angle surveying phase angle shift under operating condition is for back-to-back startup mode refers specifically to: leans against by pump-storage generator
Unlucky line mode connects primary equipment, and wherein two units, all in resting state, are not added with excitation；Put into dragged unit
Low frequency is supply-injected；Protector measuring calculates low frequency injecting voltage and electric current now, and record phase angle between the two isPump-storage generator back-to-back startup, runs to rated condition；Protector measuring calculates low frequency injecting voltage now
And electric current, record phase angle between the two is It is the angle of phase angle shift.
3. the injected type stator ground protection method adapting to pump-storage generator variable frequency starting as claimed in claim 1, it is special
Levy and be, the angle surveying phase angle shift under operating condition is for sfc Starting mode refers specifically to: run by pump-storage generator sfc
Mode connects primary equipment, and unit is not added with excitation, and sfc does not have voltage output yet；Put into the low frequency injection electricity of dragged unit
Source；Protector measuring calculates low frequency injecting voltage and electric current now, and record phase angle between the two isDraw water storage
Unit sfc can start, run to rated condition；Protector measuring calculates low frequency injecting voltage and electric current now, records two
Phase angle between person is It is the angle of phase angle shift.
4. the injected type stator ground protection method adapting to pump-storage generator variable frequency starting as claimed in claim 1, it is special
Levy and be, described phase angle that low frequency injection current signal is carried out corrects by equation below calculating:
Wherein,It is low frequency injection current,It isResult after correction,It is the phase angle of correction, u1It is that protection device is surveyed
The electromotor positive sequence voltage that amount calculates, ubaseIt is reference voltage, be definite value；
Represent that under back-to-back startup mode, unit remains static, when being not added with excitation, between low-frequency voltage and electric current
Phase angle；
Represent back-to-back startup mode, phase angle when unit operation is to rated condition, between low-frequency voltage and electric current；
Represent that under sfc Starting mode, unit remains static, phase when being not added with excitation, between low-frequency voltage and electric current
Angle；
Represent the phase angle under sfc Starting mode, when unit operation is to rated condition, between low-frequency voltage and electric current.
5. the injected type stator ground protection method adapting to pump-storage generator variable frequency starting as claimed in claim 4, it is special
Levy and be, described ubaseValue be specified phase voltage.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110535091A (en) * | 2019-08-09 | 2019-12-03 | 南京国电南自维美德自动化有限公司 | A kind of Microcomputer Protection method and apparatus adapting to electrical equipment frequency property |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106154070B (en) * | 2015-03-30 | 2019-09-27 | 南京南瑞继保电气有限公司 | Pump-storage generator operating condition method of calibration and device based on electrical measure feature |
| CN105044528B (en) * | 2015-08-13 | 2017-09-19 | 中广核工程有限公司 | Nuclear power plant's generator injected type stator ground protection dynamic test method and device |
| CN105514937A (en) * | 2015-12-31 | 2016-04-20 | 中国长江电力股份有限公司 | Method for off-line setting injection stator ground protection |
| CN110364990B (en) * | 2019-06-04 | 2021-08-24 | 岭澳核电有限公司 | Method for adjusting measurement precision of stator grounding insulation resistance of injection type generator of nuclear power station |
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| CN110535091B (en) * | 2019-08-09 | 2021-09-03 | 南京国电南自维美德自动化有限公司 | Microcomputer protection method and device adapting to frequency conversion characteristic of electrical equipment |
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