CN103760492A  Method for online testing performance of leadacid storage cells of transformer substation  Google Patents
Method for online testing performance of leadacid storage cells of transformer substation Download PDFInfo
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 CN103760492A CN103760492A CN201410021380.7A CN201410021380A CN103760492A CN 103760492 A CN103760492 A CN 103760492A CN 201410021380 A CN201410021380 A CN 201410021380A CN 103760492 A CN103760492 A CN 103760492A
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Abstract
The invention discloses a method for online testing performance of leadacid storage cells of a transformer substation. The method includes the steps that capacity of each single storage cell body is acquired through an instantaneous discharge method, the inner resistance of each single storage cell body is detected through an alternating current phase method, the instantaneous discharge method is corrected by the alternating current phase method, interference of the instantaneous discharge method in neighbors of opencircuit cells is eliminated, and then realtime online nondestructive testing of the performance of a storage cell set is achieved. According to the method for online testing the performance of the leadacid storage cells of the transformer substation, the instantaneous discharge method and the alternating current phase method are combined, the inner resistance, the capacity and other performance parameters of each single storage cell body can be measured in real time, and then the cells with degraded performance can be found in time at the early stage of degradation of the storage cells, and severe direct current system accidents caused by degradation accumulation and intensification of the storage cells are avoided.
Description
Technical field
A kind of transformer station of the present invention leadacid accumulator online performance method of testing, relates to transforming plant DC power supply monitoring field.
Background technology
Transforming plant DC power unit in electric system, is comprised of equipment such as battery pack, charging module, direct current cabinets.Accumulator is as DC standby power conventionally in floating charge state, once exchange dead electricity, accumulator can be powered for straightflow system.At present, transformer station mostly applies with accumulator be " maintenancefree battery ": valvecontrol sealed lead acid battery (VRLA).Socalled " nonmaintaining " is just without adding water, acid adding, changing the maintenances such as liquid.And detection to accumulator property state is only also the float charge voltage of measuring battery pack, electric current etc.; Cannot accurately measure the true capacity of accumulator.The up time of prediction accumulator, this,, with regard to making the operation of valvecontrol sealed lead acid battery group exist a lot of potential safety hazards, badly influences the safe operation of straightflow system.
Existing accumulator property method of testing is as follows:
1), measure floating charging platen press:
Directly use multimeter hand dipping, or by monitoring equipment, measure the float charge voltage of accumulator.The measurement of float charge voltage, can prevent the too high and too low of float charge voltage.But facts have proved, valvecontrol sealed lead acid battery has terminal voltage and capacity noncorrelation.From static float charge voltage, cannot accurately judge the performance quality of accumulator.
2), AC impedance/conductivity test method:
Testing impedance: load the alternating current of a given frequency and amplitude at electric battery two ends, measure the interchange pressure drop of each monomer/unit.The measured value of alternating voltage is taken from the maximal value (or mean value, maximal value) of each monomer both positive and negative polarity, uses Ohm law computing impedance.Conductivity test: monomer/unit is loaded to the voltage of a given frequency and amplitude, survey the response of its alternating current.It is that surveyed alternating current is divided by magnitude of voltage that electricity is led.Shortcoming is: impedance or electricity are led with accumulator capacity and do not had linear corresponding relation, also needs data analysis after measuring result.
3), internal resistance method of testing:
Internal resistance test: monomer/first two ends being added to a load, measure the stepped change value of its electric current and voltage, is exactly internal resistance value by the changing value of voltage divided by the changing value of electric current.Transient large current discharge test internal resistance value, due to the DCmethod adopting, can well solve the problem of accumulator effect of parasitic capacitance.Because what adopt is highcurrent test, also solved the problem that precision and charger ripple current disturb.Shortcoming is: very large to the tests affect of adjacent cell internal resistance for the battery pack opencircuit cell being together in series, internal resistance and capacity do not have completely linear corresponding relation in addition, after internal resistance test, still needs manual analysis, and accumulator situation is judged.
4), voltage method:
Voltage method is mainly measured the size of opencircuit voltage and load voltage, and the reduction of opencircuit voltage and load voltage all shows the deficiency of capacity.Opencircuit voltage and accumulator capacity have good corresponding relation, and shortcoming is: the measurement of opencircuit voltage must be carried out under accumulator offline state, and want continual and steady more than two hours, cannot put into existing storage batteries of transformer substation.
In addition, also have instantaneous discharge method and exchange phase method.Instantaneous discharge method can detect the true internal resistance of cell batteries, but because battery pack is cascaded, if there is opencircuit cell, affects near the test result of the accumulator of series connection.Exchanging phase method is the effectively online realtime detection method of a kind of accumulator, but the impact due to various interference such as component tolerance, charging set ripples reduces testing result confidence level greatly in practical application process.
Summary of the invention
In view of this, the invention provides a kind of transformer station leadacid accumulator online performance method of testing, adopt instantaneous discharge method and the method that exchanges phase method and combine.Can measure in real time the performance parameters such as internal resistance, capacity of each cell batteries, to can be at the deteriorated early stage performance degradation battery of finding in time of accumulator.Avoid owing to occurring the deteriorated accumulation of accumulator, aggravation, and cause serious straightflow system accident.
The technical scheme that the present invention takes is: a kind of transformer station leadacid accumulator online performance method of testing, by instantaneous discharge method, obtain the capacity of each single battery, by exchanging phase method, detect the internal resistance of each single battery, and exchange phase method to the correction of instantaneous discharge method, eliminated the interference of opencircuit battery neighborhood in instantaneous discharge method, the real time online nondestructive of realizing battery performance detects.
Step 1: battery pack is articulated on charging set, is powered to DC load by charging set, and battery pack, in floating charge state, realizes accumulator instantaneous discharge method test internal resistance;
Step 2: the ac small signal that lowfrequency ac signal generator produces, after amplifying, coupling drive circuit is added to battery pack two ends, measure the alternating voltage V0 at cell batteries two ends, existence due to internal storage battery impedance, make to have produced a phase differential between the output AC current waveform of accumulator and its input waveform, poor by measuring the input and output voltage waveform phase of accumulator of different capabilities, calculate the internal resistance of battery.
In described step 1: battery pack comprises a plurality of single batteries, a plurality of single batteries are divided into two groups, every group is utilized highpower resistance as discharge load, two solidstate relays are controlled in controller timesharing, complete instantaneous discharge operation, adopt voltage sensor and current sensor to gather sparking voltage and the discharge current of the electric discharge front and back of each single battery simultaneously.
In described step 2: produce sine wave signal with signal generator, by a capacitance, be added in battery pack, the signal of process battery pack, again through a stake resistance and a capacitance ground connection, is measured the phase differential of accumulator input/output signal, according to phase difference calculating impedance.
Adopt difference areamethod to calculate two waveform phases poor.
A kind of transformer station of the present invention leadacid accumulator online performance method of testing, technique effect is as follows:
1), by instantaneous discharge method with exchange the correction that complements one another of two kinds of methods of phase method, form overall evaluation system.By instantaneous discharge method, obtain the internal resistance of each cell, and exchange the correction of phase method to instantaneous discharge method, eliminated the interference of opencircuit battery neighborhood in instantaneous discharge method, the real time online nondestructive of the accumulator property of effectively realizing detects.
2), utilize instantaneous discharge method and exchange phase method and accurately test transformer station's leadacid accumulator internal resistance;
3) while,, can transformer station's capacity of lead acid battery changing among a small circle, accurately detect;
4), can occur under the extreme cases such as opencircuit cell suddenly, choose in time deteriorated battery and do not affect the measurement of other batteries;
5), can, at the deteriorated early stage performance degradation battery of finding in time of accumulator, avoid owing to occurring the deteriorated accumulation of accumulator, aggravation, and cause serious straightflow system accident.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is described in further detail:
Fig. 1 is basic battery model schematic diagram;
Fig. 2 is battery AC equivalent impedance illustraton of model;
Fig. 3 is battery AC impedance Simplified equivalent model;
Fig. 4 is battery impedance complex plane figure;
Fig. 5 is battery AC equiva lent impedance model;
Fig. 6 is the relation between storage battery tankage and internal resistance;
Fig. 7 is instantaneous discharge method battery equivalent model;
Fig. 8 is instantaneous discharge method test circuit figure;
Fig. 9 is battery discharging family curve;
Figure 10 is instantaneous discharge method test circuit;
Figure 11 is AC proportion method equivalent series circuit;
Figure 12 is for exchanging phase method theory diagram;
Figure 13 is signals collecting subsystem schematic diagram of the present invention;
Figure 14 is the schematic diagram of zero passage relative method;
Figure 15 is phase difference measurement oscillogram;
Figure 16 is zerocrossing comparator schematic diagram of the present invention;
Figure 17 is that areamethod of the present invention is asked phase differential oscillogram;
Figure 18 is AC method test philosophy figure of the present invention.
Embodiment
Principle analysis:
The relative merits of existing accumulator online monitoring method are known: secondary voltage method (instantaneous discharge method) detects accurately monomer.But having open circuit during cell, or while having certain monomer poorperforming in whole group, experiment contrast discovery meeting causes serious detection error near the several monomers that are connected on this monomer.Exchange phase method and can effectively revise secondary voltage method deficiency.Therefore the present invention adopts secondary voltage method and exchanges phase method and combines, comprehensively the scheme of each monomer performance of assay accumulator.Draw the voltage, internal resistance of each monomer and with reference to residual life.
Accumulator internal resistance comprises: Ohmage and polarization resistance.Ohmic internal resistance comprises: the electrode of inside battery, barrier film, electrolytic solution, connection strap and pole etc. are the resistance of parts all.Polarization resistance be with internal storage battery electrochemical reaction in the suitable resistance of electrode polarization.According to the different understanding to accumulator internal resistance, can set up different battery models.Common are basic model and AC impedance equivalent model, analyze this two kinds of models below:
1, common battery model as shown in Figure 1, this model is E0 by its voltage of ideal battery E0() and an equivalent internal resistance r form, V0 is the terminal voltage of battery, I is the electric current that flows through battery.According to whole circuit law of ohm, can obtain:
I=V0E0/r （1）
This model is not considered the variation because of battery charge state, the variation of concentration of electrolyte, and the factor such as sulfate formation and the internal resistance of cell that causes changes.This model is only applicable to hypothesis can obtain infinite energy from battery, or the unimportant situation of battery charge state.
2, battery AC equivalent impedance model: as shown in Figure 2, C is positive and negative electrode electric double layer capacitance equivalence value, R
_{Ω}ohmic internal resistance for accumulator.Ohmic internal resistance is comprised of the resistance of electrode material, barrier film, electrolytic solution, binding post.Have influence on the output characteristics of accumulator, the temperature rise while discharging and recharging etc.Total Faradaic impedance Z of battery can represent by real part R and imaginary part X, that is:
Z=RjX （2）
When ac frequency is enough low, can think that electrode reaction is reversible, now electrode reaction speed is controlled by diffusion process, has following relation between X and R:
X=RR
_{Ω}R
_{t}+2λ
^{2}C
_{d} （3）
Thereby the X recording under different frequency and R are done to complex plane figure, can obtain slope and be the straight line of 45 °.When ac frequency is enough high, can think that electrode reaction is completely irreversible.Now electrode reaction speed is mainly subject to the control of battery transmission resistance R t, and now accumulator equivalent model can be reduced to as shown in Figure 3.R
_{c}for equivalent polarization resistance, be the resistance of chemical polarization and concentration polarization, involve useful area, kinetics of electrode process and the ion transfer characteristic of electrode, its characteristic does not meet Ohm law.
Now, between X and R, there is following relation:
Thereby XR complex plane figure is semicircle.
To sum up analyze knownly, the complex plane figure of battery impedance can be represented by Fig. 4.
What the present invention adopted is battery AC equiva lent impedance Z model, as shown in Figure 5.
In figure: R
_{1}, R
_{2}the polarization resistance of positive and negative electrode;
C
_{1}, C
_{2}the polarization capacity of positive and negative electrode;
Lleadin inductance;
R
_{Ω}battery Ohmage.
Accumulator Ohmage R Ω has characterized the degree of charge of battery.
For simplified measurement conventionally from equiva lent impedance Z only separated pure resistance R(R by R1, R2, R
_{Ω}form), R and R
_{Ω}between be linear dependence, therefore available R characterizing battery degree of charge indirectly.
By the great many of experiments that the relation of the internal resistance of cell and capacity is made, discovery can reflect indirectly by the internal resistance of monitoring battery the capacity condition of battery.Generally speaking, the capacity of battery is larger, and internal resistance is just less.Therefore, can, by the measurement of accumulator internal resistance, to the capacity of battery, carry out online evaluation.Relation between battery capacity and internal resistance as shown in Figure 6, therefore detects the size that internal resistance can be judged remaining battery capacity.Thereby analyze the performance quality of accumulator, find the operating every potential safety hazard of accumulator, for guaranteeing that accumulator is stable, operation reliably provides important guarantee.
By the great many of experiments that the relation of the internal resistance of cell and capacity is made, discovery can reflect indirectly by the internal resistance of monitoring battery the capacity condition of battery.Generally speaking, the capacity of battery is larger, and internal resistance is just less, therefore can, by the measurement of accumulator internal resistance, to the capacity of battery, carry out online evaluation.Relation between battery capacity and internal resistance as shown in Figure 6, therefore detect the size that internal resistance can be judged remaining battery capacity, thereby analyze the performance quality of accumulator, find the operating every potential safety hazard of accumulator, for guaranteeing that accumulator is stable, operation reliably provides important guarantee.
3, instantaneous discharge method test philosophy and realization:
Instantaneous discharge method is exactly by battery is carried out to transient large current discharge, and the transient voltage of measuring on battery falls, and by Ohm law, calculates the internal resistance of cell.In moment direct current situation, the equivalent model of battery can think and be consisted of voltage source and internal resistance series connection (Dai Weinan equivalent model), as shown in Figure 7.Rin wherein: accumulator internal resistance; I: momentary current; RL: pullup resistor.Accumulator internal resistance computing formula: R
_{in}=Δ U/I; Δ U is voltage variety before and after accumulator instantaneous discharge.Test circuit is as Fig. 8, and switch closes, and postpones after a period of time, and electric current reaches steady state (SS), record current value I, magnitude of voltage U
_{1}.After cutoff switch K, record the magnitude of voltage U of momentary recovery
_{2}, record overall process accumulator both end voltage fluctuation situation simultaneously.After why will postponing a period of time, carrying out next step test, is mainly because in the process of closing a floodgate again, and owing to there being the existence of electric capacity, inevitably having dash current and produces.In order to reduce the impact of dash current on test result, so just adopted regular hour delay.Meanwhile, the delay that this is of short duration, also can allow battery relative equilibrium state gradually from incipient violent chemical reaction.
Accumulator, after being full of electricity, recording its internal resistance value and draws thus voltage wave cardon while being in floating charge state.When accumulator is during with the current discharge of different numerical value, the situation that its terminal voltage declines is also different.Fig. 9 has provided same accumulator discharge characteristic curve in different discharge current situations.As seen from Figure 9, discharge current is larger, must be lower at the overall process middleend voltage drop of electric discharge, and the speed declining is faster, this is because discharge current is when very large, in reaction zone the consumption of sulfuric acid also very large, but supplementary speed is very little.Therefore pole plate hole electrolyte inside density must be even lower down and is faster.And discharge current is when large, the pressure drop in internal resistance is also large, therefore that terminal voltage declines is fast, occurs in advance electric discharge end of a period phenomenon, so battery discharging electric current is larger, the duration of electric discharge is shorter.But discharge current surpasses after certain scope, the variation of internal resistance is not just very large, now just should consider that heavycurrent discharge is to the infringement problem of battery.
So from experiment, while utilizing instantaneous highcurrent discharge to carry out internal resistance test, the discharge current scope allowing should be selected in 0.3～0.5Co (Co refers to the capacity of accumulator), so both can obtain good precision, also can avoid the injury to battery simultaneously.From experiment with analyze, this method can effectively be avoided the impact of AC noise, thereby reaches good measuring accuracy, has also avoided traditional long electric discharge simultaneously, can be very fast obtain test result.
Embodiment:
A kind of transformer station of the present invention leadacid accumulator online performance method of testing, by instantaneous discharge method, obtain the capacity of each single battery, by exchanging phase method, detect the internal resistance of each single battery, and exchange phase method to the correction of instantaneous discharge method, eliminated the interference of opencircuit battery neighborhood in instantaneous discharge method, the real time online nondestructive of realizing accumulator property detects.
Test circuit of the present invention as shown in figure 10.Storage batteries of transformer substation group is articulated on charging set, conventionally by charging set, to DC load, is powered, and battery pack is in floating charge state, in order to realize accumulator instantaneous discharge method test internal resistance.It is example that monomer 12V accumulator is take in the present invention, and totally 18 of whole group storage batteries, are divided into two groups by 18 battery pack, and every group is utilized the highpower resistance of 12 Ω as discharge load, and two solidstate relays are controlled in controller timesharing, completes instantaneous discharge operation.Adopt voltage and current sensor to gather voltage and the discharge current of each battery discharging front and back simultaneously, by formula, calculate each accumulator internal resistance, adopting the main cause of sort circuit is to avoid the electricity that misplaces of charging set.
In theory, have three kinds of voltage statuss in battery discharging process, as shown in figure 11, the voltage variety here has two: 1. to hookup, add the moment of load, cell voltage fall value; 2. moment of disconnecting consumers, the recovery value of cell voltage.In experimentation, at combined floodgate transient voltage and electric current, all easily introduce very large impact, cause larger error, therefore unification adopts the value of falling of voltage, and now electric current has also reached stable state substantially, in actual test process, after electric discharge is opened 2 two seconds, test primary voltage, after disconnection discharge module, test immediately primary voltage, obtain the Δ U in Figure 11, and then utilize the internal resistance computing formula in Fig. 7 to calculate, R
_{in}=Δ U/I.
Exchange phase method and be the internal resistance of measuring accumulator to injecting the Voltage Feedback of AC signal of its certain frequency by measuring accumulator.The advantage of AC method has: without electric discharge, be safest internal resistance test mode; Can under any states such as Chong electricity ﹑ electric discharge, to accumulator, carry out internal resistance test; Can react the polarization resistance of accumulator; By selecting signal frequency can adapt to different types of accumulator.Current existing AC method has AC proportion method and exchanges phase method.
(1) AC proportion method:
Adopt AC proportion method to measure the internal resistance of accumulator, accumulator is connected with highaccuracy resistance, equivalent series circuit as shown in figure 11.Use special chip to measure and relatively accumulator and the effective value of precision resistance to AC signal dividing potential drop, internal resistance that just can calculating accumulator.R in Figure 11
_{θ}being highaccuracy resistance, is the equivalent electrical circuit of accumulator in dotted line, R
_{Ω}for the ohmic internal resistance of accumulator, Rc is polarization resistance, and C is interelectrode capacity, and the equiva lent impedance of accumulator is:
Z=R
_{Ω}+Rc/(1+JωCRc) （5）
In formula: R
_{Ω}resistance for signal generating circuit.The electric current that AC signal flows through series circuit is:
I=Ui/(Z+R
_{θ})=u2/R
_{θ} （6）
Variable in formula (6) is all plural form and has proportionate relationship, it is carried out to modulo operation, it is respectively their effective value V1 and V2 that proportionate relationship still has the mould of AC signal u1 and u2, therefore, as long as measure accumulator and the effective value of highaccuracy resistance to AC signal dividing potential drop, just can calculate the mould of the equiva lent impedance of accumulator:
Z=U1R
_{θ}/U2 （7）
It is the comprehensive of accumulator ohmic internal resistance, polarization resistance and interelectrode capacity, can be used as accumulator equivalent internal resistance:
Z=V1R
_{θ}/V2 （8）
(2) exchange phase method:
Exchange the internal resistance of phase method online measurement accumulator, battery is injected to a lowfrequency ac electric current signal.In engineering on the frequency of this Injection Signal and size all restricted condition to guarantee not affect accumulator property, then measure the lowfrequency ac voltage V at accumulator two ends
_{0}with the lowfrequency ac electric current Is flowing through and both phase differential α, according to formula Z=V
_{0}/ Is, R=Zcos α, thus calculating the internal resistance of battery, its schematic diagram is as shown in Figure 12.AC method, due to without electric discharge, need not, in static state or off line, can realize online monitoring management completely.Avoided the impact on equipment safety in operation.Because the lowfrequency ac signal frequency applying is very low, electric current is also very little, therefore can not cause adverse effect to the performance of powersupply system simultaneously.
The present invention adopts followon accumulator simple equivalent circuit illustraton of model 3 on the basis that exchanges phase method, the ac small signal that lowfrequency ac signal generator produces is added to battery pack two ends after coupling drive circuit amplifies, measure the alternating voltage V0 at cell batteries two ends, existence due to internal storage battery impedance, make to have produced a phase differential between the output AC current waveform of accumulator and its input waveform, and this phase differential reduces with the increase of accumulator internal resistance, and accumulator internal resistance reduces with capacity and increase.So the phase differential of accumulator input/output signal can reduce with the minimizing of capacity.By measuring the poor internal resistance that just can calculate battery of input and output voltage waveform phase of the accumulator of different capabilities.AC method, due to without electric discharge, need not can realize online monitoring management completely in static state or off line, has avoided the impact on equipment safety in operation.
Because the low frequency signal frequency applying is very low, the alternating current applying is also very little, therefore can not cause adverse effect to the performance of powersupply system simultaneously.Specific implementation process is as follows: with signal generator (ICL8038 chip), produce sine wave signal, by a capacitance, be added in battery pack, through the signal of battery pack again through stake resistance and a capacitance ground connection of approximately 10 Ω.Capacitance is very little, is about 1uF.Measure the impedance of accumulator, just must measure the phase differential of accumulator input/output signal, according to phase difference calculating impedance.Figure 13 is signals collecting subsystem schematic diagram of the present invention.
During image data, from the two ends of each accumulator, respectively draw a line, through after a capacitance, deliver to multicircuit switch, then deliver to data collecting plate card, can to each cell of battery pack, carry out cycle detection by controlling multicircuit switch.The phase differential now obtaining can not be thought and produced by accumulator internal resistance.Because all accessed capacitance when gathering battery tension, even the model of these capacitances, size, manufacturer is all identical, also can there is tolerance, this tolerance also can make the input/output signal of accumulator produce phase differential, so only gather the internal resistance that a time phase differential be can not determine accumulator.The phase differential of accumulator input/output signal can be with the reducing and reduce of capacity, and the phase differential that the tolerance of capacitance causes is constant, so we can carry out according to the variation of phase differential the internal resistance of calculating accumulator.In order to obtain phase differential, must change the capacity of accumulator, even if accumulator is to load discharge.In battery pack, when just charging is complete, carry out a data acquisition, then to battery discharging, carry out again at regular intervals a data acquisition, along with the increase of discharge time, phase differential can reduce gradually, so the present invention just utilizes signal acquiring system to gather this phase differential.The phase differential of the input and output voltage signal of the accumulator detecting is the phase differential between battery tension and electric current in fact namely, in conjunction with alternating voltage amplitude, and whole group of current amplitude, according to formula Z=V0/Is, R=Zcos α carrys out calculating accumulator internal resistance.Poor classic method is zero crossing relative method to calculate two waveform phases, and ultimate principle as shown in figure 14.Two signals of sampling filter various undesired signals through wave filter and go forward side by side that to become a waveform after amplifying regular for line linearity, the sinusoidal signal that amplitude is suitable, as the signal a ﹑ b in Figure 14, after zerocrossing comparator, sinusoidal signal becomes squarewave signal, be signal c ﹑ d, then signal d is become to signal e through reverser, finally two signals are sent into one with a door output signal f.
Zerocrossing comparator consists of two LM393, for detection of the zero point of twoway AC signal.When input signal is greater than zero, LM393 exports high level; When be less than5R1/R2 of applied signal voltage, LM393 output low level.
The computing method of △ T: the mistiming by monitoring voltage signal zero crossing place calculates, utilize embedded computer system collection signal, when signal is high level, start timer timing, stop timing while becoming low level, the time that now timer shows is △ T.Because accumulator has internal resistance, so between input/output signal except there is phase differential, amplitude also can change, but the internal resistance of accumulator is very little, compare the impact that can ignore it amplitude is produced with 10 external Ω resistance, so we think that the input/output signal amplitude of accumulator equates, and amplitude is done to normalized.Therefore the signal that we establish input battery pack is:
y
_{1}=cos(ωt)+n
_{1}(t) （9）
From the signal of battery pack output, be:
y
_{2}=cos(ωt+θ)+n
_{2}(t) （10）
Zero crossing relative method asks phase differential to be actually to ask the mistiming at two signal zeros or peak value place, if the time of the signal zero crossing of input battery pack is t1, the output signal zero crossing time of accumulator is t2,
△T=t
_{2}t
_{1} （11）
If true origin is at t
_{1}place,
t
_{1}=0 （12）
y
_{1}=1n
_{1}(0) （13）
y2=cos(ω△T+θ)+n
_{2}(△T) （14）
During zero crossing, there is y
_{1}=y
_{2}=0, by y
_{1}, y
_{2}this equation of expression formula substitution obtains:
cos(ω△T+θ)=1n
_{1}(0)n
_{2}(△T) （15）
θ=arccos[1n
_{1}(0)n
_{2}(△T)]ω△T （16）
But the method exists certain defect, main manifestations is:
(1) all there is tolerance in all elements, the phase differential of the input/output signal being caused by tolerance can be larger, and accumulator is when capacity is very large, the phase differential of input/output signal is very little, so the caused phase differential of tolerance likely can cover the caused phase differential of accumulator internal resistance.
(2) detecting data relies on AD at a high speed to sample to guarantee to the sensitivity of detected object variation.Because when the variable quantity of phase differential is very little, the variable quantity of corresponding mistiming △ T is also very little, must highspeed AD sampling just can obtain this very little variable quantity;
(3) by formula (16), can be found out, in the expression formula of phase differential, contain noise section, testing result is very sensitive to random noise.
The present invention adopts difference areamethod.First obtain the corresponding area of phase differential of two waveforms, then area is quadratured and just can be calculated the phase differential of two waveforms, as shown in figure 17.Input/output signal is sent into two highspeed, high precision differential paths of singlechip microcomputer, output after sampling is the difference in magnitude of two signals, during measurement to oneperiod intensive sampling, and thereby a square accumulative total summation for the difference result of two passages is obtained to a measured value A, this measured value can be approximated to be the integration of two signal difference squared absolute values, the integration of two signal difference absolute values be phase differential for area.Algorithm is as follows:
If the signal of input signal battery pack is y1,
y
_{1}=cos(ωt)+n
_{1}(t) （17）
The output signal of battery pack is y2,
y
_{2}=cos(ωt+θ)+n
_{2}(t) （18）
The integration of the squared absolute value that input/output signal is poor is:
By y
_{1}y
_{2}substitution formula (19):
Formula (20) is launched:
Because noncorrelation between input/output signal and noise signal, and noise signal is zero with the integration of any uncorrelated definite product of signals, therefore also abbreviation obtains:
Because square accumulative total summation to the difference result of two passages obtains the integration that a measured value A can be approximated to be two signal difference squared absolute values, so:
2TTcosθ=A （23）
Formula (24) is the resulting phase differential of quadraturing within a signal period, if continuous sampling is quadratured within N cycle, obtaining result is exactly the aggregatevalue of phase differential, and the method and zero passage relative method comparison phase detection result data can be amplified.In measurement result, do not contain noise section simultaneously, effectively eliminated the error that signal noise causes.
Although the amplification of phase detection result data, the phase differential that component tolerance causes is reduced relatively, measurement result reduces greatly to the tolerance susceptibility of circuit elements device, but above method cannot fundamentally be eliminated the measurement result that in testing circuit, component tolerance causes.For example divider resistance selects the copper resistance of 10 Ω, and, according to national standard IEC600281925 regulation, its error is ± 1%, ± 0.1 Ω, and the internal resistance of cell is milliohm level.In testing circuit, also have a lot of electronic components, the impact of these elements all can directly reflect in measurement result, therefore the change that cannot differentiate phase differential is that the variation of accumulator internal resistance causes, or component tolerance causes, so every cover detection system all must have the zero point drift of a testing result, and this zero point drift is far longer than accumulator internal resistance, the variable quantity of the certainly farther internal resistance detecting much larger than needs.
Main task of the present invention is the accumulator degradation in monitoring use procedure, as long as the capacity of monitoring system energy effecting reaction accumulator, and in conjunction with the temperature that detected and monomer voltage as corrected parameter, effectively provide the volume percent of current each cell.Single chip computer measurement result A is approximate to phase differential area, but the method for tabling lookup based on statistics only needs a respective value, does not need exact solution to calculate phase differential.If the funtcional relationship of capacity and internal resistance is:
C=f(x) （25）
F (x) is the continuous monotonic decreasing function of monodrome.Suppose that internal resistance and phase function pass are:
R=g(x) （26）
G (x) is the continuous monotonic decreasing function of monodrome, and the funtcional relationship of capacity and phase differential can be made as:
C=h(x) （27）
C=h (x) is the continuous monotonically increasing function of monodrome.So the mapping relations of measured value A and accumulator capacity are that A value is larger, capacity is larger.
Based on this thought, the method that the present invention adopts is first battery to be full of, and measures the phase data result in this time, obtain a data a0, then 3% of discharge capacity, then measure to obtain a data result a1, go down successively to obtain a0, a1, a2, a3 ...A0a1 is obtained to a data point b1, and a0a2 obtains b2, goes down and obtains successively: b1, b2, b3 ...Therefore b1, b2, b3 ... these group data be in accumulator operational process with respect to the 100% capacity data that 3% phase differential changes that decline successively, effectively eliminated the zero point drift that component tolerance causes.Suppose that the phase differential that tolerance causes in input/output signal is respectively φ 1, φ 2, in the expression formula of phase differential, contain △ φ, and the △ φ at every turn measuring is identical, in the process of subtracting each other, can offset.Therefore adopt and effectively eliminated in this way the zero point drift that component tolerance causes, can effectively detect the health status of accumulator.
According to theoretical research, native system has carried out following two kinds of experiments: laboratory simulation experiment and the experiment of onthespot online operation.
(1) laboratory simulation experiment
220V straightflow system is selected in experiment, and this system is comprised of 18 batteries, and the nominal voltage of accumulator is 12V, and capacity is not etc., new and old different.
In 18 batteries, choose the data analysis of 4 representative cells.These 4 batteries are respectively the used batteries of 1 200Ah, the 100Ah battery that 1 is on the verge of to scrap, 1 battery, 1 brandnew 100Ah battery that 100Ah scraps.
For accumulator is full of, rear offline carries out the voltage data that instantaneous discharge is tested front and back to table 1, and instantaneous discharge electric current is 4.8A.
Table 1 test experiment data:
Battery  U0/V  U1/V  ΔU/V  R/mΩ 
1(100Ah) be on the verge of to scrap  13.074  12.151  0.923  192 
2(200Ah) old  10.521  10.216  0.305  64 
3(100Ah) scrap  12.779  11.644  1.135  236 
4(100Ah) brandnew  12.934  12.587  0.347  72 
As known from Table 1, according to the internal resistance calculating, 1,2 and No. 4 battery of 100Ah has reacted capacity well, and No. 2 batteries are because capacity is large, and the internal resistance calculating is very little.
Table 2, for battery hangs up after charging set and load after being full of, carries out the voltage data after instantaneous discharge experiment online.
Table 2 online experiment data:
Battery  U2/V  ΔU/V  R/mΩ 
1(100Ah) be on the verge of to scrap  12.197  0.877  183 
2(200Ah) old  10.226  0.295  61 
3(100Ah) scrap  11.684  1.095  228 
4(100Ah) brandnew  12.649  0.285  59 
As known from Table 2, the internal resistance of battery changes little, because battery itself is full of, under floating charge state, battery capacity does not have large variation, therefore internal resistance is almost constant.
Table 3 and table 4 are that battery discharges after 12min with 10A electric current offline, the related data of using instantaneous discharge method to obtain in the situation that not articulating charging set and articulating charging set respectively,
Table 3 offline contrast experiment's result:
Battery  U0/V  U1/V  ΔU/V  R/mΩ 
1(100Ah) be on the verge of to scrap  12.474  12.024  0.450  93 
2(200Ah) old  10.449  10.147  0.352  73 
3(100Ah) scrap  12.670  11.582  1.088  227 
4(100Ah) brandnew  12.901  12.532  0.369  77 
The online contrast experiment's of table 4 result:
Battery  U2/V  ΔU/V  R/mΩ 
1(100Ah) be on the verge of to scrap  12.138  0.336  70 
2(200Ah) old  10.165  0.334  69 
3(100Ah) scrap  11.594  1.076  224 
4(100Ah) brandnew  12.547  0.354  74 
As may be known from Table 3 and Table 4, for every battery, when electric discharge 12min after, capacity loss 2Ah, the object of doing is like this that can the variation among a small circle of simulated battery capacity reflect by internal resistance.The data of contrast table 14, can obtain following rule: No. 1 and No. 3 batteries are waste battery, capacity is very little, when offline is after electric discharge a period of time, self voltage drop is very fast, by voltage, can judge the performance of battery, under this situation, gained internal resistance data, do not have relevant rule; Although No. 2 battery is used batteries, capacity is large, and the volume change of 2Ah equally can be by internal resistance reacting condition out; No. 4 battery is brandnew battery, is this contrast experiment's main object, test data when table 5 is No. 4 battery different capabilities.
The internal resistance of table 54 battery and capacity comparison:
Capacity/Ah  U1/V  U2/V  IS  R/mΩ 
100  12.522  12.679  5.31  29.56 
98  12.331  12.496  5.31  31.07 
90  12.054  12.243  5.24  36.07 
86  11.987  12.189  5.21  38.77 
81  11.897  12.110  5.26  40.49 
78  11.862  12.086  5.23  42.83 
As known from Table 5, when capacity changes on a small quantity, the internal resistance of measuring by instantaneous discharge method changes very obvious.By similar, repeat experiment, make the capacity loss of battery to 80Ah, during this period, the fine (see figure 4) of correlativity of the linear change rule of internal resistance and capacity, can well prove the feasibility of the method.In system actual development, using the magnitude of voltage in instantaneous discharge method as one of criterion, this has just guaranteed the reliability of system.Actual result shows: the battery that capacity is low, voltage during electric discharge is also low.By said method, test the capacity obtaining, meet the requirement of actual production, be particularly useful for the situation that needs early detection battery capacity to change.
(2) onthespot online operation experiment
This project achievement is applied to a plurality of transformer stations of certain power supply administration, is given in test data and experiment conclusion that certain transformer station that this power supply administration has under its command carries out below.
Certain transformer station is 110kV electric pressure transformer station, and straightflow system accumulator used is 18, and cell nominal voltage is 12V, capacity 100Ah, and the primary data of native system test is in Table 19:
In abovementioned figure, all accumulator internal resistances of test of process native system are all less than 50m Ω, in normal operating condition.
In order to test the effect of the deteriorated accumulator of the actual judgement of native system, according to power system transformer substation operational administrative, stipulate, handled after associative operation ticket, the accumulator short time of online operation is departed to main system, and replace No. 17 accumulators wherein with trouble accumulator of preprepared, trouble accumulator is open fault battery, cannot storing electricity.Through system, adopt instantaneous discharge method and the test that exchanges phase method, the test data obtaining is as table 20:
By the test of system, find that 17 accumulator voltages of access are normal, and slightly higher than normal battery voltage, but internal resistance is 988m Ω, be much higher than other accumulator internal resistances, can very obviously be distinguished, native system has successfully detected fail battery, and existing a lot of accumulator monitoring equipment cannot be distinguished fail battery by the mode of monitoring monomer battery voltage.
In sum, native system is tested by above two classes, preferably resolves the problem of accumulator property online monitoring, adopts instantaneous discharge method and the internal resistance that exchanges method that phase method combines and can more accurately measure accumulator, and then definite accumulator capacity, thereby judge the performance of accumulator.
Claims (5)
1.Yi Zhong transformer station leadacid accumulator online performance method of testing, it is characterized in that, by instantaneous discharge method, obtain the capacity of each single battery, by exchanging phase method, detect the internal resistance of each single battery, and exchange phase method to the correction of instantaneous discharge method, eliminated the interference of opencircuit battery neighborhood in instantaneous discharge method, the real time online nondestructive of realizing battery performance detects.
2. a kind of transformer station leadacid accumulator online performance method of testing according to claim 1, is characterized in that,
Step 1: battery pack is articulated on charging set, is powered to DC load by charging set, and battery pack, in floating charge state, realizes accumulator instantaneous discharge method test internal resistance;
Step 2: the ac small signal that lowfrequency ac signal generator produces, after amplifying, coupling drive circuit is added to battery pack two ends, measure the alternating voltage V0 at cell batteries two ends, existence due to internal storage battery impedance, make to have produced a phase differential between the output AC current waveform of accumulator and its input waveform, poor by measuring the input and output voltage waveform phase of accumulator of different capabilities, calculate the internal resistance of battery.
3. a kind of transformer station leadacid accumulator online performance method of testing according to claim 2, it is characterized in that, in described step 1: battery pack comprises a plurality of single batteries, a plurality of single batteries are divided into two groups, every group is utilized highpower resistance as discharge load, two solidstate relays are controlled in controller timesharing, complete instantaneous discharge operation, adopt voltage sensor and current sensor to gather sparking voltage and the discharge current of the electric discharge front and back of each single battery simultaneously.
4. a kind of transformer station leadacid accumulator online performance method of testing according to claim 2, it is characterized in that, in described step 2: produce sine wave signal with signal generator, by a capacitance, be added in battery pack, the signal of process battery pack is again through a stake resistance and a capacitance ground connection, measure the phase differential of accumulator input/output signal, according to phase difference calculating impedance.
5. according to a kind of transformer station leadacid accumulator online performance method of testing described in claim 2 or 4, it is characterized in that, adopt difference areamethod to calculate two waveform phases poor.
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