CN101158709A - Accumulator cell real time on-line nondestructive accurate measurement method - Google Patents

Abstract

The invention discloses a real-time and online method for lossless and precise measurement of storage batteries. The invention uses a low frequency and alternating signal generator to infuse the storage battery with low frequency and alternating signal, thus measuring the low frequency and alternating voltage at both ends of the storage battery, the low frequency and alternating electric current through the storage battery, and the phase difference between both ends. The invention achieves reliable real-time and online monitoring, provides rich and timely operating data to people who maintain the service of storage batteries, and greatly improves the maintenance level of the service of storage batteries, and the invention is markedly characterized by reliable data acquisition and precise detection of the essential resistance of storage batteries.

Description

Accumulator cell real time on-line nondestructive accurate measurement method

Technical field:

The invention belongs to the technical field of in the power industry transformer station direct current system accumulator internal resistance being carried out real time on-line monitoring.

Background technology:

Standby power supply when lead-acid accumulator has a power failure as power industry transformer station power-supply system has been widely used in commercial production, and industries such as electric power, traffic, communication.One of important symbol of battery condition is exactly its internal resistance.Therefore realize the on-line real time monitoring of accumulator internal resistance, important and practical meanings will be arranged.The present situation of present similar technology, domestic level: adopt by the electric discharge of external load module and measure internal resistance, do not realize Long-distance Control.

The defective of its existence is: 1.. (2 seconds) the in short-term discharge of must the staff reaching the spot and carrying out accumulator, just can finish internal resistance measurement, and therefore do not realize the real time on-line monitoring of internal resistance.2.. in order to measure accumulator internal resistance, need, influence the ordinary life of accumulator on the one hand at every turn all to battery discharging; On the other hand, exchange dead electricity then may face the danger that influences the tributary system works if when discharging, run into transformer station just.3.. the terminal voltage monitoring error, discharge process current fluctuation, the discharge front and back voltage that adopt the electric discharge detection technique to occur in monitoring are caught difficulty technological difficulties such as (instabilities) and are caused the internal resistance monitoring accuracy not high.

The common methods of measuring transformer station's accumulator internal resistance at present has: 1. densimetry--densimetry is mainly estimated the internal resistance of accumulator by the density of measuring battery liquid, the internal resistance measurement that is usually used in the open type lead-acid battery is not suitable for the internal resistance measurement of sealed lead acid storage battery.The narrow application range of this method.2. open-circuit voltage method-open-circuit voltage method is to estimate the internal resistance of accumulator by the terminal voltage of measuring accumulator, and precision is very poor, even derives a wrong conclusion.Even because the accumulator that capacity has become very little, its terminal voltage still may show very normally under floating charge state.3. the direct-current discharge method--by battery is carried out transient large current discharge, the transient voltage of measuring on the battery falls the direct-current discharge method, calculates the internal resistance of cell by Ohm law exactly.Though this method has also obtained using widely in practice, also there are some shortcomings in it.As with this method accumulator internal resistance being detected must be to carry out under static state or off-line state, can't realize on-line measurement.And heavy-current discharge can cause bigger infringement to accumulator, thereby influences the capacity and the life-span of accumulator.4. ac-current inject method--by accumulator is injected a constant ac current signal J., measure the voltage responsive signal at accumulator two ends, and both phase differential, determine the internal resistance R of accumulator by formula of impedance L-Vo/I and R-Zcos8.This method does not need accumulator is discharged, and can realize the online detection internal resistance of cell of safety, so can the performance of accumulator not impacted.But this method need be measured ac current signal Js, voltage responsive signal, and the phase differential between the voltage and current.This shows that this method not only disturbing factor is many, and increased the complicacy of system that the measuring accuracy problem becomes the main bottleneck that this kind of restriction method is used.

Not only disturbing factor is many for this method of ac-current inject method, and has increased the complicacy of system, the determining and obtain of AC signal, and the measuring accuracy problem becomes and hinders the main bottleneck that this kind method is used.

And above-mentioned ac-current inject method has the following disadvantages:

(1) all there is tolerance in all elements, the phase differential of the input/output signal that is caused by tolerance can be bigger, and accumulator is when capacity is very big, and the phase differential of input/output signal is very little, so the caused phase differential of tolerance might cover the caused phase differential of accumulator internal resistance.

(2) detecting sensitivity that data change detected object relies on AD at a high speed to sample to guarantee.Because when the variable quantity of phase differential was very little, the variable quantity of pairing mistiming Δ T was also very little, must the high-speed AD sampling just can obtain this very little variable quantity;

(3) contain noise section in the expression formula of phase differential, testing result is very sensitive to random noise.The two-way zero-crossing method can reduce the error that caused by drift, but can not realize the processing to noise.And electric current, voltage signal are converted to behind the width of cloth voltage signal, calculate phase differential according to two signals at the voltage difference at zero crossing place and voltage magnitude and can reduce requirement zero crossing monitoring accuracy, but owing to need carry out pre-service to signal, thereby increased the hardware handles link, brought problems such as design is complicated, cumulative errors are bigger.

Summary of the invention:

Purpose of the present invention is just in order to overcome in above-mentioned existing power industry transformer station or other lead-acid accumulator application, the weak point that the ac-current inject method technology that in straight-flow system accumulator is detected exists and provide a kind of realize to the real time on-line nondestructive of GFM accumulator internal resistance accurately measure, realtime on-line monitoring method reliably.The inventive method is to injecting the definite of AC signal and obtaining and taked a kind of new method, and solved the problem of measuring accuracy effectively, the inventive method is simple in structure, convenient control, the inventive method is injected a low-frequency ac feeble signal by accumulators, detect the phase of ac signal of every accumulator input end and output terminal, the two phase differential can accurately reflect accumulator internal resistance.Really realized the real-time monitoring of transformer station's accumulator internal resistance parameter.Adopt advanced test philosophy and algorithm, improved the reliability and the antijamming capability of system testing greatly, realized accumulator monitoring network management and intelligentized real-time diagnosis.

The objective of the invention is to realize by following technical solution.

The present invention adopts the low-frequency ac signal generator that accumulator is injected a low-frequency ac electric current signal, utilizes this ac current signal, thereby measures the low-frequency ac voltage V at accumulator two ends ₀With the low-frequency ac electric current Is that flows through, and utilize the difference area-method to measure low-frequency ac voltage V ₀Phase differential α with the low-frequency ac electric current Is that flows through.

Low-frequency ac signal generator 1 of the present invention is gathered the monomer DC voltage and the ac voltage signal of accumulator by the couple drive amplifying circuit through the voltage sample module, again ac voltage signal and the d. c. voltage signal gathered after removing undesired signal, low-pass active filter are delivered to multichannel conversion switch, send the single-chip microcomputer collection through the A/D conversion again, obtain its amplitude; Ac voltage signal converts sine wave to square-wave signal through the zero balancing pulse shaping circuit, current signal also is directly to deliver to single-chip microcomputer through multicircuit switch on the one hand, detect its amplitude, also to convert sine wave to square-wave signal simultaneously through the zero balancing pulse shaping circuit, deliver to phase detection unit with the square-wave signal of alternating voltage then and detect their phase differential, thereby according to Z=V ₀/ Is, R=Zcos α comes the calculating accumulator internal resistance; When measuring, the present invention respectively draws a lead at the two ends of each accumulator 3, on this lead, respectively be connected with a capacitance ground connection, signal through accumulator is connected with multicircuit switch through the stake resistance R of an about 8-12 Ω and the other end of capacitance earth lead again, and multicircuit switch is connected with the single-chip microcomputer collection plate.

The invention has the beneficial effects as follows, adopt the real time on-line nondestructive of AC method GFM accumulator internal resistance accurately to measure, inject a low-frequency ac feeble signal by accumulators, detect the phase of ac signal of every accumulator input end and output terminal, the two phase differential can accurately reflect accumulator internal resistance, voltage is caught measuring technique overcome the terminal voltage monitoring error that adopts the electric discharge detection technique to occur at present, discharge process current fluctuation, outage both at home and abroad in monitoring before and after, and the decline inspection etc. of online connecting line electric weight causes the not high drawback of internal resistance on-line monitoring precision.Really realized the real time on-line monitoring of transformer station's accumulator internal resistance parameter, owing to adopted advanced test philosophy and algorithm, improved the reliability of system testing and antijamming capability greatly and provide abundant, service data timely for accumulator operation maintenance personnel, improve the operation and maintenance level of accumulator greatly, realized the accumulator monitoring network management; Intelligentized real-time diagnosis, system finishes the field diagnostic to every accumulator property automatically according to the accumulator parameters of monitoring in real time, in time finds bad battery, grasp the running status of electric battery, have data acquisition reliable, detect the accurate remarkable advantage of accumulator internal resistance.

Further set forth content of the present invention below in conjunction with drawings and Examples.

Description of drawings:

Fig. 1 is ac-current inject method principal diagram intention;

Fig. 2 is the signal acquiring system principle schematic;

Fig. 3 is the output AC voltage waveform phase differential intention of accumulator;

Fig. 4 connects block diagram for the invention process system.

Embodiment:

As Fig. 1, the present invention adopts the low-frequency ac signal generator that accumulator is injected a low-frequency ac electric current signal, utilizes this ac current signal, thereby measures the low-frequency ac voltage V at accumulator two ends ₀With the low-frequency ac electric current Is that flows through, and utilize the difference area-method to measure low-frequency ac voltage V ₀Phase differential α with the low-frequency ac electric current Is that flows through; Low-frequency ac signal generator 1 of the present invention is gathered the monomer DC voltage and the ac voltage signal of accumulator by the couple drive amplifying circuit through the voltage sample module, again ac voltage signal and the d. c. voltage signal gathered after removing undesired signal, low-pass active filter are delivered to multichannel conversion switch, send the single-chip microcomputer collection through the A/D conversion again, obtain its amplitude; Ac voltage signal converts sine wave to square-wave signal through the zero balancing pulse shaping circuit, current signal also is directly to deliver to single-chip microcomputer through multicircuit switch on the one hand, detect its amplitude, also to convert sine wave to square-wave signal simultaneously through the zero balancing pulse shaping circuit, deliver to phase detection unit with the square-wave signal of alternating voltage then and detect their phase differential, thereby according to Z=V ₀/ Is, R=Zcos α comes the calculating accumulator internal resistance; When measuring, the present invention respectively draws a lead at the two ends of each accumulator, on this lead, respectively be connected with a capacitance C, C ground connection, signal through accumulator is connected with multicircuit switch through the stake resistance R of an about 8-12 Ω and the other end of capacitance earth lead again, and multicircuit switch is connected with the single-chip microcomputer collection plate.

The present invention injects an audible communication signal to battery, measures the alternating voltage V at accumulator two ends ₀, because the existence of accumulator internal resistance, make that having produced a phase differential and this phase differential between the output AC voltage waveform of accumulator and its input waveform 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.The input and output voltage waveform phase difference of the accumulator by measuring different capabilities just can calculate the internal resistance of battery.

The concrete gatherer process of AC signal of the present invention is as follows:

As Fig. 2, produce sine wave signal with signal generator 1 (ICL8038 chip), by two capacitance C ₁, C ₂Be added on the battery pack, through the signal of accumulator again through stake resistance R and a capacitance ground connection of an about 8-10 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 the phase difference calculating impedance.

We need respectively draw a line from the two ends of each accumulator during image data, through capacitance C ₁, C ₂Deliver to multicircuit switch afterwards, deliver to data single-chip microcomputer collection plate again, we just can come each cell of accumulator is carried out cycle detection by the control multicircuit switch like this.We can not think the phase differential that obtains like this and produced by accumulator internal resistance, we have inserted capacitance because when gathering battery tension, even the model of these capacitances, size, manufacturer is all identical, also can have 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.Because 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, therefore, can come the internal resistance of calculating accumulator according to the variation of phase differential.In order to obtain the capacity that phase differential must change accumulator, even accumulator is to load discharge.Carry out a data acquisition when finishing in battery pack charging just, then to battery discharging, carry out a data acquisition at regular intervals again, along with the increase of discharge time, phase differential can reduce gradually.The phase differential of accumulator input/output signal also can generate waveform with the MATLAB software emulation and observe.

Can only observe the existence of phase differential with simulation waveform but can not specifically calculate the phase place extent, so the present invention just utilizes signal acquiring system to gather this phase differential.

As Fig. 3, the present invention proposes a kind of new method of asking two waveform phase differences---difference area-method.Promptly obtain the pairing area of phase differential of two waveforms earlier, area is quadratured just to calculate the phase differential of two waveforms then, has effectively improved the precision of phase difference measurement.As shown in Figure 3, go into output signal and send into two high-speed, high precision differential paths of single-chip microcomputer, output after the sampling is the difference in magnitude of two signals, during measurement to the one-period intensive sampling, and thereby square accumulative total summation of the difference result of two passages obtained 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 y ₁,

y ₁＝cos(ωt)+n ₁(t)

The output signal of battery pack is y ₂,

y ₂＝cos(ωt+θ)+n ₂(t)

The integration of the squared absolute value of input/output signal difference is:

${\∫}_0^T{|y_1-y_2|}^2\mathrm{d\ωt}$

With y ₁y ₂Substitution formula (11):

${\∫}_0^T{|y_1-y_2|}^2\mathrm{d\ωt}={\∫}_0^T{|\cos \left(\mathrm{\ωt}\right)+n_1\left(t\right)-\cos (\mathrm{\ωt}+\mathrm{\θ})-n_2\left(t\right)|}^2\mathrm{d\ωt}$

Formula (2-20) launched:

${\∫}_0^T{|y_1-y_2|}^2\mathrm{d\ωt}={\∫}_0^T[{\cos }^2\left(\mathrm{\ωt}\right)+2\cos \left(\mathrm{\ωt}\right)n_1\left(t\right)+n_1{\left(t\right)}^2+{\cos }^2(\mathrm{\ωt}+\mathrm{\θ})+n_2{\left(t\right)}^2+2\cos (\mathrm{\ωt}+\mathrm{\θ})n_2\left(t\right)$

$-2\cos \left(\mathrm{\ωt}\right)\cos (\mathrm{\ωt}+\mathrm{\θ})-2\cos \left(\mathrm{\ωt}\right)n_2\left(t\right)-2n_1\left(t\right)\cos (\mathrm{\ωt}+\mathrm{\θ})-2n_1\left(t\right)n_2\left(t\right)]\mathrm{d\ωt}$

Because do not have correlativity between input/output signal and the noise signal, and the integration of noise signal and any uncorrelated definite product of signals is zero, so also abbreviation gets:

${\∫}_0^T{|y_1-y_2|}^2\mathrm{d\ωt}=2T-T\cos \mathrm{\θ}$

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:

2T-Tcosθ＝A

θ＝arccos(2T-A)/T＝V

This formula is the resulting phase differential of quadraturing in a signal period, if continuous sampling was quadratured in N cycle, obtaining the result is exactly the aggregate-value of phase differential, and the method and zero passage relative method comparison phase detection result data can be amplified.Do not contain noise section in the measurement result simultaneously, effectively eliminated the error that signal noise causes.

Though the amplification of phase detection result data, the phase differential that makes component tolerance cause reduces relatively, measurement result reduces greatly to the tolerance susceptibility of circuit elements device, but above method can't fundamentally be eliminated the measurement result that component tolerance causes in the testing circuit.For example divider resistance selects the copper resistance of 10 Ω, and then according to national standard IEC 60028-1925 regulation, its error is ± 1%, Ω promptly ± 0.1, and the internal resistance of cell is the milliohm level.Also have a lot of electronic components in the testing circuit, the influence of these elements all can directly reflect on measurement result, therefore the change that can't differentiate phase differential is that the variation of accumulator internal resistance causes, still 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 that need detect much larger than us.

The main task that on-line monitoring system is finished is the accumulator degradation in the monitoring use, as long as the capacity of monitoring system energy effecting reaction accumulator, and in conjunction with detected temperature and monomer voltage as corrected parameter, the volume percent that effectively provides current each cell gets final product.

Single chip computer measurement A as a result is approximate to the phase differential area, but is based on the method that statistics is tabled look-up, and 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)

F (x) is the continuous monotonic decreasing function of monodrome.Suppose that internal resistance and phase function pass is:

R＝g(x)

G (x) is the continuous monotonic decreasing function of monodrome, and then the funtcional relationship of capacity and phase differential can be made as:

C＝h(x)

C=h (x) is the continuous monotonically increasing function of monodrome.So it is big more that the mapping relations of measured value A and accumulator capacity are the A values, capacity is big more.

Based on this thought, the method that the present invention adopts is earlier battery to be full of, and measures the phase data result in this time, obtains a data a ₀, then 3% of discharge capacity, measure again data a as a result ₁, go down to obtain a successively ₀, a ₁, a ₂, a ₃...With a ₀-a ₁Obtain a data point b ₁, a ₀-a ₂Obtain b ₂, go down successively to obtain: b ₁, b ₂, b ₃...So b ₁, b ₂, b ₃... these group data be in the accumulator operational process with respect to the 100% capacity data that 3% phase differential changes that descend successively, effectively eliminated the zero point drift that component tolerance causes.Suppose that the phase differential that tolerance causes is respectively φ in input/output signal ₁, φ ₂, then contain Δ φ in the expression formula of phase differential, and the Δ φ that at every turn measures being identical, in the process of subtracting each other, can offset.Obtain a capacity during first the installation and be 100% data, the correction of the result who just obtains according to detection in the operational process and other monomer voltage, battery context temperature obtains certain capacity.This method had been done the 2V accumulator experiment commonly used of three kinds of transformer stations at present, and repeatability is fine, and capacity is 4%～5% greater than 95% o'clock resolution, and capacity is 3% less than 95% o'clock resolution.In the actual monitoring if the data that obtain are then represented capacity greater than 95% less than b1, if the capacity that between b1 b2, then illustrates greater than 92% less than 95%, compare the judgement capacity successively.Therefore adopt this method effectively to eliminate the zero point drift that component tolerance causes, can effectively detect the health status of accumulator.

After the inventive method has been arranged, not only can implement and measure control, the more important thing is also and can use the place of accumulator such as transformer station to set up the online monitoring system of remote live power industry to in-plant accumulator.For example adopt the real time on-line monitoring system general structure of the inventive method as follows:

The monitoring system that the inventive method is implemented mainly contains three parts and forms (see figure 4), is respectively:

One, high-speed microprocessor collection plate

The single-chip microcomputer collection plate mainly has high-precision A single-chip microcomputer C8051F060 and peripheral circuit (having used isolation voltage electric current special module CE-VZ01) constitutes, the collection of information such as main responsible voltage to battery pack, electric current, temperature transfers data to ARM data processor embedded computer system by serial ports.

Two, embedded-type ARM processor

Made up Software Development Platform based on arm hardware platform embedded Linux system, the main realization obtained the data of collection plate by serial ports, and store, provide web server for distance host and local man-machine interface (touch-screen) and monitor terminal displaying live view accumulator data simultaneously, and provide data to download, for the distance host data download.

Three, man-machine interface

Man-machine interface adopts the GOT-F940 touch-screen of Mitsubishi.Directly be connected by RS-232 interface with data processor, send adjust, Query Information and receive and show accumulator information, sound and light alarm is provided, daily function such as adjust realizes man-machine interaction.

Four, terrain monitor terminal

The upper computer software of native system will be installed in present monitor terminal computing machine, use serial communication mode and the communication of ARM processor, be responsible for the initialization of accumulator remote monitoring system, the battery pack monitoring, supervisory level is set, the inquiry of reporting to the police and report to the police, accumulator information management library management.

Five, remote browse main frame

So long as provide any computing machine of IE browser all to can be used as distance host, the real-time information of inquiry transformer station battery pack.

Claims (3)

1. accumulator cell real time on-line nondestructive accurate measurement method, relate to a kind of method that detects the electricity substation accumulator internal resistance, it is characterized in that, adopt the low-frequency ac signal generator that accumulator is injected a low-frequency ac electric current signal, utilize this ac current signal, thereby measure the low-frequency ac voltage at accumulator two ends and the low-frequency ac electric current that flows through; Utilize the difference area-method to measure the phase differential of low-frequency ac voltage and the low-frequency ac electric current that flows through again.

2. according to the described accumulator cell real time on-line nondestructive accurate measurement method of claim, it is characterized in that, the low-frequency ac signal generator is gathered the monomer DC voltage and the ac voltage signal of accumulator by the couple drive amplifying circuit through the voltage sample module, again ac voltage signal and the d. c. voltage signal gathered after removing undesired signal, low-pass active filter are delivered to multichannel conversion switch, send the single-chip microcomputer collection through the A/D conversion again, obtain its amplitude; Ac voltage signal converts sine wave to square-wave signal through the zero balancing pulse shaping circuit, current signal also is directly to deliver to single-chip microcomputer through multicircuit switch on the one hand, detect its amplitude, also to convert sine wave to square-wave signal simultaneously, deliver to phase detection unit with the square-wave signal of alternating voltage then and detect their phase differential through the zero balancing pulse shaping circuit

3. according to the described accumulator cell real time on-line nondestructive accurate measurement method of claim, it is characterized in that, respectively draw a lead, on this lead, respectively be connected with a capacitance C at the two ends of each accumulator ₁, C ₂Ground connection, the signal of process accumulator is connected with multicircuit switch through the stake resistance R of an about 8-12 Ω and the other end of capacitance earth lead again, and multicircuit switch is connected with the single-chip microcomputer collection plate.

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