CN115824320B - Flow calculation method and device based on frequency conversion of frequency converter - Google Patents
Flow calculation method and device based on frequency conversion of frequency converter Download PDFInfo
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- CN115824320B CN115824320B CN202310101804.XA CN202310101804A CN115824320B CN 115824320 B CN115824320 B CN 115824320B CN 202310101804 A CN202310101804 A CN 202310101804A CN 115824320 B CN115824320 B CN 115824320B
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Abstract
The invention relates to the technical field of bridge concrete construction, in particular to a flow calculation method and a measuring and calculating device based on frequency conversion of a frequency converter, wherein the method is realized based on an upper computer software system, a PLC control system, a frequency conversion system, a flow measuring and calculating device and a transmission system; the method specifically comprises the following steps: setting a frequency change range and a frequency increment interval of a variable frequency system through an upper computer software system, calibrating characteristic points, and respectively recording a flow corresponding value of each characteristic point through a flow measuring and calculating device; calculating the calibration factors of adjacent feature points; the actual flow at any frequency within the measurement range is calculated. The invention is based on the frequency converter, the frequency change range and the frequency increment interval of the frequency conversion system are set in advance through the upper computer software system, the flow corresponding value of each characteristic point is recorded through the flow measuring and calculating device, the actual flow and the total flow value in any frequency in the measuring range can be calculated, and the compactness and the plumpness of grouting can be ensured without using a flowmeter.
Description
Technical Field
The invention relates to the technical field of railway bridge concrete construction, in particular to a flow calculation method and a measuring and calculating device based on frequency conversion of a frequency converter.
Background
The bridge is the most important component in the railway construction process, and the prestressed duct grouting system is used as one of the most important links in the railway prestressed concrete bridge construction, and the quality of the prestressed concrete bridge has a great effect on guaranteeing the safety and the durability of the bridge. The prestressed duct grouting system consists of a PLC control system, a feeding system, a stirring system, a pulp storage system, a transmission system, a frequency conversion system, a flowmeter and the like, and the sum of the duct pulp inlet quantity is calculated in real time through the flowmeter, so that the actual duct pulp inlet quantity is ensured to reach the duct theoretical pulp inlet quantity, and the compactness and the fullness of duct grouting are ensured. Whether the tunnel grouting is compact and full directly influences whether the prestressed tendons are corroded, influences the joint working degree of the prestressed tendons and the structure, and further influences the safety and durability of the bridge. At present, a method for calculating flow by a flowmeter is generally adopted in a prestressed duct grouting system, but the flowmeter is high in cost and easy to damage. Therefore, it is necessary to design a calculation method and a calculation device for calculating the flow of the alternative flowmeter, which not only can ensure the compactness and the plumpness of grouting, but also can reduce the equipment cost.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a flow calculation method and a measuring and calculating device based on frequency conversion of a frequency converter.
The technical scheme adopted for solving the technical problems is as follows:
the flow calculation method based on frequency conversion of the frequency converter is realized based on an upper computer software system, a PLC control system, a frequency conversion system, a flow measuring and calculating device and a transmission system, and specifically comprises the following steps:
step 1, controlling a PLC control system to set a frequency output change range of a variable frequency system through an upper computer software system
Frequency increment interval +.>
The calibration feature point is->
Wherein->
，
The method comprises the steps of carrying out a first treatment on the surface of the The flow measuring and calculating device respectively records the flow velocity output value of each characteristic point by collecting the information of the variable frequency system and the transmission system>
Wherein->
；
Step 2, calculating the adjacent characteristic point calibration factors according to the result of the step 1
The calculation formula of the calibration factor is as follows:
wherein, the liquid crystal display device comprises a liquid crystal display device,
is a characteristic point, hz; />
Is->
Flow velocity output value corresponding to characteristic point, +.>
；
Step 3, calculating the actual flow velocity in any frequency in the measuring range, wherein the calculation formula is as follows:
wherein the method comprises the steps of
For measuring the actual flow rate value at any position in the range, < >>
Is->
Small and closest characteristic flow velocity output value, +.>
Is->
And->
Scaling factors of neighboring feature points +.>
Is->
Corresponding feature points, < >>
。
The technical scheme calculates the flow based on frequency conversion of the frequency converter, a flowmeter is not needed, the cost is low, the compactness and the fullness of grouting can be guaranteed, meanwhile, electric energy can be saved through frequency modulation of a transmission system, and the purpose of energy conservation is achieved.
Furthermore, the power-on test is performed before the step 1, so that the interaction communication of the upper computer software system, the PLC control system, the variable frequency system, the flow measuring and calculating device, the transmission system and other systems is normal.
Further, the frequency change range of the frequency converter
May be 10-50 Hz, such as 30Hz, 35Hz, 50Hz, etc.
Further, the frequency converter frequency increment interval
May be 1Hz, 1.5Hz, 2Hz, 3Hz, etc. A large amount of experimental data show that the smaller the increment interval of the frequency converter is, the better the flow velocity linearization relation is, and the higher the measured flow velocity accuracy is, so that the calculated flow value is more accurate, and the specific increment interval can be determined according to actual conditions, and generally 1Hz is taken.
Further, the initial frequency of the frequency converter is set to 15Hz.
Further, the upper computer software system is in bidirectional connection with the PLC control system, the PLC control system is in bidirectional connection with the variable frequency system, the output end of the variable frequency system is respectively connected with the input end of the transmission system and the input end of the flow measuring and calculating device, the output end of the transmission system is connected with the input end of the flow measuring and calculating device, and the output end of the flow measuring and calculating device is in bidirectional connection with the upper computer software system.
Further, the upper computer software system is used for setting a frequency change range and a frequency increment interval of the variable frequency system through the PLC control system, collecting information of the variable frequency system and the transmission system through the flow measuring and calculating device, calculating the actual flow velocity at any frequency in the measurement range, and then calculating the total flow; the variable frequency system is used for adjusting the power and slurry feeding amount of the transmission system, realizing variable speed operation, achieving the purpose of energy saving and better ensuring the compactness and the plumpness of channel grouting.
In addition, in order to achieve the above object, the present invention further provides a flow measurement device based on frequency conversion of a frequency converter, the flow measurement device comprising:
the frequency acquisition module is used for acquiring a target hysteresis frequency through the frequency of a preset frequency conversion system;
the flow velocity measurement module is used for determining each characteristic point and a flow velocity output corresponding value corresponding to each characteristic point;
the calibration factor calculation module is used for calculating the calibration factors of the adjacent feature points according to the flow velocity output corresponding values;
the flow rate calculation module is used for calculating all actual flow rates in a preset effective measurement range according to the calibration factors;
and the flow calculation module is used for calculating all the actual flows in a preset effective measurement range according to the actual flow rate and time.
The invention has the technical effects that:
compared with the prior art, the flow calculation method based on frequency conversion of the frequency converter, provided by the invention, is based on the frequency converter, the frequency change range and the frequency increment interval of the frequency conversion system are set in advance through an upper computer software system, and the flow output value of each characteristic point is recorded respectively, so that the actual flow and the total flow value in any frequency in the measurement range can be calculated, the compactness and the fullness of grouting can be ensured without using a flowmeter, and the equipment cost is saved; the frequency modulation of the driving system through the frequency conversion system can save electric energy and achieve the purpose of energy conservation.
Drawings
FIG. 1 is a block diagram of the upper computer software system, the PLC control system, the variable frequency system, the flow measuring and calculating device and the transmission system of the invention;
FIG. 2 is a block diagram of a flow measurement device according to the present invention;
FIG. 3 is a flow velocity value sampling chart calculated by the flow rate calculation method based on frequency conversion of the frequency converter;
fig. 4 is a graph of flow rate values collected by a flow meter versus samples according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings of the specification.
Example 1:
the embodiment relates to a flow calculation method based on frequency conversion of a frequency converter, which is realized based on an upper computer software system, a PLC control system, a frequency conversion system, a flow measuring and calculating device and a transmission system.
As shown in fig. 1, the upper computer software system is in bidirectional connection with the PLC control system, the PLC control system is in bidirectional connection with the variable frequency system, the output end of the variable frequency system is respectively connected with the input end of the transmission system and the input end of the flow measuring and calculating device, the output end of the transmission system is connected with the input end of the flow measuring and calculating device, and the output end of the flow measuring and calculating device is in bidirectional connection with the upper computer software system; the upper computer software system is used for setting the frequency change range and the frequency increment interval of the variable frequency system through the PLC control system, collecting information of the variable frequency system and the transmission system through the flow measuring and calculating device, measuring the actual flow velocity at any frequency in the range, and calculating the total flow; the variable frequency system is used for adjusting the power and slurry feeding amount of the transmission system, realizing variable speed operation, achieving the purpose of energy saving and better ensuring the compactness and the plumpness of channel grouting.
The flow calculation method specifically comprises the following steps:
(1) Firstly, carrying out power-on test to ensure that the interaction communication of the upper computer software system, the PLC control system, the variable frequency system, the flow measuring and calculating device, the transmission system and other systems is normal;
(2) Setting the frequency change range of the variable frequency system through an upper computer software system
For 35Hz, in order to prolong the service life of the transmission system and reduce the starting time of the bridge grouting equipment, the initial frequency of the variable frequency system is generally set to be 15Hz, namely the embodiment is preferably increased from 15Hz to 50Hz, and a frequency increasing interval is set>
1Hz, the calibration characteristic point is +.>
：
And respectively recording the flow velocity corresponding value of each characteristic point
：
(3) Calculating the adjacent characteristic point calibration factors according to the results of the steps
The calculation formula of the calibration factor is as follows:
wherein, the liquid crystal display device comprises a liquid crystal display device,
is a characteristic point, hz; />
Is->
Flow velocity output value corresponding to characteristic point, +.>
；
(4) Calculating the actual flow velocity at any frequency in the measurement range, wherein the calculation formula is as follows:
wherein the method comprises the steps of
For measuring the actual flow rate value at any position in the range, < >>
；/>
Is->
Small and closest characteristic flow velocity output value, +.>
，/>
Is->
And->
Scaling factors of neighboring feature points +.>
Is->
The corresponding characteristic points are used for the display of the display device,
。
test example:
the water-gel ratio of the prestressed duct grouting material is set to be 0.30, the flow calculation method is adopted, the frequency is set to be from 15Hz to 50Hz through an upper computer software system, the flow under each frequency is recorded, and meanwhile, the flow value is compared with the flow value acquired by the flowmeter.
As shown in fig. 3, in order to sample the flow velocity value calculated by the frequency conversion method based on the frequency converter and the flow measuring and calculating device, fig. 4 is a comparison sample of the flow velocity value collected by the flowmeter, and the slope K is basically consistent through a large amount of data comparison, so that the field requirement is completely satisfied.
When the device is used on site, the total flow is calculated through the flow calculation method based on frequency conversion of the frequency converter and the known calibration factors in an accumulated mode, so that the device can completely replace a high-cost flowmeter, ensure compactness and fullness of grouting of a pore canal, reduce equipment cost, and achieve the purpose of saving electric energy through frequency modulation of a screw pump, and has certain economic benefit.
The specific total flow calculation method comprises the following steps:
for example, calculating
Total flow in time period s, will be +.>
The time axis equally divides N equal parts according to the length of 100ms, and the +.>
Then from->
Each 100ms after the start is used for collecting the frequency value of the current variable frequency system through the flow measuring and calculating device, obtaining the flow velocity value corresponding to the frequency through a table look-up mode, and adding the flow value of the whole time point to be divided by 10 to obtain the total flow of the time period. If higher accuracy is required, samples can be taken at 50ms,20 ms.
Example 2:
as shown in fig. 2, the present embodiment relates to a flow measurement device based on frequency conversion of a frequency converter, where the flow measurement device includes:
the frequency acquisition module is used for acquiring a target hysteresis frequency through the frequency of a preset frequency conversion system;
the flow velocity measurement module is used for determining each characteristic point and a flow velocity output corresponding value corresponding to each characteristic point;
the calibration factor calculation module is used for calculating the calibration factors of the adjacent feature points according to the flow velocity output corresponding values;
the flow rate calculation module is used for calculating all actual flow rates in a preset effective measurement range according to the calibration factors;
and the flow calculation module is used for calculating all the actual flows in a preset effective measurement range according to the actual flow rate and time.
The flow measuring and calculating device realizes the calculation of the actual flow velocity and the total flow at any frequency in the measuring range, and improves the working efficiency and the calculation precision.
The above embodiments are merely examples of the present invention, and the scope of the present invention is not limited to the above embodiments, and any suitable changes or modifications made by those skilled in the art, which are consistent with the claims of the present invention, shall fall within the scope of the present invention.
Claims (6)
1. The flow calculation method based on the frequency conversion of the frequency converter is characterized by being realized based on an upper computer software system, a PLC control system, a frequency conversion system, a flow measuring and calculating device and a transmission system; the upper computer software system is in bidirectional connection with the PLC control system, the PLC control system is in bidirectional connection with the variable frequency system, the output end of the variable frequency system is respectively connected with the input end of the transmission system and the input end of the flow measuring and calculating device, the output end of the transmission system is connected with the input end of the flow measuring and calculating device, and the output end of the flow measuring and calculating device is in bidirectional connection with the upper computer software system;
the upper computer software system is used for setting the frequency change range and the frequency increment interval of the variable frequency system through the PLC control system, collecting information of the variable frequency system and the transmission system through the flow measuring and calculating device, calculating the actual flow velocity at any frequency in the measurement range, and then calculating the total flow; the variable frequency system is used for adjusting the power and slurry feeding quantity of the transmission system to realize variable speed operation;
the flow measurement device comprises:
the frequency acquisition module is used for acquiring a target hysteresis frequency through the frequency of a preset frequency conversion system;
the flow velocity measurement module is used for determining each characteristic point and a flow velocity output corresponding value corresponding to each characteristic point;
the calibration factor calculation module is used for calculating the calibration factors of the adjacent feature points according to the flow velocity output corresponding values;
the flow rate calculation module is used for calculating all actual flow rates in a preset effective measurement range according to the calibration factors;
the flow calculation module is used for calculating all actual flows in a preset effective measurement range according to the actual flow velocity and time;
the method specifically comprises the following steps:
step 1, an upper computer software system controls a PLC control system to set a frequency output change range T of a variable frequency system Range of variation Frequency increment interval T Incremental interval The calibration characteristic point is T n Wherein n= 0,1,2, 3T Range of variation ，T Incremental interval ＝T n -T n-1 The method comprises the steps of carrying out a first treatment on the surface of the The flow measuring and calculating device respectively records the flow velocity output value Y of each characteristic point by collecting the information of the variable frequency system and the transmission system n Wherein n= 0,1,2, 3T Range of variation ；
Step 2, calculating the adjacent characteristic point calibration factor K according to the result of the step 1 n The calculation formula of the calibration factor is as follows:
K n ＝(Y n -Y n-1 )/(T n -T n-1 )，n≥1，
wherein T is n Is a feature point; y is Y n Is T n The flow velocity output value corresponding to the characteristic point;
step 3, calculating the actual flow velocity in any frequency in the measuring range, wherein the calculation formula is as follows:
Y k ＝K n *T n-1 +Y n-1 ，Y n ＞Y k ＞Y n-1 ；
wherein Y is k To measure the actual flow velocity value at any position in the range, Y n-1 Is of ratio Y k Small and closest characteristic point flow velocity output value, K n Is Y n And Y is equal to n-1 Scaling factor, T, of adjacent feature points n-1 Is Y n-1 Corresponding feature points.
2. The method for calculating the flow based on the frequency conversion of the frequency converter according to claim 1, wherein the power-on test is performed before the step 1, so that the interaction communication among the upper computer software system, the PLC control system, the frequency conversion system, the transmission system and the flow measuring and calculating device is normal.
3. The method for calculating the flow based on the frequency conversion of the frequency converter according to claim 1, wherein the frequency change range T of the frequency converter Range of variation Is 10-50 Hz.
4. Frequency converter based according to claim 1The frequency-conversion flow computing method is characterized in that the frequency-conversion frequency increment interval T Incremental interval 1Hz, 1.5Hz, 2Hz or 3Hz.
5. The method for calculating the flow based on the frequency conversion of the frequency converter according to claim 1, wherein the frequency change range T of the frequency converter Range of variation Is 35Hz; the frequency converter frequency increment interval T Incremental interval Is 1Hz.
6. The method for calculating the flow based on the frequency conversion of the frequency converter according to claim 5, wherein the initial frequency of the frequency converter is set to be 15Hz.
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