CN115151759A - Method for flow and/or pressure regulation in a hydraulic system - Google Patents
Method for flow and/or pressure regulation in a hydraulic system Download PDFInfo
- Publication number
- CN115151759A CN115151759A CN202180018479.XA CN202180018479A CN115151759A CN 115151759 A CN115151759 A CN 115151759A CN 202180018479 A CN202180018479 A CN 202180018479A CN 115151759 A CN115151759 A CN 115151759A
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- regulating
- speed
- threshold value
- deviation
- valve
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- 238000000034 method Methods 0.000 title claims abstract description 28
- 230000001105 regulatory effect Effects 0.000 claims abstract description 62
- 230000003044 adaptive effect Effects 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 230000006870 function Effects 0.000 description 4
- 230000006399 behavior Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
- G05D7/0629—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means
- G05D7/0635—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means by action on throttling means
Abstract
The invention relates to a method for regulating a flow and/or a pressure in a hydraulic system, comprising a control valve and a regulating unit, wherein the regulating unit determines a regulating deviation between a setpoint value and an actual value of a supply flow and/or pressure and compares the regulating deviation with at least one first threshold value, wherein the regulating unit actuates the control valve at a defined first regulating speed if the regulating deviation lies below the threshold value and actuates the control valve at a defined second regulating speed if the regulating deviation lies above the threshold value.
Description
Technical Field
The invention relates to a method for regulating a flow and/or a pressure in a hydraulic system, comprising a control valve having a control unit for actuating the control valve.
Background
A typical task of a control valve in a hydraulic system is to constantly maintain a volume flow at a certain setpoint value Q set The above. The known regulating unit determines the measured delivery flow Q and the setpoint value Q set And minimizing the adjustment deviation by means of a PI regulator. In particular in hydraulic systems with varying operating points, as is the case in heating systems, the correct configuration of the necessary regulator parameters is a challenge. The hydraulic system equation is non-linear and is dependent on the operating point of the system, which generally results in the parameters of the PI controller that are optimal for the operating point being less suitable for the other operating points. Ideally, in such a case, the regulator parameters would also have to be adjusted as a function of the operating point.
In practice, therefore, a compromise solution is mostly used, in which regulator parameters are used that function sufficiently well over the entire operating range.
Another problem with these regulating units is that the flow sensor usually provides its signal in a time-delayed manner. In order to avoid overshooting of the PI regulator due to this time delay in all operating points, the regulator is usually adjusted very slowly. Thus, although overshoot can be avoided, a time delay must be tolerated until the theoretical value is reached. Such a delay is mostly acceptable in hydraulic systems without additional regulated components (e.g. unregulated pumps). However, this is problematic if the regulators of the different equipment components interact with each other. If the device also comprises a pump whose rotational speed is regulated, for example, an interaction between the pump and the regulating valve can occur, which makes it difficult to achieve the setpoint value. This is particularly critical if the pump is operating along the secondary regulation characteristic line.
Disclosure of Invention
The object of the present application is to improve the existing regulation based on PI regulators with respect to the previously mentioned difficulties.
The core concept of the invention is that, unlike in conventional PI regulators, the difference between the setpoint value and the actual value is not restored by means of the regulator, but instead the regulating unit opens or closes the valve at a specific regulating or lifting speed. The specific value of the adjustment speed depends on the real-time adjustment deviation. Preferably, the following applies: the greater the adjustment deviation, the greater the adjustment speed.
For the method according to the invention to be implemented by the regulating unit, it is proposed that: the control unit first determines a control deviation, i.e. the difference between the setpoint value and the actual value. The control deviation is then compared with at least one first threshold value. If the control deviation lies below a defined threshold value, the control valve is adjusted at a first adjustment speed. In the event of the threshold value being exceeded, the control valve is instead actuated at a defined second control speed.
The method according to the invention and the advantageous embodiments thereof explained below can be used for flow regulation or pressure regulation by means of a regulating valve. In the case of flow regulation, the setpoint value and the actual value are related to the setpoint volume flow or the actual volume flow. In the case of pressure regulation, the setpoint value and the actual value are associated with the respective pressure value.
The direction of adjustment of the valve actuation depends on the magnitude of the setting deviation, i.e. if the actual value is greater than the setpoint value, the valve is closed at a defined setting speed, whereas for the case of actual values less than the setpoint value, the valve is opened at a defined setting speed. In the case of pressure regulation, it should be noted that the behavior is in this case the opposite to flow regulation, i.e. if the actual value is greater than the setpoint value, the valve is opened at a defined regulation rate, whereas for the case of actual values less than the setpoint value, the valve is closed at a defined regulation rate.
Preferably, the first adjustment speed is smaller than the defined second adjustment speed. Thus, if the adjustment deviation increases, the valve is operated at a greater adjustment speed. If, in contrast, only a small deviation in the setting is present, the valve is actuated at a relatively slow setting speed.
According to the invention, at least one threshold value for setting the adjustment speed is determined. It is particularly preferred that at least two threshold values are defined. In this case, the first threshold is smaller than the second threshold. If the control deviation lies below a first threshold value, the control valve is actuated at a defined, slow first control speed. If the regulation deviation is greater than the first threshold value but less than the second threshold value, the valve is actuated at a greater regulation speed. If the control deviation is greater than a second threshold value, the valve actuation takes place at the maximum adjustment speed. For example, it is provided that the first threshold value is defined such that the first adjustment speed is applied only if the setpoint value and the actual value are substantially identical (i.e. only show slight deviations) in the first adjustment. In this case, it is sufficient to operate the valve at a very slow adjustment speed. The very slow speed may also be chosen to be zero. The valve will stop.
The first threshold value and the second threshold value are preferably defined such that the second adjustment speed is applied if the theoretical value and the actual value are closely adjacent but show a greater deviation than the first threshold value. In this case, the extremely slow speed of the first adjustment speed is not sufficient to bring the theoretical value and the actual value into agreement within a suitable time window. A slightly greater adjustment speed is thus selected in this context.
The second threshold value is then defined such that it triggers the third adjustment speed only if the setpoint value and the actual value are very far apart. This covers the following practical situation: if the system has just been switched on or the theoretical value in the system has changed. In the latter case, there is a follow-up adjustment so that the valve will be opened or closed at maximum speed to ensure high system dynamics (Systemdynamik).
It may also be expedient to define a minimum threshold value which is selected to be smaller than the first threshold value, the second threshold value and all further threshold values. In order not to cause a reaction of the control valve in each identified minimum control deviation, a minimum control deviation is thus defined, beyond which the actuation of the control valve is triggered. However, the minimum threshold may also be chosen to be zero.
There are possibilities that the threshold value and/or the adjustment speed can be configured manually from the outside via an external interface or via an operating panel. It can also be provided that the control unit is implemented with an adaptive learning method which allows the threshold values and/or the adjustment speed to be automatically adapted or optimized to the given situation during operation.
In addition to the method according to the invention, the invention also relates to a device for flow and/or pressure regulation, comprising a regulating valve and a regulating unit configured to carry out the method according to the invention. The same advantages and characteristics as have been elaborated previously in accordance with the method according to the invention are thus obtained for the device. For this reason, duplicate descriptions are omitted.
Drawings
Further advantages and details of the invention are explained below on the basis of embodiments presented in the figures. Wherein:
figure 1 shows a block diagram of an adjustment unit according to the invention with two thresholds,
FIG. 2 shows a diagram of the control deviation versus the control speed for a modified embodiment of the method, and
fig. 3 shows a block diagram of a modified method according to the invention based on the diagram of fig. 2.
Detailed Description
The method according to the invention will be discussed in detail below. Compared to conventional PI regulators for flow regulation in hydraulic systems, the novel method has the following improvements and advantages:
-the dynamic behaviour up to the threshold is improved;
improved accuracy in meeting the final value;
the effort required for setting the regulator parameters is reduced.
The core concept of the invention is that the difference between the setpoint value and the actual value is not reduced by means of a regulator, but the regulating valve is always set at a defined lifting speed (speed value SV). The speed SV chosen depends on how far from the theoretical value the actual value is. The selection of a suitable adjustment speed is made by means of a threshold comparison. This functional manner can be seen in the block diagram of fig. 1.
In 1, firstly by forming a theoretical transport flow Q set And actual transport stream Q Act The difference between them to determine the adjustment deviation. However, the absolute value is not important. Only the difference is evaluated as positive or negative, which is done in box 2. But at the same time the control deviation is supplied to a selection module 3, which selects the appropriate actuating speed SV1, SV2, SV3 by respective comparison with the threshold values S1, S2, S3 and supplies it to a regulator 4, which then generates a respective actuating variable 5 for the valve. For the selection of the threshold values, S1 < S2 < S3 applies, and for the associated actuating speed SV1 < SV2 < SV3 applies as well.
Threshold S1 is a minimum threshold and presets a minimum control deviation, beyond which valve actuation is triggered. The threshold value may also be chosen to be zero. The valve is then constantly adjusted. Thereby optimally eliminating permanent noise. By appropriately defining the remaining thresholds, the adjustment scenario can be distinguished into the following three cases:
set Act case 1: the theoretical value Q and the actual value Q are almost equal:
this occurs when the calculated adjustment deviation is above the minimum threshold S1, but does not exceed the threshold S2. In such a case the approximation involves interference amount adjustment. If the theoretical value does not change, only minor signal disturbances have to be compensated. It is sufficient that the valve is adjusted only at a very slow speed SV 1.
If the actual value Q is Act At theoretical value Q set Above, the valve is closed very slowly at speed SV 1. If the actual value Q is Act At theoretical value Q set In contrast, the valve is opened slowly at the speed SV 1. Because the speed SV1 is very low, the valve essentially stops and only corrects for disturbances in the range after the decimal point.
set Act Case 2: the theoretical value Q and the actual value Q are closely approximated:
this case describes the case where the theoretical value Q is set And the actual value Q Act Close but so far apart that the extremely slow speed SV1 in case 1 is not sufficient to bring the theoretical value Q within an acceptable duration set And the actual value Q Act A agreement is reached. In this case, the regulating deviation exceeds a threshold value S2, and the value SV2 is selected for valve adjustment. The valve thus moves slightly more rapidly.
set Act Case 3: the theoretical value Q is far from the actual value Q:
this is the case if the system is switched on or the theoretical value Q set And (4) changing. In the latter case, there is a follow-up adjustment. In this case, the valve will open or close at maximum speed SV3 to ensure high system dynamics. I.e. if the regulation deviation exceeds the highest threshold value S3, the highest regulation speed SV3 is selected.
The method according to the invention has the advantage that no PI parameters have to be configured, but only three values SV1, SV2, SV3 of the boost speed and the threshold values S1, S2, S3 are set. The advantage is that these parameters SV1, SV2, SV3, S1, S2, S3 are significantly more robust with respect to the device or the operating point, which increases the chance that good default values can already be found on the manufacturer side, which default values no longer have to be adapted on the client side.
Experience at the test station has shown that: the approach with three speed values (SV 1, SV2, SV 3) works very well and is sufficient. However, it is also conceivable that instead of three speed values a plurality or an approximately infinite number of speed values can be selected. The latter variant would result in a parabolic function of the regulation deviation dependent on the regulation speed SV, as shown in fig. 2. The curve may extend through the origin of coordinates whereby the valve speed may approach zero. However, it is better that the curve (as shown in fig. 2) moves slightly upwards. The valve then surrounds the theoretical value Q at a very small lifting speed set Movement, thereby givingTheoretical value Q set The highest precision. The relevant block diagram is shown in fig. 3.
The extension of the adjustment curve is set by the manufacturer. To improve the accuracy, the adjustment curve can be adapted manually to the device by the customer. Alternatively, it is proposed: the controller can optimize the control curve for the device by means of the learning method itself.
Applications of the method for flow regulation have been presented previously. However, the concept according to the invention can also be transferred without modification to the pressure regulation, but here in the case of a reversal of the adjustment direction depending on the regulation deviation.
One possibility of using the flow rate regulation method is derived, for example, when determining the Energy Efficiency Index (EEI) of the heating circulation pump. In order to measure the EEI, it is necessary to adjust the transport flow very precisely. This is a particular challenge, since the pump simultaneously regulates and adjusts its rotational speed as a function of the delivery flow. The method presented meets this prerequisite for particularly precise regulation.
In the context of pressure regulation, the regulation curve must also be taken into account in conjunction with the regulated pump.
Claims (8)
1. Method for regulating the flow and/or pressure in a hydraulic system, comprising a regulating valve and a regulating unit, wherein the regulating unit determines a regulating deviation between a setpoint value and an actual value of a delivery flow and/or pressure and compares the regulating deviation with at least one first threshold value, wherein the regulating unit actuates the regulating valve at a defined first regulating speed if the regulating deviation lies below the threshold value and actuates the regulating valve at a defined second regulating speed if the regulating deviation lies above the threshold value.
2. The method according to claim 1, characterized in that the defined second adjustment speed is greater than the defined first adjustment speed.
3. Method according to any one of the preceding claims, characterized in that the regulating unit carries out a comparison of the regulating deviation with at least one second threshold value, which is greater than the first threshold value, wherein the regulating unit operates the regulating valve at a defined first regulating speed if the regulating deviation lies below the first threshold value; if the regulating deviation lies above the first threshold value and below the second threshold value, the regulating unit actuates the regulating valve at a defined second regulating speed; and if the regulating deviation lies above the second threshold value, the regulating unit actuates the regulating valve at a defined third regulating speed, wherein the first regulating speed is less than the second regulating speed and the second regulating speed is less than the third regulating speed.
4. Method according to any one of the preceding claims, characterized in that a minimum threshold value is defined, which is selected to be smaller than the first threshold value, the second threshold value and all further threshold values, wherein the minimum threshold value defines a minimum regulating deviation from which the manipulation of the regulating valve is carried out.
5. Method according to any one of the preceding claims, characterized in that the magnitude of the regulating deviation determines the adjustment direction of the regulating valve.
6. Method according to any of the preceding claims, characterized in that the threshold value and/or the adjustment speed can be manually configured.
7. Method according to any of the preceding claims, characterized in that the threshold value and/or the adjustment speed is adapted automatically, preferably by means of an adaptive learning method.
8. A device for flow and/or pressure regulation, comprising a regulating valve and a regulating unit configured for carrying out the method according to any one of the preceding claims.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102020001431.3 | 2020-03-05 | ||
| DE102020001431.3A DE102020001431A1 (en) | 2020-03-05 | 2020-03-05 | Method for flow and / or pressure control in a hydraulic system |
| PCT/EP2021/055379 WO2021175945A1 (en) | 2020-03-05 | 2021-03-03 | Method for controlling the flow rate and/or pressure in a hydraulic installation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115151759A true CN115151759A (en) | 2022-10-04 |
Family
ID=74858449
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180018479.XA Pending CN115151759A (en) | 2020-03-05 | 2021-03-03 | Method for flow and/or pressure regulation in a hydraulic system |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP4115122A1 (en) |
| CN (1) | CN115151759A (en) |
| DE (1) | DE102020001431A1 (en) |
| WO (1) | WO2021175945A1 (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2429956C3 (en) | 1974-06-21 | 1979-11-22 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Control device with a controller and an actuator with at least two constant adjusting speeds |
| DE2756582A1 (en) * | 1977-12-19 | 1979-06-21 | Volkswagenwerk Ag | Flow rate regulator with diaphragm actuator - has chambers with solenoid valves for regulation of room heating system |
| DE4035620A1 (en) | 1990-11-09 | 1992-05-14 | Fichtner Gmbh & Co Kg | METHOD AND DEVICE FOR MASS CURRENT CONTROL |
| DE19528253C2 (en) * | 1995-08-01 | 1997-10-16 | Gutehoffnungshuette Man | Method and device for avoiding controller instabilities in surge limit controls when operating turbomachines with controllers with high proportional gain |
| DE19615760A1 (en) * | 1996-04-20 | 1997-10-23 | Heinrich W Prof Dr In Nikolaus | Control algorithm for PID controller e.g. for secondarily controlled hydrostatic drives |
| EP2579112B1 (en) | 2011-10-06 | 2014-01-01 | Siemens Aktiengesellschaft | Regulating device |
| DE102013001921A1 (en) * | 2013-02-05 | 2014-08-07 | Man Diesel & Turbo Se | Method for operating e.g. gas conveyer system, involves opening regulating valve of operating compressor during operating shift, based on control deviation between target and actual values of controller |
| DK3428767T3 (en) * | 2017-07-11 | 2020-03-02 | Siemens Schweiz Ag | Control gain automation |
-
2020
- 2020-03-05 DE DE102020001431.3A patent/DE102020001431A1/en active Pending
-
2021
- 2021-03-03 WO PCT/EP2021/055379 patent/WO2021175945A1/en unknown
- 2021-03-03 EP EP21709972.0A patent/EP4115122A1/en active Pending
- 2021-03-03 CN CN202180018479.XA patent/CN115151759A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021175945A1 (en) | 2021-09-10 |
| DE102020001431A1 (en) | 2021-09-09 |
| EP4115122A1 (en) | 2023-01-11 |
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