Method for operating a pump system

Abstract

A method for operating a pump system, preferably comprising more than one pump, the method comprising the steps of obtaining at least one target parameter to be optimized based on a target value for each pump, obtaining an operation target, wherein the operation target is provided by one or more of the pumps, each of which is operated with a separate operation parameter, acquiring a relationship between the operation parameter and the target value for more than one, and preferably all, of the pumps and determining an objective function, determining a maximum / minimum of the objective function and obtaining an operation parameter for at least one pump, and controlling the at least one pump to operate with the obtained operation parameter to optimize the target parameter.

Description

Technical Field

[0001] This invention relates to a method for operating a pump system, which preferably includes more than one pump, i.e., a vacuum pump or a compressor, configured as a variable speed pump (VSD) or a constant speed pump (FS). Furthermore, this invention relates to a pump system. Background Technology

[0002] Pump systems can include different types of pumps and / or various pumps to provide customers with operational objectives, such as specific flow rates or specific pressures, i.e., vacuum or pressurized fluid. The individual pumps in the pump system can be controlled in various ways to achieve these operational objectives.

[0003] The customer's objective is to operate the pump system in an optimized state, i.e., to minimize energy consumption. However, particularly regarding energy consumption, there are complex correlations between the operating values ​​(such as operating speed) of each pump contributing to the operational objective and the corresponding target parameters, for each pump type (vortex pump, screw pump, etc.) and for each pump itself (e.g., two screw pumps of different sizes or capacities). For example, Figure 1 The diagram illustrates a non-linear relationship between flow rate and power consumption for an exemplary vacuum pump, where power consumption is the power consumption per unit flow rate or power efficiency. Different vacuum pumps will have a different relationship. Furthermore, constraints must be considered for each pump: each VSD pump can deliver a continuous flow rate between its minimum and maximum flow rates. However, a VSD pump cannot deliver a flow rate between 0 and its minimum value, nor can it deliver a flow rate higher than its maximum value. Each FS pump can only deliver two flow rate values: 0 or its maximum value. The total flow rate needs to be within a certain range around the operational objectives provided to the customer. Given the complex correlation between the operating values ​​of each pump and the given constraints, operating the pump system in its optimal state is not an obvious task. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a method for operating a pump system in an optimized state.

[0005] This problem is solved by the method according to claim 1 and the pump system according to claim 12.

[0006] The method for operating a pump system according to the present invention includes the following steps, wherein the pump system preferably includes more than one pump, i.e., a vacuum pump and / or a compressor, wherein each of the pumps may be configured as a variable speed pump (VSD) or a fixed speed pump (FS):

[0007] At least one target parameter to be optimized is obtained based on the target value of each pump;

[0008] An operational objective is obtained, wherein the operational objective is provided by one or more of the pumps, each of the pumps operating with individual operational parameters;

[0009] For more than one pump in the pump system, and preferably all pumps, the relationship between the operating parameters and the target value is obtained, and an objective function is determined;

[0010] Determine the maximum / minimum value of the objective function and obtain at least one pump operating parameter; and

[0011] Control at least one pump to operate using the obtained operating parameters to optimize the target parameters.

[0012] The target parameters to be optimized are the target parameters for the entire pump system, where each individual pump contributes to the target parameters through its own target value.

[0013] The operational objective is given by the task of the pump system, i.e., the customer, and is provided by one or more pumps in the pump system in combination, with each pump operating with individual operating parameters that contribute to the operational objective.

[0014] The relationship between the operating parameters and target values ​​of the pump under consideration can be determined as a functional relationship or through a lookup table. The pump manufacturer is aware of this relationship for the pump and can easily implement it. Furthermore, the objective function provides the functional relationship between the operating target and the target parameters of the pump under consideration, based on the individual relationship between the operating parameters and target values ​​for each pump under consideration.

[0015] Based on the objective function, the maximum or minimum value is determined as the optimization point, thereby obtaining the operating parameters of at least one or more pumps. Specifically, operating parameters for the optimized state are determined for each pump under consideration.

[0016] Using the obtained operating parameters for each pump, operate at least one pump in order to optimize the target parameters.

[0017] Therefore, firstly, operational objectives and target parameters are defined, whereby the target parameters will be optimized. Then, for each pump, the relationship between the target value and the operational parameters is established, and an objective function is determined. Using the objective function, optimized operational parameters for at least one pump are obtained, and the pump system is then controlled using these at least one optimized variant parameter to optimize the target parameters. Preferably, optimized operational parameters are determined for each of the pumps from the objective function, and even more preferably, optimized operational parameters are determined for each pump in the pump system.

[0018] Preferably, the operational target is the flow rate or pressure provided by the pump system. Therefore, the pump system must provide a specific flow rate or pressure according to the task it is tasked with. This involves controlling the pumps in the system to provide the operational target, i.e., the flow rate or pressure, while optimizing the target parameters of the pump system. Preferably, the operational target needs to be within a margin offset defined by the task and delivered by the pump system. The operational target must be within these margins to ensure the quality of service of the pump system. If the operational target is, for example, flow rate, the operating parameters of individual pumps can be operating speeds to provide a specific flow rate, such that the sum of all pumps constitutes the operational target. The same applies if the operational target is pressure or any other defined operational objective.

[0019] Preferably, the target parameter is one or more of the pump system's energy consumption, water / oil consumption, and maintenance reduction. Therefore, the present invention aims to reduce energy consumption and / or water / oil consumption and / or increase the maintenance intervals of the pump system. Preferably, one or more of the target parameters can be combined, and preferably, prioritization of the target parameters is possible. If the target parameter is energy consumption, then the target value for a single pump is the energy consumption of that single pump.

[0020] Preferably, the determination of the maximum / minimum value of the objective function is performed during the first run of the FS, which is considered to be a VSD providing continuous operating parameters. In the real world, as mentioned above, the FS can only provide 0 or the maximum speed or flow rate. However, to reliably find the maximum / minimum value of the objective function, the FS is considered to be a VSD providing continuous operating parameters. Therefore, it is ensured that the maximum / minimum value of the objective function can be found, or at least the operating parameters of at least one pump that are close to this optimal value can be found.

[0021] Preferably, if not all pumps (FS) have operating parameters of 0 or full speed in the first run (i.e., the operating parameters can match the actual operating state of the FS, and the FS can be controlled accordingly), the operating parameters determined in the first run are used as the starting point for the second run to determine the maximum / minimum value of the objective function, wherein the step size for determining the maximum / minimum value of the objective function is increased. Specifically, the step size is increased only for FS. By increasing the step size to approach the full operating range of the FS, i.e., 0 and maximum speed, it is ensured that, at the end of the second run, the operating parameters of 0 or full speed for each FS are determined. Therefore, at least through the second run, it can be determined that the operating parameters of the considered pump are close to the optimal value, which can be used to control the operation of individual pumps to optimize the objective parameters.

[0022] Preferably, if the operational objective is the flow rate provided by the pump system, and the optimization parameter is energy consumption or water / oil consumption, then the objective function is given by the following equation.

[0023]

[0024] Where Q represents the flow rate distributed among all available pumps. i Indicates pump i (Pump i) flow rate, pump i For VSD or FS, and x i The flow ratio, representing the flow rate of pump i compared to its maximum flow rate at the setpoint pressure, is expressed by the following formula:

[0025]

[0026] In addition, g i This is a lookup table showing the power consumption of pump i at the setpoint pressure for VSD. j This represents the fixed power of pump j at the setpoint pressure for FS. n represents the number of all available VSDs, and m represents the number of all available FSs. The target parameters are then defined by the target vector X = {x1, x2, ... x}. n , ...x n+m The following is provided for optimization.

[0027] Preferably, constraints are considered. For VSD, the flow rate of the vacuum pump is given by the following formula:

[0028]

[0029] This means that a VSD can provide zero traffic or traffic between its minimum and maximum traffic. The constraint on the FS is about x. j The flow rate given by ∈{0,1} means that FS can provide zero or maximum flow rate. Furthermore, the provided flow rate must be within the margin of the required flow rate in order to perform the tasks of the connected pressurization system.

[0030] Preferably, the minimum / maximum value of the objective function is determined by a numerical gradient, which is applied to each of the pumps with a step size of lr, by x′. i =x i -lr*grad xj This provides the operation parameter x′. i .

[0031] Preferably, the step size for the first run is less than 0.2, and more preferably less than 0.1, to ensure that the maximum / minimum value of the objective function is found reliably. However, this will result in unrealistic values ​​for the FS with operating parameters between 0 and 1.

[0032] Preferably, the step size of the second run is greater than 0.5, and preferably 1, to ensure that the operating parameters of FS are 0 or 1, which is possible when running FS. Therefore, if the first run to determine the maximum / minimum value of the objective function provides FS operating parameters between 0 and 1 that FS cannot achieve, the second run is necessary, where the operating parameters of FS are forced to be 0 or 1 due to the increased step size.

[0033] Preferably, if the target parameter includes maintenance reduction, the method further includes a step of classifying pumps by running hours, selecting those pumps with the fewest running hours that, together, can provide the operational target. If the target parameter is maintenance reduction alone, the selected pumps are controlled to provide the operational target. This ensures that no pump in the pump system exceeds the running hours before the next maintenance, thereby increasing the maintenance interval.

[0034] If the target parameters include energy consumption or water / oil consumption and maintenance reduction, then the selected pumps are included in the objective function to find the operating parameters of the selected pumps, thereby also optimizing the target parameters for energy consumption. Specifically, more pumps can be included in the objective function on the order of operating hours to provide greater freedom in optimizing the target parameters. If two pumps are sufficient to meet the operational target, but five pumps in the pump system are below a given threshold of operating hours, then all five pumps are included in the objective function to determine the optimized target parameters.

[0035] Preferably, the threshold for the number of pumps considered, or the threshold for the maximum operating hours used to consider the pumps in the objective function, is determined based on a priority value, which is specifically set by the customer or predetermined, thereby providing a priority for the target parameter. Wherein, if the priority is maintenance reduction, only those pumps necessary to achieve the operational target are selected. If the priority is energy consumption or water / oil consumption, more pumps in the pump system are considered, and preferably all pumps in the pump system are considered, regardless of their operating hours. For priorities shifting from maintenance reduction to energy consumption or water / oil consumption, the objective function will consider an increasing number of pumps, thus having operating hours closer to the next maintenance interval. This increases the degrees of freedom of the objective function to provide the optimal value for the target parameter.

[0036] In another aspect of the invention, a pump system comprising more than one pump is provided. The pumps may be vacuum pumps and / or compressors. Furthermore, each of the pumps is preferably configured as a variable speed pump (VSD) or a fixed speed pump (FS). Additionally, the pump system includes a controller connected to each pump for controlling the operation of the pumps. The controller is configured to perform the methods described above. Attached Figure Description

[0037] The invention will now be described in more detail with reference to the accompanying drawings.

[0038] The attached diagram shows:

[0039] Figure 1 An exemplary relationship between flow rate and power consumption per unit flow rate of a pump is shown.

[0040] Figure 2 An embodiment of the method according to the present invention is shown.

[0041] Figure 3 Detailed embodiments of the method according to the present invention are shown.

[0042] Figure 4A Detailed embodiments of the method according to the present invention are shown.

[0043] Figure 4B An example of the embodiment given in Figure 4a is shown, and

[0044] Figure 5 An embodiment of the pump system according to the present invention is shown. Detailed Implementation

[0045] The method according to the invention relates to operating a pump system. Preferably, the pump system includes more than one pump, each of which can be configured as a variable speed pump (VSD) or a fixed speed pump (FS). Each of the pumps can be a compressor or a vacuum pump. Preferably, more than one VSD and / or more than one FS is used. The pumps in the pump system work together to provide flow or pressure to a pressurization system connected to the pump system, thereby performing a specific task.

[0046] The steps of the method according to the invention are as follows: Figure 2 Description in Chinese:

[0047] In step S01, at least one target parameter to be optimized is obtained by pre-setting target parameters by the manufacturer or through customer input. The target parameter is based on the target value of at least one pump in the pump system, and preferably on the target value of each pump in the pump system. Therefore, the target parameter essentially represents the parameter to be optimized by this operating method. Preferably, the target parameter can be the energy consumption of the pump system, the water / oil consumption of the pump system (especially if a water ring pump is used), or a reduction in pump system maintenance, i.e., an increase in the maintenance interval of the pump system. Each pump in the pump system contributes to the target parameter through its individual target value; for example, each pump has a specific energy consumption combined with the energy consumption of other pumps in the pump system, resulting in the total energy consumption of the entire pump system being optimized as the target parameter.

[0048] In step S02, at least one operational target can be obtained either by pre-setting the operational target by the manufacturer or through customer input. The operational target can be the flow rate or pressure delivered by the pump system. The operational target is provided by one or more pumps in the pump system, each operating with individual operating parameters. The operating parameters represent the contribution of each pump to the operational target of all pumps in the pump system or at least a combination of pumps considered in the pump system. The operating parameters can be related to the pump's operating speed.

[0049] In step S03, the relationship between operating parameters and target values ​​is obtained for each pump. Specifically, if different types of pumps and / or different pumps, such as pumps of different sizes, ages, or manufacturers, are used in the pump system, then for each individual pump, a specific relationship exists between operating parameters and a specific target value, such as the pump's operating speed or the flow rate provided at a specific pressure, and the specific target value, for example, is energy consumption. This relationship is typically non-linear. (The text then discusses non-linear behavior.) Figure 1 An example illustrating this relationship between the flow rate and energy consumption of a vacuum pump is provided. The relationship between the operating parameters and target values ​​of each pump can be provided by a lookup table. Based on the relationships obtained for each pump, a combined objective function for each pump under consideration in the pump system is determined, and preferably a combined objective function for all pumps in the pump system is determined. The objective function provides the relationship between the operating parameters and target parameters of each of the pumps under consideration.

[0050] In step S04, the maximum or minimum value of the objective function is determined. The maximum or minimum value is selected based on the target parameter to be optimized, regardless of whether the target parameter needs to be maximized or minimized. For example, energy consumption should be minimized, leading to the determination of the minimum value of the objective function. The operating parameters of at least one pump are obtained from the maximum / minimum value of the objective function, and preferably, the operating parameters of each pump in the pump system are obtained.

[0051] In step S05, at least one pump in the pump system, and preferably all pumps, are controlled to operate according to the obtained operating parameters to optimize the target parameters. Therefore, by determining the maximum / minimum value of the objective function, the target parameters can be optimized, and the corresponding operating parameters for the pumps under consideration can be obtained. The operating parameters are selected such that the operating objective is still met, i.e., the pump system provides the required flow rate or pressure to perform a specific task through the pump system.

[0052] In a specific example, Q represents the flow rate to be distributed among all available pumps as an operational target. Furthermore, Q... i Let x represent the flow rate delivered by pump i, and x iThis represents the flow ratio compared to the maximum flow rate of pump i at the setpoint pressure, according to the following equation.

[0053]

[0054] In addition, g i This is a lookup table representing the power of pump i, which acts as a VSD, at the setpoint pressure. Similarly, let Power... j Let n represent the fixed power consumed by pump j as a FS at the setpoint pressure. Furthermore, let n represent the number of all available VSDs, and let m represent the number of all available FSs. Then the objective parameter is the vector X = {x1, x2, ... x} to be optimized. n , ...x n+m Furthermore, the objective function can be provided by the following formula:

[0055]

[0056] The objective function is subject to some constraints because the VSD may not deliver traffic, or may deliver traffic between the VSD's minimum and maximum traffic, i.e.

[0057]

[0058] FS pumps can provide only 0 flow or their maximum flow, i.e., x. j ∈{0,1}.

[0059] In addition, the target of the operation must be determined by the offset. low and offset high Within certain margins of the bound, it can be written as

[0060]

[0061] Due to the multiple pumps and their interrelationships, it is impossible to determine the gradient of each pump individually and directly. Furthermore, the numerical gradient cannot be determined for the step function. Instead, each descent step is divided into n sub-steps, where N = n + m refers to the total number of pumps. In each sub-step i, the following is calculated:

[0062]

[0063]

[0064]

[0065] x′ i =g -1 (flow demand -g(x′1,x′2,...,x′ N ))

[0066] Where g -1 It is to transfer traffic Q i Convert to ratio x i The function is given by the step size lr, which is not always fixed. Instead, the step size lr can be adjusted in each sub-step. The result of the sub-step that minimizes the total power consumption is taken as the output of that step. Therefore, through the above calculations, the target parameter approaches its optimal value with a small step size lr considering the continuous flow available from the VSD.

[0067] However, if the same method is applied to a FS with only the flow corresponding to 0 or the maximum flow of the FS, it leads to unexpected and unrealistic results that cannot be achieved by the FS.

[0068] A solution was provided, and in Figure 3 The solution is described in section S41. In step S41, assuming the FS is considered VSD, i.e., the maximum / minimum value of the objective function is determined in the first run using a small step size toward the optimal value of the objective parameter. The step size lr is preferably less than 0.2, and even more preferably less than 0.1.

[0069] In step S42, it is checked whether all operating parameters of the FS are 0 or the FS can deliver at full speed during the first run.

[0070] In step S43, if not all operating parameters of the FS are 0 or at full speed, the operating parameters determined in step S41 are used as the starting point for the second run to determine the maximum / minimum value of the objective function, wherein for each FS, the step size lr used to determine the maximum / minimum value of the objective function is increased. Preferably, the step size lr is chosen to be greater than 0.5, and preferably 1. Therefore, due to the first run, the operating parameters are already close to their optimal values ​​relative to the objective parameters. In the second run, due to the increased step size of lr, it is ensured that operating parameters of 0 or 1 are obtained for each FS.

[0071] Therefore, by determining the maximum / minimum value of the objective function through two runs, the operating parameters for optimization can be found, where for FS, the constraint is considered to provide 0 flow rate or its maximum flow rate. This enables a pump system with multiple different pumps, including VSD and FS pumps, to operate reliably in an optimized state.

[0072] Alternatively, the target parameter could be a reduction in maintenance or an increase in maintenance intervals, such as... Figure 4A and 4BAs described in [the document]. In step S50, all pumps in the considered pumps and the preferred pump system are classified according to their operating hours. In step S51, those pumps with the fewest operating hours are selected, as they together can provide the operational target. Figure 4B The document also exemplarily depicts a vacuum pump system with five vacuum pumps 10. According to step S50, these vacuum pumps are categorized by operating hours to form a group of vacuum pumps 12. Those vacuum pumps 15 that can meet the operational objectives are selected. Figure 4B In the example, the selected vacuum pump 15 is vacuum pumps 2 and 1, which are sufficient to provide the operational target. Therefore, only vacuum pumps 2 and 1 are controlled to operate as operating vacuum pump 20 in order to provide the operational target, thereby reducing maintenance requirements, i.e., increasing maintenance intervals.

[0073] In addition, reducing energy consumption or increasing maintenance intervals can be prioritized. If reducing energy consumption is a priority, then in step S53, all pumps are selected, regardless of their operating hours. Figure 4B In the example, all five vacuum pumps 19 are selected to determine the maximum / minimum value of the objective function in order to optimize the energy consumption of the five vacuum pumps. Therefore, all five vacuum pumps are operated as operating vacuum pumps 24 to deliver the operational objective with minimal energy consumption.

[0074] Between a more balanced priority of increasing maintenance intervals and reducing energy consumption, more pumps are selected from the available pumps than are needed to meet the operational objectives, based on the priority in step S52. Figure 4B In the example, three of the five vacuum pumps 17 are selected and considered in the objective function to optimize the target parameters of energy consumption. In this example, the two remaining vacuum pumps 3 and 5 may have high operating hours. To avoid maintenance and to increase maintenance intervals, these two vacuum pumps 3 and 5 are excluded, and only three vacuum pumps 2, 1, and 4 operate as the operating vacuum pump 22. The number of vacuum pumps selected depends on the given priority. Therefore, by adjusting the priority from... Figure 4B The shift in priority from reducing maintenance requirements in Example 15 to reducing energy consumption, as in Example 19, allows for the availability of numerous steps corresponding to the increased number of vacuum pumps considered in the objective function, in order to determine optimized operating parameters to achieve the target parameters. The vacuum pump system can then operate in an optimized state.

[0075] refer to Figure 5The illustration shows an example of a pump system having five pumps 32, ..., 40 arranged in parallel and connected to a common inlet 42 and preferably a common outlet 44, to provide sufficient flow to a pressurized system connected to the pump system to perform a specific task. Each of the pumps 32, ..., 40 is a compressor or a vacuum pump. Furthermore, each of the pumps 32, ..., 40 is configured as a VSD or FS. All pumps 32, ..., 40 are connected to a common controller 31, which is configured to perform the aforementioned operating method.

Claims

1. A method for operating a vacuum pump system comprising more than one pump, said pump being configured as a variable speed pump or a constant speed pump, the method comprising the steps of: At least one target parameter to be optimized is obtained based on the target value of each pump; An operational objective is obtained, wherein the operational objective is provided by one or more of the pumps, each of the pumps operating with individual operational parameters; For more than one pump, the relationship between the operating parameters and the target value is obtained, and the objective function is determined; Determine the maximum / minimum value of the objective function and obtain the operating parameters of at least one pump; Control at least one pump to operate using the obtained operating parameters to optimize the target parameters; The determination of the maximum / minimum value of the objective function is performed in the first run, where the constant speed pump is considered to be a variable speed pump that provides continuous operating parameters; as well as If not all constant-speed pumps have operating parameters of zero or full speed in the first run, the determined operating parameters are used as the starting point for the second run to determine the maximum / minimum value of the objective function, wherein only the step size of the constant-speed pumps is increased.

2. The method according to claim 1, characterized in that, The operational objective is the flow rate or pressure provided by the pump system.

3. The method according to claim 1 or 2, characterized in that, The operational target is within the margin offset.

4. The method according to any one of claims 1 to 3, characterized in that, The target parameter is one or more of the pump system's energy consumption, water / oil consumption, and maintenance reduction.

5. The method according to any one of claims 1 to 4, characterized in that, If the operational objective is the flow rate provided by the pump system, and the objective parameter is energy consumption or water / oil consumption, then the objective function is given by the following equation. ， Where n is the number of variable speed pumps, and m is the number of constant speed pumps. This refers to the operating parameters of the variable speed pump i. The obtained relationship between the target value and the target value. It is the maximum flow rate of variable speed pump i at the setpoint pressure. These are the target parameters of the constant-speed pump j, and It refers to the energy consumption or water / oil consumption of the constant speed pump j.

6. The method according to claim 1, wherein, The step size for the first run is less than 0.

2.

7. The method according to claim 6, wherein, The step size for the first run is less than 0.

1.

8. The method according to any one of claims 1 to 7, characterized in that, The step size of the second run is greater than 0.

5.

9. The method according to any one of claims 8, characterized in that, The step size for the second run is 1.

10. The method according to any one of claims 1 to 9, characterized in that, If the target parameters include maintenance reduction, the method further includes the following steps: The pumps are classified according to their operating hours; Select pumps that have the minimum number of operating hours; together they will be able to achieve the stated operational objective.

11. The method according to claim 10, characterized in that, If the target parameters include energy consumption or water / oil consumption, then at least the selected pump should be included in the target function.

12. A pump system, comprising: More than one pump, wherein each pump is configured as a variable speed pump or a constant speed pump; And a controller connected to each pump to control the operation of the pump, wherein the controller is configured to perform the method according to any one of claims 1 to 11.

Images