Method for optimizing the operating costs of a pump system

Abstract

The invention relates to a method for optimizing the operating costs of a pump system comprising at least one pump assembly and at least one hydraulic system, wherein the method has the steps of: a. determining the curve of dynamic electricity costs over an upcoming time window, b. determining the desired total delivery volume of the at least one pump assembly in the hydraulic system within the upcoming time window, and c. optimizing the pump control / regulation process using the dynamic curve of electricity costs such that the at least one pump assembly delivers the desired total delivery volume within the time window with minimal electricity costs to operate the at least one pump assembly.

Description

[0001] 30286F

[0002] KSB SE & Co. KGaA 67227 Frankenthal

[0003] Description

[0004] Methods for optimizing the operating costs of a pump system

[0005] The invention relates to a method for optimizing the operating costs of a pump system comprising at least one pump unit and at least one hydraulic system.

[0006] From 2025, German electricity providers will be required to offer consumers dynamic electricity tariffs. These tariffs are based on current wholesale electricity prices and also take into account dynamic grid fees that adjust to grid load. The electricity price will be communicated to consumers at regular intervals, e.g., hourly, provided a smart meter is installed. The aim is to create incentives for adjusting consumption patterns through transparent pricing and time-variable tariffs. The resulting electricity price is referred to as the dynamic electricity price and can be viewed by customers for a specific time period in the future.

[0007] Currently, there is no provision for processing this information or adjusting pump operation to dynamic electricity prices in the application area of ​​pump systems. Therefore, any potential cost savings cannot yet be realized.

[0008] This application addresses the above-mentioned topic and seeks a solution for a pumping system to benefit from dynamic electricity pricing and save energy costs during pump operation. 2 30286F

[0009] This problem is solved by a method according to the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0010] According to the invention, the method proposes that it first determines the dynamic electricity price trend over an upcoming time period. As mentioned in the introduction, the electricity supplier will provide information on the current electricity price at regular intervals. Ideally, this information describes the expected electricity price trend over the longest possible time period of several hours or days. The information is received or retrieved, and based on this information, the electricity price trend over the upcoming time period is determined. For example, hourly electricity prices could be provided by the electricity suppliers. This information can be retrieved from the internet via an API interface.

[0011] For this time window, the desired total delivery volume of at least one pump unit in the hydraulic system is also determined. This information can either be entered by the operator of the system or determined from available data.

[0012] Using the aforementioned information, the next step involves optimizing the pump control or pump regulation of the pump unit by adjusting one or more operating parameters of the pump so that the pump achieves the desired total delivery volume within the time window with the lowest electricity costs.

[0013] Accordingly, the pump operation is adjusted to achieve the lowest possible electricity costs over the entire time period. For example, the pump is not operated, or at least only at reduced power, during periods of high electricity prices, while the pump unit operates at higher power during periods of low electricity prices. It cannot be ruled out that, in extreme cases, a negative electricity price may occur at certain times.

[0014] It is particularly advantageous if the process is executed directly on the pump itself, thus eliminating the need for a higher-level control system. The pump, i.e., its integrated electronics, first receives the dynamic electricity price for the upcoming time window, then determines the desired total flow rate, and finally optimizes its operating parameters within that time window based on this information.

[0015] In particular, the optimization of the pump control system is intended to minimize the current flow rate of at least one pump unit in order to deliver the desired total volume within the given time window while minimizing electricity costs. The electrical power consumption depends on the pump's current flow rate; that is, a reduced flow rate typically also reduces the electrical power consumption. The power consumption of pumps is unique compared to other electrical consumers because, due to pipe friction losses, the electrical power consumption increases disproportionately with increasing flow rate. This means that operating the pump at maximum flow rate during periods of low electricity prices is not always the most cost-effective option.Furthermore, the power-dependent efficiency of the pump and drive system influences power consumption, so it may be more energy-efficient to distribute pump operation across multiple phases with low or medium electricity prices at medium flow rates. The implemented optimization method takes this into account and adjusts the pump unit's flow rate throughout the entire time window so that the desired total flow rate is achieved precisely within the time frame defined by that window. Under certain circumstances, the desired total flow rate may only be reached shortly before or at the end of the time window.In other words, for each phase with a different electricity price, the pump's target flow rate is reduced as much as possible so that the total flow rate of 4 30286F is just barely achieved within the time period defined by the time window. This approach generally allows the pump to operate at the lowest possible electricity cost. However, it cannot be ruled out that the total flow rate will be reached at the lowest electricity cost long before the end of the time window.

[0016] For example, the following two extreme cases are mentioned:

[0017] Extreme case 1 - Electricity costs are constant throughout the entire time period: The pump system then runs at the lowest possible flow rate the entire time. Therefore, pipe losses and overall energy costs are minimal.

[0018] Extreme Case 2 - Electricity costs are zero for half the time window and very high for the remaining time: The pumping system operates at maximum capacity during the period with zero electricity costs. The high losses in the piping system result in no costs during this interval. During the remaining time, the pumping system switches off once the required total flow rate has been reached.

[0019] Optimizing pump control or regulation typically requires additional information such as the pump characteristic curve and the hydraulic system characteristic curve, as the latter determines the resulting electrical power consumption of the pump depending on the current flow rate. This allows for a direct calculation of the electricity cost per unit of pumped volume from the ratio of the pump unit's electrical power consumption per flow rate.

[0020] The system characteristic curve can either be known in advance or stored in the pump controller. Alternatively, it is also conceivable that the system characteristic curve is determined dynamically by the pump controller during pump operation. Numerous suitable methods already exist for this, so further information is unnecessary here.

[0021] It is also conceivable to consider any specifications regarding a minimum delivery rate and / or a minimum flow rate during the optimization process in order to prevent the pump from operating in an impermissible state. Such specifications must be entered in advance by the operator or stored in the pump control system.

[0022] In addition to the method according to the invention, the present invention also relates to a pump system comprising a hydraulic system with at least one pump unit and a control system, in particular an integrated pump control system, configured to carry out the method according to the present invention. Furthermore, the present invention also relates to a single pump unit comprising a hydraulic pump unit, an electric drive, and an internal pump control system configured to carry out the method according to the present invention. The pump may be a centrifugal pump.

[0023] Further advantages and features of the invention are explained in more detail below with reference to an exemplary embodiment shown in the figures. The figures show:

[0024] Figure 1: a diagram showing the dynamic electricity price trend over three

[0025] Days with corresponding pump power setting,

[0026] Figure 2: another diagram showing the dynamic electricity price trend over three days with alternative pump power settings,

[0027] Figure 3 shows diagrams for a scenario in which 80 cubic meters of fluid are to be pumped within three days, and

[0028] Figure 4: Diagram representations for a scenario in which 300 cubic meters

[0029] The pumped medium should be delivered by the pump within three days. 6 30286F

[0030] The invention will be explained below using an exemplary embodiment. The method according to the invention can be implemented on a pump that can be operated with a variable flow rate, for example, by using a frequency converter for speed adjustment. Possible applications include pumps for conveying or circulating fluids such as drinking water, process water, wastewater, etc. The pump operates in a pipe system, whereby the energy efficiency of the pump system, consisting of the pump and the pipeline, decreases with increasing flow rate Q due to increasing pipe losses. As a result, the electrical power input P_el of the pump drive also increases disproportionately with increasing flow rate Q. During constant operation, the electrical energy consumption E_el of the pump increases disproportionately depending on the pumped volume V due to the pipeline losses.

[0031] The pump is powered by energy supplied by an energy provider. The cost of this energy is calculated based on a dynamic electricity price, meaning the electricity is billed according to a dynamic price with periods of high and low cost per unit of energy [€ / kWh]. This dynamic electricity price is known in advance for a specific time period, typically three days or more. The integrated pump control system includes, for example, a communication module to retrieve and receive the dynamic energy price, or information from which the dynamic price trend can be determined, from a communication partner. It is also conceivable that this information could be entered by the operator via an interface.Using the available dynamic electricity price trend, the ratio between the electrical power requirement per pumped volume E_elA / can be directly converted into the ratio of the electricity price costs to the pumped volume K(t)A / based on the (hourly) electricity price costs K(t).

[0032] The operator of the system / pump can enter the desired total delivery volume that the pump should deliver within a defined time window via an interface. Specifically, the specification of the total delivery volume to be achieved and the dynamic profile of the pump are now available for this time window (see 7 30286F).

[0033] The system considers the electricity price. An optimization algorithm running on the pump's internal control unit can now adjust the target flow rate based on the electricity price so that the total electricity cost for the entire pumped volume is as low as possible. This requires not only the dynamic electricity costs but also the pump and system characteristic curves. The pump characteristic curve is usually stored in the pump's control unit, while the system characteristic curve can be calculated or determined by the pump itself using standard market methods.

[0034] The optimization algorithm is executed by the pump's control unit. The figures show examples of cost-optimized flow rates of 40 m³, 80 m³, 120 m³, 120 m³, 150 m³, and 300 m³, each over 3 days:

[0035] Figures 1 and 2 are diagrams illustrating the trend of the electricity price (solid line) over a three-day period. Taking into account the desired total volume to be pumped within three days and the depicted electricity price trend, the pump control system varies the target pump flow rate to achieve the total flow rate within the three-day period with the lowest possible energy costs.

[0036] In Figure 1, the pump operates at full power during periods of low electricity prices. During periods of high electricity costs, the pump pauses. The approach in Figure 2 differs from this in that the time window of days is used as precisely as possible to achieve the desired total delivery volume. For this purpose, the pump is not operated at full load, or at least less frequently. Instead, the pump's flow rate is set to the minimum for each electricity price value, so that the total delivery volume is just reached at the end of the three-day period. Regarding Figures 1 and 2, it should be noted that in the scenario of Figure 2, the desired total volume is larger than in Figure 1, and in Figure 1, the pump operates at a higher flow rate during periods of high demand than the pump in Figure 2. 8 30286F

[0037] Further examples are shown in Figures 3 and 4. Each of Figures 3 and 4 initially shows the dynamic electricity price over a period of 3 days. The desired total delivery volume in Figure 3 is 80 cubic meters, and in Figure 4 it is 300 cubic meters. The second diagram in Figures 3 and 4 shows the dynamic

[0038] The first diagram shows the electricity price, sorted in ascending order. The third diagram shows the target electrical power for the pump drive, calculated by the algorithm, as a function of the respective electricity price. The target flow rate is set so that the total flow volume is achieved within three days with the lowest possible energy costs. The fourth and fifth diagrams show the electricity price and the corresponding flow rate for each individual time unit, respectively, sorted in ascending order.

Claims

9 30286F Patent claims Methods for optimizing the operating costs of a pump system 1. A method for optimizing the operating costs of a pump system comprising at least one pump unit and at least one hydraulic system, wherein the method comprises the steps of: a. Determining the dynamic electricity cost profile over an upcoming time window, b. Determining the desired total delivery volume of the at least one pump unit in the hydraulic system within the upcoming time window, c. Optimizing the pump control Z-regulation using the dynamic electricity cost profile such that the at least one pump unit delivers the desired total delivery volume within the time window with minimal electricity costs for operating the at least one pump unit.

2. Method according to claim 1, characterized in that, for the optimization of the pump control Z-regulation, the current flow rate of the at least one pump unit is minimized in order to deliver the desired total flow volume within the time window with minimal electricity costs for the operation of the at least one pump unit.

3. Method according to claim 1 or 2, characterized in that the optimization of the pump control Z-regulation provides that the desired total delivery volume is achieved exactly within the time period specified by the time window. 10 30286F 4. Method according to claim 3, characterized in that the current flow rate of the at least one pump unit is minimized as far as possible, so that the desired total flow volume is achieved exactly in the time specified by the time window.

5. Method according to one of the preceding claims, characterized in that the pump characteristic curve of the pump unit and / or the system characteristic curve of the hydraulic system is taken into account for the optimization of the pump control Z-regulation.

6. Method according to claim 5, characterized in that the system characteristic curve is known in advance and retrievable, or the system characteristic curve is determined or estimated during pump operation by the at least one pump unit.

7. Method according to one of the preceding claims, characterized in that the time window is at least 24 hours, preferably at least 48 hours, particularly preferably at least 72 hours.

8. Method according to one of the preceding claims, characterized in that a minimum flow rate and / or a maximum flow rate is taken into account when optimizing the pump control Z-regulation.

9. Method according to one of the preceding claims, characterized in that the pump unit retrieves or receives information regarding electricity costs from an external communication partner and determines the course of the dynamic electricity costs over the upcoming time window based on this information.

10. Pump system comprising a hydraulic system and at least one pump unit as well as a control system configured to perform the method according to one of the preceding claims. 11 30286F 11. Pump unit comprising a hydraulic pump unit, an electric drive and an internal pump control configured to perform the method according to any one of claims 1 to 8.

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