Pump set optimizing control method

Abstract

The invention discloses a pump set optimization control method which comprises the following steps: (1) analyzing water pump performance data, and determining water pump power performance parameters forming a water pump power model; (2) constructing a water pump power model; (3) constructing a water pump power consumption model; (IV) constructing a pump set model; and (V) optimizing and controlling the pump set and the like. The MPC control thought is adopted for optimization control, rolling optimization control is conducted through the model function and the cost function of the pump set, and efficient operation of the pump set is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pump group control, and particularly relates to a pump group optimization control method. Background Art

[0002] In recent years, the rapid development of intelligent heating has formed a digital platform covering heat sources, pipe networks, heat exchange stations, and users based on the Internet of Things, big data, and AI, realizing precise regulation and energy consumption savings. The intelligent optimization control of heating systems and air conditioning systems not only meets the country's requirements for the digitalization of the energy industry and new quality production, but more importantly, it realizes the optimization control of the system, improves the system energy efficiency, and ensures the achievement of the dual-carbon goal.

[0003] Pump groups are common components in heating systems and air conditioning systems. Their main function is to undertake the water transportation in the system. Their energy consumption accounts for 5-10% of the total energy consumption of heating and air conditioning systems. The improvement of the transportation energy efficiency will reduce power consumption and carbon emissions, and at the same time increase the service life of water pump equipment.

[0004] The optimization control of pump groups is of great significance: through the optimization control algorithm (energy consumption target optimization), the pump group can match the actual working conditions in real time, ensure that the equipment operates in the high-efficiency range, improve the operation efficiency and energy-saving level; the optimization control can reduce the mechanical wear caused by frequent start-stop or overload operation of the equipment, extend the life of key components, reduce maintenance costs, and reduce the risk of unplanned shutdown; the optimization control of pump groups contributes to the achievement of the "dual-carbon" goal by reducing energy consumption and carbon emissions; its deep integration with heating and air conditioning systems also provides technical support for the digitalization and intelligent transformation of heating and air conditioning systems, and promotes the construction of intelligent heating and air conditioning.

[0005] Traditional pump group control methods have problems such as high energy consumption, low efficiency, and dependence on manual adjustment, and it is difficult to meet the requirements of energy conservation and consumption reduction and refined management. Traditional control methods have limitations: traditional pump group control is mostly based on fixed rules or manual experience, and it is difficult to cope with complex working condition changes, which easily leads to the pump group deviating from the high-efficiency operation range, resulting in energy waste and equipment loss. Summary of the Invention

[0006] The present invention is proposed to overcome the disadvantages existing in the prior art, and its purpose is to provide a pump group optimization control method.

[0007] The present invention is realized through the following technical solutions: A pump group optimization control method includes the following steps: (I) Analyze the pump performance data to determine the pump dynamic performance parameters that make up the pump dynamic model; (II) Construct a pump dynamic model; (III) Construct a pump power consumption model; (IV) Construct a pump group model; (V) Optimizing control of the pump group.

[0008] In the above technical solution, the pump power performance parameters constituting the pump power model are the pump frequency F, the flow rate Q of the pump, and the head H of the pump.

[0009] In the above technical solution, the expression of the pump power model is:

[0010] Where: H is the head of the pump, with the unit of m; Q is the flow rate of the pump, with the unit of m 3 / h; r is the frequency ratio, dimensionless; n1~n5 are pump power performance constants, obtained by fitting pump performance data.

[0011] In the above technical solution, the calculation formula of the frequency ratio r is:

[0012] Where: r is the frequency ratio, dimensionless; F is the operating frequency, with the unit of Hz.

[0013] In the above technical solution, the expression of the pump power consumption model is:

[0014] Where: N is the power consumption of the pump, with the unit of kW; H is the head of the pump, with the unit of m; Q is the flow rate of the pump, with the unit of m 3 / h; k is a constant, dimensionless; r is the frequency ratio, with the unit of Hz; n6~n 15 are pump efficiency performance constants, obtained by fitting pump performance data.

[0015] In the above technical solution, the pump group model includes the power consumption model of the parallel pump group and the power model of the parallel pump group.

[0016] In the above technical solution, the expression of the power consumption model of the parallel pump group is:

[0017] Where: N sys is the total power consumption of the parallel pump group, with the unit of kW; k is a constant, dimensionless; Q sys is the total flow rate of the parallel pump group, with the unit of m 3 / h; H sys is the head of the parallel pump group, with the unit of m; n6~n 15 are pump efficiency performance constants, obtained by fitting pump performance data; r is the frequency ratio, dimensionless.

[0018] In the above technical solution, the total flow rate Q of the parallel pump group sys The calculation formula is:

[0019] Where: Q sys is the total flow rate of the parallel pump group, with the unit of m 3 / h; Q i is the flow rate of each water pump in the total flow rate of the parallel pump group, with the unit of m 3 / h; n is the number of water pumps in the parallel pump group.

[0020] In the above technical solution, the expression of the power model of the parallel pump group is:

[0021] Where: H sys is the head of the parallel pump group, with the unit of m; H i is the independent head of each water pump in the parallel pump group in the operating state, with the unit of m; n1~n5 are water pump power performance constants, obtained by fitting the water pump performance data; r is the frequency ratio, dimensionless; Q sys is the total flow rate of the parallel pump group, with the unit of m 3 / h.

[0022] The beneficial effects of the present invention are: The present invention provides a pump group optimization control method, which uses the MPC control idea for optimization control, and realizes the efficient operation of the pump group through the model function and cost function of the pump group for rolling optimization control. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the full-spectrum data diagram of a certain water pump in Embodiment 1 of the present invention; Figure 2 is the comparison diagram of the actual performance data and theoretical data of a certain water pump in Embodiment 1 of the present invention; Figure 3 is the error comparison diagram of the actual performance data and theoretical data of a certain water pump in Embodiment 1 of the present invention; Figure 4 is the test result diagram of the optimization control power consumption of the low-zone circulating pump group in Embodiment 1 of the present invention; Figure 5 is the test result diagram of the optimization control power consumption of the high-zone circulating pump group in Embodiment 1 of the present invention.

[0024] For those of ordinary skill in the art, without creative efforts, other relevant drawings can be obtained based on the above drawings. DETAILED DESCRIPTION OF THE INVENTION

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings of the specification and through specific embodiments.

[0026] Embodiment 1 A pump unit optimization control method includes the following steps: (Ⅰ) Analyze the performance data of the water pump to determine the water pump dynamic performance parameters that make up the water pump dynamic model; According to the full-spectrum data of a certain water pump in Table 1 and Figures 1 to 3 It is found that: Under the condition that the operating frequency F of the water pump is constant, the power consumption N of the water pump increases with the increase of the flow rate Q and the head H. The flow rate Q of the water pump has a quadratic function relationship with the head H of the water pump and the efficiency η of the water pump.

[0027] According to the relevant formula of classical water pump frequency conversion:

[0028] In the above formula: F1 and F2 are two different operating frequencies of the same water pump, and the unit of both is Hz; Q1 is the flow rate of the water pump at the operating frequency F1, and the unit is m 3 / h; Q2 is the flow rate of the water pump at the operating frequency F2, and the unit is m 3 / h; H1 is the head of the water pump at the operating frequency F1, and the unit is m; H2 is the head of the water pump at the operating frequency F2, and the unit is m; N1 is the power consumption of the water pump at the operating frequency F1, and the unit is kW; N2 is the power consumption of the water pump at the operating frequency F2, and the unit is kW; The operating frequency F of the water pump affects the flow rate Q, the head H and the power consumption N of the water pump, but does not completely conform to the law of the classical formula: The flow rate Q of the water pump is basically linearly related to the operating frequency F of the water pump, and the error is small, which can be used to establish the water pump dynamic model; the head H of the water pump has a quadratic function relationship with the operating frequency F, and the error is also small, which can be used to establish the water pump dynamic model; the power consumption N of the water pump has a cubic function relationship with the operating frequency F, but the error is large, and the error increases with the decrease of the frequency. Therefore, it is not applicable to use the classical formula to construct the mathematical model of the water pump power consumption.

[0029] Therefore, the water pump dynamic performance parameters that make up the water pump dynamic model are the operating frequency F of the water pump, the flow rate Q of the water pump and the head H of the water pump; Table 1: Full-spectrum data of a certain water pump

[0030]

[0031] (Ⅱ) Construct a water pump dynamic model; The expression of the water pump power model is as follows:

[0032] In the formula: H is the head of the water pump, with the unit of m; Q is the flow rate of the water pump, with the unit of m 3 / h; r is the frequency ratio, dimensionless; n1 to n5 are the water pump power performance constants, obtained by fitting the water pump performance data; The calculation formula of the frequency ratio r is:

[0033] In the formula: r is the frequency ratio, dimensionless; F is the operating frequency, with the unit of Hz; According to the full-spectrum data of a certain water pump in Table 1 for formula fitting, the water pump power performance constants n1 to n5 are obtained. The specific coefficient values of the water pump power performance constants n1 to n5 are shown in Table 2; Table 2: Water pump power performance constants of a certain water pump

[0034] Calculate the head of the water pump in Table 1 through the expression of the water pump power model, and compare the calculated head with the actual head. It is found that the maximum relative error does not exceed 1%, indicating that the accuracy of the water pump power model meets the engineering requirements. The specific calculation results and relative errors are shown in Table 3 below: Table 3: Calculation head results and relative errors of a certain water pump power model

[0035]

[0036] (III) Construct a water pump power consumption model; According to the classical theory of water pumps, the power consumption calculation formula of the water pump is:

[0037] In the formula: N is the power consumption of the water pump, with the unit of kW; H is the head of the water pump, with the unit of m; Q is the flow rate of the water pump, with the unit of m 3 / h; η is the efficiency of the water pump, %, dimensionless; k is a constant, dimensionless; According to the above formula, as long as the functional relationship between η and Q, H is found, a water pump power consumption model can be established. Through the analysis of the actual data of the water pump, it can be known that the calculation formula of the water pump efficiency η is:

[0038] In the formula: η is the efficiency of the water pump, %, dimensionless; Q is the flow rate of the water pump, with the unit of m 3 / h; r is the frequency ratio, r = F / 50; n6 to n15 is the pump efficiency performance constant, which is obtained by fitting the pump performance data; Substitute the calculation formula of the pump efficiency η into the calculation formula of the pump power consumption, and the pump power consumption model can be obtained. The expression of the pump power consumption model is:

[0039] According to the full-spectrum data of a certain pump in Table 1 for formula fitting, the pump efficiency performance constants n6~n are obtained 15 , and the specific coefficient values of the pump efficiency performance constants n6~n 15 are shown in Table 4; Table 4: Pump efficiency performance constants of a certain pump

[0040] Calculate the power consumption of the pump in Table 1 through the expression of the pump power consumption model, and compare the calculated power consumption with the actual power consumption. It is found that the maximum relative error does not exceed 3%, indicating that the accuracy of the pump power consumption model meets the engineering requirements. The specific calculation results and relative errors are shown in Table 5 below: Table 5: Calculation results and relative errors of the power consumption of a certain pump by the power consumption model

[0041]

[0042]

[0043] (IV) Construct the pump group model; According to the relevant theory in "Fluid Mechanics Pumps and Fans": When pumps are connected in parallel, the head of each pump is equal, and the flow rates are superimposed, that is: The total flow rate calculation formula for the parallel pump group is:

[0044] In the formula: Q sys is the total flow rate of the parallel pump group, with the unit of m 3 / h; Q i is the flow rate of each pump in the total flow rate of the parallel pump group, with the unit of m 3 / h; n is the number of pumps in the parallel pump group; The head calculation formula for the parallel pump group is:

[0045] In the formula: H sys is the head of the parallel pump group, with the unit of m; H1, H2, H i , H n are the independent heads of each pump in the parallel pump group in the operating state, with the unit of m; n is the number of pumps in the parallel pump group; The total flow calculation formula of the parallel pump group and the expression of the water pump power consumption model are combined to establish the power consumption model of the parallel pump group. The expression of the power consumption model of the parallel pump group is:

[0046] When pumps of the same specification are in parallel, the control frequencies are the same.

[0047] The head calculation formula of the parallel pump group and the expression of the water pump power model are combined to establish the power model of the parallel pump group. The expression of the power model of the parallel pump group is:

[0048] Taking a parallel pump group composed of 2 pumps with the full-spectrum data of the water pumps in Table 1 as an example: When a single pump is running, the expression of the power model of the parallel pump group is:

[0049] Where: The coefficients of n1~n5 are the same as those in Table 2; When two pumps are running, the expression of the power model of the parallel pump group is:

[0050] Where: The coefficients of n1~n5 are the same as those in Table 6; Table 6: The water pump power performance constants of the water pumps in the power model of the parallel pump group when two pumps are running

[0051] When a single pump is running, the expression of the power consumption model of the parallel pump group is:

[0052] Where: The coefficients of n6~n 15 are the same as those in Table 4; When two pumps are running, the expression of the power consumption model of the parallel pump group is:

[0053] Where: The coefficients of n6~n 15 are the same as those in Table 7; Table 7: The water pump efficiency performance constants of the water pumps in the power consumption model of the parallel pump group when two pumps are running

[0054] When pumps are in parallel, the total flow of the pump group = the sum of the flows of each pump, and the head of the pump group = the head of each pump. According to the above two formulas, the performance of the pump group can be calculated based on the performance data of a single pump. Then, based on the performance data of the pump group and the aforementioned power model function and power consumption model function, the correlation coefficients can be obtained by using the least squares method; (V)Optimal control of pump group When a pump group is adopted in a heating or air-conditioning circulation system, the operator adjusts the operating frequency of the pump group continuously according to the system operating parameters to achieve the desired system circulation flow rate or system available pressure difference. At this time, the optimal control program of the pump group will calculate according to the principle of the lowest power consumption and give an operating configuration plan.

[0055] The said optimal control program specifically includes the following steps: (V-i)Establish a pump group power model and a power consumption model based on the full-spectrum data of the pump group and input the models into the program; (V-ii)Collect the system operating parameters at a certain moment and input them into the program, including system flow rate, inlet pressure of the operating pump, outlet pressure of the operating pump, as well as frequency and motor power; (V-iii)Input the system flow rate, inlet pressure of the operating pump, and outlet pressure of the operating pump as known conditions into the pump group power model and the power consumption model, judge the feasibility of the operating configuration plan of the pump group that meets the above conditions, and calculate the power consumption; (V-iv)Compare the power consumption of the feasible operating configuration plan with the power consumption of the current pump group, find out the operating configuration plan with the lowest power consumption, define it as the optimal operating configuration plan, and give the number of operating pumps and the frequency that the pumps need to be set; (V-v)Send the number of operating pumps and the set frequency of the above optimal operating configuration plan to the control system for control execution.

[0056] (VI)Experimental verification; For the secondary-side circulation pumps (double pumps in parallel) of the high and low zone heat exchange units in a heat exchange station in Tianjin, the optimal control of the pump group is adopted to achieve optimal and efficient operation. The detailed data is as follows: Design condition parameters for the parallel operation of the double pumps of the high zone circulation pump: 100 t / h, 25 m, 5.5 kW; Design condition parameters for the parallel operation of the double pumps of the low zone circulation pump: 280 t / h, 25 m, 15 kW; The full-spectrum data of a single pump of the high zone circulation pump is as shown in Table 8 below: Table 8: Full-spectrum data of a single pump of the high zone circulation pump

[0057]

[0058]

[0059]

[0060] The full-spectrum data of a single pump of the low zone circulation pump is as shown in Table 9 below: Table 9: Full-spectrum data of a single pump of the low zone circulation pump

[0061]

[0062]

[0063] According to the above data, high and low zone circulating pump sets models are established respectively, and control programs are written for testing. The test results are as Figure 4 、 5 shown. It can be seen that: After the system operation condition parameters change, the high and low zone circulating pump sets automatically perform optimization control, automatically adjust the water pump frequency and quantity, and optimize the water pump operation condition; For the power consumption models of the high and low zone circulating pump sets and the measured power consumption data, the error is extremely small, and the maximum relative error does not exceed 5%, which can be used for pump set control.

[0064] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A pump unit optimization control method, characterized in that: It includes the following steps: (Ⅰ) Analyze the performance data of the water pump to determine the water pump dynamic performance parameters that constitute the water pump dynamic model; (Ⅱ) Construct the water pump dynamic model; (Ⅲ) Construct the water pump power consumption model; (Ⅳ) Construct the pump unit model; (Ⅴ) Optimizing control of the pump unit.

2. The pump unit optimization control method according to claim 1, characterized in that: The water pump dynamic performance parameters that constitute the water pump dynamic model are the operating frequency F of the water pump, the flow rate Q of the water pump, and the head H of the water pump.

3. The pump unit optimization control method according to claim 1, wherein: The expression of the water pump dynamic model is: ， Where: H is the head of the water pump, with the unit of m; Q is the flow rate of the water pump, with the unit of m 3 / h; r is the frequency ratio, dimensionless; n1~n5 are the dynamic performance constants of the water pump, obtained by fitting the water pump performance data.

4. The pump set optimization control method according to claim 3, wherein: The calculation formula of the frequency ratio r is: , Where: r is the frequency ratio, dimensionless; F is the operating frequency, with the unit of Hz.

5. The pump unit optimization control method according to claim 1, wherein: The expression of the water pump power consumption model is: , Where: N is the power consumption of the water pump, with the unit of kW; H is the head of the water pump, with the unit of m; Q is the flow rate of the water pump, with the unit of m 3 / h; k is a constant, dimensionless; r is the frequency ratio, dimensionless; n6~n 15 is the efficiency performance constant of the water pump, obtained by fitting the water pump performance data.

6. The pump unit optimization control method according to claim 1, characterized in that: The pump unit model includes the power consumption model of the parallel pump unit and the dynamic model of the parallel pump unit.

7. The pump unit optimization control method according to claim 6, characterized in that: The expression of the power consumption model of the parallel pump unit is: , Where: N sys is the total power consumption of the parallel pump group, with the unit of kW; k is a constant, dimensionless; Q sys is the total flow rate of the parallel pump group, with the unit of m 3 / h; H sys is the head of the parallel pump group, with the unit of m; n6~n 15 is the pump efficiency performance constant, obtained by fitting the pump performance data; r is the frequency ratio, dimensionless; The total flow rate Q of the parallel pump group sys The calculation formula is as follows: , Where: Q sys is the total flow rate of the parallel pump group, with the unit of m 3 / h; Q i is the flow rate of each water pump in the total flow rate of the parallel pump group, with the unit of m 3 / h; n is the number of water pumps in the parallel pump group.

8. The pump unit optimization control method according to claim 6, wherein: The expression of the dynamic model of the parallel pump unit is: , Where: H sys is the head of the parallel pump group, in m; H i is the independent head of each water pump in the parallel pump group under the operating state, in m; n1~n5 are the water pump dynamic performance constants, obtained by fitting the water pump performance data; r is the frequency ratio, in Hz; Q sys is the total flow rate of the parallel pump group, in m 3 / h.

9. The pump unit optimization control method according to claim 1, wherein: The specific content of the step (Ⅴ) optimizing control of the pump unit is: (Ⅴ-i) Input the system flow rate, the inlet pressure of the operating water pump, and the outlet pressure of the operating water pump as known conditions into the dynamic model of the parallel pump unit and the power consumption model of the parallel pump unit to obtain the pump unit operation configuration plan, judge the feasibility of the pump unit operation configuration plan, and calculate the power consumption; (Ⅴ-ii) Compare the power consumption of the feasible pump unit operation configuration plan with the power consumption of the current pump unit, find out the operation configuration plan with the lowest power consumption as the optimal operation configuration plan, and give the number of operating water pumps and the frequency that the water pumps need to be set; (Ⅴ-iii) Execute the optimal operation configuration plan.

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