Method and device for suppressing performance dispersion of multi-pump parallel system based on pressure difference

Abstract

A method and device for suppressing the dispersion of performance of a multi-pump parallel system based on pressure difference relates to the field of multi-pump parallel system control technology, wherein the method includes: determining whether the speed difference between any two pumps in a plurality of running pumps is less than or equal to a preset speed difference; if not, maintaining the speed of the running pump at a given speed calculated by a speed balancing operation module; if so, obtaining the inlet and outlet pressure difference of the check valve located at the outlet of the running pump; when the inlet and outlet pressure difference of the check valve is less than or equal to a first preset pressure difference value, increasing the given speed of the running pump; or when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value, maintaining the given speed of the running pump. The suppression method can avoid the problem of rising pump outlet water temperature and impeller cavitation caused by long-term idling of the running pump, thereby maintaining the appropriate temperature of the pump group, improving the reliability and service life of the equipment, and the method can be put into use in a timely manner, with low cost and good effect.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-pump parallel system control, and in particular to a method and device for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference. Background Art

[0002] Steam-powered ships must monitor the water level in the boiler in real time when in use. Too low or too high a water level will cause a dry boiler or full water, which will have a serious impact on the ship's power system and even endanger the safety of the ship. The marine boiler feedwater system consists of a feedwater pump, a check valve and a control system. The feedwater pump is divided into a fixed-speed pump and a variable-speed pump. The variable-speed pump can be an electric feedwater pump or a steam turbine feedwater pump. In a multi-feedwater pump parallel system, multiple fixed-speed pumps, multiple electric feedwater pumps, multiple steam turbine pumps or mixed-type feedwater pumps are used in the ship boiler system. Usually, a stop check valve is set at the outlet of the feedwater pump to prevent feedwater backflow. When the water pressure at the outlet of the feedwater pump reaches a certain value, the check valve opens and the feedwater pump supplies water to the boiler normally.

[0003] In a boiler feedwater system with multiple feedwater pumps in parallel, it is difficult to ensure the performance consistency of components such as feedwater pumps and check valves. Differences in equipment processing technology, material properties, equipment installation location, power grid / steam fluctuations, control system signals, etc. all lead to a certain dispersion in the working performance of the feedwater branch. The performance dispersion of related equipment in a system with multiple feedwater pumps in parallel will result in low outlet pressure of one or more feedwater pumps during parallel operation, making it impossible for the check valve to open normally, which in turn causes a sharp rise in the outlet water temperature of the feedwater pump, causing cavitation of the feedwater pump impeller and damage to the feedwater pump. To solve this problem, common solutions are as follows:

[0004] 1. Adjust equipment performance parameters. In order to reduce the dispersion of the working performance of each branch, it is necessary to adjust the performance parameters of each related equipment, such as strengthening the performance consistency between water pumps and processing and modifying the impeller; or strengthening the performance consistency of the check valve and adjusting the parameters of the valve core and spring. Strengthening the consistency of equipment performance parameters involves processing and modification of the device. The modified equipment needs to be re-tested and verified, and the cycle of parameter calculation-processing-testing-processing-testing... etc. is continuously carried out. The whole cycle is relatively long. In addition, there may be excessive processing and modification of the equipment, which will cause irreversible damage to the equipment and endanger the safety of the equipment.

[0005] 2. Configure a return pipe. By setting a return pipe between the outlet and inlet of the feedwater pump, when the check valve is abnormally closed, part of the outlet water of the feedwater pump will flow back to the inlet of the feedwater pump, thereby reducing the outlet water temperature and pressure of the feedwater pump, avoiding damage to the feedwater pump and endangering the safety of the boiler feedwater system. However, the setting of the return pipe requires a certain amount of physical space. The location of the ship boiler system is usually small, and the pipeline layout is difficult. In addition, the additional feedwater return pipe will reduce the water supply and affect the water supply efficiency.

[0006] 3. Add a return pipe control system. Add a controllable return valve in the return pipe. When the feed pump is running, if the check valve at the feed pump outlet is detected to be abnormally closed, open the return valve; if the check valve is normally open, close the return valve. Configure a return pipe or add a controllable return valve to the return pipe. When the check valve at the feed pump outlet cannot be opened, the feed pump will run idle and cannot provide effective water supply to the system, increasing system power consumption. At the same time, the overall water supply cannot reach the target value, affecting boiler safety.

[0007] In summary, in the existing solutions for the decentralized performance of branches in the multi-water pump parallel system, there are problems such as complex equipment processing and the need for on-site construction. There are also disadvantages such as poor economy and long system transformation cycle. Summary of the invention

[0008] The present invention provides a method and device for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference, which is used to make up for the early design defects of the multi-pump parallel system in the prior art, and at the same time solve the problems of complex equipment processing, poor economy, and long system transformation cycle in the performance dispersion suppression measures of each branch.

[0009] The present invention provides a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference, comprising:

[0010] Step S100, determining whether the speed difference between any two pumps among a plurality of running pumps is less than or equal to a preset speed difference;

[0011] Step S200: If not, keep the speed of the running pump at the given speed calculated by the speed balancing calculation module; if yes, obtain the inlet and outlet pressure difference of the check valve located at the outlet of the running pump;

[0012] Step S300, when the inlet and outlet pressure difference of the check valve is less than or equal to a first preset pressure difference value, increasing the given speed of the running pump;

[0013] Alternatively, when the inlet and outlet pressure difference of the check valve is greater than a first preset pressure difference value, the rotation speed of the running pump is maintained at the given rotation speed calculated by the rotation speed balancing calculation module.

[0014] According to a method for suppressing performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, the step of increasing the given speed of the running pump further comprises:

[0015] Based on the preset speed increase rule, the speed is gradually increased on the basis of the given speed calculated by the speed balancing calculation module until the inlet and outlet pressure difference of the check valve is greater than or equal to the second preset pressure difference value, and the current speed is maintained.

[0016] According to a method for suppressing performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, after increasing the given speed of the running pump, the method further comprises:

[0017] Determining whether two or more pumps among the plurality of operating pumps increase a given speed;

[0018] If so, the speed of the running pump is restored to the given speed calculated by the speed balancing calculation module, and the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is re-obtained after a first preset delay, and the process jumps to step S300.

[0019] According to a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, before step S100, the method further includes:

[0020] Determining whether the control mode of the multi-pump parallel system is switched from manual control to automatic control;

[0021] If yes, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module, and the process jumps to step S100 after a delay of a second preset time;

[0022] If not, the process jumps to step S100.

[0023] According to a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, before step S100, the method further includes:

[0024] Determining whether the combination of the operating pumps has changed;

[0025] If yes, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module, and the process jumps to step S100 after a delay of a third preset time;

[0026] If not, the process jumps to step S100.

[0027] According to a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, the step of obtaining the inlet and outlet pressure difference of a check valve located at the outlet of the running pump further comprises:

[0028] Continuously and in real time collecting the inlet and outlet differential pressure signals of the check valve, and caching the collected inlet and outlet differential pressure signals of the check valve in a buffer;

[0029] The n groups of inlet and outlet pressure difference signals collected most recently in the buffer zone are filtered to calculate the inlet and outlet pressure difference of the check valve.

[0030] According to a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, the filtering process of the n groups of inlet and outlet pressure difference signal data collected most recently in the buffer zone and the calculation of the inlet and outlet pressure difference of the check valve further comprises:

[0031] The latest n groups of inlet and outlet pressure difference signal data collected are {Pd 0 , Pd 1 , Pd 2 , ..., Pd n-1}, where Pd 0 Indicates the current collected inlet and outlet pressure difference value, Pd n-1 Indicates the inlet and outlet pressure difference values ​​collected for the previous n-1 times, where n is a positive integer greater than 1;

[0032] Determine the maximum inlet and outlet pressure difference value Pd among n groups of inlet and outlet pressure difference signal data max and minimum pressure difference Pd min ;

[0033] Based on the smoothing filtering method, the calculation formula of the inlet and outlet pressure difference of the check valve is as follows:

[0034]

[0035] Among them, Pd mean is the inlet and outlet pressure difference of the check valve, Pd i is the inlet and outlet pressure difference value collected for the i-th time, Pd max is the maximum inlet and outlet pressure difference, Pd min It is the minimum inlet and outlet pressure difference.

[0036] According to a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided by the present invention, before step S100, the method further includes:

[0037] Determining a pump with the highest rotation speed and a pump with the lowest rotation speed among the plurality of operating pumps;

[0038] If the speed difference between the pump with the largest speed and the pump with the smallest speed is greater than the preset speed difference, then based on the preset adjustment parameter, the given speed of the pump with the largest speed is reduced, and the given speed of the pump with the smallest speed is increased;

[0039] Repeat the above steps until the speed difference between any two pumps in the plurality of running pumps is less than or equal to the preset speed difference.

[0040] The present invention also provides a device for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference, comprising:

[0041] A speed difference determination module, for determining whether a speed difference between any two pumps among a plurality of running pumps is less than or equal to a preset speed difference value;

[0042] The speed difference judgment module, if not, keeps the speed of the running pump at the given speed calculated by the speed balance calculation module; if so, obtains the inlet and outlet pressure difference of the check valve located at the outlet of the running pump;

[0043] The speed regulating module increases the given speed of the running pump when the inlet and outlet pressure difference of the check valve is less than or equal to the first preset pressure difference value; or maintains the speed of the running pump at the given speed calculated by the speed balancing calculation module when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value.

[0044] According to the present invention, a device for suppressing the dispersion of performance of a multi-pump parallel system based on pressure difference also includes:

[0045] The data storage module is used to store the speed control signal of the running pump, the speed feedback signal, the inlet and outlet pressure difference signal of the check valve, the running pump automatic control signal and the main pipe regulating valve pressure difference signal.

[0046] The present invention provides a method and device for suppressing the dispersion of the performance of a multi-pump parallel system based on pressure difference, wherein the method detects the inlet and outlet pressure difference of the check valve located at the outlet of the running pump after the rotation speeds of the multiple running pumps reach equilibrium. If the inlet and outlet pressure difference is less than or equal to a first preset pressure difference value, the check valve is in a closed state. At this time, the outlet head of the pump can be increased by increasing the rotation speed of the pump, thereby increasing the inlet and outlet pressure difference of the check valve. When it is higher than the static resistance of the check valve, the check valve can be opened; if the inlet and outlet pressure difference is greater than the first preset pressure difference value, the check valve is in an open state, the branch circuit operates normally, and the current rotation speed can be maintained at this time. The method for suppressing the dispersion of the performance of a multi-pump parallel system based on pressure difference can avoid the problem of the pump outlet water temperature rising and the impeller being cavitated due to the long-term idling of the running pump, thereby maintaining the appropriate temperature of the pump group and improving the reliability and service life of the equipment. In addition, the method does not require changes to the equipment or pipelines, can be put into use in a timely manner, has low cost and good effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 It is a flow chart of a method for suppressing the dispersion of performance of a multi-pump parallel system based on pressure difference provided by the present invention;

[0049] Figure 2 It is a process principle diagram of the boiler water supply system provided by the present invention;

[0050] Figure 3 It is a schematic diagram of a hysteresis curve of a rotation speed increase provided by the present invention;

[0051] Figure 4 It is a schematic diagram of a water feed pump speed control system provided by the present invention;

[0052] Figure 5 is a schematic diagram of the structure of an electronic device provided by the present invention;

[0053] Reference numerals:

[0054] 1: feed water pump; 2: speed measuring instrument; 3: check valve; 4: differential pressure measuring instrument; 5: feed water regulating valve; 6: boiler; 710: processor; 720: communication interface; 730: memory; 740: communication bus. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The terms "first" and "second" in the embodiments of the present application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a system, product or device comprising a series of parts or units is not limited to the listed parts or units, but optionally also includes parts or units that are not listed, or optionally also includes other parts or units inherent to these products or devices. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0057] Figure 2 The process principle diagram of the boiler water supply system is shown. The boiler water supply system is a typical multi-pump parallel system, which includes multiple parallel water supply branches. Each water supply branch is respectively provided with a water supply pump 1 and a check valve 3, and the outlets of the multiple check valves 3 are connected through a bridge pipe. The specific process flow is as follows: the water supply in the water supply main is first distributed to each water supply branch, and after being pressurized by the water supply pump, it is collected and enters the water supply regulating valve 5. After the water supply regulating valve 5 adjusts the water supply amount, it finally enters the boiler 6 and is converted into steam to provide power. This embodiment is mainly explained by taking a multi-water supply pump parallel system as an example. Other multi-pump parallel systems are similar and will not be described in detail.

[0058] The existing water supply control process is specifically as follows: the speed of the water supply pump 1 in each water supply branch tracks the inlet and outlet pressure difference of the water supply regulating valve 5. When the inlet and outlet pressure difference of the water supply regulating valve 5 is lower than the first set threshold, the speed of the water supply pump 1 in each water supply branch will increase; when the inlet and outlet pressure difference of the water supply regulating valve 5 is higher than the second set threshold, the speed of the water supply pump 1 in each water supply branch will decrease; when the inlet and outlet pressure difference of the water supply regulating valve 5 is maintained between the first set threshold and the second set threshold, the speed of the water supply pump 1 remains unchanged. At the same time, the speed difference of each running water supply pump 1 is controlled to be maintained within a small range, so that the running speed of each water supply pump 1 is balanced. Here, a speed balancing calculation module (belonging to the existing control module of the system) can be used to calculate the given speed signal of each water supply pump based on the PID control algorithm, and then converted into a (4-20) mA current signal for each water supply pump 1 through the water supply pump speed given signal AO conversion module. The rotation speed of the water supply pump 1 can be measured by a rotation speed measuring instrument 2 , and the inlet and outlet pressure difference of the water supply regulating valve 5 can be measured by a pressure difference measuring instrument 4 .

[0059] In actual use, especially when multiple pumps are running in parallel, due to the performance dispersion of related equipment, the outlet pressure of one or more feed pumps 1 will be low, that is, the inlet pressure of the check valve 3 will be low. If the outlet pressures of the check valves 3 are the same, the inlet and outlet pressure difference of the check valve 3 will become smaller, which may cause the check valve 3 to be abnormally closed. In the boiler feed water system, the outlet head of the feed water pump 1 and the speed of the feed water pump 1 are in a quadratic relationship:

[0060]

[0061] It can be seen from the above formula that the outlet head of the water supply pump 1 can be increased by increasing the speed of the water supply pump 1, and a small speed increment can greatly increase the outlet head of the water supply pump 1 with a quadratic increment. Therefore, by increasing the outlet pressure of the water supply pump 1, the inlet and outlet pressure difference of the check valve 3 can be increased. When the inlet and outlet pressure difference of the check valve 3 is higher than the static resistance of the check valve 3, the check valve 3 can be opened, thereby maintaining the normal operation of each water supply branch and suppressing the dispersion of branch performance.

[0062] like Figure 1 As shown, a method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided by an embodiment of the present invention includes:

[0063] Step S100: Determine whether the speed difference between any two pumps in a plurality of running pumps is less than or equal to a preset speed difference.

[0064] Specifically, the rotation speeds of all pumps currently in operation are obtained, and then the pumps with the highest and lowest rotation speeds are determined by comparison, and the rotation speed difference between the two is obtained, which is the maximum rotation speed difference between all running pumps at the current moment, and then the maximum rotation speed difference is compared with the preset rotation speed difference value to determine whether it is less than or equal to the preset rotation speed difference value. The preset rotation speed difference value can be set according to user needs.

[0065] Step S200: If not, keep the speed of the running pump at the given speed calculated by the speed balancing calculation module; if yes, obtain the inlet and outlet pressure difference of the check valve located at the outlet of the running pump.

[0066] Specifically, if the maximum speed difference is greater than the preset speed difference, it indicates that the speeds of the running pumps have not yet reached a balanced state at the current moment. At this time, it is necessary to give priority to meeting the speed balance requirement. Therefore, the speed signal received by the running pump is the given speed signal output by the speed balance operation module. At this time, the given speed will be dynamically adjusted according to the overall operating status of all current running pumps. The pump with a larger speed will be controlled to reduce the speed, and the pump with a smaller speed will be controlled to increase the speed, until the speeds of all running pumps reach a balanced state, that is, the speed difference between any two running pumps is less than or equal to the preset speed difference.

[0067] If the maximum speed difference is less than or equal to the preset speed difference, it indicates that the speed of each running pump has reached a balanced state at the current moment. However, due to the inconsistency and dispersion of the performance of each branch, when the speed is equivalent, the outlet pressure of one or more pumps may be low, which may cause the check valve 3 to be abnormally closed and the pump to run idle. In order to avoid the above situation, it is necessary to appropriately increase the speed of the pump with low outlet pressure to suppress the dispersion of branch performance. In this embodiment, the inlet and outlet pressure difference of the check valve 3 is mainly detected by the pressure difference measuring instrument 4 installed at the inlet and outlet of the check valve 3, so as to determine whether the outlet pressure of the pump is low.

[0068] Step S300, when the inlet and outlet pressure difference of the check valve 3 is less than or equal to the first preset pressure difference value, increase the given speed of the running pump corresponding to the check valve 3; or when the inlet and outlet pressure difference of the check valve 3 is greater than the first preset pressure difference value, maintain the speed of the running pump at the given speed calculated by the speed balancing calculation module.

[0069] Specifically, if the inlet and outlet pressure difference of the check valve 3 is less than or equal to the first preset pressure difference value, it indicates that the check valve 3 may be abnormally closed, and the outlet pressure of the corresponding running pump is low, so it is necessary to increase the given speed of the running pump, that is, the speed signal received by the running pump increases a certain speed increment on the basis of the given speed signal output by the speed balance calculation module. The speed increment can be comprehensively set according to user needs and system characteristics, and it can be a fixed increment or a variable increment, which is not specifically limited here. The first preset pressure difference value can also be defined according to user needs. Usually, when the inlet and outlet pressure difference of the check valve 3 is a negative value, the check valve 3 is closed, so the first preset pressure difference value can be 0.

[0070] If the inlet and outlet pressure difference of the check valve 3 is greater than the first preset pressure difference value, it indicates that the check valve 3 is in a normally open state, and the branch circuit operates normally. At this time, the current given speed of the running pump can be maintained.

[0071] The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided in this embodiment detects the inlet and outlet pressure difference of the check valve 3 located at the outlet of the running pump after the rotation speeds of the multiple running pumps reach equilibrium. If the inlet and outlet pressure difference is less than or equal to the first preset pressure difference value, the check valve 3 is in a closed state. At this time, the outlet head of the pump can be increased by increasing the rotation speed of the pump, thereby increasing the inlet and outlet pressure difference of the check valve 3. When it is higher than the static resistance of the check valve 3, the check valve 3 can be opened; if the inlet and outlet pressure difference is greater than the first preset pressure difference value, the check valve 3 is in an open state, and the branch circuit operates normally. At this time, the current rotation speed can be maintained. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference can avoid the problem of the pump outlet water temperature rising and the impeller cavitation caused by the long-term idling of the running pump, thereby maintaining the appropriate temperature of the pump group and improving the reliability and service life of the equipment. In addition, the method does not require any changes to the equipment or pipelines, can be put into use in a timely manner, has low cost and good effect.

[0072] Further, in step S300, increasing the given speed of the running pump specifically includes:

[0073] Based on the preset speed increase rule, the speed is gradually increased on the basis of the given speed calculated by the speed balancing calculation module until the inlet and outlet pressure difference of the check valve 3 is greater than or equal to the second preset pressure difference value, and the current speed is maintained.

[0074] Specifically, the preset speed increase rule can be set by the user, and a PID control algorithm or a linear increasing method can be used to gradually adjust the speed of the running pump so that the inlet and outlet pressure difference of the check valve 3 gradually increases until it is greater than or equal to the second preset pressure difference value. The second preset pressure difference value is greater than the first preset pressure difference value, forming a hysteresis control interval.

[0075] like Figure 3 As shown, Pd x Indicates the first preset pressure difference value, Pd y represents the second preset pressure difference value, and the specific change range is: (1) A→C: the pump is running to maintain a given speed, the inlet and outlet pressure difference of the check valve 3 becomes smaller, and the check valve 3 may be abnormally closed; (2) C→D: the inlet and outlet pressure difference of the check valve 3 is equal to the first preset pressure difference value Pd x , the running pump starts to increase the speed; (3) D→E is the inertia section, the inlet and outlet pressure difference of the check valve 3 will become smaller due to inertia and response delay; (4) E→F, the running pump continues to increase the speed, and the inlet and outlet pressure difference of the check valve 3 gradually increases; (5) F→B: the inlet and outlet pressure difference of the check valve 3 is equal to the second preset pressure difference value Pd y , the running pump stops increasing the speed and keeps running at the current speed.

[0076] By setting the hysteresis interval, the speed increase regulation process will not cause frequent switching of the output (increasing the speed) due to slight fluctuations in the input (the inlet and outlet pressure difference of the check valve 3), and the response hysteresis is used to accommodate environmental fluctuations.

[0077] Furthermore, after increasing the given speed of the running pump, it also includes:

[0078] Determine whether two or more pumps among the multiple running pumps increase the given speed;

[0079] If so, the speed of the running pump is restored to the given speed calculated by the speed balancing calculation module, and the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is re-obtained after a delay of the first preset time, and the execution jumps to step S300.

[0080] Specifically, when a running pump in a multi-pump parallel system increases its speed, it may cause the outlet pressure of other running pumps to be low, thereby triggering two or more pumps to execute the step of increasing the speed, and finally forming a situation where multiple pumps alternately increase or decrease the speed, that is, the unfavorable situation of taking turns to grab the load, which is more likely to occur when two pumps are running in parallel. In order to avoid the above situation, when two or more pumps need to increase the given speed, that is, after the speed is increased in the first branch, the inlet and outlet pressure difference of the check valve 3 of the second branch is detected to be low, which may trigger the step of increasing the speed. At this time, the speed of the running pump of the first branch is restored to the given speed calculated by the speed balancing operation module. Therefore, the speeds of the running pumps in the first branch and the second branch are equivalent, and both maintain the given speed (that is, the given speed signal output by the speed balancing operation module).

[0081] By restoring the running pump in the first branch to a given speed, the running pumps in the two branches return to a balanced state, and then after waiting for a first preset time, the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is obtained, and the execution of step S300 is jumped to avoid entering an unfavorable cycle of alternating speed increases and decreases of multiple pumps.

[0082] Based on the above embodiment, before step S100, the method further includes:

[0083] Determine whether the control mode of the multi-pump parallel system is switched from manual control to automatic control;

[0084] If so, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module, and the process jumps to step S100 after a delay of a second preset time; if not, the process jumps to step S100.

[0085] Specifically, when the control mode of the multi-pump parallel system is switched from manual control to automatic control, each running pump may not have reached a balanced state, so the given speed is maintained without increasing the speed additionally, and step S100 is executed after the second preset time to prevent system misjudgment.

[0086] Based on the above embodiment, before step S100, the method further includes:

[0087] Determine if the combination of operating pumps has changed;

[0088] If so, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module, and the process jumps to step S100 after a delay of a third preset time; if not, the process jumps to step S100.

[0089] Specifically, when the combination of the running pumps changes, for example, when the operation of the 1# pump and the 2# pump changes to the 1# pump and the 3# pump, the 3# pump is started, and during the start-up process of the 3# pump, its corresponding check valve 3 is in a closed state, which is a normal closure at this time. In order to prevent the system from misjudging, the speed is not increased during the start-up process of the pump, and the given speed is maintained first, and step S100 is executed after the third preset time. In addition, the combination of the running pumps can also undergo changes such as chain start, increase of running pumps, or reduction of running pumps. When the above changes occur, the running pumps all maintain the given speed calculated by the speed balance calculation module, and the speed is not increased, and step S100 is executed after the third preset time.

[0090] Based on the above embodiment, in step S200, obtaining the inlet and outlet pressure difference of the check valve located at the outlet of the running pump further includes:

[0091] Step S210: continuously and in real time collect the inlet and outlet pressure difference signals of the check valve 3, and cache the collected inlet and outlet pressure difference signals of the check valve 3 in a buffer.

[0092] Step S220: Filter the n groups of inlet and outlet pressure difference signals collected most recently in the buffer to calculate the inlet and outlet pressure difference of the check valve. Specifically, the filtering process can adopt median filtering, arithmetic average filtering, recursive average filtering, median average filtering, etc. This embodiment is described by taking median average filtering as an example.

[0093] Specifically, step S220 further includes:

[0094] Step S221: The n groups of newly collected inlet and outlet pressure difference signal data are {Pd 0 , Pd 1 , Pd 2 , ..., Pd n-1}, where Pd0 Indicates the current collected inlet and outlet pressure difference value, Pd n-1 Indicates the inlet and outlet pressure difference values ​​collected for the previous n-1 times, where n is a positive integer greater than 1;

[0095] Step S222: Determine the maximum inlet and outlet pressure difference value Pd among the n groups of inlet and outlet pressure difference signal data max and minimum pressure difference Pd min .

[0096] Step S223: The calculation formula of the inlet and outlet pressure difference of the check valve 3 is as follows:

[0097]

[0098] Among them, Pd mean is the inlet and outlet pressure difference of the check valve 3, Pd i is the inlet and outlet pressure difference value collected for the i-th time, Pd max is the maximum inlet and outlet pressure difference, Pd min is the minimum inlet and outlet pressure difference. The minimum and maximum values ​​in the pressure difference are removed by using the median average filter, and then the arithmetic mean of n-2 data is calculated. This combines the advantages of the median filter and the arithmetic mean filter, and can eliminate the occasional interference deviation. In addition, the second largest value, the second largest value, and the second smallest value in the pressure difference can also be removed. This is only an example and is not limited.

[0099] On the basis of the above embodiment, before step S100, a rotation speed balancing operation is further included:

[0100] Step S010: Determine the pump with the highest speed and the pump with the lowest speed among the multiple running pumps. Specifically, it can be determined by enumeration or one-by-one comparison. It can also be digitally encoded by various operating information of the pumps, and then the comprehensive information encoding of all running pumps is combined to solve the maximum or minimum value of the comprehensive information data, so that the pump with the highest speed and the pump with the lowest speed can be directly determined. When the number of pumps is large, the calculation amount of this method is relatively small, which is more conducive to program writing and is not easy to miss items. This method is a prior art and will not be described here.

[0101] Step S020: If the speed difference between the pump with the highest speed and the pump with the lowest speed is greater than the preset speed difference, the given speed of the pump with the highest speed is reduced based on the preset adjustment parameter, and the given speed of the pump with the lowest speed is increased. Specifically, the preset adjustment parameter can be set by the user, for example, it can be linearly increased / decreased, or based on a PID algorithm, etc., which is not limited here.

[0102] Step S030: repeat the above steps until the speed difference between any two pumps in the plurality of running pumps is less than or equal to a preset speed difference.

[0103] The present invention also provides a device for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference, comprising:

[0104] A speed difference determination module, for determining whether a speed difference between any two pumps among a plurality of running pumps is less than or equal to a preset speed difference value;

[0105] The speed difference judgment module, if not, maintains the given speed of the running pump; if so, obtains the inlet and outlet pressure difference of the check valve located at the outlet of the running pump;

[0106] The speed regulating module increases the given speed of the running pump when the inlet and outlet pressure difference of the check valve is less than or equal to the first preset pressure difference value; or maintains the given speed of the running pump when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value.

[0107] The performance dispersion suppression device of the multi-pump parallel system based on pressure difference may also include:

[0108] The data storage module is used to store important parameters such as the speed control signal of the running pump, the speed feedback signal, the inlet and outlet pressure difference signal of the check valve 3, the running pump automatic control signal (switch signal) and the main pipe regulating valve (such as the water supply regulating valve 5) pressure difference signal. Through the process control device running data storage method, the important parameters of the water supply control system are stored in a limited storage space, the data can be downloaded and the operating status of the running pump can be further analyzed. The process control device running data storage method belongs to the prior art and will not be repeated here.

[0109] like Figure 4As shown, on the basis of the above-mentioned embodiment, as another preferred implementation mode, the present invention also provides a water supply pump speed control system including a multi-pump parallel system performance dispersion suppression device based on pressure difference, wherein the speed increase control module is the branch performance dispersion suppression device of the multi-pump parallel system. The water supply pump speed control system is composed of a speed balancing operation module, n speed increase control modules and n water supply pump given signal AO conversion modules, wherein the value of n is the same as the number of water supply pumps 1. First, before each water supply pump 1 reaches a balanced state, the speed balancing operation module calculates the given speed signal of each water supply pump 1 based on the PID control algorithm, and the speed increment signal output by the speed increase control module is 0, which is converted into a (4-20) mA current signal to each water supply pump 1 through the water supply pump speed given signal AO conversion module. At this time, the water supply pump 1 directly runs at a given speed. Then, when each water supply pump 1 reaches a balanced state, if the inlet and outlet pressure difference of the check valve 3 of a branch is less than or equal to the first preset pressure difference value, the speed increase control module corresponding to the branch outputs an appropriate speed increment signal, and accordingly increases the speed of the water supply pump 1 on the branch based on the given speed, while the water supply pumps 1 of the other branches continue to operate at the given speed.

[0110] Figure 5 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 5 As shown, the electronic device may include: a processor 710, a communication interface 720, a memory 730 and a communication bus 740, wherein the processor 710, the communication interface 720 and the memory 730 communicate with each other through the communication bus 740. The processor 710 may call the logic instructions in the memory 730 to execute the method for suppressing the performance dispersion of the multi-pump parallel system based on the pressure difference provided in the above embodiments, and the method includes:

[0111] Determine whether a speed difference between any two pumps of the plurality of running pumps is less than or equal to a preset speed difference value;

[0112] If not, the given speed of the running pump is maintained; if yes, the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is obtained;

[0113] When the inlet and outlet pressure difference of the check valve is less than or equal to the first preset pressure difference value, the given speed of the running pump is increased; or when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value, the given speed of the running pump is maintained.

[0114] In addition, the logic instructions in the above-mentioned memory 730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0115] On the other hand, the present invention further provides a computer program product, the computer program product includes a computer program, the computer program can be stored in a non-transitory computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference provided in the above embodiments, the method comprising:

[0116] Determine whether a speed difference between any two pumps of the plurality of running pumps is less than or equal to a preset speed difference value;

[0117] If not, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module; if so, the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is obtained;

[0118] When the inlet and outlet pressure difference of the check valve is less than or equal to the first preset pressure difference value, the given speed of the running pump is increased; or when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module.

[0119] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to execute the method for suppressing the dispersion of performance of a multi-pump parallel system based on pressure difference provided by the above methods, the method comprising:

[0120] Determine whether a speed difference between any two pumps of the plurality of running pumps is less than or equal to a preset speed difference value;

[0121] If not, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module; if so, the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is obtained;

[0122] When the inlet and outlet pressure difference of the check valve is less than or equal to the first preset pressure difference value, the given speed of the running pump is increased; or when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module.

[0123] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference, characterized in that: include: Step S100, determining whether the speed difference between any two pumps among a plurality of running pumps is less than or equal to a preset speed difference; Step S200: If not, keep the speed of the running pump at the given speed calculated by the speed balancing calculation module; if yes, obtain the inlet and outlet pressure difference of the check valve located at the outlet of the running pump; The step of obtaining the inlet and outlet pressure difference of the check valve located at the outlet of the running pump further comprises: Continuously and in real time collecting the inlet and outlet differential pressure signals of the check valve, and caching the collected inlet and outlet differential pressure signals of the check valve in a buffer; Filtering the n groups of inlet and outlet pressure difference signals collected most recently in the buffer zone to calculate the inlet and outlet pressure difference of the check valve; Step S300, when the inlet and outlet pressure difference of the check valve is less than or equal to a first preset pressure difference value, increasing the given speed of the running pump; or When the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value, the rotation speed of the running pump is maintained at the given rotation speed calculated by the rotation speed balancing calculation module.

2. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to claim 1, characterized in that: The step of increasing the given speed of the running pump further comprises: Based on the preset speed increase rule, the speed is gradually increased on the basis of the given speed calculated by the speed balancing calculation module until the inlet and outlet pressure difference of the check valve is greater than or equal to the second preset pressure difference value, and the current speed is maintained.

3. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to claim 1, characterized in that: After increasing the given speed of the running pump, the method further comprises: Determining whether two or more pumps among the plurality of operating pumps increase a given speed; If so, the speed of the running pump is restored to the given speed calculated by the speed balancing calculation module, and the inlet and outlet pressure difference of the check valve located at the outlet of the running pump is re-obtained after a first preset delay, and the process jumps to step S300.

4. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to claim 1, characterized in that: Before step S100, the method further includes: Determining whether the control mode of the multi-pump parallel system is switched from manual control to automatic control; If yes, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module, and the process jumps to step S100 after a delay of a second preset time; If not, the process jumps to step S100.

5. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to claim 1, characterized in that: Before step S100, the method further includes: Determining whether the combination of the operating pumps has changed; If yes, the speed of the running pump is maintained at the given speed calculated by the speed balancing calculation module, and the process jumps to step S100 after a delay of a third preset time; If not, the process jumps to step S100.

6. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to claim 1, characterized in that: The filtering process of the n groups of inlet and outlet pressure difference signal data collected most recently in the buffer zone to calculate the inlet and outlet pressure difference of the check valve further includes: The latest n groups of inlet and outlet pressure difference signal data collected are {Pd0, Pd1, Pd2, ..., Pd n-1 }, where Pd0 represents the current collected inlet and outlet pressure difference value, Pd n-1 Indicates the inlet and outlet pressure difference values ​​collected for the previous n-1 times, where n is a positive integer greater than 1; Determine the maximum inlet and outlet pressure difference value Pd among n groups of inlet and outlet pressure difference signal data max and minimum pressure difference Pd min ; Based on the smoothing filtering method, the calculation formula of the inlet and outlet pressure difference of the check valve is as follows: Among them, Pd mean is the inlet and outlet pressure difference of the check valve, Pd i is the inlet and outlet pressure difference value collected for the i-th time, Pd max is the maximum inlet and outlet pressure difference, Pd min It is the minimum inlet and outlet pressure difference.

7. The method for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to any one of claims 1 to 6, characterized in that: Before step S100, the method further includes: Determining a pump with the highest rotation speed and a pump with the lowest rotation speed among the plurality of operating pumps; If the speed difference between the pump with the largest speed and the pump with the smallest speed is greater than the preset speed difference, then based on the preset adjustment parameter, the given speed of the pump with the largest speed is reduced, and the given speed of the pump with the smallest speed is increased; Repeat the above steps until the speed difference between any two pumps in the plurality of running pumps is less than or equal to the preset speed difference.

8. A device for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference, characterized in that: include: A speed difference determination module, for determining whether the speed difference between any two pumps in a plurality of running pumps is less than or equal to a preset speed difference value; The speed difference judgment module, if not, keeps the speed of the running pump at the given speed calculated by the speed balance calculation module; if so, obtains the inlet and outlet pressure difference of the check valve located at the outlet of the running pump; The step of obtaining the inlet and outlet pressure difference of the check valve located at the outlet of the running pump further comprises: Continuously and in real time collecting the inlet and outlet differential pressure signals of the check valve, and caching the collected inlet and outlet differential pressure signals of the check valve in a buffer; Filtering the n groups of inlet and outlet pressure difference signals collected most recently in the buffer zone to calculate the inlet and outlet pressure difference of the check valve; The speed regulating module increases the given speed of the running pump when the inlet and outlet pressure difference of the check valve is less than or equal to the first preset pressure difference value; or maintains the speed of the running pump at the given speed calculated by the speed balancing calculation module when the inlet and outlet pressure difference of the check valve is greater than the first preset pressure difference value.

9. The device for suppressing the performance dispersion of a multi-pump parallel system based on pressure difference according to claim 8, characterized in that: Also includes: The data storage module is used to store the speed control signal of the running pump, the speed feedback signal, the inlet and outlet pressure difference signal of the check valve, the running pump automatic control signal and the main pipe regulating valve pressure difference signal.

Images