A precise frequency conversion and voltage conversion intelligent water supply control method and device

Abstract

The present invention discloses a precise variable-frequency and variable-voltage intelligent water supply control method and device. A precise variable-frequency and variable-voltage intelligent water supply device includes an inlet pipeline, a centrifugal pump group, an inverter, a PLC controller, a pressure transmitter, a flow transmitter, an outlet pipeline and a user end. A liquid level sensor is arranged on the inlet pipeline. The centrifugal pump group includes three parallel centrifugal pumps and check valves, and each centrifugal pump is connected to the inverter one-to-one. An outlet pressure sensor, a pressure switch and an outlet flowmeter are arranged on the outlet pipeline. User-end pressure sensors and user-end flowmeters are installed at each user end. The PLC controller is connected to the inverter, and the PLC controller monitors the pressure and flow data in the system, thereby realizing the adjustment of the system state. The present invention makes the water supply system more precise, makes the water supply system more energy-saving, and at the same time avoids the damage of the pipeline of the water supply system.

Description

Technical Field

[0001] The present invention relates to the field of water supply, and mainly relates to a precise frequency conversion and variable pressure intelligent water supply control method and device. Background Art

[0002] Today, with the increasing shortage of energy, as buildings are getting taller and taller, energy conservation in high-rise water supply becomes particularly important. Due to the water pressure problem of high-rise users, most households will install a household centrifugal pump for use when the water supply is insufficient. When designing water supply equipment, in order to meet the needs of domestic and urban water use, most of the water pumps in the water supply system are in a full-load working state most of the time, which can avoid insufficient water supply. However, when the water consumption is low, excessive energy loss will occur, resulting in waste of resources. And high-rise users will install a household centrifugal pump to prevent the lack of water, but the water supply system still provides the same pressure, causing excessive pressure in the pipeline, affecting the water use of users, and causing waste of energy. Therefore, energy conservation is very important on the premise of meeting the water use needs of users on different floors.

[0003] Currently, water supply equipment generally uses constant pressure control. By adjusting the speed of the water pump, the pressure at the outlet end of the pump is maintained constant to meet the change of user water consumption, thereby achieving an energy-saving effect. However, when using this method for water supply, when the user water consumption decreases, there is excess pressure in the water supply system, resulting in waste of energy, and in severe cases, it will also damage the pipeline of the water supply system. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a precise frequency conversion and variable pressure intelligent water supply control method and device. The data detected by the pressure sensor and flowmeter at the user end are sent to the PLC controller through a transmitter. After calculation and comparison by the PLC controller, the working state of the centrifugal pump group is adjusted to make the water supply more precise, which can not only meet the water use of different floors at different times, but also meet the precise water supply of high-rise users equipped with household centrifugal pumps, avoid waste of energy, and achieve a more energy-saving purpose.

[0005] A precise frequency conversion and variable pressure intelligent water supply device includes an inlet pipeline, a centrifugal pump group, a frequency converter, a PLC controller, a pressure transmitter, a flow transmitter, an outlet pipeline and a user end.

[0006] A liquid level sensor is arranged on the inlet pipeline.

[0007] The centrifugal pump group is located between the inlet pipeline and the outlet pipeline.

[0008] The centrifugal pump group includes three parallel centrifugal pumps and one-way valves arranged at the outlet end of each centrifugal pump, and each centrifugal pump is connected to the frequency converter one by one.

[0009] An outlet pressure sensor, a pressure switch, and an outlet flowmeter are provided on the outlet water pipeline.

[0010] The outlet water pipeline is connected to the user end.

[0011] For the user end, a household centrifugal pump is installed for high-rise users, while it is not necessary for mid- and low-rise users. However, all users are equipped with a user-end pressure sensor and a user-end flowmeter.

[0012] The PLC controller is connected to the frequency converter. The PLC controller monitors the data of the outlet pressure sensor, the outlet flowmeter, the user-end pressure sensor, and the user-end flowmeter in the whole system, so as to realize the control of the whole system.

[0013] The pressure data read by the outlet pressure sensor and the user-end pressure sensor are transmitted to the PLC controller through the pressure transmitters connected thereto; the flow data read by the outlet flowmeter and the user-end flowmeter are transmitted to the PLC controller through the flow transmitters connected thereto.

[0014] A precise variable-frequency and variable-pressure intelligent water supply control method: By comparing the actual pressure value at the most unfavorable point with the theoretical pressure value that should be satisfied at the most unfavorable point, the PLC controller adjusts the operating state of the centrifugal pump set by controlling the frequency converter.

[0015] Furthermore, according to the signals of the outlet pressure sensor and the outlet flowmeter of the centrifugal pump set, combined with the relationship between the pipeline friction loss and the flow rate, and through the actual pipe section length from the outlet pressure detection point to the most unfavorable point, the actual pressure value at the most unfavorable point is determined.

[0016] Furthermore, the pipeline friction loss can be obtained according to the pump characteristics and the pipeline characteristics:

[0017] H f = S0LQ 2

[0018] Wherein, S0 is the pipe section specific resistance, the head required for a unit flow rate to pass through a unit length of pipeline, L is the pipe section length, and Q is the flow rate in the pipeline.

[0019] Furthermore, according to the signals of the user-end pressure sensor and the user-end flowmeter, combined with the relationship between the pipeline friction loss and the flow rate, and through the actual pipe section length from the user-end pressure detection point to the most unfavorable point, the theoretical pressure value that should be satisfied at the most unfavorable point is determined.

[0020] Furthermore, when the actual pressure value at the most unfavorable point is lower than the theoretical pressure that the most unfavorable point should meet, that is, when the required pressure in the user-side pipeline is high, the PLC controller controls the frequency converter to increase the number of centrifugal pumps started in the centrifugal pump group and increase the operating speed of the centrifugal pumps; when the theoretical pressure value at the most unfavorable point is less than the actual pressure value at the most unfavorable point, that is, when the required pressure in the user-side pipeline is low, the PLC controller reduces the number of centrifugal pumps started in the pump group and decreases the operating speed of the centrifugal pumps through the frequency converter.

[0021] Furthermore, for high-rise users installing household centrifugal pumps, the pressure in the pipeline is detected by the user-side pressure sensor to determine whether the household centrifugal pump is started. If the household centrifugal pump is started, the pressure in the user-side pipeline increases. At this time, the PLC controller controls the frequency converter to control the number of centrifugal pumps started or the speed in the centrifugal pump group, reducing the water outlet pressure at the water outlet pipe end of the centrifugal pump group; if not started, the PLC controller only needs to compare the theoretical pressure value and the actual pressure value at the most unfavorable point, and then adjusts the working state of the centrifugal pump group by controlling the frequency converter.

[0022] The beneficial effects of the present invention are as follows: The PLC controller reads the data transmitted by the outlet pressure sensor, the user-side pressure sensor, the user-side flowmeter, and the user-side flowmeter through the transmitter, processes the data, and thus controls the centrifugal pump group through the frequency converter. Through the joint debugging of each part in the whole system, water supply is provided to users. When it is uncertain whether a household centrifugal pump is installed at the user side, the operation state of the centrifugal pump group can be adjusted according to the processing and comparison of the data of the pressure sensor and the flowmeter at the user side, making the water supply system more accurate, avoiding damage to the pipeline of the water supply system, and at the same time reducing energy consumption, making the water supply system more energy-saving. Description of the Drawings

[0023] Figure 1 Shown is the water supply system;

[0024] Figure 2 Shown is the flowchart of the water supply system;

[0025] Figure 3 Shown is the flowchart of Embodiment III. Detailed Embodiments

[0026] A precise frequency conversion and variable pressure intelligent water supply control device includes an inlet pipeline, a centrifugal pump group, a frequency converter, a PLC controller, a pressure transmitter, a flow transmitter, an outlet pipeline, and a user side.

[0027] Such as Figure 1As shown in the figure, a liquid level sensor 2 is provided on the inlet pipeline; the centrifugal pump unit is located between the inlet pipeline and the outlet pipeline; an outlet pressure sensor 6, a pressure switch 7 and an outlet flowmeter 8 are provided on the outlet pipeline.

[0028] The centrifugal pump unit 3 is connected to the municipal water supply network 1, including the liquid level sensor 2 therebetween, and is connected to the PLC controller 5 and is controlled and monitored by the PLC controller 5. The liquid level sensor 2 can detect the water condition of the inlet pipeline in real time; when the water level is too low, the sensor reads the liquid level signal and transmits it to the PLC controller 5, and the PLC controller 5 shuts down the operation of the centrifugal pump unit 3 to play a protective role.

[0029] The centrifugal pump unit 3 includes three parallel centrifugal pumps. The centrifugal pumps are connected to the frequency converters 4 in a one-to-one correspondence, achieving the effect of one frequency converter controlling one centrifugal pump. A check valve 14 is installed at the water outlet end of the centrifugal pump to prevent the water in the pump unit pipeline from flowing back. The frequency converter 4 is connected to the PLC controller 5. The outlet pipeline of the centrifugal pump unit 3 is connected to the user end, and an outlet pressure sensor 6, a pressure switch 7 and an outlet flowmeter 8 are provided on the outlet pipeline. The pressure sensor in the pressure switch 7 can monitor the pressure in the outlet pipeline in real time to prevent excessive pressure in the pipeline from damaging the pipeline and affecting the use of the user end. The outlet pressure sensor 6 and the pressure switch 7 are both connected to the PLC controller 5 through a pressure transmitter 11, and the outlet flowmeter 8 is connected to the PLC controller 5 through a flow transmitter 13.

[0030] The user end is connected to the outlet pipeline of the centrifugal pump unit. A household centrifugal pump 10 may be installed at the user end, but a user end pressure sensor 9 is installed at all times. The user end pressure sensor 9 reads the pressure of the user end pipeline and transmits the pressure data to the PLC controller 5 through the pressure transmitter 11; a user end flowmeter 12 is installed at the user end. The user end flowmeter 12 reads the flow in the user end pipeline and transmits the flow data to the PLC controller 5 through the flow transmitter 13.

[0031] A precise frequency conversion and variable pressure intelligent water supply control method: By comparing the actual pressure value at the most unfavorable point with the theoretical pressure value that should be satisfied at the most unfavorable point, the operating state of the centrifugal pump unit is adjusted.

[0032] Example 1:

[0033] A household centrifugal pump 10 will be installed at the high-rise user end to prevent its use in case of insufficient water supply. Middle and low-rise users do not need to install the household centrifugal pump 10. However, whether the high-rise users use the household centrifugal pump 10 or not, the pressure sensor 9 at the user end detects the water pressure at the user end and transmits the pressure data to the PLC controller 5 through the pressure transmitter 11. The flowmeter 12 at the user end detects the flow rate and transmits the flow rate data to the PLC controller 5 through the flow transmitter 13. The PLC controller 5, based on the data from the pressure sensor and the flowmeter at the user end, combines the relationship between the head loss along the pipeline and the flow rate, and through the actual pipe section length from the pressure detection point at the user end to the most unfavorable point, obtains the theoretical pressure value that the most unfavorable point should satisfy. At the same time, the PLC controller 5 reads the data from the outlet pressure sensor 6 and the outlet flowmeter 8, combines the relationship between the head loss along the pipeline and the flow rate, and through the actual pipe section length from the outlet pressure detection point to the most unfavorable point, determines the actual pressure value at the most unfavorable point. This value is compared with the theoretical pressure value that the most unfavorable point should satisfy, so as to adjust the working state of the centrifugal pump unit 3.

[0034] According to the pump characteristics and pipeline characteristics, the head loss along the pipeline can be obtained as follows:

[0035] H f = S0LQ 2

[0036] where S0 is the specific resistance of the pipe section, which is the head required for a unit flow rate to pass through a unit length of the pipeline; L is the pipe section length; and Q is the flow rate in the pipeline.

[0037] When the household centrifugal pump 10 is enabled, the pressure sensor 9 at the user end detects that the pressure in the user end pipeline is high. However, it is necessary to consider that the high pressure is due to the activation of the household centrifugal pump 10. According to the pump characteristics, the original pressure in the user end pipeline without the pressure increase by the household centrifugal pump 10 can be obtained. At this time, the theoretical pressure value at the most unfavorable point is less than the actual pressure value at the most unfavorable point. The PLC controller 5 reduces the number of working centrifugal pumps in the centrifugal pump unit or reduces the rotational speed of the centrifugal pump through the frequency converter 4. When the household centrifugal pump 10 is not enabled, only the theoretical pressure value at the most unfavorable point is calculated based on the data detected by the pressure sensor 9 at the user end and compared with the actual pressure value at the most unfavorable point. The PLC controller 5 adjusts the working state of the centrifugal pump unit through the frequency converter 4.

[0038] When the water consumption of the user is large, the pressure in the pipe decreases, and the actual pressure value at the most unfavorable point is lower than the theoretical pressure that the most unfavorable point should satisfy. At this time, the PLC controller 5 increases the speed or the number of pumps in the centrifugal pump group 3 through the frequency converter 4 to increase the pressure value at the most unfavorable point; when the water consumption at the user end is small, the pressure in the pipe increases, and the actual pressure value at the most unfavorable point is higher than the theoretical pressure that the most unfavorable point should satisfy. At this time, the PLC controller 5 decreases the speed or the number of pumps in the centrifugal pump group 3 through the frequency converter 4 to decrease the actual pressure value at the most unfavorable point. Thus, accurate water supply is achieved, energy waste is not caused, and the purpose of more energy conservation is realized. The specific process is as Figure 2 shown.

[0039] Embodiment 2:

[0040] Currently, the water meters used at the user end are basically intelligent water meters. These intelligent water meters can realize a long-distance and low-power consumption meter reading system, making the use at the user end more convenient and allowing the user to master the water usage situation at any time. Therefore, the intelligent water meter at the user end can be used to replace the flowmeter 12 at the user end, and the intelligent water meter is also connected to the PLC controller 5 through a Bluetooth module. At this time, regardless of whether the household centrifugal pump 10 is turned on, the flow at the user end can be used to read the real-time flow data in the pipeline through the water volume measurement unit of the intelligent water meter. Combining the relationship between the pipeline friction loss and the flow at the user end, the theoretical pressure value that the most unfavorable point should satisfy is calculated through the data of the pressure sensor 9 at the user end.

[0041] Meanwhile, when reading the data of the pressure sensor 9 at the user end to calculate the theoretical pressure value that the most unfavorable point should satisfy, it is necessary to judge whether the user has turned on the household centrifugal pump 10 according to the data of the pressure sensor 9 at the user end. If the household centrifugal pump 10 is turned on, at this time, it is necessary to calculate the pressure in the pipeline at the user end when the household centrifugal pump 10 is not turned on according to the characteristics of the pump and the flow read by the intelligent water meter. The PLC controller 5 reads the data of the outlet flowmeter 8 through the flow transmitter 13, combines the relationship between the pipeline friction loss and the flow at the pump group outlet, and calculates the actual pressure at the most unfavorable point according to the data of the pressure sensor 6 at the pump group outlet. The PLC controller 5 compares the actual pressure value at the most unfavorable point with the theoretical pressure value that the most unfavorable point should satisfy, and adjusts the operating state of the centrifugal pump group 3 through the frequency converter 4. If the actual pressure value at the most unfavorable point is less than the theoretical pressure value that the most unfavorable point should satisfy, the PLC controller 5 increases the speed of the centrifugal pump or increases the number of centrifugal pumps turned on through the frequency converter 4; if the actual pressure value at the most unfavorable point is greater than the theoretical pressure value that the most unfavorable point should satisfy, the PLC controller 5 decreases the speed of the centrifugal pump or decreases the number of centrifugal pumps turned on through the frequency converter 4. In this way, the purpose of accurate water supply is achieved, and the water supply system is made more energy-efficient.

[0042] Embodiment 3:

[0043] As Figure 3 shown, the centrifugal pump at the user end is also controlled by the PLC controller 5. Since the efficiency of the household centrifugal pump 10 is relatively low, if all high-rise users turn on the household centrifugal pump 10, more energy will be wasted. Therefore, the purpose of high-rise water supply can be achieved by turning on individual household centrifugal pumps 10 and increasing or decreasing the rotational speed or the number of centrifugal pumps in the centrifugal pump group 3.

[0044] The household centrifugal pump 10 can be turned on in descending order. Taking only the highest-level household centrifugal pump 10 being turned on as an example, the PLC controller calculates the theoretical pressure value that the most unfavorable point should satisfy based on the data transmitted by the pressure transmitter 11 and the smart electricity meter, combined with the relationship between the pipeline friction loss and the flow rate. The PLC controller calculates the actual pressure value of the most unfavorable point through the actual pipe section length from the outlet pressure detection point to the most unfavorable point based on the data of the pump outlet pressure sensor 6 and the pump outlet flowmeter 8, combined with the relationship between the pipeline friction loss and the flow rate. The PLC controller 5 adjusts the operating state of the centrifugal pump group 3 by comparing the actual pressure of the most unfavorable point with the theoretical pressure value that should be satisfied. At this time, the pipeline pressure at the highest-level user end is the data of the user end pressure sensor 9. At this time, the theoretical pressure value that the most unfavorable point of the water supply network should satisfy is calculated by the PLC controller 5. When the water consumption at the user end is large, the pressure in the pipeline will decrease at this time, and the actual pressure value of the most unfavorable point will decrease. At this time, multiple household centrifugal pumps 10 can be turned on to achieve the purpose of boosting the pressure at the user end. However, because the efficiency of small pumps is relatively low, the more household centrifugal pumps 10 are turned on, the more energy loss will be caused. Therefore, try not to turn on multiple household centrifugal pumps 10, but increase the rotational speed or the number of the centrifugal pump group 3 to increase the actual pressure of the most unfavorable point to achieve the purpose of water supply, making the entire water supply system more energy-efficient and having less energy loss.

Claims

1. A precise frequency - variable and voltage - variable intelligent water supply control method. The water supply equipment used includes an inlet pipeline, a centrifugal pump group, a frequency converter, a PLC controller, a pressure transmitter, a flow transmitter, an outlet pipeline, and a user end; A liquid - level sensor is arranged on the inlet pipeline; The centrifugal pump group is located between the inlet pipeline and the outlet pipeline; The centrifugal pump group includes three parallel centrifugal pumps and one - way valves arranged at the outlet end of each centrifugal pump, and each centrifugal pump is connected to the frequency converter one - to - one; An outlet pressure sensor, a pressure switch, and an outlet flowmeter are arranged on the outlet pipeline; The outlet pipeline is connected to the user end; For the user end, household centrifugal pumps are installed for high - rise users, while household centrifugal pumps are not installed for middle - and low - rise users. However, all users are equipped with a user - end pressure sensor and a user - end flowmeter; The PLC controller is connected to the frequency converter; The pressure data read by the outlet pressure sensor and the user - end pressure sensor are transmitted to the PLC controller through the pressure transmitter connected to them; The flow data read by the outlet flowmeter and the user - end flowmeter are transmitted to the PLC controller through the flow transmitter connected to them; It is characterized in that: By comparing the actual pressure value at the most unfavorable point with the theoretical pressure value at the most unfavorable point, the PLC controller controls the frequency converter to adjust the operating state of the centrifugal pump group. Specifically: According to the signals of the outlet pressure sensor and the outlet flowmeter of the centrifugal pump group, combined with the relationship between the pipeline frictional loss and the flow rate, and through the actual pipe section length from the outlet pressure detection point to the most unfavorable point, the actual pressure value at the most unfavorable point is determined; According to the signals of the user - end pressure sensor and the user - end flowmeter, combined with the relationship between the pipeline frictional loss and the flow rate, and through the actual pipe section length from the user - end pressure detection point to the most unfavorable point, the theoretical pressure value that the most unfavorable point should satisfy is determined; When the actual pressure value at the most unfavorable point is lower than the theoretical pressure value at the most unfavorable point, the PLC controller controls the frequency converter to increase the number of centrifugal pumps started in the centrifugal pump group and increase the operating speed of the centrifugal pumps; when the theoretical pressure value at the most unfavorable point is less than the actual pressure value at the most unfavorable point, the PLC controller reduces the number of centrifugal pumps started in the pump group and reduces the operating speed of the centrifugal pumps through the frequency converter; High - rise users install household centrifugal pumps. The pressure in the pipeline is detected by the user - end pressure sensor to determine whether the household centrifugal pump is started; If the household centrifugal pump is started, the pressure in the user - end pipeline increases. The PLC controller controls the number of centrifugal pumps started or the speed of the centrifugal pumps in the centrifugal pump group through the frequency converter to reduce the water outlet pressure at the outlet pipeline end of the centrifugal pump group; If the household centrifugal pump is not started, the PLC controller compares the theoretical pressure value and the actual pressure value at the most unfavorable point, and then adjusts the working state of the centrifugal pump group by controlling the frequency converter.

2. The precise variable-frequency and variable-voltage intelligent water supply control method according to claim 1, characterized in that: The specific calculation of the pipeline frictional loss is shown in the following formula: H f = S0LQ 2 Among them, S0 is the pipe - section specific resistance, the head required for a unit flow rate to pass through a unit - length pipeline, L is the pipe - section length, and Q is the flow rate in the pipeline.

3. The precise frequency conversion and variable voltage intelligent water supply control method according to claim 1, characterized in that: It also includes that the PLC controller controls the household centrifugal pump to achieve the purpose of water supply.

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