阅读说明：本技术 一种基于液位调节的变频提升泵的控制方法 (Control method of variable-frequency lift pump based on liquid level regulation ) 是由 胡嘉宁 董亮 于 2020-12-30 设计创作，主要内容包括：本发明涉及一种基于液位调节的变频提升泵的控制方法,包括：步骤1：在需要执行多泵变频切换前,关闭提升泵所对应的变频器；步骤2：由相关设备采集水厂内提升泵相关数据,基于相关数据判断吸水井水位是否大于调节水位；步骤3：若判断为是,则启动PID频率调节,判断提升泵所对应的变频器的频率是否满足大于第一频率或等于第二频率的判定条件,并执行对应的换泵操作；步骤4：换泵操作执行完毕后,在提升泵由工频向变频的切换前,将变频器频率强制提升到设定的频率值,再次打开提升泵所对应的变频器以对提升泵进行控制,同时继续由相关设备实时采集水厂内提升泵相关数据以进行循环监测判断。本发明具有提高提升泵寿命且能实现自适应调整等优点。(The invention relates to a control method of a variable-frequency lift pump based on liquid level regulation, which comprises the following steps: step 1: before multi-pump variable frequency switching needs to be executed, closing a frequency converter corresponding to the lifting pump; step 2: collecting related data of a lifting pump in a water plant by related equipment, and judging whether the water level of a suction well is greater than an adjusting water level or not based on the related data; and step 3: if so, starting PID frequency regulation, judging whether the frequency of a frequency converter corresponding to the lift pump meets a judgment condition that the frequency is greater than a first frequency or equal to a second frequency, and executing corresponding pump changing operation; and 4, step 4: after the pump replacement operation is completed, before the lift pump is switched from power frequency to frequency conversion, the frequency of the frequency converter is forcibly increased to a set frequency value, the frequency converter corresponding to the lift pump is opened again to control the lift pump, and meanwhile, related data of the lift pump in the water plant are continuously collected by related equipment in real time to carry out circulation monitoring and judgment. The invention has the advantages of prolonging the service life of the lift pump, realizing self-adaptive adjustment and the like.)

1. A control method of a variable-frequency lift pump based on liquid level regulation is characterized by comprising the following steps:

step 1: before multi-pump variable frequency switching needs to be executed, closing a frequency converter corresponding to the lifting pump;

step 2: collecting related data of a lifting pump in a water plant by related equipment, and judging whether the water level of a suction well is greater than an adjusting water level or not based on the related data;

and step 3: if so, starting PID frequency regulation, judging whether the frequency of a frequency converter corresponding to the lift pump meets a judgment condition that the frequency is greater than a first frequency or equal to a second frequency, and executing corresponding pump changing operation;

and 4, step 4: after the pump replacement operation is completed, before the lift pump is switched from power frequency to frequency conversion, the frequency of the frequency converter is forcibly increased to a set frequency value, the frequency converter corresponding to the lift pump is opened again to control the lift pump, and meanwhile, related data of the lift pump in the water plant are continuously collected by related equipment in real time to carry out circulation monitoring and judgment.

2. The method for controlling the variable-frequency lift pump based on the liquid level regulation as claimed in claim 1, wherein the step 2 further comprises: if not, returning to continue to collect the related data of the lifting pump in the water plant in real time by the related equipment.

3. The method for controlling the variable-frequency lift pump based on the liquid level regulation as claimed in claim 1, wherein the step 3 further comprises: and if the frequency of the frequency converter corresponding to the lift pump is judged not to meet the judgment condition that the frequency is greater than the first frequency or equal to the second frequency, returning to continue to collect the related data of the lift pump in the water plant in real time by related equipment.

4. The method for controlling the variable-frequency lift pump based on the liquid level regulation as claimed in claim 1, wherein the related equipment in the step 2 is a liquid level meter.

5. The method for controlling the variable-frequency lift pump based on the liquid level regulation as claimed in claim 1, wherein the step 3 comprises the following substeps:

step 301: if so, starting PID frequency regulation, judging whether the frequency of a frequency converter corresponding to the lift pump meets a judgment condition that the frequency is greater than a first frequency or equal to a second frequency, and executing corresponding pump changing operation;

step 302: the pump-up flow-path operation is performed when a determination condition greater than the first frequency is satisfied, and the pump-down flow-path operation is performed when a determination condition equal to the second frequency is satisfied.

6. The method as claimed in claim 1, wherein the first frequency in step 3 is 47Hz, and the second frequency is 20 Hz.

7. The method as claimed in claim 5, wherein the step 302 of controlling the variable-frequency lift pump includes: when the water level of the suction well continuously rises, the frequency of the variable frequency pump is adjusted to full frequency, namely when the frequency is higher than the first frequency, the next lifting pump is started in a variable frequency mode, the starting frequency is set as the second frequency, the accumulated operation time of the selectable pumps is searched before the pumps are selected to be started, the lifting pump with the minimum accumulated operation time is selected, then, the water level of the suction well is continuously sampled and compared, the next variable frequency adjustment stage is started until the variable frequency pump is adjusted to full frequency, namely, the variable frequency pump operates under the condition of being higher than the first frequency, the next lifting pump is started in the same mode, and the like.

8. The method as claimed in claim 5, wherein the step 302 of controlling the variable-frequency lift pump comprises: and when the water level of the water suction well continuously drops, the frequency of the variable frequency pump is reduced to the pump stopping frequency, namely when the frequency is equal to the second frequency, the lifting pump is stopped, the lifting pump which is put into operation at the earliest is set as the variable frequency pump, the water level of the water suction well is continuously sampled and compared, the next variable frequency adjusting stage is started until the variable frequency pump is adjusted to the pump stopping frequency, namely, the lifting pump is stopped in the same way when the frequency is equal to the second frequency, the next pump is set as the variable frequency pump, and the like.

9. Terminal device comprising a memory, a processor and a computer program stored in said memory and executable on said processor, characterized in that said processor, when executing said computer program, carries out the steps of the method for controlling a variable-frequency lift pump based on level regulation according to any one of claims 1 to 8.

10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method for controlling a variable-frequency lift pump based on level regulation according to any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of lift pumps, in particular to a control method of a variable-frequency lift pump based on liquid level regulation.

Background

The lift pump is a common device in the aspects of community water supply, water works, sewage treatment plants, hydraulic engineering and the like, and along with the development of the motor frequency conversion technology, the control on the lift pump device is started and stopped conventionally, and the output power of the lift pump is gradually increased to be adjusted through the frequency conversion technology, so that the effects of high efficiency and energy conservation are achieved.

At present, when a plurality of variable frequency pumps are automatically switched, because the power-on time of the put-in-service water pumps reaches a load from a no-load moment, the current of a motor can instantly rise, so that current impact is formed on a frequency converter, the service life of equipment is shortened, and the operation quality and the environment of the variable frequency pumps are deteriorated.

Secondly, the current general liquid level feedback speed regulation mode before the pump directly feeds back the current liquid level value, so that the frequency conversion pump can be repeatedly and frequently regulated, particularly when the frequency conversion pump is at the operation critical point, the frequency conversion pump can be caused to surging, and the service life of the pump is shortened.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a control method of a variable-frequency lift pump based on liquid level regulation.

The purpose of the invention can be realized by the following technical scheme:

a control method of a variable-frequency lift pump based on liquid level regulation comprises the following steps:

step 1: before multi-pump variable frequency switching needs to be executed, closing a frequency converter corresponding to the lifting pump;

step 2: collecting related data of a lifting pump in a water plant by related equipment, and judging whether the water level of a suction well is greater than an adjusting water level or not based on the related data;

and step 3: if so, starting PID frequency regulation, judging whether the frequency of a frequency converter corresponding to the lift pump meets a judgment condition that the frequency is greater than a first frequency or equal to a second frequency, and executing corresponding pump changing operation;

and 4, step 4: after the pump replacement operation is completed, before the lift pump is switched from power frequency to frequency conversion, the frequency of the frequency converter is forcibly increased to a set frequency value, the frequency converter corresponding to the lift pump is opened again to control the lift pump, and meanwhile, related data of the lift pump in the water plant are continuously collected by related equipment in real time to carry out circulation monitoring and judgment.

Further, the step 2 further comprises: if not, returning to continue to collect the related data of the lifting pump in the water plant in real time by the related equipment.

Further, the step 3 further comprises: and if the frequency of the frequency converter corresponding to the lift pump is judged not to meet the judgment condition that the frequency is greater than the first frequency or equal to the second frequency, returning to continue to collect the related data of the lift pump in the water plant in real time by related equipment.

Further, the related device in the step 2 is a liquid level meter.

Further, the step 3 comprises the following sub-steps:

step 301: if so, starting PID frequency regulation, judging whether the frequency of a frequency converter corresponding to the lift pump meets a judgment condition that the frequency is greater than a first frequency or equal to a second frequency, and executing corresponding pump changing operation;

step 302: the pump-up flow-path operation is performed when a determination condition greater than the first frequency is satisfied, and the pump-down flow-path operation is performed when a determination condition equal to the second frequency is satisfied.

Further, the first frequency in step 3 is 47Hz, and the second frequency is 20 Hz.

Further, the pump-increasing flow operation in step 302 specifically includes: when the water level of the suction well continuously rises, the frequency of the variable frequency pump is adjusted to full frequency, namely when the frequency is higher than the first frequency, the next lifting pump is started in a variable frequency mode, the starting frequency is set as the second frequency, the accumulated operation time of the selectable pumps is searched before the pumps are selected to be started, the lifting pump with the minimum accumulated operation time is selected, then, the water level of the suction well is continuously sampled and compared, the next variable frequency adjustment stage is started until the variable frequency pump is adjusted to full frequency, namely, the variable frequency pump operates under the condition of being higher than the first frequency, the next lifting pump is started in the same mode, and the like.

Further, the pump-reducing flow operation in step 302 specifically includes: and when the water level of the water suction well continuously drops, the frequency of the variable frequency pump is reduced to the pump stopping frequency, namely when the frequency is equal to the second frequency, the lifting pump is stopped, the lifting pump which is put into operation at the earliest is set as the variable frequency pump, the water level of the water suction well is continuously sampled and compared, the next variable frequency adjusting stage is started until the variable frequency pump is adjusted to the pump stopping frequency, namely, the lifting pump is stopped in the same way when the frequency is equal to the second frequency, the next pump is set as the variable frequency pump, and the like.

The invention also provides terminal equipment which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor realizes the steps of the control method of the variable-frequency lift pump based on the liquid level regulation when executing the computer program.

The invention also provides a computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method for controlling a variable-frequency lift pump based on level regulation.

Compared with the prior art, the invention has the following advantages:

(1) the problem of the inverter pump when switching because of the load current when sudden change to the electric current impact of converter is solved to the life of converter has been improved greatly, simultaneously, has also avoided the converter to cause the phenomenon of equipment damage because of impulse current is too big, and this method has the practicality in the aspect of many inverter pump switching control.

(2) The method is suitable for the production process control of residential community water supply systems and water supply plants.

Drawings

FIG. 1 is a schematic diagram of a process of frequency conversion switching protection of a water pump in an embodiment of the method of the present invention;

FIG. 2 is a schematic diagram illustrating a process of switching timing in an embodiment of the method of the present invention;

FIG. 3 is a schematic process diagram of a pump increase flow in an embodiment of the method of the present invention;

FIG. 4 is a schematic process diagram of a pump reduction flow in an embodiment of the method of the present invention;

FIG. 5 is a schematic diagram of the PID frequency conversion control process in the embodiment of the method of the invention;

FIG. 6 is a schematic flow chart of the practice of the method of the present invention;

fig. 7 is a schematic structural diagram of a lift pump house in an actual application example of the method of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Fig. 6 is a schematic diagram of an actual flow of the method of the present invention, wherein the specific implementation parts are as follows:

(1) protection is switched in the water pump frequency conversion: in order to ensure the operation safety of the frequency converter and avoid the possibility of damage caused by the impact of the voltage on the frequency converter at the moment of frequency conversion switching, the control system closes the frequency converter (outputs a STOP signal to a STOP port of the frequency converter) before executing multi-pump frequency conversion switching, and opens the frequency converter (outputs an operation signal to an RUN port of the frequency converter) when the frequency conversion switching is completed, so that one RUN contact and one STOP contact of the frequency converter are required to be added in the PLC control cabinet, and the total number of the RUN contacts and the STOP contacts is 4. The control system frequency conversion switching control flow is shown in fig. 1;

frequency conversion switching time sequence: as shown in fig. 2, before the lift pump is switched from the power frequency to the variable frequency, the frequency of the frequency converter is forced to be raised to a set frequency value (e.g. 49.5Hz, which can be set on the HMI interface by the user).

(2) The variable frequency regulation method of the lift pump controlled by liquid level feedback comprises the following steps:

the variable frequency regulation control of the lift pump adopts a constant water level PID variable frequency regulation mode of water level tracking of a suction well.

1. As shown in fig. 3, the pump-increasing process: when the pump operates normally, the lift pump operates in a full-frequency state (defined as a full-frequency pump) and one of the lift pumps operates in a variable-frequency state (defined as a variable-frequency pump). When the water level of the suction well continuously rises, the frequency of the variable frequency pump is adjusted to full frequency (>47Hz), the system starts the next lift pump in a variable frequency mode, the starting frequency is set to 20Hz, before the pump is selected to be started, the control system searches the accumulated running time of the selectable pump, the lift pump with the minimum accumulated running time is selected, then, the water level of the suction well is continuously sampled and compared, the next variable frequency adjustment stage is started until the variable frequency pump is adjusted to full frequency operation (>47Hz), the next lift pump is started in the same mode, and the like.

2. As shown in fig. 4, the pump-decreasing flow: when the pump operates normally, the lift pump operates in a full-frequency state (defined as a full-frequency pump) and one of the lift pumps operates in a variable-frequency state (defined as a variable-frequency pump). When the water level of the water suction well continuously drops and the frequency of the variable frequency pump is reduced to the pump stopping frequency (20 Hz), the system stops the lifting pump, sets the lifting pump which is operated earliest as the variable frequency pump, continuously samples and compares the water level of the water suction well, enters the next variable frequency adjusting stage until the variable frequency pump is adjusted to the pump stopping frequency (20 Hz), stops the lifting pump in the same way, sets the next pump as the variable frequency pump, and so on.

Normally, the inverter pump is adjusted to be below 20Hz, that is, the water pump efficiency of the parallel water pumps is lost, so the 20Hz inverter point is set as the pump stop switching point in the present scheme.

3. PID frequency conversion control flow: the variable frequency operated lift pump employs a PID closed loop regulation control mode, as shown in fig. 5.

In order to track the water level change process of the water absorption well in time, the execution period of the PID instruction is set to be 200 milliseconds. Generally, when determining the PID parameters (Kp, Ki, Kd), the sensitivity and stability of the system are considered, in the actual working condition process, the PID adjustment is an approaching tracking process, the system sets an adjustment deviation range to avoid the overshoot phenomenon of the adjustment, and the smooth operation of the system is achieved.

The practical application case is as follows:

the technology of the invention is applied to a plurality of water plants.

The daily water production capacity of a household bridge branch plant is 10 ten thousand cubic meters, a mechanical stirring type clarification tank and a siphon filter tank are mainly adopted in the water production process, and a PLC system is built in the drug adding link and the two-pump house link of the water plant in advance.

The medicine adding system PLC adopts 5 sets of PLC to respectively control medicine adding, chlorination, ammoniation, manganese adding and collection of flow and water quality parameters of process water and factory water, and is connected with a local upper computer through a token network and adopts DH-485 protocol communication.

The PLC of the two pump rooms adopts Schneider Premium series (CPU: TSX 573623), and respectively monitors 4 water pumps, 2 related reservoirs and 2 water absorption wells of the two pump rooms, and acquires the flow and water quality parameters of factory water. The two-pump room PLC is connected with the local host computer and the company dispatching center through the Ethernet, and the network communication adopts a Modbus TCP/IP protocol.

In a technical updating and transforming project, the factory carries out comprehensive upgrading and transforming on process links such as a lifting pump room, a drainage pump room and the like, newly establishes a PLC monitoring system and adopts the method;

this many variable frequency pump control of factory's elevator pump room is mainly for realizing the water balance control of whole factory: the water source of the domestic bridge water plant is provided by a raw water company and enters the water plant lift pump house through a raw water pipeline. Water plants require optimal control of upstream water intake: according to the total flow of factory water, the factory water flow and the upstream water inflow, the start-stop switching of the lift pump is automatically controlled, the running rotating speed of the lift pump is automatically adjusted in a frequency conversion mode, the pipeline switching of a water inlet system is automatically controlled, and the valve position of a water inlet valve is automatically adjusted.

The lift pump room is composed of three variable frequency submersible pumps, as shown in fig. 7:

the process parameters participating in the water balance control of the water plant are as follows:

the lift pump room water inlet flow control process parameters are as follows:

after the system is installed, the operation test is carried out, and the result is as follows:

debugging content

1) Testing the operation parameters of 3 new submersible pumps: water volume, inlet and outlet water pressure, pump current

2) Testing of 3 New Pump matching operating parameters

Purpose of debugging

1) Providing test basis for production operation and operation.

2) And evaluating the investment benefit of the modified lift pump.

Delta single pump commissioning

Delta two pump parallel debugging data

Delta 2# pump frequency conversion test data

Minimum water absorption water inlet level for safe operation of delta pump

The lowest pressure of the suction well is more than 0.03MPa when the pump is started and operates

Delta lift pump matching

Daily water supplyMeasurement of	Mode of operation	Number of pumps started	Upstream inflow
				<10 ten thousand tons	Upstream override tube		4000-4500m3/h
10-12 ten thousand tons	Open and lift pump house	2# submersible pump	4500-5000m3/h
				12-14.8 ten thousand tons	Open and lift pump house	1# -3# submersible pump	5000-6200m3/h

Comparison before and after delta transformation

Delta debugging knot

1) The speed regulation and frequency conversion range of the 1#2# submersible axial-flow pump is 30-50.HZ, and the speed regulation flow rate of the 1# pump is 3000-; the speed regulation flow rate of the 2# submersible pump is 3000-5300m 3/h; the 3# submersible pump is full-speed (no frequency conversion) and has a flow rate of 3900m3/h. The pump safe operating condition is upstream pressure 0.020 MPa).

2) And (one large and one small): the 1# submersible axial-flow pump is generally adjusted to the frequency conversion of 30HZ for starting, and then matched with the 3# submersible pump for running. The flow regulation is convenient, the times of starting and stopping and pump regulation are reduced, and the water quantity is convenient to dispatch.

3) When the upstream lifting water amount is below 4200-.

4) The submersible pump is flat in operation, low in noise and capable of achieving the environment-friendly noise standard, and the problem that the original noise affects the life of surrounding residents is solved.

5) And under the large water volume running state, after the lift pump is transformed, the pump scheduling matching running condition is superior to that of starting 3 pumps before the transformation, the running is stable, and the running sound of the pumps is light. The upstream water inlet capacity is increased to 6200 ton/hour), the electricity is saved by about 12 to 18 percent.

6) And 2# immersible pump inlet wire power need be reformed transform, makes it can connect in parallel with 1# or 3# pump, ensures elevator pump operation security and flexibility.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.