Method, system and equipment for controlling water level in sewage pump pit

Abstract

The invention provides a sewage pump pit water level control method, system and equipment, a first liquid level switch and a second liquid level switch are both in communication connection with a programmable logic controller, and a first sewage pump and a second sewage pump are both in communication connection with the programmable logic controller; the method comprises the steps that the water level in a sewage pump pit is detected through a first liquid level switch and a second liquid level switch, and a first detection signal and a second detection signal are generated and sent to a programmable logic controller; the programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relation between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signals, isolation of the liquid level switch and the sewage pumps is achieved through the programmable logic controller, the liquid level switch can be effectively protected, then the sewage pumps are protected, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage pump control, and in particular to a method, system and equipment for controlling the water level in a sewage pump pit. Background Art

[0002] There are many sewage collection pits in the power plant. Various sewage is collected in the pump pit, and then the start and stop of the sewage pump is controlled by the liquid level switch in the pump pit, so as to realize the control of the liquid level in the pump pit. There are two main control methods at present: one is to set two liquid level switches in the pump pit, one for high and one for low liquid level. When the high liquid level signal comes, the pump is started and the pump control circuit is self-protected. Even if the high liquid level signal disappears, the sewage pump still runs. When the low liquid level signal comes, the sewage pump is stopped, so as to maintain the liquid level in the sewage pump pit within the specified range. The second is to set a liquid level switch to control the liquid level height by adding an iron block to the control cable, and control the start and stop of the pump through a liquid level switch. Both control circuits use 220VAC or 110VDC voltage, and control the AC contactor through the liquid level switch.

[0003] However, since the capacity of the liquid level switch contacts is relatively small and the AC contactor is an inductive circuit, it is more damaging to the liquid level control switch during the start and stop stages. After a certain number of closing and opening, the liquid level switch is easily damaged, which in turn causes damage to the sewage pump. Summary of the invention

[0004] The present invention provides a method, system and equipment for controlling the water level in a sewage pump pit, which are used to solve the defect in the prior art that damage to the liquid level switch easily leads to damage to the sewage pump.

[0005] In a first aspect, the present invention provides a method for controlling the water level in a sewage pump pit, wherein a first liquid level switch and a second liquid level switch are both communicatively connected to a programmable logic controller, and a first sewage pump and a second sewage pump are both communicatively connected to the programmable logic controller, and the method comprises:

[0006] Detecting the water level in the sewage pump pit by means of the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller;

[0007] The programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal;

[0008] The first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0009] According to a method for controlling the water level in a sewage pump pit provided by the present invention, the first liquid level switch and the second liquid level switch are both floats controlled by a control cable, the first liquid level switch is used to detect a first liquid level in the pit, and the second liquid level switch is used to detect a second liquid level in the pit, and the height of the second liquid level is higher than the height of the second liquid level.

[0010] According to a method for controlling the water level in a sewage pump pit provided by the present invention, the water level in the sewage pump pit is detected by the first liquid level switch and the second liquid level switch to generate a first detection signal and a second detection signal, including:

[0011] When the float of the first liquid level switch deviates sideways, a first detection signal is generated, and the first detection signal is used to indicate that the water level in the pit exceeds the height of the first liquid level;

[0012] When the float of the second liquid level switch deviates sideways, a second detection signal is generated, and the second detection signal is used to indicate that the water level in the pit exceeds the height of the second liquid level.

[0013] According to a method for controlling the water level in a sewage pump pit provided by the present invention, sending corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal, comprising:

[0014] When the first detection signal is valid and the second detection signal is invalid, the first sewage pump is controlled to start and the second sewage pump is controlled to stop;

[0015] When the first detection signal is converted from valid to invalid, the first sewage pump is controlled to stop after delaying for a preset time period.

[0016] A method for controlling the water level in a sewage pump pit provided by the present invention further includes:

[0017] When the first detection signal is valid and the second detection signal is valid, the first sewage pump and the second sewage pump are controlled to start simultaneously;

[0018] When the second detection signal is converted from valid to invalid, the second sewage pump is controlled to stop after delaying for a preset time period.

[0019] A method for controlling the water level in a sewage pump pit provided by the present invention further includes:

[0020] When the first sewage pump and the second sewage pump are started simultaneously for more than a safe period of time, an alarm is issued and the operation of the first sewage pump and the second sewage pump is stopped.

[0021] According to a method for controlling the water level in a sewage pump pit provided by the present invention, the control voltage of the programmable logic controller is 24V direct current.

[0022] According to a method for controlling the water level in a sewage pump pit provided by the present invention, the sewage pump control circuit and the programmable logic controller are independent of each other, and the programmable logic controller is detachably connected to the sewage pump control circuit;

[0023] The two output signals of the programmable logic controller respectively control the start and stop of the first sewage pump and the start and stop of the second sewage pump.

[0024] In a second aspect, the present invention further provides a sewage pump pit water level control system, comprising:

[0025] A liquid level switch module, used for detecting the water level in the sewage pump pit through the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller;

[0026] A control module is used for the programmable logic controller to send corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0027] In a third aspect, the present invention further provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for controlling the water level in a sewage pump pit as described in any one of the above is implemented.

[0028] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for controlling the water level in a sewage pump pit.

[0029] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program, which, when executed by a processor, implements any of the above-described methods for controlling the water level in a sewage pump pit.

[0030] The present invention provides a method, system and equipment for controlling the water level in a sewage pump pit, wherein a first liquid level switch and a second liquid level switch are both communicatively connected to a programmable logic controller, and the first sewage pump and the second sewage pump are both communicatively connected to the programmable logic controller. The method comprises: detecting the water level in the sewage pump pit by means of the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending the signals to the programmable logic controller; the programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal, and isolation of the liquid level switch and the sewage pump is achieved by means of the programmable logic controller, so as to effectively protect the liquid level switch, and then protect the sewage pump, thereby extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 It is a flow chart of the water level control method in the sewage pump pit provided in this embodiment;

[0033] Figure 2 is a schematic diagram of a first liquid level switch and a second liquid level switch provided in this embodiment;

[0034] Figure 3 is a control logic diagram of the PLC provided in this embodiment;

[0035] Figure 4 is a control logic diagram of the alarm circuit provided in this embodiment;

[0036] Figure 5 is a schematic diagram of a sewage pump water level control circuit provided in this embodiment;

[0037] Figure 6 It is a schematic diagram of the structure of the water level control system in the sewage pump pit provided in this embodiment;

[0038] Figure 7 It is a schematic diagram of the structure of the electronic device provided in this embodiment. DETAILED DESCRIPTION

[0039] 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.

[0040] Figure 1 It is a flow chart of the water level control method in the sewage pump pit provided in this embodiment.

[0041] like Figure 1 As shown, the water level control method in the sewage pump pit provided by the embodiment of the present invention, the first liquid level switch and the second liquid level switch are both connected to the programmable logic controller for communication, the first sewage pump and the second sewage pump are both connected to the programmable logic controller for communication, and the method mainly includes the following steps:

[0042] 101. Detect the water level in the sewage pump pit through the first liquid level switch and the second liquid level switch, generate a first detection signal and a second detection signal, and send them to the programmable logic controller.

[0043] In a specific implementation process, the first liquid level switch and the second liquid level switch are both floats controlled by a control cable. The first liquid level switch is used to detect the first liquid level in the pit, and the second liquid level switch is used to detect the second liquid level in the pit. The height of the second liquid level is higher than the height of the second liquid level. When the liquid level in the pit exceeds the first liquid level, the first liquid level switch is closed to generate a first detection signal. Similarly, when the liquid level in the pit exceeds the second liquid level, the second liquid level switch is closed to generate a second detection signal. Both the first detection signal and the second detection signal are electrical signals. By converting the physical signal of the liquid level height into an electrical signal, signal transmission and control are more convenient.

[0044] The first liquid level switch and the second liquid level switch are floats that change the liquid level switch state at a set water surface, such as Figure 2 As shown, the first liquid level switch and the second liquid level switch are directly connected to a programmable logic controller (PLC), using a 24VDC voltage to avoid direct connection to the sewage pump, thereby ensuring more reasonable control of the sewage pump.

[0045] 102. The programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal.

[0046] There are multiple relationships between the first detection signal and the second detection signal. If the first detection signal is valid and the second detection signal is invalid, it means that the liquid level is between the first liquid level and the second liquid level. If the first detection signal is invalid and the second detection signal is invalid, it means that the liquid level is below the first liquid level. If the first detection signal is valid and the second detection signal is valid, it means that the liquid level is above the second liquid level.

[0047] Then, according to the different liquid level relationships, the PLC generates control signals with different meanings through logical operations, and controls the first sewage pump and the second sewage pump differently to ensure that the sewage in the pit is discharged. At the same time, after the sewage is discharged, the rotation is stopped in time to avoid damage to the sewage pump.

[0048] 103. The first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0049] The first sewage pump and the second sewage pump are connected to the PLC through a relay. The contact capacity of the relay output is large and can withstand large current control without damage. According to the different detection signals, that is, the different liquid levels, different sewage pumps are controlled to be enabled, including enabling one or two at the same time, to ensure the discharge efficiency of sewage in the pit. At the same time, since there is no inductance in the PLC circuit, the damage to the liquid level switch can be reduced and the service life of the equipment can be improved. Logical operations are performed in the PLC, and then control instructions are output to select the relay output point. In this way, the capacity of the relay output contact is large, and it is not easy to be damaged when connected to the inductance circuit. It can also eliminate the hidden danger of a short liquid level control range, thereby achieving the reliability of sewage pump control.

[0050] Further, based on the above embodiment, the present embodiment detects the water level in the sewage pump pit by using the first liquid level switch and the second liquid level switch to generate the first detection signal and the second detection signal, including:

[0051] When the float of the first liquid level switch deviates to the side, a first detection signal is generated, indicating that the water level at this time needs to be drained, and the first detection signal is used to represent that the water level in the pit exceeds the first liquid level; when the float of the second liquid level switch deviates to the side, a second detection signal is generated, indicating that the water level at this time cannot be discharged in time by the first sewage pump alone, and the first sewage pump and the second sewage pump need to be started at the same time for drainage. The second detection signal is used to represent that the water level in the pit exceeds the second liquid level.

[0052] Among them, the operating relationship between the liquid level and the start and stop of the first sewage pump and the second sewage pump is: when the first detection signal is valid and the second detection signal is invalid, the first sewage pump is controlled to start and the second sewage pump is controlled to stop; when the first detection signal is converted from valid to invalid, the first sewage pump is controlled to stop after a preset delay; when the first detection signal is valid and the second detection signal is valid, the first sewage pump and the second sewage pump are controlled to start at the same time; when the second detection signal is converted from valid to invalid, the second sewage pump is controlled to stop after a preset delay; when the first sewage pump and the second sewage pump are started at the same time for more than the safe time, an alarm is issued and the operation of the first sewage pump and the second sewage pump is stopped.

[0053] Figure 3 is a control logic diagram of the PLC provided in this embodiment, specifically, Figure 3 As shown in the figure, when the #1 liquid level switch (I0.0) is closed, a self-protection circuit is formed, which is controlled by the timer T37, and the first sewage pump starts to pump water to reduce the liquid level in the sewage pump pit. Under normal circumstances, when the liquid level decreases, the first liquid level switch is disconnected, and the timer T37 starts timing. After the specified time, that is, the preset time, the control circuit of the first sewage pump is cut off, and the operation of the first sewage pump is stopped.

[0054] After the first sewage pump is running, if the liquid level does not drop or suddenly rises during the falling process, the first liquid level switch is closed, the timing is not started or stopped, and the first sewage pump continues to run. If the liquid level continues to rise, when the liquid level #2 (I0.1) is closed, a self-protection circuit is formed, which is controlled by the timer T38, and the second sewage pump starts to pump water to lower the liquid level in the sewage pump pit. Under normal circumstances, the liquid level drops, the second liquid level switch is disconnected, and the timer T38 starts timing. After the specified time, the control circuit of the second sewage pump is cut off and the operation of the second sewage pump is stopped. If the liquid level does not drop or suddenly rises during the falling process, the second liquid level switch is closed, the timing is not started or stopped, and the second pump continues to run.

[0055] Figure 4 is a control logic diagram of the alarm circuit provided in this embodiment, such as Figure 4 As shown, during the entire operation process, the alarm circuit will continue to monitor the operating time of the first sewage pump and the second sewage pump. When the operating time exceeds the monitoring time, the alarm signal will continue to be issued to remind the operating personnel to pay attention. After the operating personnel check, they can stop the operation of the sewage pump while ensuring safety.

[0056] After the liquid level exceeds the second liquid level, the first sewage pump and the second sewage pump are started at the same time. After the liquid level drops, the corresponding liquid level switch is activated. After the preset delay time, the corresponding sewage pump is stopped. If the second sewage pump has been running and the running time exceeds the set time, an alarm is issued through the alarm circuit, and the operation of the second sewage pump is stopped at the same time. This indicates that the drainage system is abnormal and requires human intervention. In this way, the damage to the motor or sewage pump caused by the liquid level switch can be reduced, and the reliability of equipment operation can be improved.

[0057] Figure 5 It is a schematic diagram of the sewage pump water level control circuit provided in this embodiment.

[0058] like Figure 5 As shown, the first sewage pump M1 and the second sewage pump M2 are controlled by PLC, and different pins of PLC respectively control the start or stop of the first sewage pump and the start or stop of the second sewage pump. The output of the PLC control part is connected to the corresponding terminals in the circuit, the part connected to terminal 7 and terminal 9 directly controls the first sewage pump, and the part connected to terminal 15 and terminal 17 directly controls the second sewage pump, and the input of PLC is directly connected to the first liquid level switch and the second liquid level switch. Compared with the conventional control circuit, the influence of inductance on the circuit is removed, and the damage of inductance to the first liquid level switch and the second liquid level switch is avoided. At the same time, the first sewage pump control circuit board and the second sewage pump control circuit board are removed, which is more convenient to improve the long-term reliable operation of the sewage pump. The connection relationship of other parts in the circuit schematic diagram and the meaning of symbols are not described in detail.

[0059] The control circuit part and the PLC part are independent of each other, that is, the PLC can be detachably connected to the sewage pump control circuit; the two output signals of the PLC control the start and stop of the first sewage pump and the start and stop of the second sewage pump respectively. Compared with the traditional control circuit, there is no need to make major modifications to the traditional circuit. It is only necessary to add a PLC between the contact of the liquid level switch and the sewage pump after replacing the liquid level switch, and at the same time increase the contact capacity of the relay, the structural change is small, and the control logic is simple and reliable.

[0060] Based on the same general inventive concept, the present invention also protects a sewage pump pit water level control system. The sewage pump pit water level control system provided by the present invention is described below. The sewage pump pit water level control system described below and the sewage pump pit water level control method described above can be referenced to each other.

[0061] Figure 6 It is a schematic diagram of the structure of the water level control system in the sewage pump pit provided in this embodiment.

[0062] like Figure 6As shown, the present embodiment provides a sewage pump pit water level control system, the first liquid level switch and the second liquid level switch are both connected to the programmable logic controller for communication, the first sewage pump and the second sewage pump are both connected to the programmable logic controller for communication, and the system includes:

[0063] The liquid level switch module 601 is used to detect the water level in the sewage pump pit through the first liquid level switch and the second liquid level switch, generate a first detection signal and a second detection signal, and send them to the programmable logic controller;

[0064] The control module 602 is used for the programmable logic controller to send corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0065] Furthermore, the first liquid level switch and the second liquid level switch in this embodiment are both floats controlled by control cables, the first liquid level switch is used to detect the first liquid level in the pit, and the second liquid level switch is used to detect the second liquid level in the pit, and the height of the second liquid level is higher than the height of the second liquid level.

[0066] Furthermore, the liquid level switch module 601 in this embodiment is specifically used for:

[0067] When the float of the first liquid level switch deviates sideways, a first detection signal is generated, and the first detection signal is used to indicate that the water level in the pit exceeds the height of the first liquid level;

[0068] When the float of the second liquid level switch deviates sideways, a second detection signal is generated, and the second detection signal is used to indicate that the water level in the pit exceeds the height of the second liquid level.

[0069] Furthermore, the liquid level switch module 601 in this embodiment is specifically used for:

[0070] When the first detection signal is valid and the second detection signal is invalid, the first sewage pump is controlled to start and the second sewage pump is controlled to stop;

[0071] When the first detection signal is converted from valid to invalid, the first sewage pump is controlled to stop after delaying for a preset time period.

[0072] Furthermore, the liquid level switch module 601 in this embodiment is specifically used for:

[0073] When the first detection signal is valid and the second detection signal is valid, the first sewage pump and the second sewage pump are controlled to start simultaneously;

[0074] When the second detection signal is converted from valid to invalid, the second sewage pump is controlled to stop after delaying for a preset time period.

[0075] Furthermore, the liquid level switch module 601 in this embodiment is specifically used for:

[0076] When the first sewage pump and the second sewage pump are started simultaneously for more than a safe period of time, an alarm is issued and the operation of the first sewage pump and the second sewage pump is stopped.

[0077] Furthermore, the control voltage of the programmable logic controller in this embodiment is 24V DC.

[0078] Furthermore, the sewage pump control circuit and the programmable logic controller in this embodiment are independent of each other, and the programmable logic controller can be detachably connected to the sewage pump control circuit;

[0079] The two output signals of the programmable logic controller respectively control the start and stop of the first sewage pump and the start and stop of the second sewage pump.

[0080] Figure 7 It is a schematic diagram of the structure of the electronic device provided in this embodiment.

[0081] like Figure 7 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 water level control method in the sewage pump pit, the method comprising: detecting the water level in the sewage pump pit through the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller; the programmable logic controller sends a corresponding control signal to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0082] 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, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of 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 and other media that can store program codes.

[0083] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the water level control method in the sewage pump pit provided by the above methods, and the method includes: detecting the water level in the sewage pump pit by the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller; the programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0084] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to execute the water level control method in the sewage pump pit provided by the above-mentioned methods, the method comprising: detecting the water level in the sewage pump pit by the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller; the programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal.

[0085] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0086] 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.

[0087] 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 controlling the water level in a sewage pump pit, characterized in that: The first liquid level switch and the second liquid level switch are both connected to the programmable logic controller for communication, and the first sewage pump and the second sewage pump are both connected to the programmable logic controller for communication. The method includes: Detecting the water level in the sewage pump pit by means of the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller; The programmable logic controller sends corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; The first sewage pump and the second sewage pump are started or stopped according to the control signal.

2. The method for controlling the water level in a sewage pump pit according to claim 1, characterized in that: The first liquid level switch and the second liquid level switch are both floats controlled by control cables. The first liquid level switch is used to detect a first liquid level in the pit, and the second liquid level switch is used to detect a second liquid level in the pit. The height of the second liquid level is higher than the height of the second liquid level.

3. The method for controlling the water level in a sewage pump pit according to claim 2, characterized in that: The method of detecting the water level in the sewage pump pit by using the first liquid level switch and the second liquid level switch to generate a first detection signal and a second detection signal includes: When the float of the first liquid level switch deviates sideways, a first detection signal is generated, and the first detection signal is used to indicate that the water level in the pit exceeds the height of the first liquid level; When the float of the second liquid level switch deviates sideways, a second detection signal is generated, and the second detection signal is used to indicate that the water level in the pit exceeds the height of the second liquid level.

4. The method for controlling the water level in a sewage pump pit according to claim 3, characterized in that: The sending corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal comprises: When the first detection signal is valid and the second detection signal is invalid, the first sewage pump is controlled to start and the second sewage pump is controlled to stop; When the first detection signal is converted from valid to invalid, the first sewage pump is controlled to stop after delaying for a preset time period.

5. The method for controlling the water level in a sewage pump pit according to claim 4, characterized in that: Also includes: When the first detection signal is valid and the second detection signal is valid, the first sewage pump and the second sewage pump are controlled to start simultaneously; When the second detection signal is converted from valid to invalid, the second sewage pump is controlled to stop after delaying for a preset time period.

6. The method for controlling the water level in a sewage pump pit according to claim 5, characterized in that: Also includes: When the first sewage pump and the second sewage pump are started simultaneously for more than a safe period of time, an alarm is issued and the operation of the first sewage pump and the second sewage pump is stopped.

7. The method for controlling the water level in a sewage pump pit according to claim 1, characterized in that: The control voltage of the programmable logic controller is 24V DC.

8. The method for controlling the water level in a sewage pump pit according to claim 1, characterized in that: The sewage pump control circuit and the programmable logic controller are independent of each other, and the programmable logic controller is detachably connected to the sewage pump control circuit; The two output signals of the programmable logic controller respectively control the start and stop of the first sewage pump and the start and stop of the second sewage pump.

9. A water level control system in a sewage pump pit, characterized in that: The first liquid level switch and the second liquid level switch are both connected to the programmable logic controller in communication, and the first sewage pump and the second sewage pump are both connected to the programmable logic controller in communication. The system includes: A liquid level switch module, used for detecting the water level in the sewage pump pit through the first liquid level switch and the second liquid level switch, generating a first detection signal and a second detection signal, and sending them to the programmable logic controller; A control module is used for the programmable logic controller to send corresponding control signals to the first sewage pump and the second sewage pump according to the relationship between the first detection signal and the second detection signal; the first sewage pump and the second sewage pump are started or stopped according to the control signal.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for controlling the water level in the sewage pump pit as described in any one of claims 1 to 8 is implemented.

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