CN220849978U - Frequency conversion top cap drainage control system - Google Patents

Abstract

The utility model provides a variable-frequency top cover drainage control system, which comprises a control system 1, wherein the control system 1 is connected with a drainage system 2, a water level monitoring system 3, a man-machine interaction system 4 and an external power supply 5, and the control system 1 comprises a frequency converter 11, a PLC12 and an on-site control box 13. A universal change-over switch is arranged in the local control box 13 and is used for switching the manual/automatic/cutting control mode. The PLC12 and the inverter 11 control the drainage system 2 by a liquid level signal of the water level monitoring system 3, a control signal of a remote control system, and a control mode signal of the local control box 13. The variable-frequency top cover drainage control system and the control method thereof have wide applicability, the drainage pump runs and starts and stops at variable frequency according to the liquid level, the start and stop frequency is improved, the failure rate of the drainage pump is reduced, and the safe and stable running of the unit is ensured.

Description

A variable frequency top cover drainage control system

Technical Field

The utility model relates to the field of drainage system control, in particular to a variable frequency top cover drainage control system and a control method thereof.

Background technique

With the long-term operation of the hydropower station top cover drainage pump, the rotating parts and fixed parts of the turbine generator set are sealed by anti-wear rings and sealing rings. With the long-term operation of the unit, the anti-wear rings and sealing rings will continue to wear and age, the water level on the top cover will increase faster, the pump will start and stop frequently, the pump will be damaged, and the safe and stable operation of the unit will be affected.

At present, the water accumulated in the top cover is usually drained by using a liquid level switch plus one or several drainage pumps. The drainage pump automatically starts and stops the drainage pump according to the pre-set start and stop pump liquid level values. The drainage pump maintains the rated frequency of the power grid at 50Hz during operation. In the early stage, the leakage was not large and the pump was not started and stopped frequently. As the unit's operating life increases, the unit's leakage increases, the water accumulates in the top cover faster, and the drainage pump starts and stops more frequently, affecting the service life of the pump. In the later stage, the drainage pump's drainage efficiency does not meet the drainage requirements of the top cover, and it is necessary to replace a drainage pump with a larger power. The transformation and replacement of the drainage pump and the control system requires a lot of manpower, material and financial resources.

Among the existing patents, the patent with application number CN202011621501.3 and publication date of May 11, 2021 provides a water level maintenance system and adaptive control method based on variable frequency water level maintenance equipment, the system includes a drainage tank, a water storage tank, and a water level maintenance equipment. The drainage tank is connected to the water storage tank through the water level maintenance equipment, the drainage tank is provided with a sensor, the sensor is used to collect parameter information of the drainage tank, the sensor and the water level maintenance equipment are connected to the controller, and the controller is connected to the human-computer interaction device. The method includes using a drainage pump to maintain the water level within the rated range; detecting the water level twice before and after a period of time t and calculating the system water load flow, calculating the number of variable frequency drainage working pumps through known parameters, and starting the drainage working pump; real-time detection of the water level of the water level maintenance system, when the water level is less than the lower water level or the lowest water level, unloading and stopping a number of standby variable frequency drainage pumps, and loading a number of standby variable frequency drainage pumps when the water level is greater than the higher water level or the highest water level. The shortcoming of this patent is that it only has an automatic control system, and no on-site manual control system and remote control system are designed. It cannot avoid the problem that the water level maintenance system cannot work normally when the on-site sensor fails. The on-site staff cannot control the start and stop of the water pump in real time on-site when debugging the system.

Utility Model Content

In order to overcome the defects existing in the above-mentioned prior art, the utility model provides a variable frequency top cover drainage control system and a control method thereof, which have wide applicability and can realize the top cover drainage pump to automatically adjust the drainage pump operating frequency according to the liquid level information in the top cover, thereby extending the single start-up operation time of the drainage pump and reducing the start and stop frequency of the pump; at the same time, it can meet the requirement of accelerating drainage when the water accumulation speed in the top cover increases after the unit has been running for a period of time. The drainage pump increases the operating frequency through the frequency converter to achieve rapid drainage requirements and save the later modification costs.

The technical means of the utility model mainly include: a variable frequency top cover drainage control system, characterized in that the system includes a drainage system, the drainage system is connected to the control system, the control system is connected to the water level monitoring system and the human-computer interaction system, and the control system includes a frequency converter, a PLC and an on-site control box.

Preferably, the power supply output terminal of the frequency converter is connected to the drainage system, and the power supply input terminal of the frequency converter is connected to an external power supply.

Preferably, the drainage system comprises a variable frequency drainage pump M1, and the operating state and fault state of the variable frequency drainage pump M1 are fed back to the digital input ports Ia3 and Ia4 of the PLC by the frequency converter.

Preferably, the analog output ports AO1 and AO2 of the frequency converter are connected to the analog input ports AI2 and AI3 of the PLC respectively, and the analog input port AI2 of the frequency converter is connected to the analog output port AO1 of the PLC.

Preferably, the analog input port AI1 of the PLC is connected to a water level monitoring system, and the water level monitoring system includes a liquid level sensor installed in the top cover.

Preferably, the digital input ports Ia1 and Ia2 of the PLC receive a remote start signal and a remote stop signal respectively, and the analog input port AI4 of the PLC receives a remote frequency signal.

Preferably, the on-site control box includes a universal conversion switch, which includes multiple control gears and inputs the control mode signal into the digital input port Ia5 of the PLC through the output end.

Preferably, the on-site control box further comprises a potentiometer, and an output end of the potentiometer is connected to an analog input port AI1 of the frequency converter.

Preferably, the on-site control box comprises water pump operation status indicator lights HR1, HG1 and HY1, which are controlled by the output signal of the frequency converter.

Preferably, the human-computer interaction system includes a touch screen, and the touch screen is connected to the communication interface of the PLC.

Compared with the prior art, the beneficial effects of the utility model are:

The variable frequency top cover drainage control system provided by the utility model can realize that the top cover drainage pump automatically adjusts the drainage pump operation frequency according to the liquid level information in the top cover, prolongs the single start-up operation time of the drainage pump, and reduces the start-stop frequency of the pump;

This control system can meet the requirement of faster drainage when the water accumulates in the top cover after the unit has been running for a period of time. The drainage pump increases the operating frequency through the inverter to achieve the requirement of rapid drainage, saving the cost of later transformation.

The control system is equipped with an on-site control system and a remote control system. The on-site control system makes it easy for on-site staff to control the system to start and stop in real time to meet the needs of debugging and troubleshooting inside the top cover. The remote control system avoids the top cover drainage pump from not working properly due to failure of the on-site liquid level sensor or abnormality of the on-site control system, thereby ensuring the normal operation of the control system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a module connection provided in an embodiment of the utility model;

FIG2 is a circuit diagram of a control system provided in an embodiment of the present utility model;

FIG3 is a circuit diagram of an automatic control part of a control system provided in an embodiment of the utility model;

FIG. 4 is a schematic diagram of a drainage pump start-stop process provided in an embodiment of the present utility model.

Detailed ways

The specific implementation of the technical solution of the utility model is further described below through examples and in conjunction with the accompanying drawings.

In the description of the present utility model, unless otherwise specified or limited, the technical terms or scientific terms used in the present application shall have the common meanings understood by technicians in the field to which the present application belongs.

Referring to Figure 1, a module connection diagram provided in an embodiment of the utility model is shown. As shown in the figure, the control system includes a control system 1, and the control system 1 is connected to a drainage system 2, a water level monitoring system 3, a human-computer interaction system 4 and an external power supply 5. The control system 1 includes a frequency converter 11, a PLC 12 and an on-site control box 13.

Referring to FIG2 , a control system circuit diagram of the local control part provided in the embodiment of the utility model is shown. As shown in the figure, the power supply input end of the inverter 11 is connected to the external power supply 5, and the power supply output end of the inverter 11 is connected to the drainage system 2. The external power supply 5 provides power output for the inverter 11, and the inverter 11 controls the drainage system 2 to work.

The drainage system 2 includes a variable frequency drainage pump M1, which is used to pump out the water in the top cover and drain it outside the turbine pit. The variable frequency drainage pump M1 is connected to the inverter 11 through a three-phase power cable, and the operation and stop of the variable frequency drainage pump M1 are controlled by the operation signal and stop signal output by the control system.

The analog output ports AO1 and AO2 of the frequency converter 11 are respectively connected to the analog input ports AI2 and AI3 of the PLC 12 .

The frequency converter 11 detects the working status of the variable frequency drainage pump M1 in real time, outputs the operating speed of the motor that controls the operation of the water pump through the analog output port AO1 of the frequency converter 11 to the analog input port AI2 of the PLC12, and outputs the current parameter of the motor through the analog output port AO2 of the frequency converter 11 to the analog input port AI3 of the PLC12.

The analog input port AI2 of the frequency converter 11 is connected to the analog output port AO1 of the PLC 12, and is used to set the operating frequency parameters of the drainage pump in automatic control mode and remote control mode.

3 is a circuit diagram of an automatic control part of a control system provided in an embodiment of the present utility model. As shown in the figure, the analog input port AI1 of the PLC 12 is connected to the output end of the water level monitoring system 3 .

The water level monitoring system 3 includes an on-site liquid level sensor, which is installed in the top cover and is used to receive the liquid level signal (EL) in the top cover and input it into PLC12 to run the top cover liquid level and motor probability logic control program.

PLC12 is used to automatically control the start and stop of the drainage pump M1 and adjust the operating frequency of the drainage pump M1. Its digital input ports Ia1 and Ia2 receive remote pump start (KX1) and pump stop signals (KX2) respectively.

The frequency converter 11 is connected to the digital input ports Ia3 and Ia4 of the PLC 12 through a shielded cable to receive the drainage pump operation signal (TB/TC) and fault signal (PB/PC) from the frequency converter 11 .

The digital input port Ia5 of PLC12 receives the feedback signal (KA2) of automatic control selected by the local control box 13.

The local control box 13 is constructed by a universal conversion switch SAC, relays KA1, KA2, buttons SB1, SB2 and relay contacts, and includes the functions of switching control modes and on-site manual control.

The universal conversion switch SAC is used to switch the manual/automatic/cut-off control mode and input the control mode conversion signal into PLC12.

The buttons SB1 and SB2 can be used to control the operation of the drainage system 2 on site. When in manual control mode, the drainage pump M1 can be started by the button SB2 on the control box, and the drainage pump M1 can be stopped by the button SB1 on the control box.

The local control box 13 is also provided with a potentiometer RP1, which is connected to the AI1 port on the inverter. By rotating the potentiometer knob on the local control box 13 to adjust the output rate of the inverter 11, the running speed of the drainage pump M1 can be controlled locally. At this time, the local operation command takes precedence over the remote and automatic control commands.

When the universal conversion switch SAC is in the automatic control position, the control modes include remote control mode and automatic control mode, and the control priority of the two is remote control command>automatic control command from large to small.

When this control system is in remote control mode, the remote control system sends start/stop signals and frequency adjustment signals to PLC12 through electrical hard contacts. The digital input port of PLC12 receives remote pump start (KX1) and pump stop signals (KX2), and outputs pump start signals (KA3) and pump stop signals (KA4) from the relay output port for remote control of the start and stop of the variable frequency drainage pump M1.

The analog input port AI4 of PLC12 receives the specified frequency signal from the remote control system and outputs the variable frequency signal from the relay output port, thereby changing the operating frequency of the variable frequency drainage pump M1.

When the control system is in automatic control mode, when the unit is turned on, the monitoring sends a start command to send a drainage pump start signal to PLC12. At the same time, the analog input port AI1 of PLC12 is connected to the local liquid level meter to receive the liquid level signal in the top cover.

PLC12 gives the inverter 11 startup and frequency parameter instructions according to the startup signal and the liquid level signal. The inverter 11 automatically adjusts the working frequency of the drainage pump according to the liquid level signal when the unit is started.

When the unit is shut down, the monitoring system issues a stop command to stop the pump. Automatic control instructions need to be executed when the local control system and remote control system are in the off state.

Indicator lights HR1, HG1 and HY1 are provided in the local control box. When the variable frequency drainage pump M1 works normally, the inverter 11 inputs the normal operating signal of the variable frequency drainage pump M1 into the PLC12, and the indicator light HR1 lights up.

When the frequency converter 11 receives the pump stop signal, it controls the variable frequency drainage pump M1 to stop running. The frequency converter 11 detects that the variable frequency drainage pump M1 stops running and inputs the stop signal into the PLC12. At this time, the indicator light HG1 lights up.

When the variable frequency drainage pump M1 fails, the inverter 11 detects the fault and outputs a fault signal to PLC12. PLC12 outputs a drainage pump fault signal (KA6), and the control indicator HY1 lights up.

The control system also includes a human-computer interaction system 4, which includes a touch screen connected to the communication interface of PLC12 via a communication cable and is used to display parameters such as real-time operating speed, operating frequency, and operating current of the top cover drainage pump.

4 is a schematic diagram of a drainage pump start-stop process provided in an embodiment of the present utility model. The steps of the automatic control system are shown in the figure, and specifically include the following steps:

S1: When the control mode is local control, when the external power source 5 is connected, the top cover drainage pump M1 is started to run at the rated frequency and the drainage pump M1 is stopped by the start SB2/stop button SB1 on the local control box 13. The running status light of the drainage pump M1 on the local control box indicates accordingly.

S2: When the operating speed of the top cover drainage pump needs to be manually adjusted on site, the operating speed of the drainage pump M1 is adjusted by rotating the potentiometer knob RP1 on the control box.

S3: When the initial control mode is the automatic control mode and the external power supply 5 has been connected, the PLC 12 sends a command to the frequency converter 11 to put the frequency converter 11 in the remote given frequency state.

S4: If there is a remote pump start signal and the pump stop signal is not turned on, PLC12 issues a command to the inverter 11 to start the drainage pump M1 at the default frequency of 37.5 Hz. The remote and local indicator lights change positions accordingly.

S5: When a remote party issues a designated frequency instruction to PLC12, PLC12 outputs the corresponding frequency parameter to the frequency converter 11 through the analog output port, so that the frequency converter 11 operates according to the remote designated frequency.

S6: When the initial control mode is automatic control mode, and the external power supply 5 has been connected, and the remote pump start signal and pump stop signal have not been issued, PLC12 controls the drainage pump M1 according to the liquid level information collected by the liquid level sensor in the top cover. If the liquid level exceeds the pump start level pre-set in PLC12, the drainage pump M1 is started.

S7: When the drain pump M1 is started, the drain speed of the drain pump is adjusted in real time according to the relationship between the liquid level and the drain pump starting frequency pre-programmed in PLC12, and the drain pump frequency decreases when the liquid level drops.

S8: When the liquid level in the top cover drops to the preset pump stop level, PLC12 issues a pump stop command.

S9: until the liquid level in the top cover reaches the pump start liquid level preset in PLC12 again, return to step S1.

In summary, this embodiment provides a variable frequency top cover drainage control system, which includes a control system 1, and the control system 1 includes a frequency converter 11, a PLC 12 and a local control box 13. The control mode can be changed by a universal conversion switch in the local control box 13.

The drainage is controlled by the frequency converter 11, and the operating frequency of the frequency converter pump M1 is automatically adjusted by using the water level analog measured by the liquid level sensor in the top cover. During remote control, the central control room can start and stop the frequency converter pump for the top cover drainage and set the frequency parameters through a single point of electrical hard contact; during automatic control, the monitoring sends a start command when the unit is started, and the frequency converter 11 automatically adjusts the working frequency of the drainage pump according to the water level to operate the pumping. When shutting down, the monitoring system issues a stop command to stop the pump. During local control, the drainage pump is started and stopped by the start/stop button on the local control box 13, and the motor operating frequency is reduced/increased by the potentiometer RP1. The touch screen displays the motor frequency, operating speed, and operating current.

The utility model discloses a variable frequency top cover drainage control system and a control method thereof, which have wide applicability. The drainage pump performs variable frequency operation and starts and stops according to the liquid level, improves the start and stop frequency, reduces the failure rate of the drainage pump, and ensures the safe and stable operation of the unit.

In addition to the above-mentioned embodiments, within the scope disclosed in the claims and the specification of the utility model, the technical features or technical data of the utility model can be reselected and combined to form new embodiments, which can be achieved by those skilled in the art without creative work. Therefore, these embodiments that are not described in detail in the utility model should also be regarded as specific embodiments of the utility model and within the protection scope of the utility model.

Claims (10)

1. The variable-frequency top cover drainage control system is characterized by comprising a drainage system (2), wherein the drainage system (2) is connected with a control system (1), the control system (1) is connected with a water level monitoring system (3) and a man-machine interaction system (4), and the control system (1) comprises a frequency converter (11), a PLC (programmable logic controller) (12) and an on-site control box (13).

2. The variable frequency top cover drainage control system according to claim 1, wherein a power supply output end of the frequency converter (11) is connected with the drainage system (2), and a power supply input end of the frequency converter (11) is connected with an external power supply (5).

3. The variable frequency roof drain control system according to claim 2, wherein the drain system (2) includes a variable frequency drain pump M1, and an operation state and a failure state of the variable frequency drain pump M1 are fed back to digital quantity input ports Ia3 and Ia4 of the PLC (12) by the frequency converter (11).

4. The variable frequency roof drainage control system according to claim 1, wherein analog output ports AO1, AO2 of the frequency converter (11) are connected to analog input ports AI2, AI3 of the PLC (12), respectively, and the analog input port AI2 of the frequency converter (11) is connected to analog output port AO1 of the PLC (12).

5. The variable frequency roof drain control system of claim 4, wherein the analog input port AI1 of the PLC (12) is connected to a water level monitoring system (3), the water level monitoring system (3) including a level sensor mounted within the roof.

6. The variable frequency roof drain control system of claim 5, wherein digital input ports Ia1 and Ia2 of the PLC (12) receive a remote start signal and a remote stop signal, respectively, and wherein analog input port AI4 of the PLC (12) receives a remote frequency signal.

7. The variable frequency roof drain control system of claim 1, wherein the local control box (13) includes a universal switch comprising a plurality of control gears and inputs control mode signals to the digital input port Ia5 of the PLC (12) via an output.

8. The variable frequency roof drain control system of claim 7, wherein the local control box (13) further comprises a potentiometer, an output of which is connected to an analog input port AI1 of the frequency converter (11).

9. The variable frequency roof drain control system according to claim 7 or 8, wherein the local control box (13) comprises water pump operation status indicator lamps HR1, HG1 and HY1, controlled by an output signal of the frequency converter (11).

10. The variable frequency roof drainage control system of claim 1, wherein the human-machine interaction system (4) comprises a touch screen, the touch screen being connected to a communication interface of a PLC (12).