An intelligent oil mist absorption device for a hydropower unit

Abstract

The present invention discloses an intelligent oil mist suction device for a hydroelectric generating unit, which includes a negative pressure regulating unit, a negative pressure control unit, and a negative pressure monitoring and alarm unit; the negative pressure regulating unit is used to adjust the negative pressure of the oil sump according to the instruction of the negative pressure control unit; the negative pressure control unit is used to issue a closed-loop instruction according to the negative pressure signal of the negative pressure monitoring and alarm unit and the feedback signal of the negative pressure regulating unit; the negative pressure monitoring and alarm unit is used to receive the signals of on-site pressure measuring elements and the oil level signal of the oil collecting tank, send out commands to the negative pressure control unit and the remote LCU unit, and issue negative pressure high and low alarm signals and oil level high and low alarm signals. The present invention is used to always maintain the oil sump in a slightly negative pressure operation to prevent oil mist from overflowing.

Description

Technical Field

[0001] The present invention relates to an intelligent oil mist suction device for a hydro-generating unit, which is used to always maintain a slightly negative pressure operation in the oil sump and prevent oil mist from overflowing. Background Art

[0002] The vertical shaft arrangement is adopted for hydro-generating units. Among them, for large-sized units, the oil sumps are mostly arranged in the form of four oil sumps: upper guide, lower guide, thrust, and water guide; for medium and small-sized units, the oil sumps are mostly arranged in the form of three oil sumps: upper guide, lower guide, and water guide. In the guide bearing oil sump, a self-circulation cooling system is mostly adopted, and there are also some with an external circulation system. The oil flows from the hot oil sump to the cold oil sump by gravity due to the centrifugal force inside the oil sump. The oil mist is generated due to the oil flow, resulting in a local positive pressure. Generally, an oil mist suction device is often installed at the oil sump to suck out the oil mist and maintain a slightly negative pressure operation inside the oil sump. During the production process, due to factors such as the wear of the oil sump comb tooth seal and the change of centrifugal force in the oil sump during the transient process of the unit, oil mist often overflows and escapes everywhere with the cooling air of the generator rotor, polluting components and automation elements such as the generator rotor, stator coils, stator core, oil level gauge, and air cooler. For some in-service units, due to the oversized installation or configuration of the oil mist suction device, the negative pressure in the oil sump is too large, and even the oil is sucked out of the oil sump; too large a negative pressure will cause the suspended matter in the wind tunnel to enter the oil sump through the oil sump gap with the air, polluting the oil in the oil sump; sucking the oil out of the oil sump will reduce the oil level in the oil sump, which is harmful to the safe operation of the unit.

[0003] After the oil mist diffuses in the generator wind tunnel rotor and stator coils and generates electrochemical corrosion under a strong magnetic field, it reduces the insulation of the generator and seriously threatens the safety of the generator. Summary of the Invention

[0004] Aiming at the deficiencies and defects of the prior art, the purpose of the present invention is to provide an intelligent oil mist suction device for the oil sump of a hydro-generating unit, which completely solves the problem of oil mist overflow and the harm caused by oil mist overflow, and provides a guarantee for the safe, long-term and stable operation of the hydro-generating unit.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] An intelligent oil mist suction device for a hydro-generating unit, comprising a negative pressure regulating unit, a negative pressure control unit, and a negative pressure monitoring and alarm unit;

[0007] The negative pressure regulating unit is used to adjust the negative pressure of the oil sump according to the instructions of the negative pressure control unit;

[0008] The negative pressure control unit is used to issue a closed-loop instruction according to the negative pressure signal of the negative pressure monitoring and alarm unit and the feedback signal of the negative pressure regulating unit;

[0009] The negative pressure monitoring and alarm unit is used to receive signals from on-site pressure measuring elements and the oil level signal in the oil collecting tank, send out commands to the negative pressure control unit and the remote LCU unit, and issue high and low negative pressure alarm signals and high and low oil level alarm signals for the oil.

[0010] A further improvement of the present invention is that the negative pressure regulating unit includes an explosion-proof centrifugal fan, a U-shaped oil discharge pipe, an oil collecting tank, an oil mist suction and discharge pipe, an exhaust pipe for discharging oil-contaminated exhaust gas to the atmosphere, and a U-shaped pipe;

[0011] One end of the oil mist suction and discharge pipe is connected to the sampling hole of the oil basin cover, and the other end is connected to the inlet of the explosion-proof centrifugal fan. The exhaust gas outlet of the explosion-proof centrifugal fan is connected to the inlet of the exhaust pipe for discharging oil-contaminated exhaust gas to the atmosphere. The oil outlet of the explosion-proof centrifugal fan is connected to the inlet of the U-shaped pipe, and the outlet of the U-shaped pipe is connected to the inlet of the oil collecting tank through the U-shaped oil discharge pipe.

[0012] A further improvement of the present invention is that an electric regulating valve, an electric stop valve and a manual regulating valve are arranged on the oil mist suction and discharge pipe.

[0013] A further improvement of the present invention is that a U-shaped pipe sewage valve is arranged at the bottom of the U-shaped pipe.

[0014] A further improvement of the present invention is that an automatic breather valve for the oil discharge tank and a liquid level gauge for the oil collecting tank are arranged on the oil collecting tank.

[0015] A further improvement of the present invention is that an oil basin pressure sensor and a pressure sampling pipe stop valve are arranged at the sampling hole of the oil basin cover.

[0016] A further improvement of the present invention is that the negative pressure control unit performs closed-loop regulation of the throttle opening according to the negative pressure of the oil basin and informs the operation and maintenance personnel of the regulation result, including a power supply module, input signals, output signals, a controller, a relay, and the on-off action logic;

[0017] The on-off action logic includes: Fan start: Handle in automatic position & No fault & Unit start auxiliary machine command & Delay T1; Fan stop: Handle in automatic & Unit stop auxiliary machine command & Delay T1; Throttle open direction command: Handle in automatic position & No fault & Fan running & High oil basin pressure; Throttle close direction command: Handle in automatic position & No fault & Fan running & Low oil basin pressure; Electric stop valve closing command: Handle in automatic position & No fault & No fan running & Pressure measurement value valid or Unit stop auxiliary machine command & Delay T2; Electric stop valve opening command: Handle in automatic position & No fault & No fan running & Pressure measurement value valid or Unit start auxiliary machine command & Delay T2; Oil basin pressure measurement value valid judgment logic: Oil basin pressure feedback value valid & Pressure change less than 0.5 kpa / s, otherwise the measurement value is invalid;

[0018] The power supply module is used to supply power to the controller and on-site components, including an electric control valve, an electric globe valve, a fan power supply, a controller, and a relay;

[0019] The input signals include: high oil pan oil pressure alarm, low oil pan oil pressure alarm, high oil tank liquid level alarm, start auxiliary machine command, and stop auxiliary machine command;

[0020] Input relays: KC31 to KC36;

[0021] The output signals include: comprehensive fault, control system power supply monitoring, negative pressure monitoring and alarm fault, open electric control valve, close electric control valve, electric control valve fault, start explosion-proof axial flow fan, stop explosion-proof axial flow fan, explosion-proof axial flow fan fault, liquid level abnormal alarm, open electric globe valve, close electric globe valve, and electric globe valve fault:

[0022] Output relays: KC1 to KC8 and KC21 to KC28.

[0023] A further improvement of the present invention is that the negative pressure monitoring and alarm unit includes: a pressure measuring element, an oil level measuring element, a liquid level switch quantity measuring element, a pressure measuring point sampling hole, a sampling tube gauge valve, a relay, and an alarm logic;

[0024] The pressure measuring element has two output functions of analog quantity and switch. The oil level measuring element can output analog quantity for monitoring the liquid level of the return oil tank. The liquid level switch quantity measuring element can output switch quantity for monitoring the high liquid level alarm of the oil tank. The pressure measuring point sampling hole is at a distance of 0.15 circumference upstream in the rotation direction from the oil mist suction outlet, and the diameter of the sampling hole is Φ10mm. The sampling tube gauge valve is an isolating sensor and an oil pan sampling hole gauge valve with a diameter of Φ10mm. High pressure alarm: the oil pan pressure feedback value is valid & the pressure change is less than 0.5 KPa / s & the oil pan oil pressure is greater than P1 & delay T3. Low pressure alarm: the oil pan pressure feedback value is valid & the pressure change is less than 0.5 KPa / s & the oil pan oil pressure is less than P2 & delay T3;

[0025] The output relays are KC41 to KC45, and the input signals include the output signal of the oil pan pressure sensor, the high liquid level alarm signal, and the ultra-low alarm of the liquid level gauge.

[0026] The present invention has at least the following beneficial technical effects:

[0027] An intelligent oil mist suction device for a hydro-generator set provided by the present invention integrates monitoring the negative pressure of the oil sump, controlling the negative pressure of the oil sump, and collecting oil stains, and can realize the escape of oil mist from the oil sump of the generator, thereby avoiding polluting the generator rotor, reducing the maintenance cost and the labor cost for cleaning after pollution. According to the estimated cleaning man-hours of the generator rotor and stator after pollution in existing projects, the cost can be reduced or saved by more than 50,000 yuan for each overhauled unit, and the invention of this device can effectively prevent electrochemical pollution inside the generator and damage to automation components. Description of the Drawings

[0028] Figure 1 It is a diagram of the oil sump pressure control system.

[0029] Figure 2 In (a) and (b) are respectively diagrams of the oil sump pressure sampling holes.

[0030] Figure 3 It is the pressure regulation control principle Figure 1 .

[0031] Figure 4 It is the pressure regulation control principle Figure 2 .

[0032] Figure 5 It is the pressure regulation control principle Figure 3 .

[0033] Figure 6 It is the pressure monitoring and alarm principle Figure 1 .

[0034] Figure 7 It is the pressure monitoring and alarm principle Figure 2 .

[0035] Figure 8 It is a diagram of the relationship between pressure regulation control and pressure monitoring and alarm.

[0036] Description of the Reference Numerals:

[0037] 1-1 is an electric control valve; 1-2 is an electric stop valve; 1-3 is a manual control valve; 1-4 is an explosion-proof centrifugal fan; 1-5 is a U-shaped oil discharge pipe; 1-6 is a U-shaped pipe sewage valve; 1-7 is an oil collection tank; 1-10 is an oil mist suction and discharge pipe; 1-11 is a pipe for discharging oil stain exhaust gas to the atmosphere for emptying; 1-12 is a U-shaped pipe; 4-3 is an automatic breathing valve for the oil discharge tank; 4-4 is an analog quantity of the oil collection tank liquid level gauge; 4-8 is a high liquid level alarm; 4-7 is a high liquid level alarm; 4-6 is a low liquid level alarm; 4-5 is an ultra-low liquid level alarm;

[0038] 1-21 is an oil sump pressure sensor; 1-22 is a stop valve for the pressure sampling pipe; 1-23 is an oil sump cover sampling hole;

[0039] 10-1 is the first controller; 10-1-1 is the fault alarm; 10-1-2 is the main body power supply monitoring; 10-1-3 is the negative pressure monitoring and alarm for controller failure; 10-1-4 is to open the electric control valve; 10-1-5 is to close the electric control valve; 10-1-6 is the electric control valve failure; 10-1-7 is to start the explosion-proof centrifugal fan; 20-1-8 is to stop the explosion-proof centrifugal fan;

[0040] 10-2 is the second controller; 10-2-1 is the explosion-proof centrifugal fan failure; 10-2-2 is the fault alarm for the liquid level of the oil collecting tank; 10-2-3 is to open the electric stop valve; 10-2-4 is to close the electric stop valve; 10-2-5 is the electric stop valve failure; 10-2-6 is the abnormal liquid level of the oil collecting tank; 10-2-7 is the abnormal negative pressure of the oil basin;

[0041] 10-3 is the third controller; 10-3-1 is the high pressure alarm for the oil basin; 10-3-2 is the low pressure alarm for the oil basin; 10-3-3 is the high level alarm for the oil collecting tank; 10-3-4 is the instruction to start the auxiliary machine; 10-3-5 is the instruction to stop the auxiliary machine;

[0042] 10-4 is the fourth controller; 10-4-1 is the high pressure alarm for the oil basin; 10-4-2 is the low pressure alarm for the oil basin; 10-4-3 is the high level alarm for the oil collecting tank; 10-4-4 is the low level alarm for the oil collecting tank;

[0043] 10-5 is the fifth controller; 10-5-1 is the high pressure alarm for the pressure from pressure transmitter 1-21 to the fifth controller; 10-5-2 is the low pressure alarm for the pressure from the pressure transmitter to the fifth controller; 10-5-3 is the high level alarm for the liquid level from the liquid level gauge node to the fifth controller; 10-5-4 is the low level alarm for the liquid level from the liquid level gauge node to the fifth controller; 10-5-5 is the pressure analog quantity from the pressure transmitter to the fifth controller; 10-5-6 is the liquid level analog quantity from the oil collecting tank liquid level gauge to the fifth controller. Detailed implementation mode

[0044] Hereinafter, the exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.

[0045] The specific connection relationships of the relays, sensors, regulating valves, fans, liquid level switches, and relays involved in the negative pressure regulating unit, negative pressure control unit, and negative pressure monitoring and alarm unit are as follows: The devices controlled by the first controller 10-1 include the explosion-proof centrifugal fan 1-4, the electric control valve 1-1, and the relays KC1 to KC8; the devices controlled by the second controller 10-2 include the electric stop valve 1-2 and the relays KC21 to KC28; the third controller 10-3 mainly receives the output signal of the explosion-proof centrifugal fan 10-4 and provides basic parameters for the logic control of the negative pressure control unit. The fourth controller 10-4 uses the signal of the fifth controller 10-5 as the basis for control output through internal data exchange. The fifth controller 10-5 receives the output signals of the transmitter 1-21, the high liquid level alarm 4-8 of the liquid level gauge, the high liquid level alarm 4-7 of the liquid level gauge, the low liquid level alarm 4-6 of the liquid level gauge, and the ultra-low liquid level alarm 4-5 of the liquid level gauge, as Figure 8 shown.

[0046] The first negative pressure regulating unit, as Figure 1 involved, the diameters of the oil mist suction pipes and valves are all 150 mm, the U-shaped bend is 30 mm, the diameter of the drain valve is 10 mm, the diameter of the vent pipe is 80 mm, and the water-guided oil basin, lower oil guide basin, and upper oil guide basin are all arranged according to Figure 1 the layout method. Figure 1 The cut-off flow direction in

[0047] is as follows: Through the electric control valve 1-1 to the oil mist suction and discharge pipe 1-10, the electric stop valve 1-2, and the manual control valve 1-3, it enters the explosion-proof centrifugal fan 1-4. The exhausted gas from the outlet of the explosion-proof centrifugal fan 1-4 is discharged to the atmosphere through the oil and dirt exhausted gas to the atmosphere vent pipe 1-11. The oil liquid enters the U-shaped bend through the U-shaped pipe 1-12 and flows by gravity to the U-shaped oil discharge pipe 1-5 and then enters the oil collecting tank 1-7. A liquid level gauge 4-4 of the oil collecting tank is installed on the oil collecting tank 1-7. Among them, 4 liquid level switch nodes are installed on the liquid level gauge 4-4 of the oil collecting tank, which are: high liquid level alarm 4-8, high liquid level alarm 4-7, low liquid level alarm 4-6, and ultra-low liquid level alarm 4-5 of the liquid level gauge. An automatic breather valve 4-3 of the drain tank is installed on the oil collecting tank 1-7 to break the positive / negative pressure in the oil collecting tank 1-7. A drain valve 1-6 of the U-shaped pipe is installed on the U-shaped pipe 1-12 to discharge the oil dirt or impurities when replacing and maintaining the U-shaped pipe.

[0047] The second part: The negative pressure control unit, as Figure 3 , Figure 4 and Figure 5 mainly involves: the first controller 10-1, the second controller 10-2, and the third controller 10-3.

[0048] Among them, the first controller 10-1 includes two output modules, namely DO1 and DO2. Its corresponding specific functions are as follows: 10-1-1 is for fault alarm, controlling the KC1 relay, and sending signals to the unit LCU through the KC1 relay nodes 2 and 3; 10-1-2 is for monitoring the main body power supply, controlling the KC2 relay, and sending signals to the unit LCU through the KC2 relay nodes 2 and 3; 10-1-3 is for negative pressure monitoring and alarm controller fault alarm, controlling the KC3 relay, and sending signals to the unit LCU through the KC3 relay nodes 5 and 6; 10-1-4 is for opening the electric control valve, controlling the KC4 relay, and sending signals to the unit LCU through the KC4 relay nodes 2 and 3. The KC4 relay nodes 5 and 6 control the opening degree of the electric control valve 1-1; 10-1-5 is for closing the electric control valve, controlling the KC5 relay, and sending signals to the unit LCU through the KC5 relay nodes 2 and 3. The KC5 relay nodes 5 and 6 control the opening degree of the regulating valve 1-4; 10-1-6 is for electric control valve fault, controlling the KC6 relay, and sending signals to the unit LCU through the KC6 relay nodes 2 and 3; 10-1-7 is for starting the explosion-proof centrifugal fan, controlling the KC7 relay, and sending signals to the unit LCU through the KC7 relay nodes 5 and 6. The KC7 relay nodes 2 and 3 control the start of the explosion-proof centrifugal fan 1-4; 10-1-8 is for stopping the explosion-proof centrifugal fan, controlling the KC8 relay, and sending signals to the unit LCU through the KC8 relay nodes 2 and 3. The KC8 relay nodes 5 and 6 control the stop of the explosion-proof centrifugal fan 1-4.

[0049] Among them, the second controller 10-2 includes two output modules, namely DO1 and DO2. Its corresponding specific functions are as follows: 10-2-1 is for explosion-proof centrifugal fan fault, controlling the KC21 relay, and sending signals to the unit LCU through the KC21 relay nodes 2 and 3; 10-2-2 is for oil sump liquid level fault alarm, controlling the KC22 relay, and sending signals to the unit LCU through the KC22 relay nodes 2 and 3; 10-2-3 is for opening the electric globe valve, controlling the KC23 relay, and sending signals to the unit LCU through the KC23 relay nodes 2 and 3. The KC23 relay nodes 5 and 6 control the opening of the electric globe valve; 10-2-4 is for closing the electric globe valve, controlling the KC24 relay, and sending signals to the unit LCU through the KC24 relay nodes 2 and 3. The KC24 relay nodes 5 and 6 control the closing of the electric control valve 1-2; 10-2-5 is for electric globe valve fault, controlling the KC25 relay, and sending signals to the unit LCU through the KC25 relay nodes 2 and 3; 10-2-6 is for abnormal oil sump liquid level, controlling the KC27 relay, and sending signals to the unit LCU through the KC27 relay nodes 2 and 3; 10-2-7 is for abnormal negative pressure in the oil pan, controlling the KC28 relay, and sending signals to the unit LCU through the KC28 relay nodes 2 and 3.

[0050] Among them, the third controller 10-3 includes 1 input module, namely DI01. Its corresponding specific functions are as follows: 10-3-1 is the high oil sump pressure alarm, which controls the KC31 relay and receives the control 10-4 signal using the nodes 2 and 3 of the KC31 relay; 10-3-2 is the low oil sump pressure alarm, which controls the KC32 relay and receives the control 10-4 signal using the nodes 2 and 3 of the KC32 relay; 10-3-3 is the high oil collecting tank liquid level alarm, which controls the KC33 relay and receives the control 10-4 signal using the nodes 5 and 6 of the KC33 relay; 10-3-4 is the auxiliary machine start instruction, which controls the KC34 relay and receives the unit LCU instruction using the nodes 2 and 3 of the KC34 relay; 10-3-5 is the auxiliary machine stop instruction, which controls the KC35 relay and receives the unit LCU instruction using the nodes 2 and 3 of the KC35 relay.

[0051] The logic involved in the negative pressure control system is as follows: Fan start: handle in automatic position & no fault & unit auxiliary machine start instruction & delay T1; Fan stop: handle in automatic & unit auxiliary machine stop instruction & delay T1; Throttle opening instruction: handle in automatic position & no fault & fan running & high oil sump pressure; Throttle closing instruction: handle in automatic position & no fault & fan running & low oil sump pressure; Electric stop valve closing instruction: handle in automatic position & no fault & no fan running & pressure measurement value valid or unit auxiliary machine stop instruction & delay T2; Electric stop valve opening instruction: handle in automatic position & no fault & no fan running & pressure measurement value valid or unit auxiliary machine start instruction & delay T2; Logic for judging the validity of the oil sump pressure measurement value: the oil sump pressure feedback value is valid & the pressure change is less than 0.5 kpa / s, otherwise the measurement value is invalid.

[0052] The third part is the negative pressure monitoring and alarm unit, including the fourth controller 10-4, the fifth controller 10-5 and the current measurement unit. Among them, the fourth controller 10-4 is a DO output module, and the fifth controller 10-5 is a DI input module.

[0053] Among them, the controller 10-4 includes 1 output module, namely DO2. Its corresponding specific functions are as follows: 10-4-1 is the high oil sump pressure alarm, which controls the KC41 relay and outputs signals to the controller 10-3 using the nodes 2 and 3 of the KC41 relay; 10-4-2 is the low oil sump pressure alarm, which controls the KC42 relay and outputs signals to the controller 10-3 using the nodes 2 and 3 of the KC42 relay; 10-4-3 is the high oil collecting tank liquid level alarm, which controls the KC43 relay and outputs signals to the controller 10-3 using the nodes 2 and 3 of the KC43 relay; 10-4-4 is the low oil collecting tank liquid level alarm, which controls the KC44 relay and outputs signals to the controller 10-3 using the nodes 2 and 3 of the KC44 relay.

[0054] Among them, the fifth controller 10-5 includes 1 input module, namely DI01, and its corresponding specific functions 10-5-1 to 10-5-6 are as follows: 10-5-1 is the high-pressure alarm of the pressure transmitter to the fifth controller; 10-5-2 is the low-pressure alarm of the pressure transmitter to the fifth controller; 10-5-3 is the high-level alarm of the liquid level gauge node to the fifth controller; 10-5-4 is the ultra-low liquid level alarm of the liquid level gauge node to the fifth controller; 10-5-5 is the pressure analog quantity of the pressure transmitter 1-21 to the fifth controller; 10-5-6 is the liquid level analog of the liquid level gauge node to the fifth controller.

[0055] Among them, the on-site measurement unit mainly consists of an oil sump pressure sensor 1-21, a pressure sampling pipe stop valve 1-22, and an oil sump cover sampling hole 1-23. The sampling pipe orifices all use stainless steel pipes with a diameter of Φ10mm. The oil sump pressure sensor 1-21 is powered by the fifth controller 10-5 and transmits digital and analog signals to the fifth controller 10-5. The liquid level switches involved in the fourth controller 10-4 all use the fifth controller 10-5 to control the power supply module and transmit the signals to the fifth controller 10-5.

[0056] Among them, the logical judgment is as follows: High-pressure alarm: The oil sump pressure feedback value is valid & the pressure change is less than 0.5 KPa / s & the oil sump oil pressure is greater than P1 & delay T3; Low-pressure alarm: The oil sump pressure feedback value is valid & the pressure change is less than 0.5 KPa / s & the oil sump oil pressure is less than P2 & delay T3.

[0057] Although the present invention has been described in detail above with general descriptions and specific implementation examples, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An intelligent oil mist suction device for a hydropower unit, characterized in that, It includes a negative pressure regulating unit, a negative pressure control unit, and a negative pressure monitoring and alarm unit; The negative pressure regulating unit is used to adjust the negative pressure of the oil basin according to the instructions of the negative pressure control unit; the negative pressure regulating unit includes an explosion-proof centrifugal fan (1-4), a U-shaped oil discharge pipe (1-5), an oil collecting tank (1-7), an oil mist suction and discharge pipe (1-10), an exhaust pipe for discharging oil-contaminated exhaust gas to the atmosphere (1-11), and a U-shaped pipe (1-12); One end of the oil mist suction and discharge pipe (1-10) is connected to the sampling hole (1-23) of the oil basin cover, and the other end is connected to the inlet of the explosion-proof centrifugal fan (1-4). The exhaust gas outlet of the explosion-proof centrifugal fan (1-4) is connected to the inlet of the exhaust pipe for discharging oil-contaminated exhaust gas to the atmosphere (1-11). The oil liquid outlet of the explosion-proof centrifugal fan (1-4) is connected to the inlet of the U-shaped pipe (1-12). The outlet of the U-shaped pipe (1-12) is connected to the inlet of the oil collecting tank (1-7) through the U-shaped oil discharge pipe (1-5); The negative pressure control unit is used to issue a closed-loop instruction according to the negative pressure signal of the negative pressure monitoring and alarm unit and the feedback signal of the negative pressure regulating unit; The negative pressure monitoring and alarm unit is used to receive the signals of on-site pressure measuring elements and the oil liquid position signals of the oil collecting tank, issue commands to the negative pressure control unit and the remote LCU unit, and issue negative pressure high and low alarm signals and oil liquid level high and low alarm signals.

2. The intelligent oil mist suction device for a hydropower unit according to claim 1, characterized in that, An electric control valve (1-1), an electric stop valve (1-2), and a manual control valve (1-3) are arranged on the oil mist suction and discharge pipe (1-10).

3. The intelligent oil mist suction device for a hydropower unit according to claim 1, characterized in that A U-shaped pipe drain valve (1-6) is arranged at the bottom of the U-shaped pipe (1-12).

4. The intelligent oil mist suction device for a hydropower unit according to claim 1, wherein An automatic breather valve (4-3) for the oil discharge tank and a liquid level gauge (4-4) for the oil collecting tank are arranged on the oil collecting tank (1-7).

5. The intelligent oil mist suction device for a hydropower unit according to claim 1, wherein An oil basin pressure sensor (1-21) and a pressure sampling pipe stop valve (1-22) are arranged at the sampling hole (1-23) of the oil basin cover.

6. The intelligent oil mist suction device for a hydropower unit according to claim 1, characterized in that The negative pressure control unit performs closed-loop adjustment of the throttle opening according to the negative pressure of the oil basin and informs the operation and maintenance personnel of the adjustment result, including a power supply module, input signals, output signals, a controller, a relay, and an input / output action logic; The input / output action logic includes: Fan start: The switch handle is in the automatic position, there is no fault, the unit issues an auxiliary machine start command, and a delay of T1; Fan stop: The switch handle is in the automatic position, the unit issues an auxiliary machine stop command, and a delay of T1; Throttle opening command: The switch handle is in the automatic position, there is no fault, the fan is running, and the oil basin pressure is high; Throttle closing command: The switch handle is in the automatic position, there is no fault, the fan is running, and the oil basin pressure is low; Electric stop valve closing command: The switch handle is in the automatic position, there is no fault, the fan is not running, the pressure measurement value is valid, or the unit issues an auxiliary machine stop command, and a delay of T2; Electric stop valve opening command: The switch handle is in the automatic position, there is no fault, the fan is not running, the pressure measurement value is valid, or the unit issues an auxiliary machine start command, and a delay of T2; The power supply module is used to supply power to the controller and on-site components, including an electric control valve, an electric stop valve, fan power supply, a controller, and a relay; The input signals are: high oil pressure alarm for the oil basin, low oil pressure alarm for the oil basin, high liquid level alarm for the oil collecting tank, auxiliary machine start command, and auxiliary machine stop command; Input relays: KC31 to KC36; The output signals include: comprehensive fault, control system power supply monitoring, negative pressure monitoring and alarm fault, opening the electric control valve, closing the electric control valve, electric control valve fault, starting the explosion-proof axial flow fan, stopping the explosion-proof axial flow fan, explosion-proof axial flow fan fault, liquid level abnormal alarm, opening the electric globe valve, closing the electric globe valve, and electric globe valve fault: Output relays: KC1 to KC8 and KC21 to KC28.

7. An intelligent oil mist suction device for a hydropower unit according to claim 1, characterized in that The negative pressure monitoring and alarm unit includes: a pressure measuring element, an oil level measuring element, a liquid level switch quantity measuring element, a pressure measuring point sampling hole, a sampling pipe gauge valve, a relay, and an alarm logic; The pressure measuring element has two output functions of analog quantity and switch. The oil level measuring element can output analog quantity for monitoring the liquid level of the oil return tank. The liquid level switch quantity measuring element can output switch quantity for high liquid level alarm monitoring of the oil collecting tank. The sampling pipe gauge valve is an isolation sensor and an oil sump sampling hole gauge valve with a diameter of Φ10mm. High pressure alarm: the oil sump pressure feedback value is valid, the pressure change is less than 0.5 KPa / s, the oil sump oil pressure is greater than P1, and the delay is T3. Low pressure alarm: the oil sump pressure feedback value is valid, the pressure change is less than 0.5 KPa / s, the oil sump oil pressure is less than P2, and the delay is T3; The output relays are KC41 to KC45, and the input signals include the output signal of the oil sump pressure sensor (1-21), the liquid level too high alarm (4-8) signal, and the liquid level gauge ultra-low alarm (4-5).

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