A kind of water power station high oil tank oil level redundancy control device and method

Abstract

The present application relates to the field of hydropower unit control, in particular to a kind of hydropower station high oil tank oil level redundancy control device and method;The present application is by being arranged at the top of each set of high oil tank switch quantity liquid level sensor and analog quantity liquid level transmitter, two kinds of signals are sent into PLC controller by signal acquisition module;PLC controller built-in oil level redundancy judging module, when two signals are consistent, according to state output oil supplement or pump stop instruction, when inconsistent, analog quantity is used as reference and alarm;While setting operation mode switching module, different logic is used to judge the oil level of multiple oil tanks according to series or independent mode;And with unit start-stop linkage, ensure that oil level meets the standard before starting.The present application realizes the cross verification and intelligent oil supplement control of oil level, improves the monitoring reliability and working condition adaptability, and reduces the risk of unplanned shutdown.

Description

Technical Field

[0001] This invention relates to the field of hydropower station unit control, specifically to a redundant control device and method for the oil level of a high-level oil tank in a hydropower station. Background Technology

[0002] In the external circulating oil system of hydropower station unit bearings, oil level monitoring of the high-level oil tank is a critical link to ensure bearing lubrication safety. Currently, oil level monitoring is generally carried out using a single digital or analog signal, which poses a risk of signal malfunction, easily leading to erroneous start and stop of the oil pump, which in turn causes oil overflow due to excessively high oil level or supply interruption due to excessively low oil level, seriously threatening the lubrication safety of the unit bearings.

[0003] In existing technologies, oil level monitoring in high-level oil tanks mainly relies on two types of sensors: one is a digital level sensor, which outputs discrete signals such as low, low, high, and high to trigger the start and stop of the oil pump; the other is an analog level transmitter, which outputs a 4-20mA continuous current signal for continuous oil level monitoring. With a dual-high-level oil tank configuration, the operating modes are either series operation or independent operation. Traditional control systems typically use fixed oil level judgment logic without differentiated design for different operating modes.

[0004] The above solution has two problems: First, when a single sensor fails or a signal is falsely triggered, there is a lack of cross-verification methods, which can easily lead to the oil pump starting or stopping falsely, resulting in abnormal oil levels. Second, when switching between series and independent operation modes, the oil level judgment logic does not distinguish between different operating conditions, resulting in low control accuracy and poor adaptability to operating conditions, which cannot meet the oil supply reliability requirements under different operating scenarios. Summary of the Invention

[0005] To address the problems mentioned in the prior art, this invention proposes a redundant control device and method for oil level in the high-level oil tank of a hydropower station. The aim is to solve the problems of single oil level monitoring signals and inaccurate operating condition switching logic in traditional methods, so as to achieve reliable oil level monitoring and oil replenishment control, and ensure the stable operation of the unit's bearing lubrication system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention proposes a redundant control device for the oil level of a high-level oil tank in a hydropower station, comprising: The monitoring unit includes a digital level sensor, an analog level transmitter, and a signal acquisition module installed on the top of each high-level oil tank; the digital level sensor is used to output discrete oil level signals, and the analog level transmitter is used to output continuous oil level signals; the signal acquisition module is connected to the digital level sensor and the analog level transmitter respectively. The control unit includes a PLC controller connected to a signal acquisition module for receiving discrete oil level signals and continuous oil level signals. The PLC controller has a built-in oil level redundancy judgment module for judging the consistency between the discrete oil level signals and the continuous oil level signals. When the judgment results are consistent, an oil replenishment command or a pump stop command is generated based on the signal status. When the judgment results are inconsistent, an oil replenishment command or a pump stop command is generated based on the continuous oil level signal, and an alarm signal is output. The operation mode switching module is used to perform oil level redundancy judgment on the oil level status of at least two sets of high-level oil tanks according to the preset series operation mode or independent operation mode, so as to output oil replenishment command or pump stop command. An execution unit, comprising at least one oil pump and at least one cooler electric valve; the oil pump and the cooler electric valve are respectively electrically connected to a PLC controller.

[0007] As a further improvement of the present invention, the discrete oil level signal output by the switch liquid level sensor includes at least four discrete oil level signals: too low, low, high, and too high. The continuous oil level signal output by the analog liquid level transmitter includes a 4-20mA current signal, which corresponds to the oil level range 0-H. The signal acquisition module synchronously acquires signals from all digital and analog level sensors at a frequency of 1Hz.

[0008] As a further improvement of the present invention, the PLC controller also has a built-in oil level threshold module, which includes a normal low oil level threshold L1 and a working high oil level threshold L2, and sets a hysteresis L2-L1≥50mm.

[0009] As a further improvement of the present invention, in the oil level redundancy judgment module, when the deviation between the discrete oil level signal and the continuous oil level signal exceeds ±10%, it is determined that the judgment result is inconsistent.

[0010] As a further improvement of the present invention, the specific judgment logic of the operation mode switching module is as follows: In series operation mode, when the two high-level oil tanks are at the same level, the oil level signal of either oil tank can be taken. When the oil level signal is lower than the normal low oil level threshold, a replenishment command is generated. When the oil level signal is higher than the working high oil level threshold, a pump stop command is generated. In independent operation mode, the oil level signals of the two high-level oil tanks are judged independently. When the oil level signal is lower than the normal low oil level threshold, a replenishment command is generated accordingly. When the oil level signal is higher than the working high oil level threshold, a pump stop command is generated accordingly.

[0011] As a further improvement of the present invention, the oil pump of the execution unit is three screw oil pumps, with a configuration of 1 main and 2 backup pumps, and the cooler electric valve is four. The PLC controller also has a built-in oil pump start-up judgment module, which is used to determine whether at least one cooler electric valve is in the fully open state before outputting the oil pump start command. If so, the oil pump start command is output. Otherwise, the oil pump must not be started.

[0012] As a further improvement of the present invention, the execution unit also includes a flow sensor installed in the oil supply pipeline of the high-level oil tank, and the output end of the flow sensor is electrically connected to the PLC controller; when the main oil pump is started, if the oil supply flow detected by the flow sensor is lower than a preset threshold, the PLC controller automatically starts the backup oil pump.

[0013] As a further improvement of the present invention, a touch screen is also included. The touch screen is electrically connected to the PLC controller and is used to manually set the series operation mode or the independent operation mode, modify the normal low oil level threshold and the working high oil level threshold online, and display the oil level status and alarm information.

[0014] This invention proposes a redundant control method for the oil level in the high-level oil tank of a hydropower station, applied to the aforementioned system, comprising the following steps: Step 1: Real-time acquisition of discrete and continuous oil level signals from the high-level oil tank; wherein the discrete oil level signal includes at least two states: low and high. Step 2: When the continuous oil level signal is between the preset normal low oil level threshold and the working high oil level threshold, and the discrete oil level signal is in the trigger low state and high state, the oil level is determined to be normal, and no oil replenishment or pump stop command is generated. When the continuous oil level signal is lower than the normal low oil level threshold and the discrete oil level signal is in a low state, a refueling command is generated. When the continuous oil level signal is higher than the working high oil level threshold and the discrete oil level signal is in a high state, a pump stop command is generated. When the oil level deviation between the continuous oil level signal and the discrete oil level signal exceeds ±10%, an oil replenishment command or a pump stop command is generated based on the continuous oil level signal, and an alarm signal is generated at the same time. Step 3: Based on the pre-set series operation mode or independent operation mode, perform different logical judgments on the oil level signals of at least two sets of high-level oil tanks: In series operation mode, since the two high-level oil tanks have the same oil level, the oil level signal of either oil tank is used for judgment: when the oil level signal is lower than the normal low oil level threshold, an oil replenishment command is generated; when the oil level signal is higher than the working high oil level threshold, a pump stop command is generated. In independent operation mode, the two high-level oil tanks independently determine their own oil level signals and generate corresponding oil replenishment or pump stop commands. The control of the two oil tanks does not affect each other.

[0015] As a further improvement of the present invention, a start-stop linkage control step is also included, comprising: When the receiving unit starts up, it first determines whether the oil level in the high-level oil tank has reached the working high oil level threshold. If it has not reached it, the oil replenishment command is executed first. After the oil level reaches the working high oil level threshold, the bearing oil supply regulating valve is opened. When the unit shutdown order is received, the bearing oil supply regulating valve is immediately closed, and the oil level in the high-level oil tank is maintained between the normal low oil level threshold and the working high oil level threshold. At the same time, the pump stop command is executed.

[0016] Compared with the prior art, the present invention achieves the following technical effects: This invention achieves cross-verification of signals through dual redundant signal acquisition and redundant judgment modules. When the signals are consistent, normal control is maintained; when they are inconsistent, the continuous oil level signal is used as the standard and an alarm signal is generated. This fundamentally eliminates the risk of malfunction by a single sensor and also makes discrete and continuous oil level signals backups. The failure of any sensor will not lead to system out of control, significantly reducing the risk of unit shutdown due to abnormal oil levels. At the same time, this invention has a built-in operating mode switching module in the PLC controller, which can automatically switch the oil level judgment logic according to the series or independent mode. This solves the problem of low control accuracy and poor adaptability caused by the use of the same fixed logic in the prior art, making the oil replenishment strategy match the actual oil supply demand and avoiding ineffective or insufficient oil replenishment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0018] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0024] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0026] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] See Figure 1 This embodiment proposes a redundant control device for the oil level of a high-level oil tank in a hydropower station, comprising: The monitoring unit includes a digital level sensor, an analog level transmitter, and a signal acquisition module installed on the top of each high-level oil tank; the digital level sensor is used to output discrete oil level signals, and the analog level transmitter is used to output continuous oil level signals; the signal acquisition module is connected to the digital level sensor and the analog level transmitter respectively. The control unit includes a PLC controller connected to a signal acquisition module for receiving discrete oil level signals and continuous oil level signals. The PLC controller has a built-in oil level redundancy judgment module for judging the consistency between the discrete oil level signals and the continuous oil level signals. When the judgment results are consistent, an oil replenishment command or a pump stop command is generated based on the signal status. When the judgment results are inconsistent, an oil replenishment command or a pump stop command is generated based on the continuous oil level signal, and an alarm signal is output. The operation mode switching module is used to perform oil level redundancy judgment on the oil level status of at least two sets of high-level oil tanks according to the preset series operation mode or independent operation mode, so as to output oil replenishment command or pump stop command. An execution unit, comprising at least one oil pump and at least one cooler electric valve; the oil pump and the cooler electric valve are respectively electrically connected to a PLC controller.

[0028] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the monitoring unit in this embodiment is installed on each high-level oil tank. Taking a single high-level oil tank as an example, a digital level sensor and an analog level transmitter are installed on the top. The digital level sensor is made of stainless steel, and its probe is vertically inserted into the oil tank to a depth of H + 100mm of the full range of the tank, ensuring that the probe is always submerged in the oil and outputting four discrete signals: low, low, high, and high. The analog level transmitter is also installed on the top of the oil tank. In this embodiment, its core component preferably has a temperature compensation function, which can eliminate the influence of different oil temperatures on the measurement accuracy. The analog level transmitter outputs a 4-20mA continuous current signal, where 4mA corresponds to oil level 0 (empty tank) and 20mA corresponds to oil level H (full tank), and outputs the corresponding continuous oil level signal based on the current signal.

[0030] In this embodiment, the signal acquisition module is electrically connected to the signal output terminals of both the digital liquid level sensor and the analog liquid level transmitter via shielded cables. The signal acquisition module synchronously acquires signals at a frequency of 1Hz and has a built-in fault diagnosis function, capable of automatically identifying abnormal conditions such as sensor disconnection or short circuit. The processed signal is then transmitted to the PLC controller via another shielded cable.

[0031] The control unit includes a PLC controller, which is electrically connected to the output of the signal acquisition module to obtain discrete and continuous oil level signals for each high-level oil tank in real time. The PLC controller integrates various functional modules: an oil level redundancy judgment module, an oil level threshold storage module, an operating mode switching module, an oil pump pre-start judgment module, and a unit linkage control module. It also includes a touchscreen connected to the PLC controller, allowing operators to manually set the operating mode (serial or independent), modify the normal low oil level threshold L1 and the operating high oil level threshold L2 online, and view oil level data, alarm information, and equipment status in real time.

[0032] In this embodiment, the output of the PLC controller is connected to the execution unit. The execution unit includes three screw oil pumps (one main and two backup) and four cooler electric valves. The start / stop control terminal of each oil pump and the open / close control terminal of each cooler electric valve are electrically connected to the corresponding output terminal of the PLC controller via cables. In addition, a flow sensor is installed on the oil supply line of the high-level oil tank. The output of this flow sensor is also connected to the analog input terminal of the PLC controller for real-time feedback of the oil supply flow.

[0033] In this embodiment, each set of elevated oil tanks is equipped with a monitoring unit. The discrete signal output by the on-off level sensor has a total of four gears: too low, low, high, and too high. Among them, low and high correspond to the threshold intervals of the normal low oil level L1 and the working high oil level L2 respectively, while too low and too high are used for limit alarming. The 4-20mA signal output by the analog level transmitter continuously reflects the full range of the oil level from 0 to H. When the signal acquisition module performs synchronous acquisition, it will align the timestamps of the two signals at the same time, so as to avoid misjudgment caused by unsynchronized acquisition time, enabling the system to obtain two independent sets of oil level information from the on-off signal and the analog signal. When any one of the sensors is damaged, the other one can still continue to provide oil level information, thereby avoiding the risk that a single sensor failure causes the entire control system to crash.

[0034] In this embodiment, the system first compares whether the interval indicated by the discrete oil level signal at the current moment is consistent with the interval where the value calculated from the continuous oil level signal is located.

[0035] When the continuous oil level signal h satisfies L1≤h≤L2, and the discrete oil level signal is neither low nor high (it can be considered that the discrete oil level signal is not triggered), it is determined that the oil level is in the normal range, and no oil replenishment or pump stop instruction is generated.

[0036] When h<L1 and the discrete oil level signal is low, it is determined as an oil shortage state, and an oil replenishment instruction is generated; When h>L2 and the discrete oil level signal is high, it is determined that the oil level is too high, and a pump stop instruction is generated.

[0037] If the oil level intervals indicated by the discrete oil level signal and the continuous oil level signal are inconsistent (for example, the continuous oil level shows h<L1, but the discrete signal does not output a low level), the relative deviation between the two will be calculated. When the relative deviation is within ±10%, it is determined to be inconsistent. At this time, the module generates an oil replenishment or pump stop instruction based on the continuous oil level signal, and simultaneously outputs an alarm signal to prompt the staff to check the corresponding sensor.

[0038] In this embodiment, an operation mode switching module is provided in the PLC controller, and the staff can manually set the system to the series operation mode or the independent operation mode through the touch screen. According to the current mode, the operation mode switching module performs combined logic judgment on the oil level signals of at least two oil tanks, and finally outputs an oil replenishment instruction or a pump stop instruction to the execution unit.

[0039] In series operation mode, two high-level oil tanks are connected by pipelines, ensuring that the oil levels in both tanks remain the same. Therefore, it is unnecessary to separately determine the oil levels in each tank; the oil level signal from either tank can be used as a representative to obtain the common oil level status. Specifically, the PLC controller compares the oil level signal obtained after redundant checks of this tank with preset normal low oil level threshold L1 and working high oil level threshold L2: when the oil level is below L1, a replenishment command is generated; when the oil level is above L2, a pump stop command is generated.

[0040] Independent Operation Mode: The oil supply lines of the two high-level oil tanks are independent of each other, each supplying different units or different bearing lubrication points. In this mode, the oil levels in the two tanks differ due to variations in downstream oil consumption; therefore, the oil level status of each tank is collected and judged separately. The PLC controller operates redundant oil level judgment logic independently for each tank, generating corresponding replenishment or pump stop commands. The control of the two tanks is decoupled and does not interfere with each other. For example, when the oil level in tank 1 is lower than L1, only the replenishment oil circuit corresponding to unit 1 is activated; when the oil level in tank 2 is normal, its corresponding oil pump remains stopped.

[0041] In this embodiment, the three screw oil pumps in the execution unit are configured with one main pump and two backup pumps. Under normal circumstances, the main pump is responsible for replenishing oil; if the main pump fails or the oil supply flow is insufficient, the PLC controller will automatically switch to the first backup pump; if the flow is still insufficient, the second backup pump will be started, thereby significantly improving the reliability of the oil supply system.

[0042] Four electric valves for the coolers are distributed in the oil circulation cooling circuit. Before the oil pump starts, the oil pump start-up judgment module built into the PLC controller checks whether at least one electric valve for the coolers is fully open. The oil pump is only allowed to start when this precondition is met. The purpose is to ensure that the lubricating oil is cooled by the coolers during circulation. If the oil pump is started directly without opening the cooler valves, the high-temperature oil will directly enter the bearing, causing lubrication failure or even bearing failure.

[0043] In addition, flow sensors on the oil supply pipeline monitor the actual oil supply flow in real time. A preset normal flow threshold is initially set. After the main oil pump starts, the PLC controller continuously reads the flow value. If the detected flow value is lower than the normal flow threshold, and the duration exceeds a short delay (preferably 3 seconds), it is determined that the main oil pump output is insufficient or there is a pipeline leak, and the first backup oil pump is immediately and automatically started. If the flow returns to normal, the current operating state is maintained; if it is still insufficient, the second backup oil pump is started. This setting enhances the continuity of oil supply.

[0044] When the PLC controller in this embodiment receives the start-up command from the unit control system, it first determines whether the oil level in the high-level oil tank has reached the working high oil level threshold. If not, it immediately executes the oil replenishment command (calling the oil pump start-up logic). Only after the oil level rises to the working high oil level threshold will it output the command to open the corresponding unit bearing oil supply regulating valve, ensuring that the unit has sufficient lubricating oil at the moment of start-up.

[0045] When a shutdown order is received, the PLC controller immediately issues a command to close the bearing oil supply regulating valve. At the same time, as the oil level in the high-level oil tank will gradually decrease due to the valve closure, when the oil level drops to near the normal low oil level threshold, the redundant judgment module will automatically issue a pump stop command to stop the oil pump. Ultimately, the oil level in the high-level oil tank will be maintained between the normal low oil level threshold and the working high oil level threshold.

[0046] This embodiment also provides a method for redundant control of oil level in the high-level oil tank of a hydropower station. It includes the following steps: Step 1: Real-time acquisition of discrete and continuous oil level signals from the high-level oil tank. The discrete oil level signal includes at least two states: low and high.

[0047] Step 2: When the continuous oil level signal h satisfies L1≤h≤L2, and the discrete oil level signal does not trigger low or high, the oil level is determined to be normal, and no command is generated.

[0048] When h < L1 and the discrete signal is low, a refueling command is generated.

[0049] When h > L2 and the discrete signal is high, a pump stop command is generated.

[0050] If the oil level deviation between the continuous oil level signal and the discrete oil level signal exceeds ±10%, a command will be generated based on the continuous oil level signal, and an alarm signal will be output.

[0051] Step 3: Based on the preset operating mode, perform logical judgment on the oil level signals of at least two high-level oil tanks.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A redundant control device for the oil level of a high-level oil tank in a hydropower station, characterized in that, include: The monitoring unit includes a digital level sensor, an analog level transmitter, and a signal acquisition module installed on the top of each high-level oil tank; the digital level sensor is used to output discrete oil level signals, and the analog level transmitter is used to output continuous oil level signals; the signal acquisition module is connected to the digital level sensor and the analog level transmitter respectively. The control unit includes a PLC controller connected to a signal acquisition module for receiving discrete oil level signals and continuous oil level signals. The PLC controller has a built-in oil level redundancy judgment module for judging the consistency between the discrete oil level signals and the continuous oil level signals. When the judgment results are consistent, an oil replenishment command or a pump stop command is generated based on the signal status. When the judgment results are inconsistent, an oil replenishment command or a pump stop command is generated based on the continuous oil level signal, and an alarm signal is output. The operation mode switching module is used to perform oil level redundancy judgment on the oil level status of at least two sets of high-level oil tanks according to the preset series operation mode or independent operation mode, so as to output oil replenishment command or pump stop command. An execution unit, comprising at least one oil pump and at least one cooler electric valve; the oil pump and the cooler electric valve are respectively electrically connected to a PLC controller.

2. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 1, characterized in that, The discrete oil level signal output by the switch liquid level sensor includes at least four discrete oil level signals: too low, low, high, and too high. The continuous oil level signal output by the analog liquid level transmitter includes a 4-20mA current signal, which corresponds to the oil level range 0-H. The signal acquisition module synchronously acquires signals from all digital and analog level sensors at a frequency of 1Hz.

3. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 1, characterized in that, The PLC controller also has a built-in oil level threshold module, which includes a normal low oil level threshold L1 and a working high oil level threshold L2, and sets a hysteresis L2-L1≥50mm.

4. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 1, characterized in that, In the oil level redundancy judgment module, when the deviation between the discrete oil level signal and the continuous oil level signal exceeds ±10%, it is determined that the judgment result is inconsistent.

5. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 1, characterized in that, The specific judgment logic of the operation mode switching module is as follows: In series operation mode, when the two high-level oil tanks are at the same level, the oil level signal of either oil tank can be taken. When the oil level signal is lower than the normal low oil level threshold, a replenishment command is generated. When the oil level signal is higher than the working high oil level threshold, a pump stop command is generated. In independent operation mode, the oil level signals of the two high-level oil tanks are judged independently. When the oil level signal is lower than the normal low oil level threshold, a replenishment command is generated accordingly. When the oil level signal is higher than the working high oil level threshold, a pump stop command is generated accordingly.

6. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 1, characterized in that, The execution unit has three screw oil pumps, configured as one main and two backup pumps, and four electric valves for the cooler. The PLC controller also has a built-in oil pump start-up judgment module, which is used to determine whether at least one cooler electric valve is in the fully open state before outputting the oil pump start command. If so, the oil pump start command is output. Otherwise, the oil pump must not be started.

7. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 6, characterized in that, The execution unit also includes a flow sensor installed on the oil supply pipeline of the high-level oil tank. The output terminal of the flow sensor is electrically connected to the PLC controller. When the main oil pump is started, if the oil supply flow detected by the flow sensor is lower than the preset threshold, the PLC controller will automatically start the backup oil pump.

8. The redundant oil level control device for a high-level oil tank in a hydropower station according to claim 1, characterized in that, It also includes a touch screen, which is electrically connected to the PLC controller and is used to manually set the series operation mode or the independent operation mode, modify the normal low oil level threshold and the working high oil level threshold online, and display the oil level status and alarm information.

9. A method for redundant control of oil level in a high-level oil tank of a hydropower station, characterized in that, The system applied to any one of claims 1 to 8 is characterized by comprising the following steps: Step 1: Real-time acquisition of discrete and continuous oil level signals from the high-level oil tank; wherein the discrete oil level signal includes at least two states: low and high. Step 2: When the continuous oil level signal is between the preset normal low oil level threshold and the working high oil level threshold, and the discrete oil level signal is in the trigger low state and high state, the oil level is determined to be normal, and no oil replenishment or pump stop command is generated. When the continuous oil level signal is lower than the normal low oil level threshold and the discrete oil level signal is in a low state, a refueling command is generated. When the continuous oil level signal is higher than the working high oil level threshold and the discrete oil level signal is in a high state, a pump stop command is generated. When the oil level deviation between the continuous oil level signal and the discrete oil level signal exceeds ±10%, an oil replenishment command or a pump stop command is generated based on the continuous oil level signal, and an alarm signal is generated at the same time. Step 3: Based on the pre-set series operation mode or independent operation mode, perform different logical judgments on the oil level signals of at least two sets of high-level oil tanks: In series operation mode, since the two high-level oil tanks have the same oil level, the oil level signal of either oil tank is used for judgment: when the oil level signal is lower than the normal low oil level threshold, an oil replenishment command is generated; when the oil level signal is higher than the working high oil level threshold, a pump stop command is generated. In independent operation mode, the two high-level oil tanks independently determine their own oil level signals and generate corresponding oil replenishment or pump stop commands. The control of the two oil tanks does not affect each other.

10. The method for redundant control of oil level in a high-level oil tank of a hydropower station according to claim 9, characterized in that, It also includes start-stop linkage control steps, including: When the receiving unit starts up, it first determines whether the oil level in the high-level oil tank has reached the working high oil level threshold. If it has not reached it, the oil replenishment command is executed first. After the oil level reaches the working high oil level threshold, the bearing oil supply regulating valve is opened. When the unit shutdown order is received, the bearing oil supply regulating valve is immediately closed, and the oil level in the high-level oil tank is maintained between the normal low oil level threshold and the working high oil level threshold. At the same time, the pump stop command is executed.

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