Water level control method and system

Abstract

The invention discloses a water level control method and system, and relates to the technical field of automatic control, an adjusting side comprises a main pipeline connected with an external water storage tank of a water supply side and a controlled water storage tank of a controlled side, and a variable-frequency water feeding pump, a pneumatic adjusting valve and a water inlet flow measuring instrument which are sequentially mounted on the main pipeline according to the water flow direction in the main pipeline; the water supply side comprises a first differential pressure liquid level meter, and the controlled side further comprises a second differential pressure liquid level meter and a water outlet flow measuring instrument installed on a drain pipe of the controlled water storage tank. The water level data in the controlled water storage tank is monitored in real time through the second differential pressure liquid level meter, the water inlet flow measuring instrument and the water outlet flow measuring instrument, and then the water supply amount supplied from the external water storage tank to the controlled water storage tank is roughly adjusted by adjusting the frequency conversion water supply pump according to the monitored water level data. And then the water supply amount is finely adjusted by adjusting the pneumatic adjusting valve, so that the dynamic change of the controlled water storage tank can be adapted, the accuracy of water supply adjustment is improved, and a satisfactory water level control effect is achieved.

Description

Technical Field

[0001] The present application relates to the field of automatic control technology, and in particular to a water level control method and system. Background Art

[0002] In nuclear power plants, water level control systems are mainly used in key equipment such as steam generators and pressurizers. Among them, the water level control system of the steam generator is mainly responsible for adjusting the feed water flow entering the secondary side to keep the water level within the prescribed program range. This control process is crucial to ensure the safe, reliable and economical operation of nuclear power plants.

[0003] However, since the steam generator is a highly complex, nonlinear, and time-varying system, the water level control system in the known technology usually controls the water level of the controlled water storage tank based on a linear model and constant parameters. It cannot adapt to the dynamic changes of the system, and improper adjustment problems often occur, making it difficult to achieve satisfactory water level control effects. Summary of the invention

[0004] In view of the above problems, the present application provides a water level control method and system to provide a water level control system that can adapt to the dynamic changes of the controlled water storage tank and achieve satisfactory water level control effects. The specific scheme is as follows:

[0005] In a first aspect, the present application provides a water level control method, which is applied to a digital control cabinet in a water level control system; the digital control cabinet is connected to a variable frequency water pump in the water level control system, and the digital control cabinet is connected to a pneumatic regulating valve in the water level control system, and the method comprises:

[0006] Obtaining the measured water level of the controlled water storage tank, and determining the first water level deviation of the controlled water storage tank according to the measured water level and the first level set water level of the controlled water storage tank;

[0007] Determine a speed control signal of the variable frequency water supply pump according to the first water level deviation, and send the speed control signal to the variable frequency water supply pump to adjust the water supply amount of the variable frequency water supply pump;

[0008] Obtain the water inflow and drainage of the controlled water storage tank, and calculate the water supply and drainage flow deviation of the controlled water storage tank;

[0009] A valve opening control signal of the pneumatic regulating valve is determined according to the first water level deviation and the water supply and drainage flow deviation, and the valve opening control signal is sent to the pneumatic regulating valve to adjust the opening of the pneumatic regulating valve.

[0010] In a possible implementation, determining a valve opening control signal of the pneumatic regulating valve according to the first water level deviation and the water supply and drainage flow deviation includes:

[0011] The second water level deviation is calculated by adding the water supply and drainage flow deviation to the first water level deviation;

[0012] The second water level deviation is input into the transfer function to obtain a valve opening control signal.

[0013] The second aspect of the present application provides a water level control system, including a water supply side, a regulating side, a controlled side and a digital control cabinet; wherein:

[0014] The water supply side includes an external water storage tank and a first differential pressure level gauge installed on the external water storage tank;

[0015] The controlled side includes a controlled water storage tank, a second differential pressure level gauge installed on the controlled water storage tank, and a water outlet flow measuring instrument installed on a drainage pipe of the controlled water storage tank;

[0016] The regulating side includes a main pipeline connecting the external water storage tank and the controlled water storage tank, and a variable frequency water supply pump, a pneumatic regulating valve and a water inlet flow meter installed in the main pipeline in sequence according to the water flow direction in the main pipeline;

[0017] The digital control cabinet includes a process state monitor group and a controller group; the process state monitor group is connected with the variable frequency water supply pump, the pneumatic regulating valve and the water inlet flow meter; the controller group is connected with the variable frequency water supply pump and the pneumatic regulating valve; the second differential pressure level meter is connected with the controller group;

[0018] The controller group obtains the measured water level of the controlled water storage tank from the second differential pressure level gauge, determines the first water level deviation of the controlled water storage tank according to the measured water level and the first-level set water level of the controlled water storage tank, determines the speed control signal of the variable frequency water supply pump according to the first water level deviation, and sends the speed control signal to the variable frequency water supply pump to adjust the water supply amount of the variable frequency water supply pump;

[0019] The process state monitor group obtains the water inflow of the controlled water storage tank from the water inflow flow meter, obtains the water discharge of the controlled water storage tank from the water discharge flow meter, and sends the water inflow of the controlled water storage tank and the water discharge of the controlled water storage tank to the controller group;

[0020] The controller group calculates the water supply and drainage flow deviation of the controlled water storage tank based on the water intake and drainage flow deviation of the controlled water storage tank, determines the valve opening control signal of the pneumatic regulating valve based on the first water level deviation and the water supply and drainage flow deviation, and sends the valve opening control signal to the pneumatic regulating valve to adjust the opening of the pneumatic regulating valve.

[0021] In a possible implementation, the process state monitor group includes a process signal display and a first process state monitor, a second process state monitor, and a third process state monitor respectively connected to the process signal display;

[0022] The first process state monitor is connected to the variable frequency water supply pump and obtains the speed information of the variable frequency water supply pump from the variable frequency water supply pump;

[0023] The second process state monitor is connected to the pneumatic control valve to obtain valve opening information of the pneumatic control valve from the pneumatic control valve;

[0024] The third process state monitor is connected to the flow meter group, and obtains the water inflow of the controlled water storage tank from the water inflow flow meter; the flow meter group includes a water inflow flow meter and a water outflow flow meter;

[0025] The process signal display is used to display the speed information of the variable frequency water supply pump, the valve opening information of the pneumatic control valve, the water intake of the controlled water storage tank, and the water discharge of the controlled water storage tank.

[0026] In one possible implementation, the controller group includes a proportional-integral-derivative controller, a control information processor, and a programmable logic controller;

[0027] The proportional-integral-differential controller is connected to the first process state monitor, the second process state monitor and the third process state monitor respectively, and the proportional-integral-differential controller obtains the speed information of the variable frequency water supply pump from the first process state monitor, obtains the valve opening information of the pneumatic control valve from the second process state monitor, and obtains the water inflow and the water discharge of the controlled water storage tank from the third process state monitor;

[0028] The proportional-integral-differential controller processes the initial speed control signal through the control information processor and sends it to the programmable logic controller. The programmable logic controller processes the speed control signal and sends the speed control signal to the variable frequency water supply pump.

[0029] The proportional-integral-differential controller processes the initial valve opening control signal through the control information processor and sends it to the programmable logic controller. The programmable logic controller processes the valve opening control signal and sends the valve opening control signal to the pneumatic regulating valve.

[0030] In one possible implementation, the first process state monitor includes a first acquisition module and a first allocation module;

[0031] The first acquisition module is connected to the variable frequency water supply pump, and the first distribution module is connected to the process signal display and the proportional integral differential controller respectively; the first acquisition module is used to collect the speed information of the variable frequency water supply pump, and the first distribution module is used to process the speed information of the variable frequency water supply pump into a display format matching the process signal display, and send the processed speed information to the process signal display;

[0032] The second process state monitor includes a second acquisition module and a second distribution module; the second acquisition module is connected to the pneumatic control valve, and the second distribution module is respectively connected to the process signal display and the proportional integral differential controller; the second acquisition module is used to collect valve opening information of the pneumatic control valve, and the second distribution module is used to process the valve opening information of the pneumatic control valve into a display format matching the process signal display, and send the processed valve opening information to the process signal display;

[0033] The third process status monitor includes a third acquisition module and a third distribution module; the third acquisition module is connected to the water inlet flow meter and the water outlet flow meter respectively, and the third distribution module is connected to the process signal display and the proportional integral differential controller respectively; the third acquisition module is used to collect the water inlet volume and the water discharge volume of the controlled water storage tank, and the third distribution module is used to process the water inlet volume and the water discharge volume of the controlled water storage tank into a display format matching the process signal display, and send the processed water inlet volume and the processed water discharge volume to the process signal display.

[0034] In a possible implementation, it also includes a first visual liquid level gauge and a second visual liquid level gauge;

[0035] The first visual level gauge is installed on the external water storage tank; the second visual level gauge is installed on the controlled water storage tank.

[0036] In a possible implementation, the first visual liquid level gauge and the second visual liquid level gauge are both visual magnetic flap liquid level gauges.

[0037] In a possible implementation, an electric isolation valve is also included;

[0038] The electric isolation valve is installed on the main pipeline near the external water storage tank to control the on and off of water flow in the main pipeline.

[0039] In a possible implementation, the first differential pressure level gauge and the second differential pressure level gauge are both level gauges with a condensing tank and a remote transmission function, and the proportional integral differential controller is connected to the first differential pressure level gauge;

[0040] The proportional-integral-differential controller is connected to the second differential pressure level meter.

[0041] By means of the above-mentioned technical scheme, the water level control method and system provided by the present application include a water supply side, a regulating side and a controlled side. The regulating side includes a main pipeline connecting an external water storage tank on the water supply side and a controlled water storage tank on the controlled side, and a variable frequency water supply pump, a pneumatic regulating valve and a water inlet flow meter installed in sequence on the main pipeline according to the water flow direction in the main pipeline. The water supply side also includes a first differential pressure level gauge for monitoring the water level in the external water storage tank. The controlled side also includes a second differential pressure level gauge for monitoring the water level in the controlled water storage tank and a water outlet flow meter installed on the drain pipe of the controlled water storage tank. The present application monitors the water level data in the controlled water storage tank in real time through a second differential pressure level gauge, a water inlet flow meter and a water outlet flow meter, and roughly adjusts the water supply from the external water storage tank to the controlled water storage tank by adjusting the variable frequency water supply pump according to the monitored water level data, and fine-adjusts the water supply by adjusting the pneumatic regulating valve, thereby being able to adapt to the dynamic changes of the controlled water storage tank, improve the accuracy of water supply regulation, and achieve satisfactory water level control effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0043] Figure 1 A schematic diagram of a flow chart of the water level control method provided in this application;

[0044] Figure 2 A schematic diagram of the structural composition of the field process control system in the water level control system provided in this application;

[0045] Figure 3 A schematic diagram of the structure of the digital control cabinet provided for this application;

[0046] Figure 4 An example flow chart of the water level control method provided in this application;

[0047] Figure 5 Example diagram of Mitsubishi safety-grade DCS structure provided for this application;

[0048] Figure 6 This is an example diagram of the implementation principle of the liquid level function of the PID controller provided in this application. DETAILED DESCRIPTION

[0049] The following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0050] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0051] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, which is only to describe the distinction mode adopted by the objects of the same attributes when describing in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0052] The main function of the evaporator of a nuclear power plant is to transfer the heat generated by the reactor to the secondary circuit working medium, generate steam to drive the steam turbine to do work, and at the same time serve as a barrier between the primary and secondary circuit media to prevent the leakage of radioactive substances. The evaporator is a highly complex, nonlinear, time-varying system, and the regulation of its water level control system is crucial to ensure the safe, reliable and economical operation of the nuclear power plant.

[0053] However, the water level control system in the known technology usually performs water level control based on linear models and constant parameters, which cannot adapt to the dynamic changes of the evaporator system and often causes improper adjustment problems, resulting in large fluctuations in the water level of the evaporator unit, seriously endangering the safety of the unit.

[0054] In order to solve the above problems, the present application provides a water level control method and system.

[0055] The present application can be applied to, but is not limited to, a digital control cabinet in a water level control system. The digital control cabinet is connected to a variable frequency water supply pump in the water level control system, and the water level in a controlled water storage tank in the water level control system is controlled by adjusting the speed of the variable frequency water supply pump; the digital control cabinet is connected to a pneumatic regulating valve in the water level control system, and the water level in a controlled water storage tank in the water level control system is controlled by adjusting the valve opening of the pneumatic regulating valve.

[0056] Specifically, the water level control method provided in the present application is mainly applied to a controller group of a digital control cabinet in a water level control system.

[0057] Optional, see Figure 1 , a flow chart of the water level control method provided in this application.

[0058] like Figure 1As shown, the water level control method includes the following steps:

[0059] Step 101, obtaining the measured water level of the controlled water storage tank, and determining the first water level deviation of the controlled water storage tank according to the measured water level and the first-level set water level of the controlled water storage tank.

[0060] It should be noted that the controlled water storage tank is the water level regulation object of the water level control system; the measured water level is obtained from the second differential pressure level gauge installed on the controlled water storage tank, and the second differential pressure level gauge can specifically be a level gauge with a condensation tank and a remote transmission function.

[0061] Optionally, the controller group obtains the measured water level of the controlled water storage tank from a differential pressure level gauge with a remote transmission function installed in the controlled water storage tank and then calculates the first water level deviation by subtracting the measured water level from the first-level set water level of the controlled water storage tank.

[0062] Step 102: determine a speed control signal of the variable frequency water supply pump according to the first water level deviation, and send the speed control signal to the variable frequency water supply pump to adjust the water supply amount of the variable frequency water supply pump.

[0063] Then, the proportional-integral-derivative controller (PID controller) in the controller group will determine the speed control signal of the variable frequency water supply pump according to the first water level deviation. Specifically, the PID controller will use an appropriate control algorithm to process the real-time first water level deviation, calculate the real-time control quantity, and then determine the output frequency of the inverter according to the real-time control quantity. The output frequency determines the motor speed of the variable frequency water supply pump. Generally, when the amount of water in the controlled water storage tank increases, the programmable logic controller in the controller group will reduce the speed of the variable frequency water supply pump by reducing the output frequency of the inverter. When the water consumption decreases, the programmable logic controller will increase the output frequency of the inverter to increase the speed of the variable frequency water supply pump. It can be understood that the output frequency of the inverter is equivalent to the speed control signal of the variable frequency water supply pump.

[0064] Optionally, the PID controller in the controller group generates a speed control signal that needs to be input into the variable frequency water supply pump based on the first water level deviation. After the speed control signal is generated, it is sent by the programmable logic controller in the controller group to the variable frequency water supply pump to adjust the water supply of the variable frequency water supply pump.

[0065] Step 103, obtaining the water inflow and the water discharge of the controlled water storage tank, and calculating the water supply and drainage flow deviation of the controlled water storage tank.

[0066] It should be noted that the water inlet volume of the controlled water storage tank is obtained by the process status monitor group in the digital control cabinet from the water inlet flow meter, and the water inlet flow meter is installed on the main pipeline that transports water to the controlled water storage tank, next to one side of the controlled water storage tank; the water discharge volume of the controlled water storage tank is obtained by the process status monitor group from the water outlet flow meter, and the water outlet flow meter is installed on the drain pipe of the controlled water storage tank.

[0067] Optionally, the process status monitoring group obtains the water inlet volume of the controlled water storage tank from the water inlet flow meter and the water discharge volume of the controlled water storage tank from the water outlet flow meter, and then inputs the obtained water inlet volume and water discharge volume of the controlled water storage tank into the controller group. The PID controller in the controller group will calculate the water supply and drainage flow deviation of the controlled water storage tank based on the water inlet volume and the water discharge volume.

[0068] It should be noted that the discharge volume of the controlled water storage tank obtained by the PID controller is a fixed flow rate virtualized by the water inlet rate collected by the water inlet flow meter and the discharge rate collected by the water outlet flow meter. Specifically, the corresponding flow change is calculated by the water inlet flow meter, the water outlet flow meter and the observation of the change of the liquid level of the controlled water storage tank per unit time, thereby virtualizing the fixed flow of the controlled water storage tank. Subsequently, the opening of the pneumatic control valve will be adjusted according to the deviation between the fixed flow and the water inlet flow.

[0069] Step 104: determine a valve opening control signal of the pneumatic regulating valve according to the first water level deviation and the water supply and drainage flow deviation, and send the valve opening control signal to the pneumatic regulating valve to adjust the opening of the pneumatic regulating valve.

[0070] Next, the PID controller will use the water supply and drainage flow deviation to superimpose the first water level deviation to calculate the second water level deviation, input the second water level deviation into the transfer function, and obtain the valve opening control signal of the pneumatic control valve. Finally, the PID controller will input the generated valve opening control signal into the pneumatic control valve to adjust the opening of the pneumatic control valve.

[0071] In summary, the water level control method provided in the present application monitors the water level data in the controlled water storage tank in real time through the second differential pressure level gauge, the water inlet flow meter and the water outlet flow meter, and roughly adjusts the water supply from the external water tank to the controlled water storage tank by adjusting the variable frequency water supply pump according to the monitored water level data, and fine-adjusts the water supply by adjusting the pneumatic regulating valve, thereby being able to adapt to the dynamic changes of the controlled water storage tank, improve the accuracy of water supply regulation, and achieve satisfactory water level control effect.

[0072] A water level control method provided in an embodiment of the present application is introduced above, and a system for executing the water level control method will be introduced below.

[0073] Optional, see Figure 2 , a schematic diagram of the structural composition of the field process control system in the water level control system provided in this application.

[0074] The water level control system provided in this application mainly includes four parts, the water supply side, the regulation side, the controlled side and the digital cabinet. Figure 2 The figure mainly shows the water supply side, the regulation side and the controlled side. The water supply side, the regulation side and the controlled side can be called the local process control system (LPR).

[0075] like Figure 2 As shown, the water supply side mainly includes an external water storage tank and a first differential pressure level gauge installed on the external water storage tank. The external water storage tank is used to supply water to the controlled water storage tank on the controlled side, and the first differential pressure level gauge is used to measure the real-time liquid level in the external water storage tank. The differential pressure level gauge can be a differential pressure level gauge with a condensing tank.

[0076] The controlled side includes a controlled water storage tank, a second differential pressure level gauge installed on the controlled water storage tank, and a water flow meter installed on the drain pipe of the controlled water storage tank. The water flow meter is installed near the manual drain valve and close to the water outlet of the controlled water storage tank. The second differential pressure level gauge is used to measure the real-time liquid level in the controlled water storage tank.

[0077] The regulating side includes a main pipeline connecting the external water storage tank and the controlled water storage tank, as well as a variable frequency water supply pump, a pneumatic regulating valve and a water inlet flow meter installed in the main pipeline in sequence according to the water flow direction of the main pipeline. Among them, the variable frequency water supply pump is mainly used to pump water from the external water storage tank to the controlled water storage tank through the main pipeline; the pneumatic regulating valve can be specifically an intelligent pneumatic regulating valve, which is mainly used to control the water flow of the main pipeline; the water inlet flow meter is used to measure the pipeline flow from the main pipeline into the controlled water storage tank.

[0078] It should be noted that the water supply side also includes a first visual level gauge, which is installed on the external water tank. Specifically, it can be a visual magnetic flap level gauge. The deviation between the first differential pressure level gauge and the first visual level gauge is generally not more than 2 cm (2%); the water replenishment of the external water tank comes from fixed replenishment, which is added to the external water tank through a manual water supply valve; the liquid level of the external storage tank will affect the adjustment effect of the variable frequency water supply pump. The variable frequency water supply pump may overshoot and over-adjust during the adjustment process. In order to avoid cavitation after the variable frequency water supply pump overshoots, it is necessary to set a variable frequency water supply pump protection water level for the variable frequency water supply pump. In addition, when the liquid level of the external water tank is low, for example, when the liquid level is lower than 20%, the variable frequency water supply pump will stop. Therefore, in the process of adjusting the variable frequency water supply pump, attention should be paid to the liquid level of the external water tank.

[0079] The minimum opening of the pneumatic regulating valve on the regulating side is 60%. If the opening is too small, it will cause pressure buildup and the pump will stop. During the adjustment process, attention will be paid to the valve opening of the pneumatic regulating valve and the speed of the variable frequency water pump. The two will cooperate with each other to achieve the best water level control effect.

[0080] In addition, the main pipeline on the regulating side also includes an electric isolation valve on one side close to the external storage tank, and the electric isolation valve is used to control the on-off of the main pipeline.

[0081] The above introduces the water supply side, regulation side and controlled side in the water level control system. Next, we will introduce the fourth part, the digital control cabinet.

[0082] See also Figure 3 , a schematic diagram of the composition structure of the digital control cabinet provided in this application.

[0083] like Figure 3 As shown, the digital control cabinet mainly includes two parts, the process status monitor group and the controller group. The process status monitor group is connected to the variable frequency water supply pump, the pneumatic regulating valve and the water inlet flow meter; the controller group is connected to the variable frequency water supply pump and the pneumatic regulating valve. In addition, the controller group is also connected to the second differential pressure level meter installed on the controlled water storage tank.

[0084] The process status monitor group includes a process signal display, a first process status monitor, a second process status monitor and a third process status monitor, and the process signal display is connected to the first process status monitor, the second process status monitor and the third process status monitor respectively.

[0085] Specifically, the first process status monitor is connected to the variable frequency water supply pump, and is mainly used to monitor the status of the variable frequency water supply pump and obtain the speed information of the variable frequency water supply pump from the variable frequency water supply pump; the second process status monitor is connected to the pneumatic control valve, and is mainly used to monitor the status of the pneumatic control valve and obtain the valve opening information of the pneumatic control valve from the pneumatic control valve; the third process status monitor is connected to the flow meter group, the flow meter group includes an inlet flow meter and an outlet flow meter, and is mainly used to monitor the status of process instruments such as the inlet flow meter and the outlet flow meter. The third process status monitor obtains the water inflow of the controlled water storage tank from the inlet flow meter and obtains the water discharge of the controlled water storage tank from the outlet flow meter; the process signal display can also be called a recorder, which is used to display the speed information of the variable frequency water supply pump collected by the first process status monitor, the valve opening information of the pneumatic control valve collected by the second process status monitor, and the water inflow of the controlled water storage tank and the water discharge of the controlled water storage tank collected by the third process status monitor.

[0086] The first process state monitor, the second process state monitor and the third process state monitor are all connected to the PID controller in the controller group.

[0087] The first process status monitor includes a first acquisition module and a first distribution module. The first acquisition module is connected to the variable frequency water supply pump and is used to collect the speed information of the variable frequency water supply pump. The first distribution module is connected to the process signal display and the PID controller respectively. The first distribution module is used to collect the speed information of the variable frequency water supply pump, process the speed information of the variable frequency water supply pump into a display format matching the process signal display, and send the processed speed information to the process signal display for display.

[0088] The second process status monitor includes a second acquisition module and a second distribution module. The second acquisition module is connected to the pneumatic control valve and is used to collect the valve opening information of the pneumatic control valve; the second distribution module is connected to the process signal display and the PID controller respectively, and the second distribution module is used to process the valve opening information of the pneumatic control valve into a display format matching the process signal display, and send the processed valve opening information to the process signal display for display.

[0089] The third process control status monitor includes a third acquisition module and a third distribution module; the third acquisition module is connected to the water inlet flow meter and the water outlet flow meter, and the third distribution module is connected to the process signal display and the PID controller respectively; the third acquisition module is used to collect the water inlet volume and the water discharge volume of the controlled water storage tank, and the third distribution module is used to process the water inlet volume and the water discharge volume of the controlled water storage tank into a display format matching the process signal display, and send the processed water inlet volume and the processed water discharge volume to the process signal display.

[0090] The controller group includes a PID controller (proportional integral derivative controller), a control information processor and a PLC controller (programmable logic controller).

[0091] Among them, the PID controller is connected to the first process state monitor, the second process state monitor and the third process state monitor respectively, and obtains the speed information of the variable frequency water pump from the first process state monitor, the valve opening information of the pneumatic control valve from the second process state monitor, and the water intake and discharge of the controlled water storage tank from the third process state monitor.

[0092] The PID controller will process the initial speed control signal obtained through the control information processor and send it to the PLC controller. The PLC controller will process the speed control signal and send it to the variable frequency water pump.

[0093] The PID controller processes the initial valve opening control signal obtained through the control information processor and sends it to the programmable controller. The programmable controller processes the valve opening control signal and sends the valve opening control signal to the pneumatic regulating valve.

[0094] Optionally, the above-mentioned water level control method is implemented based on the water level control system.

[0095] Specifically, the controller group obtains the measured water level of the controlled water storage tank from the second differential pressure level gauge, determines the first water level deviation of the controlled water storage tank according to the measured water level and the first-level set water level of the controlled water storage tank, determines the speed control signal of the variable frequency water supply pump according to the first water level deviation, and sends the speed control signal to the variable frequency water supply pump to adjust the water supply amount of the variable frequency water supply pump;

[0096] The process state monitor group obtains the water inflow of the controlled water storage tank from the water inflow flow meter, obtains the water discharge of the controlled water storage tank from the water discharge flow meter, and sends the water inflow of the controlled water storage tank and the water discharge of the controlled water storage tank to the controller group;

[0097] The controller group calculates the water supply and drainage flow deviation of the controlled water storage tank based on the water intake and drainage flow deviation of the controlled water storage tank, determines the valve opening control signal of the pneumatic regulating valve based on the first water level deviation and the water supply and drainage flow deviation, and sends the valve opening control signal to the pneumatic regulating valve to adjust the opening of the pneumatic regulating valve.

[0098] In summary, the water level control system provided by the present application includes a water supply side, a regulating side and a controlled side. The regulating side includes a main pipeline connecting an external water storage tank on the water supply side and a controlled water storage tank on the controlled side, and a variable frequency water supply pump, a pneumatic regulating valve and a water inlet flow meter installed in sequence on the main pipeline according to the water flow direction in the main pipeline. The water supply side also includes a first differential pressure level gauge for monitoring the water level in the external water storage tank. The controlled side also includes a second differential pressure level gauge for monitoring the water level in the controlled water storage tank and a water outlet flow meter installed on the drainage pipe of the controlled water storage tank. The present application monitors the water level data in the controlled water storage tank in real time through the second differential pressure level gauge, the water inlet flow meter and the water outlet flow meter. According to the monitored water level data, the variable frequency water supply pump is adjusted to roughly adjust the water supply from the external water storage tank to the controlled water storage tank, and then the pneumatic regulating valve is adjusted to finely adjust the water supply, so as to adapt to the dynamic changes of the controlled water storage tank, improve the accuracy of water supply regulation, and achieve satisfactory water level control effect.

[0099] Optional, see Figure 4 , a flow chart of an example of the water level control method provided in this application.

[0100] The water level control method implemented in the present application can be divided into two levels. The first level is the coarse adjustment (also known as primary adjustment) for the variable frequency water pump, and the second level is the fine adjustment for the pneumatic control valve.

[0101] like Figure 4As shown, the given liquid level is the first-level set water level (also called the target liquid level) of the controlled water tank, and the actual liquid level is the measured water level of the controlled water tank. The deviation between the given liquid level and the actual water level is input into the transfer function W1 (s) of the variable frequency water pump to generate the adjustment instruction of the variable frequency water pump. It should be noted that the flow rate of the variable frequency water pump is large, and the impact on the entire water level control system is large during the adjustment process, resulting in large disturbances. In order to reduce the disturbance effect and make the adjustment effect more refined, the second-level adjustment of the pneumatic control valve is introduced.

[0102] Then, the deviation between the water supply flow (the water intake of the controlled water storage tank) and the drainage flow (the drainage of the controlled water storage tank) of the controlled water storage tank is calculated to obtain the water supply and drainage flow deviation. The water supply and drainage flow deviation is superimposed on the above-mentioned first water level deviation and input into the transfer function W2 (s) to obtain the adjustment instruction of the pneumatic control valve. The pneumatic control valve has strong control energy, which can further improve the control accuracy of the water level in the controlled water storage tank.

[0103] It should be noted that the water level control system provided in the present application can be used in combination with the safety-level DCS (Distributed Control System) control system in a nuclear power plant. Specifically, the water supply flow, the drainage flow and the liquid level of the controlled water storage tank are used as three impulses, and a variable frequency water supply pump is used as an actuator to drive the water supply, and a pneumatic regulating valve is used as an actuator to control the flow in the main pipeline, thereby forming a cascade water level control system.

[0104] Illustratively, the water level control system provided in the present application is combined with a nuclear power plant digital system.

[0105] For example, see Figure 5 , this application provides an example diagram of the Mitsubishi safety-level DCS structure.

[0106] like Figure 5 As shown in the figure, the digital system of the nuclear power plant adopts a distributed control system that combines MCAS-6 + MELTAC-N Plus R3, in which MCAS-6 is mainly used to complete the routine monitoring of the nuclear power plant; MELTAC-N Plus R3 is mainly used for the control and protection of the safety-related systems of the nuclear power plant, and the functional division belongs to the 1E level. The digital control system of the non-safety-level part is basically the same as the digital control system of general thermal power. The main difference of the safety-level part is that it adopts design principles and methods such as multiple redundancy and voting, single fault, diversity, fault isolation, V&V, etc. to ensure that the safety-level part has higher reliability and safety.

[0107] Mitsubishi MELTAC-N series is a distributed and centralized control system designed to control and monitor nuclear power plant equipment, such as reactors and steam turbines, using the most cutting-edge process control technology, microcomputer technology, and human-machine interface technology.

[0108] In practical applications, the logic language of DCS is POL (Problem Oriented Language), and the PID controller is used in safety-level DCS control systems.

[0109] The liquid level control principle of PID controller is shown in Figure 6 , an example diagram of the implementation principle of the liquid level function of the PID controller provided in this application.

[0110] Among them, the output function y=y P +y I +y D , where y P It is the product of the parameter P of the proportional PID regulator and the given deviation X, y P The purpose is to make the measured water level of the controlled water tank as close to the target water level as possible, so as to adjust the control quantity in time to reduce the deviation. Specifically, in the water level control system, the deviation between the given water level and the actual measured water level will be input into the PID controller, and the P ratio will adjust the speed of the variable frequency water pump, which can quickly increase or decrease the speed, thereby achieving the purpose of reducing the deviation.

[0111] y I is the integration step, which is the y at the previous moment I The sum of the value and the change in the deviation within the sampling time is mainly used to eliminate static errors. In the actual adjustment process of the PID controller, the P proportional adjustment is prone to overshoot, and the actual water level adjustment effect is much higher or lower than the required given water level. Therefore, it is necessary to use integral to gradually accumulate and reduce the overshoot phenomenon.

[0112] y D It is a differential link, which is used to predict future trends so that the control amount can be adjusted in advance to reduce overshoot and oscillation, making the water level more stable and gentle.

[0113] In summary, the water level control system and method provided in this application, combined with the liquid level control principle of the steam generator of a nuclear power plant, links the safety-level DCS control system with the on-site liquid level measurement and control system, establishes a liquid level control model, and successfully realizes the control of liquid level and flow, which can fill the gap in safety-level DCS measurement and control field equipment within the scope of training, research and teaching.

[0114] An embodiment of the present application also provides a computer program product, including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any water level control method provided in the embodiment of the present application.

[0115] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any water level control method provided in the embodiment of the present application.

[0116] It should also be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the drawings of the device embodiments provided by the present application, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines.

[0117] Through the description of the above implementation mode, the technicians in the field can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present application, software program implementation is a better implementation mode in more cases. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, etc.) to execute the method of each embodiment of the present application.

[0118] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0119] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, a computer, a training device or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, training device or data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integration. Available media can be magnetic media, (e.g., floppy disk, hard disk, tape), optical media (e.g., DVD), or semiconductor media (e.g., solid-state hard disk (SSD)), etc.

Claims

1. A water level control method, characterized in that: A digital control cabinet applied to a water level control system; the digital control cabinet is connected to a variable frequency water supply pump in the water level control system, and the digital control cabinet is connected to a pneumatic regulating valve in the water level control system. The method comprises: Obtaining a measured water level of a controlled water storage tank, and determining a first water level deviation of the controlled water storage tank according to the measured water level and a first-level set water level of the controlled water storage tank; Determining a speed control signal of the variable frequency water supply pump according to the first water level deviation, and sending the speed control signal to the variable frequency water supply pump to adjust the water supply amount of the variable frequency water supply pump; Obtaining the water inflow of the controlled water storage tank and the water discharge of the controlled water storage tank, and calculating the water supply and water discharge flow deviation of the controlled water storage tank; A valve opening control signal of the pneumatic regulating valve is determined according to the first water level deviation and the water supply and drainage flow deviation, and the valve opening control signal is sent to the pneumatic regulating valve to adjust the opening of the pneumatic regulating valve.

2. The water level control method according to claim 1, characterized in that: The method of determining the valve opening control signal of the pneumatic regulating valve according to the first water level deviation and the water supply and drainage flow deviation comprises: The second water level deviation is calculated by adding the water supply and drainage flow deviation to the first water level deviation; The second water level deviation is input into the transfer function to obtain the valve opening control signal.

3. A water level control system, characterized in that: It includes water supply side, regulation side, controlled side and digital control cabinet; among which: The water supply side includes an external water storage tank and a first differential pressure level gauge installed on the external water storage tank; The controlled side includes a controlled water storage tank, a second differential pressure level gauge installed on the controlled water storage tank, and a water outlet flow meter installed on a drainage pipe of the controlled water storage tank; The regulating side includes a main pipeline connecting the external water storage tank and the controlled water storage tank, and a variable frequency water supply pump, a pneumatic regulating valve and a water inlet flow meter installed in sequence on the main pipeline according to the water flow direction in the main pipeline; The digital control cabinet includes a process state monitor group and a controller group; the process state monitor group is connected to the variable frequency water pump, the pneumatic regulating valve and the water inlet flow meter; the controller group is connected to the variable frequency water pump and the pneumatic regulating valve; the second differential pressure level meter is connected to the controller group; The controller group obtains the measured water level of the controlled water storage tank from the second differential pressure level gauge, determines the first water level deviation of the controlled water storage tank according to the measured water level and the first-level set water level of the controlled water storage tank, determines the speed control signal of the variable frequency water supply pump according to the first water level deviation, and sends the speed control signal to the variable frequency water supply pump to adjust the water supply amount of the variable frequency water supply pump; The process state monitor group obtains the water inflow of the controlled water storage tank from the water inflow flow meter, obtains the water discharge of the controlled water storage tank from the water outflow flow meter, and sends the water inflow of the controlled water storage tank and the water discharge of the controlled water storage tank to the controller group; The controller group calculates the water supply and drainage flow deviation of the controlled water storage tank based on the water intake and drainage flow deviation of the controlled water storage tank, determines the valve opening control signal of the pneumatic regulating valve based on the first water level deviation and the water supply and drainage flow deviation, and sends the valve opening control signal to the pneumatic regulating valve to adjust the opening of the pneumatic regulating valve.

4. The water level control system according to claim 3, characterized in that: The process state monitor group includes a process signal display and a first process state monitor, a second process state monitor and a third process state monitor respectively connected to the process signal display; The first process state monitor is connected to the variable frequency water supply pump and obtains the speed information of the variable frequency water supply pump from the variable frequency water supply pump; The second process state monitor is connected to the pneumatic control valve and obtains valve opening information of the pneumatic control valve from the pneumatic control valve; The third process state monitor is connected to the flow meter group, and obtains the water inflow of the controlled water storage tank from the water inflow flow meter; the flow meter group includes the water inflow flow meter and the water outflow flow meter; The process signal display is used to display the speed information of the variable frequency water supply pump, the valve opening information of the pneumatic control valve, the water intake of the controlled water storage tank, and the water discharge of the controlled water storage tank.

5. The water level control system according to claim 4, characterized in that: The controller group includes a proportional-integral-derivative controller, a control information processor and a programmable logic controller; Wherein, the proportional-integral-differential controller is connected to the first process state monitor, the second process state monitor and the third process state monitor respectively, and the proportional-integral-differential controller obtains the speed information of the variable frequency water supply pump from the first process state monitor, obtains the valve opening information of the pneumatic regulating valve from the second process state monitor, and obtains the water inflow of the controlled water storage tank and the water discharge of the controlled water storage tank from the third process state monitor; The proportional-integral-differential controller processes the initial speed control signal obtained by processing through the control information processor and sends it to the programmable logic controller. The programmable logic controller processes and obtains the speed control signal and sends the speed control signal to the variable frequency water supply pump. The proportional-integral-differential controller processes the initial valve opening control signal through the control information processor and sends it to the programmable logic controller. The programmable logic controller processes the valve opening control signal and sends the valve opening control signal to the pneumatic regulating valve.

6. The water level control system according to claim 5, characterized in that: The first process state monitor includes a first acquisition module and a first allocation module; The first acquisition module is connected to the variable frequency water supply pump, and the first distribution module is connected to the process signal display and the proportional integral differential controller respectively; The first acquisition module is used to collect the speed information of the variable frequency water supply pump, and the first distribution module is used to process the speed information of the variable frequency water supply pump into a display format matching the process signal display, and send the processed speed information to the process signal display; The second process state monitor includes a second acquisition module and a second allocation module; The second acquisition module is connected to the pneumatic control valve, and the second distribution module is respectively connected to the process signal display and the proportional integral differential controller; the second acquisition module is used to collect the valve opening information of the pneumatic control valve, and the second distribution module is used to process the valve opening information of the pneumatic control valve into a display format matching the process signal display, and send the processed valve opening information to the process signal display; The third process state monitor includes a third acquisition module and a third distribution module; the third acquisition module is respectively connected to the water inlet flow meter and the water outlet flow meter, and the third distribution module is respectively connected to the process signal display and the proportional integral differential controller; The third acquisition module is used to collect the water intake and the water discharge of the controlled water storage tank, and the third distribution module is used to process the water intake and the water discharge of the controlled water storage tank into a display format matching the process signal display, and send the processed water intake and the processed water discharge to the process signal display.

7. The water level control system according to claim 3, characterized in that: Also included is a first visual level gauge and a second visual level gauge; The first visual liquid level gauge is installed on the external water storage tank; the second visual liquid level gauge is installed on the controlled water storage tank.

8. The water level control system according to claim 7, characterized in that: The first visual liquid level gauge and the second visual liquid level gauge are both visual magnetic flap liquid level gauges.

9. The water level control system according to claim 3, characterized in that: Also included are electric isolation valves; The electric isolation valve is installed on one side of the main pipeline close to the external water storage tank, and is used to control the on and off of the water flow in the main pipeline.

10. The water level control system according to claim 5, characterized in that: The first differential pressure level gauge and the second differential pressure level gauge are both level gauges with a condensing tank and a remote transmission function, and the proportional integral differential controller is connected to the first differential pressure level gauge; The proportional-integral-differential controller is connected to the second differential pressure level meter.

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