Control method for reducing fluctuation of condensed water flow regulating valve

Abstract

The invention provides a control method for reducing fluctuation of a condensed water flow regulating valve. The control method comprises the following steps: step 1, establishing an automatic control loop; 2, configuring a signal address; 3, a calculation module used for calculating the main water supply total flow value of the three loops is arranged, and the real-time main water supply total flow is obtained; 4, setting a feedforward control logic block with a dead zone to obtain flow for calculating a feedforward item; step 5, configuring PID control parameters and a module of a feed-forward item; 6, a control signal is output to a field valve; and 7, calibrating the valve positioner to enable the control signal to correspond to the opening degree of the valve. According to the method, the advantage of fast response of the feed-forward item during dynamic adjustment can be taken into account, and the fluctuation problem caused by stable adjustment is avoided. The central position of the dead zone can be automatically changed along with the change of the actual fluctuation central value, and manual adjustment is not needed.

Description

Technical Field

[0001] The invention relates to the technical field of condensate flow regulating valves for pressurized water reactor nuclear power units, and in particular to a control method for reducing fluctuations of condensate flow regulating valves. Background Art

[0002] The condensate flow control valve of the domestic pressurized water reactor nuclear power unit (M310 unit) is responsible for controlling the liquid level of the deaerator, and the main feed water pump pumps water from the deaerator to the steam generator. The control logic of the control valve is a feedforward term plus a proportional integral differential (PID) method, with the main feed water flow as the feedforward term. Due to the large periodic fluctuations in the main feed water flow, the condensate flow control valve also has large fluctuations, with a fluctuation range of up to 5%. This not only affects the stability of the system, but also causes a large movement of the valve stem of the condensate flow control valve, with a maximum movement speed of up to 40mm / s, which greatly reduces the life of the valve and has caused multiple valve failures. Summary of the invention

[0003] The object of the present invention is to provide a control method for reducing fluctuations of a condensate flow regulating valve, thereby solving the problem of fluctuations of a downstream control system caused by fluctuations of an upstream feedforward term.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A control method for reducing fluctuations of a condensate flow regulating valve comprises the following steps:

[0006] Step 1: Establish an automated control loop;

[0007] Step 2: Configure the signal address;

[0008] Step 3: Set a calculation module for calculating the total flow value of the main water supply of the three loops to obtain the real-time total flow of the main water supply;

[0009] Step 4: Set the feedforward control logic block with dead zone to obtain the flow rate used to calculate the feedforward term;

[0010] Step 5: Configure the PID control parameters and the module of the feedforward item;

[0011] Step 6: Output control signal to the on-site valve;

[0012] Step 7: Calibrate the valve positioner so that the control signal corresponds to the valve opening.

[0013] Step 1 specifically includes:

[0014] Step 1.1: Select an automation platform with programmable functions as the control system platform;

[0015] Step 1.2: Build a main water flow measurement circuit;

[0016] Step 1.3: Build the deaerator level measurement circuit;

[0017] Step 1.4: Build a condensate flow control loop through hard wiring, and send the analog output loop of the DCS control platform to the positioner of the on-site flow control valve.

[0018] In step 1.1, the automation platform is a distributed control system or a programmable controller or a DCS platform of INVES.

[0019] Step 1.2 includes: using Rosemount flow transmitters to send the flows of the three evaporator circuits to the analog input card of the control platform.

[0020] Furthermore, the flow transmitter has a measuring range of 0 to 2442 T / h, and a flow value of 2000 T / h when operating at full power.

[0021] Step 1.3 includes: using a Rosemount level transmitter and sending the liquid level to the analog input card of the control platform.

[0022] Furthermore, the measuring range of the liquid level transmitter is 0 to 4500 mm, and the liquid level setting value during normal full power operation is 3800 mm.

[0023] Step 2 consists in configuring the internal addresses of the input and output signals:

[0024] The main water supply flow address of the first ring: 1ADG_N3:401KM1;

[0025] The main water supply flow address of the second ring: 1ADG_N3:402KM1;

[0026] The main water supply flow address of Sanhuan: 1ADG_N3:403KM1;

[0027] Deaerator liquid level: 1ADG_N3:N02608_G;

[0028] Address of liquid level design value: 1ADG_N3:002KU_S2;

[0029] The address of analog output is: 1CEX_N5:025RG.

[0030] In step 7, the AOV device is calibrated using a pneumatic valve standard so that a current signal of 4 to 20 mA corresponds to an opening of 0 to 100%.

[0031] Furthermore, when the total main water supply flow of the three loops is less than 5500 tons per hour (T / h), feedforward control without dead zone is adopted; when the real-time main water supply flow is greater than 5500 T / h, feedforward control with dead zone is adopted; the main water supply flow value used to calculate the feedforward item is FwF, the real-time main water supply flow value is Fw, and the absolute value of the dead zone range of the feedforward item is DFw. The specific feedforward item algorithm logic is as follows:

[0032] (1) Calculate the real-time main water supply flow of the three loops: Fw = Fw1 + Fw2 + Fw3;

[0033] (2) Calculate the feedforward flow:

[0034] If Fw<=5500, adopt feedforward control without dead zone, FwF=Fw;

[0035] Otherwise feedforward control with deadband is enabled:

[0036] If |Fw-FwF|<=DFw, FwF remains unchanged;

[0037] Otherwise: If Fw>FwF, FwF increases the value of Fw beyond the dead zone range, FwF=FwF+Fw-FwF-DFw; otherwise, FwF decreases the value of Fw beyond the dead zone range, FwF=FwF-(FwF-Fw-DFw);

[0038] (3) Calculate the feedforward term: Vf = FwF / 6000*54 (i.e., a flow rate of 6000 T / h corresponds to a valve opening of 54%;

[0039] (4) Calculate the total valve opening output: V = Vf + Vpid.

[0040] Compared with the prior art, the control method for reducing fluctuations of the condensate flow regulating valve provided by the present invention has the following beneficial effects:

[0041] The present invention can take into account the advantages of fast response of the feedforward term in dynamic adjustment and avoid the fluctuation problem caused by stable adjustment. The center position of the dead zone can automatically change with the change of the actual fluctuation center value without manual adjustment.

[0042] The present invention is applied to two M310 reactor units, successfully reducing the fluctuation amplitude of the condensate flow regulating valve from 5% to within 2%, and the RMS value of the valve stem movement speed is also reduced from 40.5 mm / s to 17 mm / s. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the technical description.

[0044] Figure 1 The algorithm logic block diagram provided by the present invention;

[0045] Figure 2 A schematic diagram of the relationship between the modules provided by the present invention;

[0046] Figure 3 This is a feedforward control effect diagram of the lifting power and full power operation with dead zone (150T / h) provided by the present invention;

[0047] Figure 4 This is an enlarged diagram of the feedforward control effect with dead zone (150T / h) during the lifting power and full power operation provided by the present invention;

[0048] Figure 5 This is an enlarged diagram of the feedforward control effect with dead zone (140T / h) during the lifting power and full power operation provided by the present invention;

[0049] Figure 6 A schematic diagram comparing valve fluctuations before and after adding a dead zone of a feedforward term provided by the present invention;

[0050] Figure 7 A schematic diagram for comparing the valve stem vibration conditions before and after adding the dead zone of the feedforward term provided by the present invention. DETAILED DESCRIPTION

[0051] The following is further explained in detail through specific implementation methods.

[0052] The present invention provides a control method for reducing fluctuations of a condensate flow regulating valve, comprising the following steps:

[0053] Step 1: Establish an automated control loop.

[0054] Specifically, step 1 includes:

[0055] Step 1.1: Select an automation platform with programmable functions, such as a distributed control system (DCS) or a programmable logic controller (PLC), as the control system platform. In the implemented application, the INVES DCS platform is used.

[0056] Step 1.2: Build a main feedwater flow measurement loop, use Rosemount flow transmitters to send the flow of the three evaporator loops to the analog input card of the control platform. The flow transmitter has a range of 0 to 2442 T / h, and the flow value is 2000 T / h when running at full power.

[0057] Step 1.3: Build the deaerator level measurement circuit, use Rosemount level transmitter, and send the level to the analog input card of the control platform. The range of the level transmitter is 0-4500mm, and the level setting value is 3800mm when running at full power.

[0058] Step 1.4: Build a condensate flow control loop through hard wiring, and send the analog output loop of the DCS control platform to the positioner of the on-site flow control valve.

[0059] The following describes the control algorithm using the DCS platform as an example.

[0060] Step 2: Configure the signal address.

[0061] Specifically, step 2 includes configuring the internal addresses of the input and output signals for easy reference during programming:

[0062] The main water supply flow address of the first ring: 1ADG_N3:401KM1;

[0063] The main water supply flow address of the second ring: 1ADG_N3:402KM1;

[0064] The main water supply flow address of Sanhuan: 1ADG_N3:403KM1;

[0065] Deaerator liquid level: 1ADG_N3:N02608_G;

[0066] Address of liquid level design value: 1ADG_N3:002KU_S2;

[0067] The address of analog output is: 1CEX_N5:025RG.

[0068] Step 3: Add calculation module N02614_L1 to calculate the total flow rate of the main water supply of the three loops.

[0069] The input of this module is the main feed water flow of the three evaporator loops. Its function is to add the main feed water flow of the three evaporator loops to obtain the real-time total main feed water flow. The output of this module is the real-time total main feed water flow.

[0070] Specific program content written in assembly language:

[0071]

[0072] Step 4: Add feedforward control logic block N02614_L2 with dead zone.

[0073] The input of this module is the real-time main water supply total flow, which is the output of N02614_L1. The function is to apply the feedforward item flow calculation logic with dead zone to the real-time main water supply flow to obtain the flow used to calculate the feedforward item. The output of this module is the feedforward item flow.

[0074] Specific program content written in assembly language:

[0075]

[0076]

[0077]

[0078] Step 5: Configure the PID control parameters and the feedforward term of module 1CEX_N5:025RG.

[0079] The specific information and configuration results of key parameters are as follows:

[0080]

[0081]

[0082] The functions and relationships of step 3, step 4, and step 5 are as follows:

[0083] N02614_L1: Module for calculating the total flow value of the main water supply of three loops;

[0084] N02614_L2: Feedforward control logic block with dead zone;

[0085] N5:025RG: Module for configuring PID control parameters and feedforward items;

[0086] The relationship between each module is as follows Figure 1 shown.

[0087] Step 6: Output control signal to the on-site valve.

[0088] The analog output of the feedforward control module 1CEX_N5:025RG.OUT with dead zone is sent to the positioner of the valve CEX025VL on site through hard wiring.

[0089] Step 7: Calibrate the valve positioner so that the control signal corresponds to the valve opening.

[0090] The AOV device is calibrated using a pneumatic valve standard so that a current signal of 4 to 20 mA corresponds to an opening of 0 to 100%.

[0091] The present invention modifies the feed - forward control logic of the main feed - water flow. When the total main feed - water flow of the three loops (hereinafter referred to as the real - time total main feed - water flow) is less than 5500 tons per hour (T / h), feed - forward control without dead zone is adopted; when the real - time total main feed - water flow is greater than 5500 T / h (close to full - power operation), a feed - forward control method with dead zone is adopted. Let the value of the main feed - water flow used to calculate the feed - forward term (hereinafter referred to as the feed - forward term flow) be FwF, the value of the real - time total main feed - water flow be Fw, and the absolute value of the dead - zone range of the feed - forward term be DFw. As Figure 2 shown, the specific algorithm logic is as follows:

[0092] (1) Calculate the real - time main feed - water flow of the three loops: Fw = Fw1 + Fw2 + Fw3

[0093] (2) Calculate the feed - forward term flow

[0094] If Fw <= 5500, adopt feed - forward control without dead zone, FwF = Fw;

[0095] Otherwise (that is, Fw > 5500, enable feed - forward control with dead zone):

[0096] If |Fw - FwF| <= DFw (the change in the Fw value is within the dead zone), FwF remains unchanged;

[0097] Otherwise (that is, |Fw - FwF| > DFw, the change in the Fw value exceeds the dead - zone range):

[0098] If Fw > FwF, FwF increases by the value by which Fw exceeds the dead - zone range, FwF = FwF + Fw - FwF - DFw; otherwise (that is, Fw < FwF), FwF decreases by the value by which Fw exceeds the dead - zone range, FwF = FwF - (FwF - Fw - DFw);

[0099] (3) Calculate the feed - forward term: Vf = FwF / 6000 * 54 (that is, a flow of 6000 T / h corresponds to a valve opening of 54%);

[0100] (4) Calculate the total valve - opening output: V = Vf+Vpid.

[0101] This algorithm can achieve the following effects:

[0102] (1) When operating near full - power, when the fluctuation of the real - time total main feed - water flow is within the dead - zone range, the value of the feed - forward term flow remains unchanged, which can completely avoid the valve fluctuation caused by the fluctuation of the feed - forward term;

[0103] (2) When the fluctuation of the real - time total main feed - water flow exceeds the dead - zone range, the fluctuation range of the feed - forward term flow is reduced by 2 * DFw compared with the range of the main feed - water flow, which can greatly reduce the valve fluctuation caused by the fluctuation of the feed - forward term;

[0104] When the fluctuation center value of the total main water supply flow changes and exceeds the dead zone, the dead zone center value of the feedforward item flow can be automatically modified accordingly. When the main water supply flow stabilizes in a new range again, the dead zone center value can also stabilize at the new value.

[0105] The effect of the algorithm is simulated and verified as follows:

[0106] Assuming that the fluctuation range of the main feedwater flow is ±130 T / h, two different dead zone values ​​of 150 T / h and 100 T / h are used for offline simulation.

[0107] (1) Simulate the flow rate changes during the unit power increase period.

[0108] 1) Power increase will lead to an increase in the main feed water flow rate. Assuming that the increase rate of the main feed water flow rate is 50T / h (see Figure 1 The blue dotted line in the figure), with a fluctuation of 150T / h, the real-time main water supply total flow curve is: Figure 1 According to the above algorithm, when the actual main water supply total flow rate is lower than 5500T / h, the feedforward item flow rate (yellow solid line) will follow the real-time main water supply total flow rate, so the two are overlapped.

[0109] 2) When the real-time main water supply total flow reaches 5500T / h, it enters the range of the feedforward item dead zone, and the feedforward item flow value no longer synchronously follows the real-time main water supply total flow. Therefore, it will stagnate for a period of time while the real-time main water supply total flow continues to rise.

[0110] 3) When the real-time main water supply total flow value exceeds the feedforward item flow value and reaches 150T / h, the feedforward item flow will continue to rise with the real-time main water supply total flow, but always maintain a distance of 150T / h.

[0111] 4) When the total main water supply flow rate rises to the highest point and begins to decline, the flow rate of the real-time main water supply flow rate feedforward item will remain unchanged.

[0112] (2) During stable operation at full power.

[0113] 5) The real-time total main water supply flow rate fluctuates within the range of 130 T / h above and below 6000 T / h, and the feedforward item flow rate remains stable at 5980 T / h.

[0114] 6) The real-time main water supply total flow rate drops from 6000T / h to 5700T / h, and fluctuates within the range of 130T / h above and below this flow rate. The feedforward item flow rate automatically drops to 5720T / h and remains unchanged.

[0115] (3) During power reduction.

[0116] 7) When the real-time main water supply total flow rate starts to decrease from 5700T / h, the feedforward item flow rate automatically decreases and coincides with it when the real-time main water supply total flow rate is lower than 5500T / h, and decreases synchronously.

[0117] (4) If the dead zone value is 100 T / h, the effect is similar to 150 T / h, but during stable operation, the feedforward flow rate fluctuates by ±30 T / h.

[0118] The above effect diagram is as follows Figures 3 to 7 shown.

[0119] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A control method for reducing fluctuations in a condensate flow regulating valve, characterized in that: The following steps are involved: Step 1: Establish an automated control loop; Step 2: Configure the signal address; Step 3: Set a calculation module for calculating the total flow value of the main water supply of the three loops to obtain the real-time total flow of the main water supply; Step 4: Set the feedforward control logic block with dead zone to obtain the flow rate used to calculate the feedforward term; Step 5: Configure the PID control parameters and the module of the feedforward item; Step 6: Output control signal to the on-site valve; Step 7: Calibrate the valve positioner so that the control signal corresponds to the valve opening.

2. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 1, characterized in that: Step 1 specifically includes: Step 1.1: Select an automation platform with programmable functions as the control system platform; Step 1.2: Build a main water flow measurement circuit; Step 1.3: Build the deaerator level measurement circuit; Step 1.4: Build a condensate flow control loop through hard wiring, and send the analog output loop of the DCS control platform to the positioner of the on-site flow control valve.

3. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 2, characterized in that: In step 1.1, the automation platform is a distributed control system or a programmable controller or a DCS platform of INVES.

4. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 2, characterized in that: Step 1.2 includes: using Rosemount flow transmitters to send the flows of the three evaporator circuits to the analog input card of the control platform.

5. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 4, characterized in that: The flow transmitter has a range of 0 to 2442 T / h, and the flow value when operating at full power is 2000 T / h.

6. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 2, characterized in that: Step 1.3 includes: using a Rosemount level transmitter and sending the liquid level to the analog input card of the control platform.

7. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 6, characterized in that: The measuring range of the liquid level transmitter is 0~4500mm, and the liquid level setting value when operating at normal full power is 3800mm.

8. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 1, characterized in that: Step 2 consists in configuring the internal addresses of the input and output signals: The main water supply flow address of the first ring: 1ADG_N3:401KM1; The main water supply flow address of the second ring: 1ADG_N3:402KM1; The main water supply flow address of Sanhuan: 1ADG_N3:403KM1; Deaerator liquid level: 1ADG_N3:N02608_G; Address of liquid level design value: 1ADG_N3:002KU_S2; The address of analog output is: 1CEX_N5:025RG.

9. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 1, characterized in that: In step 7, the AOV device is calibrated using a pneumatic valve standard so that a current signal of 4 to 20 mA corresponds to an opening of 0 to 100%.

10. The control method for reducing fluctuation of a condensate flow regulating valve according to claim 1, characterized in that: When the total main water supply flow of the three loops is less than 5500 tons per hour (T / h), feedforward control without dead zone is adopted; when the real-time main water supply flow is greater than 5500T / h, feedforward control with dead zone is adopted; suppose the main water supply flow value used to calculate the feedforward item is FwF, the real-time main water supply flow value is Fw, and the absolute value of the dead zone range of the feedforward item is DFw. The specific feedforward item algorithm logic is as follows: (1) Calculate the real-time main water supply flow of the three loops: Fw = Fw1 + Fw2 + Fw3; (2) Calculate the feedforward flow: If Fw<=5500, adopt feedforward control without dead zone, FwF=Fw; Otherwise feedforward control with deadband is enabled: If |Fw-FwF|<=DFw, FwF remains unchanged; Otherwise: If Fw>FwF, FwF increases the value of Fw beyond the dead zone range, FwF=FwF+Fw-FwF-DFw; otherwise, FwF decreases the value of Fw beyond the dead zone range, FwF=FwF-(FwF-Fw-DFw); (3) Calculate the feedforward term: Vf = FwF / 6000*54 (i.e., a flow rate of 6000 T / h corresponds to a valve opening of 54%; (4) Calculate the total valve opening output: V = Vf + Vpid.

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