Water machine backup protection master command contact position control system and method considering water head

Abstract

The invention discloses a water machine backup protection master command contact position control system and method considering a water head. The system comprises a servomotor, and a piston rod of the servomotor is connected with a guide vane control ring connecting rod; a master command contact push rod is fixed under the joint of a servomotor piston rod and a guide vane control ring connecting rod and is matched with a lead screw sliding table control mechanism, during control, position data per unit is firstly carried out, position setting is calculated, then position ring control, speed ring control and current ring control are sequentially executed, and finally parameter setting is sequentially carried out from an inner ring to an outer ring. The problems that in the prior art, the installation position of a no-load master command contact is difficult to determine and check, and the no-load master command contact cannot be adjusted in real time along with the change of a water head, so that equipment operates abnormally or is damaged are solved. The position of the master control contact can be accurately adjusted in real time according to a water head, position marking is not needed when the master control contact of a unit is disassembled during overhaul, installation position checking is automatically carried out when installation is recovered, and the working efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of no-load opening master contacts, and particularly to a control system and method for the position of a master contact of a water turbine backup protection considering water head. Background Art

[0002] The no-load opening master contact is a local component indicating the no-load opening state of the unit, and is often used in the water turbine backup protection circuit as a judgment condition for tripping the CCB or GCB switch and de-exciting the excitation system. The water turbine backup protection circuit is an important part of the water turbine generator unit protection system. Its main function is to provide an additional safety protection measure when abnormal conditions occur in the unit's LCU (local control unit) to prevent equipment damage and ensure personnel safety. The water turbine backup protection circuit is a hard-wired circuit. When the temperature of the three bearing bushings of the unit is too high or the unit runs at high speed, the water turbine backup protection circuit triggers the rapid gate to drop, activates the emergency stop solenoid valve and the accident pressure regulating valve to close the guide vane. When the guide vane opening is reduced to the no-load opening, the no-load opening master contact operates. At this time, the CCB or GCB switch is tripped and the excitation system is de-excited to achieve safe shutdown of the unit.

[0003] In the prior art, a master contact bracket is fixed on the ground below the piston rod of the main servomotor, and a no-load opening master contact is installed on the bracket. The contact uses a travel switch to output a switching quantity signal. A push rod is fixed below the connection between the piston rod of the servomotor and the control ring, and the front end of the push rod is inclined upward by about 30°. When opening the guide vane, the piston rod of the servomotor drives the push rod to move forward. When the guide vane opening is greater than the no-load opening, the push rod does not contact the travel switch, and the signal of the no-load opening master contact returns; when closing the guide vane, the piston rod of the servomotor drives the push rod to move backward. When the guide vane opening is less than the no-load opening, the push rod presses the travel switch, and the signal of the no-load opening master contact operates.

[0004] The disadvantages of the prior art are as follows: 1. The no-load opening is negatively correlated with the operating water head of the unit. When the water head increases, the no-load opening decreases; when the water head decreases, the no-load opening increases. The existing no-load opening master contact is installed at a fixed position on the bracket and cannot be adjusted in real time according to the change of the water head. After the water turbine backup protection process is started, if the installation position is greater than the no-load opening, the CCB or GCB switch will be tripped in advance, which will cause the unit speed to rise rapidly and may cause equipment damage in severe cases; if the installation position is less than the no-load opening, the tripping of the CCB or GCB switch will be delayed, which will cause the unit to operate in reverse power.

[0005] 2. During the major overhaul of the unit, the control ring, the main servomotor, the master contact and its bracket will be removed. When reinstalling, it is difficult to determine the installation position and it is difficult to check. Therefore, it is necessary to design a control system and method for the position of a master contact of a water turbine backup protection considering water head to solve the above problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a main command contact position control system and method for a water turbine backup protection considering water head, aiming to solve the problems in the prior art that it is difficult to determine the installation position of the no-load main command contact and the verification is difficult, and the no-load main command contact cannot be adjusted in real time with the change of water head, thus causing abnormal operation or damage of the equipment.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: A main command contact position control system for a water turbine backup protection considering water head includes a servomotor. The piston rod of the servomotor is connected to the connecting rod of the guide vane control ring. When pressure oil is introduced into the opening cavity of the servomotor, the guide vanes open; when pressure oil is introduced into the closing cavity of the servomotor, the guide vanes close. The main command contact push rod is fixed directly below the connection between the piston rod of the servomotor and the connecting rod of the guide vane control ring and cooperates with the lead screw and slide control mechanism to perform a linear displacement movement following the piston rod of the servomotor.

[0008] Preferably, the lead screw and slide control mechanism includes a bracket. A bottom plate is connected above the bracket. A guide rail is connected to the upper surface of the bottom plate. The guide rail is slidably connected to a moving plate. The main command contact is connected to the upper surface of the moving plate. The bottom of the moving plate is threadedly connected to the lead screw. One end of the lead screw is connected to the output end of the servo motor to achieve lead screw drive. The lead screw and slide control mechanism controls the main command contact to move to a given position according to the current water head of the unit operation. The bracket is fixed on the floor of the water turbine chamber.

[0009] Further, the controller calculates the position setpoint according to the current water head of the unit operation and receives the encoder data for position loop and speed loop control. The servo driver is responsible for current loop control and outputs a control signal to the servo motor. The servo motor receives the control signal from the servo driver to perform forward and reverse rotation, and pushes the main command contact on the moving plate to move back and forth through the lead screw.

[0010] The above main command contact position control method for a water turbine backup protection considering water head includes the following steps: S1, perform per-unit conversion of position data, convert the encoder data to 0 - 10000 per-unit, corresponding to the guide vane opening of 0 - 100%; S2, calculate the position setpoint ; S3, use a proportional controller as the position controller to perform position loop control; S4, use a proportional-integral controller as the speed controller to perform speed loop control; S5, use a servo driver as the current controller to perform current loop control; S6, from the inner loop to the outer loop, perform parameter tuning in the order of current loop, speed loop, and position loop.

[0011] Preferably, in step S1, the encoder data is normalized to 0 - 10,000, and the corresponding guide vane opening 0 - 100% is expressed by the formula: ; Wherein, is the normalized position data, X is the original code value output by the encoder; the guide vane is fully closed, and the master command contact is controlled to move; when the master command contact is actuated by the push rod, the original code value collected by the encoder is ; the guide vane is fully opened, and the master command contact is controlled to move. When the master command contact is actuated by the push rod, the original code value collected by the encoder is .

[0012] Preferably, in step S2, in the position calibration mode, calculating the position setpoint includes: The guide vane is fully closed, and the position setpoint is equal to the manually set value , until the master command contact is actuated, the position feedback is assigned to the position setpoint . At this time, the negative feedback deviation is equal to 0, the servo motor maintains the current position unchanged, and the original code value X output by the encoder is assigned to ; The guide vane is fully opened, and the position setpoint is equal to the manually set value , until the master command contact is actuated, the position feedback is assigned to the position setpoint . At this time, the negative feedback deviation is equal to 0, the servo motor maintains the current position unchanged, and the original code value X output by the encoder is assigned to ; by detecting the state of the master command contact and switching the position setpoint value, the position calibration data can be automatically collected.

[0013] Preferably, in step S2, in the automatic control mode, calculating the position setpoint includes: If the unit is not synchronized, the position setpoint is equal to the position feedback , the negative feedback deviation is equal to 0, and the servo motor maintains the current position unchanged; If the unit is synchronized, the current operating head data H of the unit is collected, and the no-load opening corresponding to the current head is calculated through the head no-load opening curve Y ; then, according to the no-load opening relay travel curve Calculate the servomotor travel value corresponding to the current operating head, i.e., .

[0014] Preferably, in step S3, the position loop control method is: The position controller is a proportional controller, with inputs: ; Output: ; where is the position setpoint and the position feedback the difference, is the input of the speed loop, is the proportional control coefficient.

[0015] Preferably, in step S4, the speed loop control method is: The speed controller is a proportional-integral controller, with inputs: ; Output: ; where is the position setpoint and the position feedback the difference, is the input of the current loop, is the proportional control coefficient, is the integral control coefficient.

[0016] Preferably, in step S5, the current loop control method is: The servo drive acts as a current controller and uses proportional-integral control; the current feedback comes from the servo drive output current collected by the internal Hall element of the servo drive; inputs: ; To After proportional-integral operation, output the voltage signal that drives the servo motor to rotate.

[0017] Preferably, in step S6, the parameter tuning method is: Proceed from the inner loop to the outer loop in sequence, first tune the current loop, then the speed loop, and finally the position loop; The current loop has the fastest response speed, and the default parameters inside the servo drive are used or the proportional control coefficient and integral control coefficient are slightly adjusted according to the actual situation; The response speed of the speed loop is faster than that of the position loop. Appropriately tune the proportional control coefficient and integral control coefficient, and select the optimal parameters as the final values with the goal of fast dynamic response speed and high system stability; The response speed of the position loop is slower than that of the speed loop. Appropriately tune the proportional control coefficient and select the parameters without speed oscillation as the final values; After determining the parameters of the three closed loops, manually set the position given value, check the dynamic response ability and stability of the control system, and fine-tune the parameters according to the test conditions until the dynamic response ability and stability indicators of the system meet the set values.

[0018] The beneficial effects of the present invention are as follows: The present invention can accurately adjust the position of the master contact in real time according to the water head. After the backup process of the water turbine is started, it can avoid overspeed or reverse power events of the unit caused by inaccurate position of the master contact; when disassembling the master contact of the overhauled unit, there is no need to mark the position. When reinstalling, the installation position is automatically checked, which greatly improves the work efficiency. Description of the Drawings

[0019] Figure 1 is the overall structural schematic diagram of the system of the present invention; Figure 2 is the structural schematic diagram of the lead screw slide control mechanism of the system of the present invention; Figure 3 is the component connection logic block diagram of the no-load opening master contact position control system of the present invention; Figure 4 is the principle block diagram of the no-load opening master contact position control of the present invention; The reference numerals in the drawings are: servomotor 1, guide vane control ring connecting rod 2, master contact push rod 3, lead screw slide control mechanism 4, bracket 401, base plate 402, guide rail 403, moving plate 404, master contact 405, servomotor 406, lead screw 407. Detailed Embodiments

[0020] Embodiment 1: As Figure 1 shown, a no-load opening master contact 405 position control system considering water head includes a servomotor 1, and the piston rod of the servomotor 1 is connected to the guide vane control ring connecting rod 2; when the opening chamber of the servomotor 1 is connected to the pressure oil, the guide vane opens, and when the closing chamber of the servomotor 1 is connected to the pressure oil, the guide vane closes; the master contact push rod 3 is fixed directly below the connection between the piston rod of the servomotor 1 and the guide vane control ring connecting rod 2 and cooperates with the lead screw slide control mechanism 4 to perform a linear displacement movement following the piston rod of the servomotor 1.

[0021] As Figure 2As shown in the figure, the lead screw slide control mechanism 4 includes a bracket 401. Above the bracket 401, a bottom plate 402 is connected. On the upper surface of the bottom plate 402, a guide rail 403 is connected. The guide rail 403 is slidably connected to a moving plate 404. On the upper surface of the moving plate 404, a master contact 405 is connected. At the bottom of the moving plate 404, it is threadedly connected to a lead screw 407. One end of the lead screw 407 is connected to the output end of a servo motor 406 to realize the transmission of the lead screw 407. The lead screw slide control mechanism 4 controls the master contact 405 to move to a given position according to the current operating head of the unit. The bracket 401 is fixed on the ground of the waterwheel chamber.

[0022] Further, the controller calculates the position setpoint according to the current operating head of the unit and receives the encoder data for position loop and speed loop control. The servo driver is responsible for current loop control and outputs a control signal to the servo motor 406. The servo motor 406 receives the control signal from the servo driver to rotate forward and backward, and pushes the master contact 405 on the moving plate 404 to move back and forth through the lead screw.

[0023] Embodiment 2: As Figure 3 , Figure 4 shown, a method for controlling the position of the no-load opening master contact 405 considering the water head includes the following steps: S1, perform per-unit conversion of position data, convert the encoder data to per-unit values from 0 to 10,000, corresponding to the guide vane opening from 0 to 100%; S2, calculate the position setpoint ; S3, use a proportional controller as the position controller to perform position loop control; S4, use a proportional-integral controller as the speed controller to perform speed loop control; S5, use a servo driver as the current controller to perform current loop control; S6, from the inner loop to the outer loop, perform parameter tuning in the order of current loop, speed loop, and position loop.

[0024] Preferably, in step S1, the formula for converting the encoder data to per-unit values from 0 to 10,000, corresponding to the guide vane opening from 0 to 100% is expressed as: ; Where is the per-unit position data, X is the original code value output by the encoder; when the guide vanes are fully closed, control the master contact 405 to move; when the master contact 405 is actuated by the push rod, the original code value collected by the encoder is ; when the guide vanes are fully open, control the master contact 405 to move, and when the master contact 405 is actuated by the push rod, the original code value collected by the encoder is .

[0025] Preferably, in step S2, in the position calibration mode, calculate the position setpoint including: Fully close the guide vane, and the position setpoint is equal to the manually set value , until the master contact 405 operates, assign the position feedback to the position setpoint . At this time, the negative feedback deviation is equal to 0, the servo motor 406 maintains the current position unchanged, and assign the original code value output by the encoder X to ; Fully open the guide vane, and the position setpoint is equal to the manually set value , until the master contact 405 operates, assign the position feedback to the position setpoint . At this time, the negative feedback deviation is equal to 0, the servo motor 406 maintains the current position unchanged, and assign the original code value output by the encoder X to ; By detecting the state of the master contact 405 and switching the position setpoint value, the automatic acquisition of the position calibration data can be realized .

[0026] Preferably, in step S2, in the automatic control mode, calculate the position setpoint including: If the unit is not connected to the grid, the position setpoint is equal to the position feedback , the negative feedback deviation is equal to 0, and the servo motor 406 maintains the current position unchanged; If the unit is connected to the grid, collect the current operating head data of the unit H , and calculate the no-load opening corresponding to the current head through the head-no-load opening curve ; Then, according to the no-load opening servomotor 1 stroke curve Y , calculate the servomotor 1 stroke value corresponding to the current operating head, that is . .

[0027] Preferably, in step S3, the position loop control method is: The position controller is a proportional controller, input: ; Output: ; where is the difference between the position setpoint and the position feedback , is the input of the speed loop, and

[0028] is the proportional control coefficient. Preferably, in step S4, the speed loop control method is: ; The output is: ; where is the difference between the position command and the position feedback , is the input of the current loop, is the proportional control coefficient, and

[0029] is the integral control coefficient. Preferably, in step S5, the current loop control method is: The servo drive acts as the current controller and adopts proportional-integral control; the current feedback ; After is subjected to proportional-integral operation, a voltage signal for driving the servo motor 406 to rotate is output.

[0030] Preferably, in step S6, the parameter tuning method is: It is carried out from the inner loop to the outer loop in sequence. First, the current loop is tuned, then the speed loop is tuned, and finally the position loop is tuned; The current loop has the fastest response speed. The default parameters inside the servo drive are adopted or the proportional control coefficient and the integral control coefficient are slightly adjusted according to the actual situation; The response speed of the speed loop is faster than that of the position loop. The proportional control coefficient and the integral control coefficient are properly tuned, and the optimal parameters are selected as the final values with the goal of fast dynamic response speed and high system stability; The response speed of the position loop is slower than that of the speed loop. The proportional control coefficient is properly tuned, and the parameters without speed oscillation are selected as the final values; After the parameters of the three closed loops are determined, the position command is manually set, and the dynamic response ability and stability of the control system are tested. The parameters are slightly adjusted according to the test situation until the dynamic response ability and stability indexes of the system meet the set values.

Claims

1. A main command contact position control system for the backup protection of a water machine considering water head, characterized in that, It includes a servomotor. The piston rod of the servomotor is connected to the connecting rod of the guide vane control ring. The master contact push rod is fixed directly below the connection between the piston rod of the servomotor and the connecting rod of the guide vane control ring and cooperates with the lead screw slide control mechanism to perform a linear displacement movement following the piston rod of the servomotor.

2. The main contact position control system of the water machine backup protection considering water head according to claim 1, characterized in that, The lead screw slide control mechanism includes a bracket. A base plate is connected above the bracket. A guide rail is connected to the upper surface of the base plate, and the guide rail is slidably connected to the moving plate. A master contact is connected to the upper surface of the moving plate. The bottom of the moving plate is threadedly connected to the lead screw. One end of the lead screw is connected to the output end of the servo motor to achieve lead screw drive. The lead screw slide control mechanism controls the master contact to move to a given position according to the current operating head of the unit. The bracket is fixed on the ground of the turbine pit.

3. A method for controlling the position of the main command contact of the backup protection of a water machine considering the water head according to claim 2, characterized in that, It includes the following steps: S1. Perform per-unit conversion of position data, convert the encoder data to per-unit values from 0 to 10,000, corresponding to the guide vane opening from 0 to 100%; S2, Calculate the given position ; S3. Use a proportional controller as the position controller to perform position loop control; S4. Use a proportional-integral controller as the speed controller to perform speed loop control; S5. Use a servo driver as the current controller to perform current loop control; S6. From the inner loop to the outer loop, perform parameter tuning in the order of current loop, speed loop, and position loop.

4. A control method for the position of the main command contact of the backup protection of a water machine considering the water head, as described in claim 3, characterized in that In step S1, the formula for converting the encoder data to per-unit values from 0 to 10,000, corresponding to the guide vane opening from 0 to 100% is: ； Among them, is the per-unit position data, X is the original code value output by the encoder; fully close the guide vane and control the main command contact to move; when the main command contact is squeezed and actuated by the push rod, the original code value collected by the encoder is ; fully open the guide vane and control the main command contact to move. When the main command contact is squeezed and actuated by the push rod, the original code value collected by the encoder is .

5. A method for controlling the position of the main command contact of the backup protection of a water machine considering the water head according to claim 3, characterized in that, In step S2, in the position calibration mode, calculate the position setpoint including: Full-closed guide vane, position given Equal to the manually set value , until the master contact operates, the position feedback Is assigned to the position given , at this time the negative feedback deviation is equal to 0, the servo motor maintains the current position unchanged, and the original code value output by the encoder X Is assigned to ; Fully opened guide vane, position given Equal to the manually set value Until the master command contact operates, the position feedback Is assigned to the position given At this time, the negative feedback deviation is equal to 0, the servo motor maintains the current position unchanged, and the original code value output by the encoder X Is assigned to .

6. A method for controlling the position of the main command contact of the backup protection of a water machine considering the water head, characterized in that, In step S2, under the automatic control mode, calculate the position setpoint including: If the unit is not connected to the grid, the position setpoint is equal to the position feedback , the negative feedback deviation is equal to 0, and the servo motor maintains its current position unchanged; If the unit is already connected to the grid, collect the current operating head data of the unit H , and through the head-no-load opening curve calculate the no-load opening corresponding to the current head Y ; then according to the no-load opening servomotor stroke curve calculate the servomotor stroke value corresponding to the current operating head, that is .

7. A control method for the position of the main command contact of the backup protection of a water machine considering water head, as described in claim 3, characterized in that In step S3, the position loop control method is: The position controller is a proportional controller, input: ； Output: ； wherein is the given position and the difference from the position feedback is the input of the speed loop and is the proportional control coefficient 8. A control method for the position of the main command contact of the standby protection of a water machine considering the water head according to claim 3, characterized in that, In step S4, the speed loop control method is: The speed controller is a proportional-integral controller, input: ； Output: ； wherein is the given position and the difference from the position feedback is the input of the current loop is the proportional control coefficient is the integral control coefficient ​ 9. A control method for the position of the main command contact of the backup protection of a water machine considering the water head according to claim 3, characterized in that, In step S5, the current loop control method is: The servo driver acts as a current controller and adopts proportional-integral control; current feedback The output current of the servo driver collected by the internal Hall element of the servo driver; Input: ； To Output a voltage signal that drives the servo motor to rotate after proportional-integral operation.

10. A control method for the position of the main command contact of the backup protection of a water machine considering the water head according to claim ⑶, characterized in that In step S6, the parameter tuning method is: The current loop adopts the default parameters inside the servo driver or adjusts the proportional control coefficient and integral control coefficient according to the actual situation; The speed loop tunes the proportional control coefficient and integral control coefficient, and selects the optimal parameters as the final values with the goal of fast dynamic response speed and high system stability; The position loop tunes the proportional control coefficient, and selects the parameters that meet the goal without speed oscillation as the final values; After the parameters of the three closed loops are determined, manually set the position reference, check the dynamic response ability and stability of the control system, and adjust the parameters according to the test situation until the dynamic response ability and stability indicators of the system meet the set values.

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