Water machine backup protection master control joint position control system and method considering water headTechnical Field
The invention relates to the technical field of idle opening master control joints, in particular to a system and a method for controlling the positions of backup protection master control joints of a water machine, which are used for counting a water head.
Background
The idle opening master contact is a local element for indicating the idle opening state of the unit, and is often used for a backup protection loop of the water machine as a judgment condition of a skip CCB or GCB switch and a de-excitation system. The water machine backup protection loop is an important component part in a water turbine generator set protection system, and has the main function of providing an additional safety protection measure when an abnormal condition occurs in a set LCU (local control unit) so as to prevent equipment from being damaged and ensure personnel safety. The water machine backup protection loop is a hard wiring loop, when the temperature of three bearing bushes of the unit is too high or the unit is too fast, the water machine backup protection loop is triggered to fall down to the fast door, the emergency stop electromagnetic valve and the accident pressure distribution valve are operated to close the guide vane, when the opening of the guide vane is reduced to the idle opening, the idle opening mainly enables the contact to act, at the moment, the CCB or GCB switch is jumped, the excitation system is de-energized, and the safe shutdown of the unit is realized.
In the prior art, a main command contact support is fixed on the ground below a main servomotor piston rod, and an idle opening main command contact is installed on the support and outputs a switching value signal by adopting a travel switch. A push rod is fixed below the joint of the servomotor piston rod and the control ring, and the forefront end of the push rod is inclined upwards by about 30 degrees. When the guide vane is opened, the servomotor piston rod drives the push rod to move forwards, when the opening of the guide vane is larger than the no-load opening, the push rod is not contacted with the travel switch, the no-load opening mainly enables the joint signals to be reset, when the guide vane is closed, the servomotor piston rod drives the push rod to move backwards, and when the opening of the guide vane is smaller than the no-load opening, the push rod presses the travel switch, and the no-load opening mainly enables the joint signals to act.
The disadvantages of the prior art are as follows:
1, the no-load opening degree and the unit operation water head are in negative correlation, when the water head is increased, the no-load opening degree is reduced, when the water head is reduced, the no-load opening degree is increased, the existing no-load opening degree main contact is arranged on a fixed position of a bracket, and the installation position cannot be adjusted in real time according to the water head change. After the backup protection flow of the water machine is started, if the installation position is larger than the idle opening, the CCB or GCB switch is jumped in advance, so that the rotating speed of the machine set is quickly increased, equipment damage is caused in severe cases, and if the installation position is smaller than the idle opening, the CCB or GCB switch is jumped in a delayed manner, so that the reverse power operation of the machine set is caused.
And 2, the control ring, the main servomotor, the main contact and the support thereof are removed during unit overhaul, and the installation position is difficult to determine and check during restoration installation. Therefore, there is a need to design a system and method for controlling the position of the backup protection master contact of a water machine, which takes into account the water head, so as to solve the above problems.
Disclosure of Invention
The invention aims to solve the technical problems that the installation position of an idle main command contact is difficult to determine and check and the idle main command contact cannot be adjusted in real time along with the change of a water head so as to cause abnormal operation or damage of equipment.
In order to solve the technical problems, the invention adopts the following technical scheme:
A water machine backup protection master joint position control system taking a water head into account comprises a servomotor, wherein a servomotor piston rod is connected with a guide vane control ring connecting rod, when pressure oil is communicated with a servomotor cavity, a guide vane is opened, when pressure oil is communicated with a servomotor cavity, the guide vane is closed, and a master joint push rod is fixed under the joint of the servomotor piston rod and the guide vane control ring connecting rod and is matched with a screw rod sliding table control mechanism to perform linear displacement motion along with the servomotor piston rod.
The screw rod sliding table control mechanism comprises a support, a bottom plate is connected above the support, the upper surface of the bottom plate is connected with a guide rail, the guide rail is in sliding connection with a moving plate, the upper surface of the moving plate is connected with a master joint, the bottom of the moving plate is in threaded connection with a screw rod, one end of the screw rod is connected with the output end of a servo motor to realize screw rod transmission, the screw rod sliding table control mechanism controls the master joint to move to a given position according to the current unit operation water head, and the support is fixed on the ground of a water car room.
Further, the controller calculates position setting according to the current running water head of the unit, and receives encoder data to control a position loop and a speed loop. The servo driver is responsible for current loop control and outputs a control signal to the servo motor. The servo motor receives a control signal of the servo driver to perform forward and reverse rotation, and the lead screw pushes the main contact on the moving plate to move forwards and backwards.
The method for controlling the positions of the joints of the backup protection master command of the water machine, which takes the water head into account, comprises the following steps:
S1, carrying out position data per unit, wherein the encoder data per unit is 0-10000, and the corresponding guide vane opening is 0-100%;
S2, calculating position given;
S3, executing position loop control by taking the proportional controller as a position controller;
s4, executing speed loop control by taking the proportional-integral controller as a speed controller;
s5, executing current loop control by taking the servo driver as a current controller;
S6, parameter setting is carried out from the inner ring to the outer ring according to the sequence of the current ring, the speed ring and the position ring.
Preferably, in step S1, the encoder data per unit is 0-10000, and the formula corresponding to the vane opening of 0-100% is expressed as:
;
Wherein, theX (t) is the original code value output by the encoder, the full-closing guide vane controls the main joint to move, and when the main joint is extruded by the push rod, the original code value acquired by the encoder isWhen the main joint is extruded by the push rod, the original code value acquired by the encoder is。
Preferably, in step S2, in the position calibration mode, a position set is calculatedComprising the following steps:
Full-closing guide vane, position givenEqual to the manual setting valueUntil the main contact point is operated, the position is fed backAssignment to position givenAt the moment, the negative feedback deviation is equal to 0, the servo motor keeps the current position unchanged, and the original code value X (t) output by the encoder is assigned to;
Full-open guide vane, position givenEqual to the manual setting valueUntil the main contact point is operated, the position is fed backAssignment to position givenAt the moment, the negative feedback deviation is equal to 0, the servo motor keeps the current position unchanged, and the original code value X (t) output by the encoder is assigned toBy detecting the state of the master contact point and switching the position given value, the position calibration data can be realized,Is provided.
Preferably, in step S2, in the automatic control mode, the position setting is calculatedComprising the following steps:
if the unit is not connected to the grid, the position is givenEqual to position feedbackThe negative feedback deviation is equal to 0, and the current position of the servo motor is kept unchanged;
If the unit is connected with the grid, collecting current running water head data H of the unit, and passing through a water head no-load opening curveCalculating the idle opening Y corresponding to the current water head, and then according to the travel curve of the idle opening servomotorCalculating a servomotor stroke value corresponding to the current operating water head, namely。
Preferably, in step S3, the position loop control method is as follows:
the position controller is a proportional controller, and inputs:
;
And (3) outputting:
;
Wherein the method comprises the steps ofGiven for positionWith position feedbackIs used for the difference in (a),For a given speed, as an input to the speed loop,Is a proportional control coefficient.
Preferably, the speed loop control method is as follows:
The speed controller is a proportional-integral controller, and the input is:
;
And (3) outputting:
;
Wherein the method comprises the steps ofGiven for speedAnd velocity feedbackIs used for the difference in (a),The output of the speed controller is used as the input of the current loop; is used as a control coefficient of the proportion,Is an integral control coefficient.
Preferably, the current loop control method comprises the following steps:
The servo driver is used as a current controller, proportional-integral control and current feedback are adoptedOutput current of the servo driver collected by the Hall element in the servo driver, input:
;
For a pair ofOutputting a voltage signal for driving the servo motor to rotate after proportional-integral operation, whereinIs the output of the speed controllerWith current feedbackIs a difference in (c).
Preferably, in step S6, the method for parameter tuning is as follows:
sequentially from the inner ring to the outer ring, firstly setting the current ring, then setting the speed ring and finally setting the position ring;
the current loop response speed is the fastest, default parameters in the servo driver or proportional control coefficients are compared according to actual conditions, and integral control coefficients are finely adjusted;
The response speed of the speed loop is faster than that of the position loop, the integral control coefficient is properly set, and the optimal parameter is selected as a final value by taking the high dynamic response speed and the high system stability as targets;
the response speed of the position loop is slower than that of the speed loop, the control coefficient of the comparative example is properly set, and the parameter without speed oscillation is selected as a final value;
After the three closed loop parameters are determined, setting the position manually, checking the dynamic response capability and stability of the control system, and fine-tuning the parameters according to the test condition until the dynamic response capability and stability index of the system meet the set values.
The beneficial effects of the invention are as follows:
The invention can accurately adjust the position of the main joint in real time according to the water head, after the backup flow of the water machine is started, the overspeed or reverse power event of the machine set caused by inaccurate position of the main joint is avoided, the overhaul machine set does not need to carry out position marking when the main joint is disassembled, and the installation position check is automatically carried out when the installation is restored, thereby greatly improving the working efficiency.
Drawings
FIG. 1 is a schematic diagram of the overall structure of the system of the present invention;
FIG. 2 is a schematic diagram of a lead screw sled control mechanism of the system of the present invention;
FIG. 3 is a block diagram of the connection logic of the components of the idle opening master contact position control system of the present invention;
FIG. 4 is a schematic block diagram of the idle opening master contact position control of the present invention;
The reference numerals in the figure are a servomotor 1, a guide vane control ring connecting rod 2, a main joint push rod 3, a screw rod sliding table control mechanism 4, a bracket 401, a bottom plate 402, a guide rail 403, a movable plate 404, a main joint 405, a servo motor 406 and a screw rod 407.
Detailed Description
Embodiment one:
As shown in fig. 1, the system for controlling the position of a main joint 405 of an empty-load opening degree of a water head comprises a servomotor 1, wherein a piston rod of the servomotor 1 is connected with a guide vane control ring connecting rod 2, when pressure oil is communicated through a cavity of the servomotor 1, a guide vane is opened, when the pressure oil is communicated through a cavity of the servomotor 1, the guide vane is closed, a main joint push rod 3 is fixed under the joint of the piston rod of the servomotor 1 and the guide vane control ring connecting rod 2 and is matched with a screw rod sliding table control mechanism 4, and the piston rod of the servomotor 1 is followed to perform linear displacement motion.
As shown in FIG. 2, the screw sliding table control mechanism 4 comprises a support 401, a bottom plate 402 is connected above the support 401, a guide rail 403 is connected to the upper surface of the bottom plate 402, the guide rail 403 is in sliding connection with a moving plate 404, a master joint 405 is connected to the upper surface of the moving plate 404, the bottom of the moving plate 404 is in threaded connection with a screw 407, the screw 407 is continuously connected with the output end of a servo motor 406 to realize the transmission of the screw 407, the screw sliding table control mechanism 4 controls the master joint 405 to move to a given position according to the current unit operation water head, and the support 401 is fixed on the ground of a water vehicle.
Further, the controller calculates position setting according to the current running water head of the unit, and receives encoder data to control a position loop and a speed loop. The servo driver is responsible for current loop control and outputs control signals to the servo motor 406. The servo motor 406 receives a control signal from the servo driver to perform forward and reverse rotation, and pushes the main contact 405 on the moving plate 404 to move forward and backward through the lead screw.
Embodiment two:
As shown in fig. 3 and 4, a method for controlling the position of a contact 405 according to the idle opening of a water head includes the following steps:
S1, carrying out position data per unit, wherein the encoder data per unit is 0-10000, and the corresponding guide vane opening is 0-100%;
S2, calculating position given;
S3, executing position loop control by taking the proportional controller as a position controller;
s4, executing speed loop control by taking the proportional-integral controller as a speed controller;
s5, executing current loop control by taking the servo driver as a current controller;
S6, parameter setting is carried out from the inner ring to the outer ring according to the sequence of the current ring, the speed ring and the position ring.
Preferably, in step S1, the encoder data per unit is 0-10000, and the formula corresponding to the vane opening of 0-100% is expressed as:
;
Wherein, theX (t) is the original code value output by the encoder, the full-closing guide vane controls the main joint 405 to move, and when the main joint 405 is extruded by the push rod, the original code value acquired by the encoder isWhen the main joint 405 is extruded by the push rod, the original code value acquired by the encoder is as follows。
Preferably, in step S2, in the position calibration mode, a position set is calculatedComprising the following steps:
Full-closing guide vane, position givenEqual to the manual setting valueUntil the main contact 405 is operated, the position is fed backAssignment to position givenAt this time, the negative feedback deviation is equal to 0, the servo motor 406 keeps the current position unchanged, and the original code value X (t) output by the encoder is assigned to;
Full-open guide vane, position givenEqual to the manual setting valueUntil the main contact 405 is operated, the position is fed backAssignment to position givenAt this time, the negative feedback deviation is equal to 0, the servo motor 406 keeps the current position unchanged, and the original code value X (t) output by the encoder is assigned toBy detecting the state of the master contact 405 and switching the position given value, position calibration data can be realized,Is provided.
Preferably, in step S2, in the automatic control mode, the position setting is calculatedComprising the following steps:
if the unit is not connected to the grid, the position is givenEqual to position feedbackThe negative feedback deviation is equal to 0, and the servo motor 406 keeps the current position unchanged;
If the unit is connected with the grid, collecting current running water head data H of the unit, and passing through a water head no-load opening curveCalculating the idle opening Y corresponding to the current water head, and then according to the travel curve of the idle opening servomotor 1Calculating a stroke value of the servomotor 1 corresponding to the current operating water head, namely。
Preferably, in step S3, the position loop control method is as follows:
the position controller is a proportional controller, and inputs:
;
And (3) outputting:
;
Wherein the method comprises the steps ofGiven for positionWith position feedbackIs used for the difference in (a),For a given speed, as an input to the speed loop,Is a proportional control coefficient.
Preferably, the speed loop control method is as follows:
The speed controller is a proportional-integral controller, and the input is:
;
And (3) outputting:
;
Wherein the method comprises the steps ofGiven for speedAnd velocity feedbackIs used for the difference in (a),The output of the speed controller is used as the input of the current loop; is used as a control coefficient of the proportion,Is an integral control coefficient.
Preferably, the current loop control method comprises the following steps:
The servo driver is used as a current controller, proportional-integral control and current feedback are adoptedOutput current of the servo driver collected by the Hall element in the servo driver, input:
;
For a pair ofOutputting a voltage signal for driving the servo motor to rotate after proportional-integral operation, whereinIs the output of the speed controllerWith current feedbackIs a difference in (c).
Preferably, in step S6, the method for parameter tuning is as follows:
sequentially from the inner ring to the outer ring, firstly setting the current ring, then setting the speed ring and finally setting the position ring;
the current loop response speed is the fastest, default parameters in the servo driver or proportional control coefficients are compared according to actual conditions, and integral control coefficients are finely adjusted;
The response speed of the speed loop is faster than that of the position loop, the integral control coefficient is properly set, and the optimal parameter is selected as a final value by taking the high dynamic response speed and the high system stability as targets;
the response speed of the position loop is slower than that of the speed loop, the control coefficient of the comparative example is properly set, and the parameter without speed oscillation is selected as a final value;
After the three closed loop parameters are determined, setting the position manually, checking the dynamic response capability and stability of the control system, and fine-tuning the parameters according to the test condition until the dynamic response capability and stability index of the system meet the set values.