RU1815478C - Method of liquid level control in steam turbine condenser - Google Patents

Abstract

Usage: heat power and can be used to automate the regulation of the liquid level in the condenser of a steam turbine and other tanks. SUMMARY OF THE INVENTION: The value of the constant time and the run-out of the actuator is identified. These values are compared with predetermined threshold values. When the values of the constant time and run outside the limits set by the threshold values are exceeded, the control signal is not output. If these values do not go beyond the specified limits, the identified stick out value is compared with the control action the value of the required increment of the position of the actuator in the next control step. If the run-out value exceeds the value of the required increment of the position of the actuating body, the control signal is not produced, otherwise, the next control pulse is generated. The duration of this pulse is chosen equal to the ratio of the difference between the required increment of the position of the actuator and the identified stick out value to the identified value of the constant time of the actuator. 1 ill. ate with

Description

The invention relates to the field of power engineering and can be used to automate the regulation of the liquid level in a condenser of a steam turbine and other tanks.

The purpose of the invention is to improve the accuracy of regulation.

The drawing shows an example block diagram of a device for implementing the proposed method. . ,.

A device for controlling the liquid level in the condenser 1 of a steam turbine by means of an actuator 2 comprises a current level sensor 3, a level adjuster 4, first, second, third, fourth 5, 6,7,8 comparison elements, an actuator position sensor 9, element 10 memory, computing device 11, first, second, third threshold elements 12, 13, 14, element 15 And, first, second, third; the fourth key elements 16, 17, 18, 19, a shaper. 20 pulse duration / differentiator 21, a shaper 22 of the input signal module, a delay element 23, a divider 24, an inverter 25, a controller 26.

The first and second inputs of the comparison element 5 are connected respectively to the output

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the sensor 3 of the current level and the master 4 levels, and the output to the input of the differentiator 21, the output of which is connected to the first input of the divider 24, the input of the driver 22 of the input signal module and the first input of the controller 26. The output of the driver 22 of the input signal module is connected to the first input the fourth comparison element 8, through the delay element 23 with the second input of the fourth comparison element 8, the output of which is connected through the third threshold element 14 to the control input of the third key element 18, and through the third key element 18 with the second the input of the divider 24, the output of which through the inverter 25 is connected to the second input of the controller 26, the control output of which through the fourth key element 19 is connected to the actuator 2, the position sensor 9 is connected to the actuator 2, the output of which is connected to the first input of the second the comparison element 6 and through the memory element 10 with the second input, the comparison element 6, the output of which is connected to the first input of the computing device 11, the second output of which is connected to the first information output of the controller 26, and the first output through h the first key element 16 with the first input of the third comparison element 7 and through the first threshold element 12 with the first input of the element 15 I. The second output of the computing device 11 through the second key element 17 is connected to the first input of the pulse width former 20 and through the second threshold element 13 to the second input element 15 And, the output of which is connected to the control input of the first key element 16.

The second information output of the controller 26 is connected to the second input of the third comparison element 7, the output of which is connected to the control inputs of the second 17 and fourth 19 key elements and the second input of the pulse width former 20, the output of which is connected to the third input of the controller 26.

The apparatus provides a method for adjusting a liquid level in a steam turbine condenser as follows. The level 3 sensor measures the current condensate level, determines the deviation of the current level from the level set by the level controller 4 using the first comparison element 5, from the output of which a signal is used to the first input of the regulator 26, which is used by the regulator to generate the next control signal.

The deviation rate is determined using a differentiator 21. The direction of change of the deviation module is determined as follows: the imager 22 of the input signal module converts the deviation signal arriving at its input into a signal modulated by the deviation;

which is then compared in the fourth comparison element 8 with a signal modulating the deviation, which is delayed by the delay element 23 for a predetermined time (the duration of the delay is chosen as short as possible provided that the difference between the current and delayed signals exceeds the deviation modulus of the level sensor error), and when the signal is exceeded according to the current deviation module of the delayed signal, the third threshold element 14 generates at the output a constant signal corresponding to an increase in the deviation module, which, entering the control input of the third key element

18, allows the divider 24 to generate a correction signal, which, through the inverter 25, is supplied to the second input of the controller 26.

Since the actuators are mechanisms with an uncontrolled constant speed of position and almost all of them have slowly varying coasts and time constants, a simplified equation that determines the position

executive body at each step of management, can be represented as:

V VJ -i + Ui-i (b + ri-iT 1).

where I is the index of the control step;

cr - position of the executive body;

and - control signal (0, ± 1);

t is the duration of the control signal;

b - run-out of the executive body; T is time constant of the executive body.

The duration of the control pulses t constantly varies during the operation of the controller, and the stick out value for a long time can be considered constant. As a result of this, it is in principle possible to estimate the run-out value b and the time constant T from the known values of y; and g.

After each control action is issued by the regulator 26, the position of the actuator 2 is measured using the sensor 9. Compare it in the second element 6 of the comparison with the previous value of the position of the actuator stored by the memory element 10 (the values remembered by the memory element 10 are updated after issuing the next control action). The increment value of position A is t / 1 h /. 1/. - i of the executive body 2 from the output of the second comparison element 6 is fed to the first input of the computing device 11, the second input of which receives a signal corresponding to the duration of the control signal from the first information output of the controller 26. The computing device 11 identifies the values of the constant time T and run-out of actuator b, using the modified increment values of the position of the actuator and the duration of the previous control pulse to determine.

The identified stick-out values b and the time constant T are supplied from the first and second outputs of the second counting device 11 to the first and second threshold elements 12 and 13 and compared with predetermined threshold values.

Only if the constant time values do not go beyond the set limits and the run-out signals from the outputs of the first 12 and second 13 threshold elements are supplied to the first and second inputs of the element 15 And, the signal from the output of the element And 15 goes to the control input of the first key element 16, which closes and allows the passage of a signal (corresponding run-out) from the first output of the computing device to the first input of the third comparison element 7. In the third comparison element 7, the identified stick out value is compared with the predicted controller 26 by the value of the increment of the position of the actuator, which is supplied to the second input of the comparison element 7 from the second information output of the controller 26.

.If the identified stick-out value does not exceed the value of the increment of position of the actuator 2 required by the regulator 26, a signal equal to the difference of the required increment of position and run-out from the output of the third comparison element 7 is fed to the control input of the fourth key element 19 and closes the control signal path from the control output of the controller 26 to the executive body 2. In this case, the signal from the output of the third comparison element 7 is fed to the second input of the pulse width former 20 and to the the input of the second key element 17. causing the passage of a signal (corresponding to the identified value of the constant

time) from the second output of the computing device 11 to the first input of the pulse shaper 20, which generates the duration of the next control pulse 5 equal to the ratio of times. the required increment of the position of the actuator and the identified run-out value to the identified value of the time constant 0 of the actuator 2.

Otherwise, if the identified run-out value exceeds the value of the increment of the position of the actuator 2 required by the regulator 26, the signal from the output of the third comparison element 7 does not go to the control inputs of the second 17 and fourth 19 key elements, the control signal circuit does not It closes and does not produce a control signal.

Thus, in the process of regulating the liquid level in the condenser of a steam turbine, the time constant and the run-out of the actuator are identified, the timely assessment of which allows more accurate formation of control laws and blocks the generation of control signals when the identified values exceed technologically permissible limits. 0 This technical solution is intended to be used in the design of liquid level regulators in the condenser of a steam turbine. Such regulators are part of the automated and turbine control systems for nuclear power plants developed and manufactured by the 5th Association.

Claims (1)

SUMMARY OF THE INVENTION A method for controlling a liquid level in a condenser of a steam turbine by measuring the deviation of the current level value from a predetermined one, its speed and the change in the deviation modulus, and with an increase in the deviation modulus, adjust the level by changing the position of the actuator according to the control action from the controller taking into account the magnitude and rate of deflection, characterized in that. in order to increase accuracy, after the issuance of each control action 0, the values of the constant time and the run-out of the executive body are identified, these values are compared with the set threshold values, and when the values of the constant time and run-out exceed the limits set by 5 threshold values, issuing the control no signal is produced, if these values do not go beyond the specified limits before issuing the control action, the identified stick out value is compared with the value of the required increments of the position of the actuator in the next control step, when the run-out value exceeds the value of the required increment of position, the signal, the duration of which is chosen equal to the ratio of the difference between the required increment of the position of the actuator and the identified value body issuance of the manager5 run-out to the identified value they don’t have any impact; otherwise, the next managing director is formed, a signal whose duration is chosen equal to the ratio of the difference between the required increment of the position of the executive body and the identified value