RU2799504C1 - Automatic control system for the supply of producer and process gases in various modes of operation of a tokamak-type plant - Google Patents

Abstract

FIELD: controlled thermonuclear fusion.

SUBSTANCE: means for automated control of production processes in the field of controlled thermonuclear fusion implemented on plants of the tokamak type. The automatic control system for the inlet of producer and process gases in various modes of operation of a tokamak-type plant consists of a vacuum chamber, which is connected via a channel for controlling the glow discharge current in the process gas to a unit of the system for cleaning the chamber with a glow discharge, which is connected via a digital channel for transmitting the gas pressure setpoint to a mismatch signal calculation unit, through the pressure control channel in the preliminary gas purge mode with the producer gas pressure control system unit before breakdown. The mismatch signal calculation unit and the universal controller are interconnected by a digital mismatch signal transmission channel and form a multipurpose real-time controller. Moreover, a multipurpose real-time controller, a digital-to-analog converter unit, an analog-to-digital converter unit and a reflective memory module unit form a crate with a controller and interfaces.

EFFECT: implementation of an automatic process for controlling the inlet of producer and process gases into the installation in various operating modes of the tokamak by cascade control of piezoelectric valves using a controller with a multipurpose regulator.

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Description

Technical field

The invention relates to means for automated control of technological processes in the field of controlled thermonuclear fusion and can be implemented on installations of the tokamak type.

State of the art

To supply working and process gases to the vacuum chamber of the tokamak, fast-acting piezoelectric valves insensitive to magnetic fields are used, the throughput of which depends on the applied voltage.

The main disadvantages of the piezo valves used are the partially non-linear dependence of the throughput on the magnitude of the applied voltage, the change in this dependence during the operation of the valve, as well as the decrease in the valve life in the pulse-width modulation (PWM) mode with a cyclic full opening / closing of the valve.

From the prior art, systems for puffing gases into tokamak-type installations using single piezo valves with partially non-linear characteristics are known.

A device for regulating the gas discharge into the plasma (author's certificate SU 13 76791) is known, consisting of the diagnosis of the magnetohydrodynamic activity of the plasma, a digital-to-analog controller and one piezoelectric valve.

A known system for controlling the electron density of plasma in installations of the tokamak type "(patent for invention RU 2654518), consisting of a microwave interferometer, with a reference channel and the main channel passing through the tokamak chamber, at one end of which a backward wave lamp is installed, connected by a modulation signal channel with modulating signal generator, and on the other - a block of detectors connected to the reference channel of the interferometer and through the block of amplifiers and a module for determining the difference between the calculated and set values of the phase with a controlled voltage source, the output of which is connected to the piezo valve of the gas inlet, while the module for determining the difference between the calculated and set values phase is connected to the operator's workstation, characterized in that the module for determining the difference between the calculated and set phase values is made in the form of a hardware-software complex consisting of a modulating signal generator connected by a wave modulation channel to a reverse wave lamp, a synchronization module connected by input channels of the synchronization signal the start of gas purge and the synchronization signal for starting the interferometer from the operator's workstation, the signal digitizing unit, the input of which is connected to the amplification and filtering unit, and the output to the first input of the phase incursion calculation unit, the second input of which is connected to the output of the synchronization module, and the output to the first input of the control unit , the second input of which is connected by a communication channel with the plasma electron density program installed on the workstation, and the output through the digital and analog signal matching unit with the input of a controlled voltage source.

The main disadvantage of such systems is the dependence of the gas flow on the spent resource and the non-linear dependence of the valve throughput, which worsens the accuracy of regulation.

The main difference between the proposed solution and the above-mentioned patents is the ability to effectively control not a single piezo valve, but a group of piezo valves (which is necessary for large installations such as toakmak), not only in the mode of controlling the electron density of the plasma during the plasma experiment, but also in the modes of preparing the chamber by cleaning with smoldering discharge and puffing of the working gas for breakdown at the stage of plasma current growth, using one unified regulator and controller.

The technical problem to be solved by the claimed invention is to increase the efficiency of preparing the tokamak for discharge and increase the stability of plasma discharges using one unified regulator.

Disclosure of the essence of the invention

The technical result is the implementation of an automatic process for controlling the inlet of working and process gases into the installation in various operating modes of the tokamak by cascade control of piezoelectric valves using a controller with a unified regulator.

To achieve the technical result, a system for automatic control of the inlet of working and process gases in various modes of operation of a tokamak-type installation is proposed, consisting of a tokamak vacuum chamber, which is connected via a channel for controlling the glow discharge current in the process gas with a unit for cleaning the chamber with a glow discharge, which, via a digital channel, transmission of the gas pressure setpoint is connected to the mismatch signal calculation unit, through the pressure control channel in the preliminary gas purge mode with the unit of the working gas pressure control system before breakdown, which is connected to the mismatch signal calculation unit through the digital channel for transmitting the gas pressure setpoint, through the control channel of the electronic plasma density with a control system unit for the plasma electron density, which is connected via a digital channel for transmitting a setpoint for the plasma electron density to a mismatch signal calculation unit, via a channel for recording analog diagnostic signals of a microwave interferometer with a unit for recording and real-time calculation of the plasma electron density from diagnostic signals Microwave interferometer, which is connected via a digital channel for transmitting the current value of the plasma electron density to a reflective memory module unit, which is connected via a digital channel for transmitting the current value of the plasma electron density to a mismatch signal calculation unit, via a gas pressure measurement channel with gas pressure sensors, which are analog channel for transmitting the effective value of gas pressure is connected to an analog-to-digital converter unit, which is connected via a digital channel for transmitting the effective value of gas pressure to a unit for calculating the error signal, while the unit for calculating the error signal and the universal regulator, interconnected by a digital channel for transmitting the error signal, form a universal real-time controller, which is connected to a digital-to-analog converter unit via a digital channel for transmitting a control action, while the universal real-time controller, a digital-to-analog converter unit, an analog-to-digital converter unit and a reflective memory module unit form a crate with a controller and interfaces , which is connected via an analog channel for transmitting a control action to a signal conversion unit, which is connected via an analog channel for transmitting a control voltage to a group of 12 high-speed piezo valves, including rulers

piezoelectric valves, which is connected to the vacuum chamber of the tokamak through a pneumatic channel for supplying gas to the vacuum chamber, while gas is supplied to the vacuum chamber of the tokamak from the storage of working and process gases, connected to the gas preparation unit through high-speed piezoelectric valves, cascade control of which is carried out by a universal regulator, connected to the digital-to-analog converter unit connected to the signal conversion unit.

Brief description of the drawings

In FIG. 1 shows a block diagram of the automatic control system for the admission of working and process gases in various modes of operation of a tokamak-type plant, where:

1 - block of the system for cleaning the chamber with a glow discharge;

2 - block of the working gas pressure control system before breakdown;

3 - block of the plasma electron density control system;

4 - vacuum chamber of the tokamak;

5 - block for calculating the error signal;

6 - universal regulator;

7 - block of digital-to-analog converter (DAC);

8 - signal conversion unit;

9 - a group of 12 high-speed piezo valves;

10 - gas pressure sensors;

11 - unit for recording and calculating in real time the electron density of the plasma according to the diagnostic signals of the microwave interferometer;

12 - block of analog-to-digital converter (ADC);

13 - universal real-time controller;

14 - channel for controlling the glow discharge current in the process gas;

15 - pressure control channel in the preliminary gas purge mode;

16 - channel for controlling the electron density of the plasma;

17 - channel for recording analog diagnostic signals of the microwave interferometer;

18 - channel for measuring gas pressure;

19 - analog channel for transmission of the current value of gas pressure;

20 - digital channel for transmitting the effective value of the electron density of the plasma;

21 - digital channel for transmitting the current value of gas pressure;

22 - digital channel for transmission of the gas pressure setting;

23 - digital channel for transmission of the gas pressure setting;

24 - digital channel for transmitting the setpoint for the electron density of the plasma;

25 - digital channel for transmitting the error signal;

26 - digital channel for transmitting the control action;

27 - analog channel for transmission of the control action;

28 - analog channel for transmitting control voltage;

29 - pneumatic channel for supplying gas to the vacuum chamber;

30 - crate with controller and interfaces;

31 - network channel for data exchange with the central control system of the tokamak;

32 - block of the reflective memory module;

33 - digital channel for transmitting the current value of the plasma electron density.

In FIG. 2 is a block diagram that explains the principle of cascaded valve control, where:

4 - vacuum chamber of the tokamak;

6 - universal regulator;

7 - block of digital-to-analog converter (DAC);

8 - signal conversion unit;

9 - a group of 12 high-speed piezo valves;

34 - storage of working and process gases;

35 - gas treatment unit;

36…39 - lines of piezoelectric valves;

40…51 - high-speed piezoelectric valve.

In FIG. 3 shows a graph for selecting a linear portion of the control range of a piezoelectric valve.

Implementation of the invention

The automatic control system for the inlet of working and process gases in various modes of operation of a tokamak-type installation shown in figure 1 consists of a tokamak vacuum chamber 4, which is connected via a control channel for the glow discharge current in the process gas 14 with a unit of the system for cleaning the chamber with a glow discharge 1, which is digital channel for transmitting the gas pressure setpoint 22 is connected to the mismatch signal calculation unit 5, through the pressure control channel in the preliminary gas purge mode 15 with the unit of the working gas pressure control system before breakdown 2, which is connected to the calculation unit via the digital channel for transmitting the gas pressure setpoint 23 error signal 5, via the plasma electron density control channel 16 with the plasma electron density control system unit 3, which is connected 24 via a digital channel for transmitting the plasma electron density setpoint to the error signal calculation unit 5, via the channel for recording analog diagnostic signals of the microwave interferometer 17 s a unit for recording and calculating in real time the electron density of the plasma according to the diagnostic signals of the microwave interferometer 11, which is connected via a digital channel for transmitting the current value of the electron density of the plasma 20 to the block of the reflective memory module 32, which is connected via a digital channel for transmitting the current value of the electron density of the plasma 33 to mismatch signal calculation unit 5, through the gas pressure measurement channel 18 with gas pressure sensors 10, which are connected to the analog-to-digital converter unit 12 via the analog channel for transmitting the effective value of gas pressure 12, which is connected to the unit via the digital channel for transmitting the effective value of gas pressure 21 error signal calculation 5, wherein the error signal calculation unit 5 and the universal controller 6, interconnected by a digital error signal transmission channel 25, form a universal real-time controller 13, which is connected to the digital-to-analog converter unit 7 via a digital control action transmission channel 26, at the same time, the universal real-time controller 13, the digital-to-analog converter unit 7, the analog-to-digital converter unit 12 and the reflective memory module unit 32 form a crate with a controller and interfaces 30, which is connected to the signal conversion unit 8 via an analog control action transmission channel 27 , which is connected via an analog control voltage transmission channel 28 to a group of 12 high-speed piezo valves 9, including a line of piezoelectric valves 36-39, which is connected to the tokamak vacuum chamber 4 via a pneumatic channel for supplying gas to the vacuum chamber 29; The vacuum chamber of the tokamak 4 is carried out from the storage of the working and process gases 34, connected to the gas preparation unit 35 through high-speed piezoelectric valves 40-51, the cascade control of which is carried out by the universal regulator 6, connected to the digital-to-analog converter unit 7, connected to the signal conversion unit 8.

The core of the system is a universal real-time controller 13, consisting of a mismatch signal calculation module 5 and a universal controller 6. The digital-to-analog converter unit 7 converts digital signals from the universal controller into unified analog signals, and the actual value of gas pressure measured by pressure sensors 10 and the current the value of the plasma electron density calculated using the unit for recording and calculating in real time the electron density of the plasma according to the diagnostic signals of the microwave interferometer 11 is entered into the mismatch calculation unit 5 through the analog-to-digital converter unit 12 and the reflective memory module 32. All of the above equipment is installed in the crate thirty.

In FIG. 2 shows the principle of cascaded valve control.

The described system implements an automatic process of controlling the inlet of working and technological gases into the vacuum chamber of the tokamak in the modes of cleaning the chamber with a glow discharge, preliminary inlet of the working gas (for breakdown at the stage of plasma current growth) and control of the plasma electron density in the quasi-stationary discharge mode by cascade control of the group, from 12 high-speed piezoelectric valves 9 located on four lines (3 valves each) with the help of a unified controller 6, using the error input signal corresponding to the control mode data sources: signals from gas pressure sensors in the chamber or plasma electron density values n _e , calculated in real time based on microwave interferometry diagnostic signals, for feedback and setpoints for pressure or electron density, taking into account the specifics and features of each mode, which allows you to calculate the total flow of the working or process gas required at the current time and form the appropriate control actions on piezo valves.

To solve the problems of the gas inlet system in all 3 operating modes, the system allows using one unified controller with a common set of parameters on one controller. For each piezovalve, the coefficient of participation in the regulation, and the voltage range for regulation, falling on the relatively linear section of the valve transfer function, can be set.

The controller is based on proportional-integral-derivative (PID) controller. The system can use proportional control, when the coefficients corresponding to the differential and integral components of the output signal of the regulator are chosen so as to reduce the contribution of these components to zero. Differential control can be used, which allows the feedback system to respond to rapid changes, or integral control, which helps prevent a deviation from the setpoint from slowly increasing.

Depending on the operating mode of the tokamak, the error signal in the control loop with feedback uses the difference between the set and actual values of the gas pressure or plasma electron density n _e . As a result, a control signal is generated in the PID controller, which is proportional to the required total flow of the gas used at a given time. Further, this signal can, taking into account the individual coefficients of participation of the piezo valves, be converted into voltages applied to the piezo valves, which either open or close the piezo valves by a certain amount from the upper to the lower value of the control voltage limit. Increasing the gas flow (increasing the opening of the valves) increases the value of the gas pressure, and reducing the gas flow (reducing the opening of the valves) leads to a decrease in the gas pressure in the chamber. The pressure balance is ensured by a constantly operating chamber vacuum pumping system.

From the universal regulator 6, through the digital-to-analog converter unit 7, individual levels of opening voltages are fed to the input of the signal conversion unit.

From the output of the transducers, the signals of opening voltages are fed to high-speed piezoelectric valves 40 ... 51, which are assembled in parallel in 3 to 4 lines of piezoelectric valves 36-39.

The working or process gases from the storage of working and process gases 34 are supplied for mixing to the gas preparation unit 35, and from there they are fed through four parallel pipelines to the inputs of four lines of piezoelectric valves 36-39. From each valve, through a separate channel, the gas enters the vacuum chamber of the tokamak.

The pressure in the chamber is measured by the pressure sensor 10, and the electron density n _e is calculated in real time according to the microwave interferometry diagnostic data. The actual values of pressure and electron density are fed to the mismatch signal calculation unit 5, and the calculated mismatch signal to the universal controller 6.

To control the valve, the linear section of the control range is experimentally determined and the lower (U _min ) and upper (U _max ) boundaries for the control voltage are set, within which this linear section is located (see Fig. 3). The boundaries of the control range, along with the selected coefficients of the PID controller, are common for all 3 considered modes of operation of the system.

To reduce the error associated with the non-linearity and difference in the characteristics of the piezo valves, the cascade connection of the piezo valves is used in such a way that the number of piezoelectric valves simultaneously involved in the smooth regulation of the working gas flow at the current time is minimized (while the remaining piezo valves are in a fully open or fully closed state ), to do this, the additional controller unit converts the output setpoint of the PID controller into the number of fully open piezo valves and the setpoint to control the flow of one (maximum 4, according to the number of lines) valves.

In the mode of cleaning the vacuum chamber of the tokamak 4 by a glow discharge with process gases (argon, helium, etc.), the control of gas inlet into the chamber is carried out according to the process gas pressure settings set by the chamber cleaning system with a glow discharge using a unified regulator with feedback on the pressure sensor in the tokamak chamber. The error signal is calculated from the programmed and measured process gas pressures. A logical-program control mode without pressure feedback is possible, when signals are applied to the piezo valves in accordance with a predetermined pressure program.

In the mode of preliminary puffing of the working gas into the vacuum chamber of the tokamak, before the start of the cyclogram of the experiment, fuel is puffed - a mixture of working gases (hydrogen, deuterium) according to the pressure settings of the working gas in the chamber before breakdown from the discharge scenario. The regulation is carried out until the specified gas pressure in the tokamak chamber is reached and maintained for a specified time using a unified regulator with feedback on the pressure sensor in the tokamak chamber. The pressure balance is ensured by a constantly operating chamber vacuum pumping system. The discrepancy signal is calculated on the basis of the programmed and measured values of the working gas pressure. A logical-program control mode without pressure feedback is possible, when signals are applied to the piezo valves in accordance with a predetermined pressure program.

и пропорционален

Усиление потока рабочего газа во время плазменного разряда (увеличение открытия клапанов) увеличивает значение электронной плотности плазмы, а уменьшение потока газа (уменьшение открытия клапанов) приводит к снижению электронной плотности плазмы.In the mode of maintaining the electron density of the plasma during the discharge, the control of the inlet of the working gas (fuel) into the chamber of the tokamak is carried out according to the mismatch signal in accordance with the values specified in the discharge scenario and the actual values of the electron density of the plasma n _e , calculated in real time from the diagnostic signals of the microwave interferometer . The operating principle of a microwave interferometer is based on the fact that the total phase shift Δϕ of electromagnetic oscillations of monochromatic microwave radiation probing the plasma depends on the plasma electron density n _e along the probing segment

and proportional

An increase in the working gas flow during a plasma discharge (increasing the opening of the valves) increases the electron density of the plasma, and a decrease in the gas flow (decrease in the opening of the valves) leads to a decrease in the electron density of the plasma.

The unified regulator can also act as a program block of a cyclogram in the open-loop mode, issuing control actions according to a predetermined (or taken from a previous experiment) table of settings.

The choice of one or another mode of operation of all components of the gas purge system is carried out by transmitting over the Ethernet network from the central control system of the tokamak the parameters of the controller, the mode of operation and the degree of participation of the piezo valves.

The opening of the piezo valve is ensured by applying a control voltage to its plate in the operating range U _min ... U _max , which is converted from a unified voltage of 0 ... 10 V at the DAC output using a signal conversion unit (controlled voltage source). There are two valve control modes:

1. Cascade valve control mode. In this mode, the valves on each line are opened one by one, while smooth regulation is carried out by the last open one, while the previous valves on the line are open in accordance with the applied voltage U _max , and the subsequent ones are closed with a applied voltage of 0 V: if one valve is open, then smooth flow control is carried out with the help of it; if two valves are open, then the first one opens completely, and the smooth flow control is carried out by the second valve; if three valves are open, the first two open fully, and the third valve controls the flow smoothly. And so for each of the four lines. To do this, the output of the PID controller is normalized within the range from 0 to N*U _max , where N is the number of valves on the line (a simplified formula is given).

2. Proportional valve control mode. In this mode, all valves are opened and controlled simultaneously. To do this, the output of the PID controller is normalized within U _min ... U _max , while for each valve an individual correction of the form can be set: setpoint×Coef+Const.

Data on the operation of all elements of the system are recorded in the database: the calculated total setpoint for the gas flow and individual settings for the piezo valves, the pressure in the chamber, the calculated current value and the required value of the electron density of the plasma, the required value of the gas pressure in the chamber and other information necessary for analysis the result of the experiment, emergency protection and tracking of key events of the experiment.

Thus, the main advantages of the proposed system are:

- simplification of the technical and software part of the system;

- setting and using one common set of PID controller coefficients and parameters of piezoelectric valves (U _min , U _max , Coef, Const) for 3 operating modes of the system;

- no need to use PWM valve control, which increases the life of the valves;

- improving the accuracy of regulation, which depends little on the exhausted resource and the non-linear dependence of the valve capacity;

- increasing the efficiency of preparing the chamber for discharge and the stability of plasma discharges.

Claims (1)

Automatic control system for the inlet of working and process gases in various modes of operation of a tokamak type plant, consisting of a tokamak vacuum chamber, which is connected via a channel for controlling the glow discharge current in the process gas with a unit for cleaning the chamber with a glow discharge, which, via a digital channel for transmitting the gas pressure setting connected to the mismatch signal calculation unit, through the pressure control channel in the preliminary gas purge mode to the unit of the working gas pressure control system before breakdown, which is connected to the mismatch signal calculation unit through the digital channel for transmitting the gas pressure setting, through the plasma electron density control channel to the system unit control of the plasma electron density, which is connected via a digital channel for transmitting the setpoint for the electron density of the plasma to a mismatch signal calculation unit, via a channel for recording analog diagnostic signals of a microwave interferometer with a unit for registering and calculating in real time the electron density of the plasma from diagnostic signals of a microwave interferometer, which via a digital channel for transmitting the current value of the plasma electron density is connected to a reflective memory module unit, which is connected via a digital channel for transmitting the current value of the plasma electron density to a mismatch signal calculation unit, via a gas pressure measurement channel with gas pressure sensors, which are via an analog channel for transmitting the effective value of gas pressure are connected to an analog-to-digital converter unit, which is connected via a digital channel for transmitting the effective value of gas pressure to a unit for calculating the error signal, while the unit for calculating the error signal and the universal controller, interconnected by a digital channel for transmitting the error signal, form a universal real-time controller , which is connected to the digital-to-analog converter unit via a digital channel for transmitting a control action, while the universal real-time controller, the digital-to-analog converter unit, the analog-to-digital converter unit and the reflective memory module unit form a crate with a controller and interfaces, which is connected via an analog control action transmission channel with a signal conversion unit, which is connected via an analog control voltage transmission channel to a group of 12 high-speed piezo valves, including a series of piezoelectric valves, which is connected to the vacuum chamber of the tokamak via a pneumatic channel for supplying gas to the vacuum chamber, while gas is admitted to the vacuum chamber of the tokamak from the storage of working and process gases, connected to the gas treatment unit through high-speed piezoelectric valves, which are controlled in cascade by a universal regulator connected to a digital-to-analog converter unit connected to a signal conversion unit.

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