SU807210A1 - System for automatic control of technological objects - Google Patents

Description

(54) AUTOMATIC CONTROL SYSTEM OF TECHNOLOGICAL OBJECTS

one

The invention relates to automatic control and is intended for use in direct digital control systems (NCU) of technological processes, for example, in chemical production plants.

This system can be used in automated systems in which a single control computer (UBM) replaces all control devices of the classical type. Receiving information from the sensors about the values corresponding to different parameters of the production process (pressure, temperature, level, etc.), the ACU determines the magnitudes of the mismatches between the necessary and actual values of each parameter and, depending on the magnitude of these mismatches, impact on the inputs of the actuators.

Systems are known that contain devices that include an operator's console, a PCM, switches, memory devices, executive furs .HH3NH I and.

The main disadvantage of the above devices is their insufficiently high reliability due to the lack of control over the output signal coming from the ACU.

The closest in technical essence to the present invention is an automatic control system (with direct digital control) comprising a serially connected calculator, a key and an analog storage device, the output of which is connected to an actuator 12J through an integrating unit.

The disadvantage of such a system is that there are situations where the calculator can detect its error ONLY after issuing a control action, for example, issuing a control action not through its own control channel, which leads to process disturbances and accidents.

5 In addition, in order to detect many errors in the operation of the ACU (for example, addressing code, looping, etc.), leading to disruption of the normal operation of the NCU system,

Claims (2)

0 requires a large amount of RAM and computer time, which is economically inefficient. The purpose of the invention is to increase the reliability that is achieved by introducing an AND element, a waiting multivibrator and a threshold comparison unit, the first input of which is connected to the output of the analog storage device, and the second input - with the analogue output of the calculator ,, the first output of the threshold comparison unit is connected through the AND element to the second input of the key, and the second output to the second input of the calculator whose second output through the waiting multivibrator connected to the second input of the element I, Figure 1 shows the block diagram of the automatic control system; figure 2 - timing diagram of the system. The system contains calculator 1, threshold comparison unit 2, analog storage device 3, standby multivibrator 4, element 5, key 6 integrating unit 7, executive mechanism H, control object 9 Lenin 10-22 communication. On the timing diagram of the system (figure 2) is indicated on the y-axis and - the analog output of the computer; and 2 is the output of the threshold comparison unit; U-, - discrete output of the calculator; Od is the output of the waiting multivibrator 4; and J - key output 6; and - the output of the analog storage device 3 .; U-j- is the output of the integrating unit 7, and on the abscissa axis is time t. The proposed system works as follows. In the NTSU mode, the calculator 1, processing information arriving along the circuit 22 from the sensors monitoring the state of the control object 9, calculates and outputs at the instants of time t, t,. .., tn control actions in the form of analog signals U () U (2j,., U (n)), which are fed to the input of the threshold comparison block through circuit 11. The other input of this block receives an analog signal through circuit 12 of device 3 that stores control actions calculated by calculator 1 in the previous cycle. The algorithm of operation of calculator 1, operating in the NCU mode, is such that the absolute value of the relative change in the control signals of the VIY arriving at the input of the executive mechanism calculated by calculator 1 in two consecutive In this case, should not exceed a certain value, which is chosen from the conditions of the technology, i.e. U, li) -U, (/ i-) UU-i) where U ((i) is the control action calculated by the CCM in the current cycle, and (i-1) is the control action calculated by the CCM in the previous cycle, 8 is the absolute value of the relative change in the control action. Block 2 is adjusted to the value S and, depending on the combination of these signals at its inputs, controls the operation of element 5 along circuit 13. Suppose that at time t, the calculator calculated and issued a new control return effect of U (), Block 2, analyzing the state of the signals at its inputs, establishes that S lies within the specified limits, as a result of which the resolving potential U2 () goes through circuit 13 to one of the inputs element A and 5. Through time ut, necessary for analyzing the incoming signal, calculator 1 issues a command signal Uj () with duration T, taking into account the state of the process variables and other conditions stipulated by the program, determined by its control algorithm. This command signal through the circuit 14 is fed to the input of the multivibrator 4, which produces a pulse Od (A) with a duration of 1, appears to another input element And 5 through the circuit 15. Element And 5 in the presence of two enabling signals at its inputs (from the multivibrator 5 and -2) triggers and opens the key 6 via the circuit 16, as a result of which a new control action (/ () / equal to J () via the circuit 17 goes to the input of the analog storage device 3, the output of which is set to U ((( n), which through the chain 18 is fed to the input of the integra block 7 and smoothed by block 7, the value of the control action along circuit 19 affects Mechanism 8, which controls object 9 of control along circuit 20. After the action of the pulse generated by the waiting multivibrator 5, i.e., through time, element 5 closes key 6 and the input of the device 3 is disconnected from the output of the calculator 1, while the analog storage device 3 retains the value of the control action of the value u, (/ () r equal to the time t2. + ut, i.e. before repeating the above cycle. Suppose that transmitter 1 was functioning normally until time t. i.e. at the output of the analog storage device, the 3 values of the control actions were P (), U6 (z),. .vU6 (h) a at the output of the integrating unit 7 values of control actions) (2) (p), respectively. At time t. The calculator 1 outputs the control action of the value, +, and. Block 2, analyzing the ratio of signals and) at its inputs, establishes that the correlation takes the form Ulfn-Ki), which indicates the occurrence of an emergency situation in the operation of calculating bodies 1, since , according to the control algorithm, calculator 1 must fulfill relation (1). As a result, block 2 produces a inhibitory potential and ((c) arriving at the input of element I5 via circuit 13, preventing the latter from tripping even when there is a command discrete signal and the memorization coming from the calculator 1. This does not allow opening the key b, and the erroneous control action U ((will not arrive at the input of the device 3, which saves the control action U ((,) i) ( „|, Up to the transition to backup operation modes. Simultaneously with the emergency situation, unit 2 via circuit 21 signals the evaluator 1 about the occurrence of an emergency situation in its operation, on the basis of which the calculator 1, according to the control algorithm embedded in it, should accept error recovery measures . The use of the present invention allows to reduce the amount of RAM occupied by self-checking programs and to increase the reliability of the NCU system without the use of a backup control computing complex, increasing the normal operation time of the NCU system for the production of layered fertilizers by 1.2 times. Claims The system of automatic control of technological objects containing sequentially connected calculator, key, analog storage device, the output of which is connected to an actuator through an integrating unit, characterized in that, in order to increase the reliability of operation, elements waiting for a multivibrator and a threshold comparison unit, the first input of which is connected to. the output of the analog storage device, the second input - with the encoder output of the calculator, the first output of the threshold comparison unit is connected via element I to the second input of the key, and the second output - to the second input of the calculator: tel, the second output of which through the waiting multivibrator is connected to the second input of the element I. Sources of information taken into account during the examination 1. USSR author's certificate number 427535, - cl. G 05 B 15/02, 1974. 2. The patent of Japan. No. 49-8672, cl. 541 7 G 05 B 15/00, published 1975. 22