Cascade regulation. Uncoupled control Example of a cascade control system
Connecting installations according to the diagram Not related regulation ensures the independence of the operation of both installations, i.e. changing the water flow for hot water supply within a wide range from zero (at night) to maximum has virtually no effect on the operation of the heating system.
To do this, the water flow in the supply line must be equal to the total water flow for heating - ventilation and hot water supply. Moreover, the water consumption for hot water supply should be taken according to maximum load hot water supply and the minimum water temperature in the supply line, i.e. in the mode when the DHW load is completely covered from the supply line (if the consumer does not have storage tanks installed).
Water consumption for heating, ventilation, hot water supply and total water consumption by each network subscriber does not depend on the network configuration. The calculated flow rate by the subscriber is set using a throttle diaphragm, the diameter of the hole of which is determined by the formula (clause 4.17 SP 41-101-95)
where G is the estimated water flow in the pipeline, equal to Gtotal t/hour
DN - pressure damped by the diaphragm, m
The minimum size of the aperture opening is 3 mm
Automation of the make-up system
Automated make-up devices maintain a constant or varying water pressure at the network make-up point.
For heating networks with relatively small pressure losses in the mains and a favorable terrain profile, the pressure at the recharge point in all modes (including the mode when the network pumps are stopped) is maintained constant. It is planned to maintain constant pressure in the return manifold in front of the network pumps using a downstream pressure regulator (make-up regulator) installed on the make-up water pipeline.
In the case when the static pressure of the heating network exceeds the pressure in the return manifold of the boiler room when the network pumps are operating, adjustment to static pressure is carried out manually. Water pressure is measured in the pressure pipes of the feed pumps with local indicating and signaling pressure gauges, which give an impulse to turn on the backup pump, and in the return manifold - with indicating, recording and signaling pressure gauges on the local switchboard. At the local switchboard, they also provide for the installation of a secondary device indicating, recording and signaling flow meter for measuring the flow rate of make-up water and a secondary device of recording and signaling oxygen meter for measuring the oxygen content in the make-up water. The resistance thermometer on the make-up line is connected to a common recording device, which simultaneously records the temperature of the supply water.
In open heating networks, when installing central storage tanks, the pressure in the return pipeline is automatically regulated by two control valves, the first of which is installed on the bypass pipeline of excess network water to the storage tanks, and the second on the pipeline from the storage tanks after the transfer pumps. During hours when the hot water supply load is below the daily average, the transfer pumps are turned off and the pressure in the return pipeline is regulated by the first valve. During hours when the hot water load is higher than the daily average, the transfer pumps are automatically turned on, the first control valve is closed, and the pressure regulator switches to the control valve installed after the transfer pumps.
To provide constant flow For make-up water in an open heating network, a flow regulator is installed on the pressure pipeline of the make-up pumps.
The water level in the deaerator make-up tank is maintained by a control valve on the chemically purified water line. If instead of a vacuum deaerator operating on sliding pressure, an atmospheric one is used, then an additional regulator is installed that maintains constant pressure in the deaerator column. The scheme provides emergency stop workers: make-up and transfer pumps and automatic switching on of reserve ones, as well as pressure signaling in the return pipeline of the level in the make-up deaerator tank and network water storage tanks and the oxygen content in make-up water.
IZVESTIYA
GOMSK ORDER OF THE RED BANNER OF LABOR POLYTECHNIC
INSTITUTE NAMED AFTER S. M. KIROV
RESEARCH OF THE SYSTEM OF CONNECTED REGULATION OF ONE CLASS OF OBJECTS WITH DISTRIBUTED
PARAMETERS
V. I. KARNACHUK, V. Y. DURNOVTSEV
(Presented by the scientific seminar of the Department of Physics and Technology)
Multiply connected control systems (MCC) are currently finding increasing use in the automation of complex objects. This is due to the fact that complex automation production processes requires a transition from the regulation of one parameter to the associated regulation of several quantities that influence each other. Among similar systems great place are occupied by the same type of installation and installation works, consisting of several identical, identically configured regulators operating from a common source of raw materials or a common load. Multi-channel ACS of objects with distributed parameters, the task of which is to automatically optimize the parameter distribution, can be classified as the same type of SMR. This problem cannot be solved correctly if mutual influence is not taken into account adjustable parameters. Taking into account mutual influence significantly complicates the analysis of the system, since in a coupled system the dynamics of each parameter is described differential equation high order.
The founder of the theory of regulation of several parameters is I. N. Voznesensky. He showed that in order to eliminate the influence of parameters on each other, it is necessary to introduce artificial connections into the system to compensate for the influence of natural connections. In this case, the connected system turns into an unconnected one, i.e., autonomous. The problem of autonomy is a specific problem that is absent in the theory of one-dimensional ATS. I. N. Voznesensky solved this problem for a first-order plant controlled by an ideal controller. Later, physically and technically feasible conditions for autonomy were found for more complex systems. In these works, the range of objects considered is, as a rule, limited to first-order objects. However, in practice, when researching in the field of regulation of objects with distributed parameters such as distillation column, oil and gas reservoir, vulcanization chambers, various types of reactors, etc., a more complex approximation is often required.
IN this work Some issues of synthesis of two-dimensional SMR of an astatic object with phase advance are considered.
when the object for each controlled quantity is described by a second-order differential equation:
t dH dx 2 dt2 dt
koTi -U- +kou. dt
The block diagram of the coupled regulation system is shown in Fig. 1. The system is designed to maintain the specified value of parameter X in two various areas large object.
2 regulator w
Rice. 1. Block diagram of two-dimensional construction and installation work
The object of regulation is a multiply connected system with a ^-structure according to the accepted classification. The transfer functions of objects for each direct channel are equal:
K0(T,p+1) ■
SR) - ^02 (P)
P(T2P+> 1)
The relationship between the adjustable parameters is presented in the block diagram through constant coefficients Li2 = ¿2b, although in the general case it is not time invariant. Integrated regulators with a transfer function are considered:
The regulators receive control signals from inertial sensors (thermocouples) located near the corresponding regulators. Transfer functions of sensors:
Wn(p) = WT2(p) =
Analysis connected system using equations of motion, written even in operator form, is inconvenient due to the high order of the equations. The matrix method of writing equations has much greater convenience, especially for structural synthesis.
In a matrix form of notation, the equation for an object with a Y-structure has the form:
■ WciWcalia^i 1 - W 01^02^12^21
1 - 1^0] 1 - 12^21
a ^ and the column matrices of the controlled and regulating quantities, respectively.
For the controller you can write:
^^(¿y-X). (6)
u%(p)=G 0 [o
5 - transforming matrix of control actions; y is a matrix-column of control actions.
Elements of matrices and 5 can be obtained after simple structural transformations:
p(Tar+\)(TTr+\)
Then the equation of closed SMR can be written in the following form(hereinafter we will assume that the disturbances acting on the system / = 0):
X = (/ + Г0г р)"1 - W оГ р5Г, (7)
where / is the identity matrix.
From (7) we can obtain the characteristic equation of a closed SMR if we equate the determinants of the matrix (/ + WqWp) to zero:
| / + W0WP | = 0. (8)
Sufficient for construction and installation work has not yet been found general criteria stability checks. Determining the roots of the characteristic equation (8) is also a rather cumbersome task, since it can be shown that even in the two-dimensional case it is necessary to solve a tenth order equation. Under such conditions, the use of funds computer technology for calculating construction and installation work is not only desirable, but also necessary. The importance of analogue models is especially great for solving problems of synthesizing construction and installation equipment that have certain specified properties, and, above all, autonomous installation and installation equipment. It is known that the implementation of the conditions of autonomy is often impossible; in any case, for each specific system, finding the conditions of autonomy that could be implemented in fairly simple steps is an independent task. From expression (7) it is clear that the conditions of autonomy are reduced to the diagonalization of the matrix
Ф, = (/ + ^р)-1" wQwps.
In this case, the SMR equations break down into independent equations. Obviously, the matrix Fu will be diagonal only if the matrix W0Wpj, which is the transfer matrix of the open-loop SMR, is diagonal. To implement these conditions, artificial compensating connections, transmission
Rice. 2. Electronic model of autonomous construction and installation work,
the functions of which can be determined from a more convenient for these purposes notation of the matrix equation SMR:
Fu= ^o Gr(5-Fu). (9)
Exists big number options for implementing compensating connections. However, calculations carried out according to equation (9) show that the most convenient option for implementation is block diagram, when cross-connections are imposed between the inputs of the regulator amplifiers. For this case, the transfer functions of the compensating connections have the form:
/Xu (/>) = - №«¿12; K2\(p) = -
Taking into account expression (2) we have: * and (P)<= К21 (р) =
To study two-dimensional SMR, an electronic model of the system was used, assembled on the basis of the EMU-8 analog installation. The diagram of the electronic model of the SMR is shown in Fig. 2. The following numerical values of the parameters were adopted: a;o=10; KuK^/(r == 0.1; Tx = 10 sec; G2 = 0.1 sec; Tt = 0.3 Tg = 0.5 sec/s; I = 0.1 0.9.
Rice. 3. Curves of transient processes in the channels of non-autonomous (a) and autonomous (c) construction and installation works
Studies of the model have shown that a system without compensating connections remains stable up to the value of the relationship ¿ = 0.5. A further increase in L leads to divergent oscillations of the controlled variable. However, even with L<0,5 характер переходного процесса в системе является неудовлетворительным. Полное время успокоения составляет 25-ъЗО сек при максимальном выбросе 50%. Введение перекрестных связей, соответствующих условиям автономности, позволяет резко улучшить качество регулирования.
As can be seen from the graphs (Fig. 3), the sensitivity of each channel to changes in the setting in the adjacent channel is noticeably reduced. The duration of the transient process and the magnitude of the maximum overshoot can be reduced by reducing the gain of the amplifiers of both channels by a factor of 2 compared to the gain adopted for an uncoupled separate system.
1. Autonomy conditions have been found that are realized by simple active CN circuits for SMR of second-order objects - with phase advance.
2. Analysis of complex construction and installation work using analog computers allows you to select the optimal values of construction and installation work parameters.
An electronic model of two-dimensional autonomous construction and installation work has been proposed.” The influence of the magnitude of the relationship on the stability of the system is shown.
LITERATURE
1. M. V. Meerov, Multiply connected control systems. Ed. "Science", 1965.
2. V. T. Morozovsky. “Automation and telemechanics”, 1962, No. 9.
3. M. D. Mezarovich. Multiply connected control systems. Proceedings of the I FAC Congress, Ed. USSR Academy of Sciences, 1961.
2. Classification of ACP. Management principles.
Control- this is a targeted impact on an object, which ensures its optimal (in a certain sense) functioning and is quantitatively assessed by the value of the quality criterion (indicator). The criteria may be of a technological or economic nature (productivity of a process plant, cost of production, etc.).
During operation, output values deviate from specified values due to disturbances z V and a discrepancy appears between the current at T and given and 3 values of the output quantities of the object. If available disturbances z V the object independently ensures normal functioning, i.e., it independently eliminates any discrepancies that arise y T -i 3, then it does not need management. If the object does not ensure the fulfillment of normal operating conditions, then in order to neutralize the influence of disturbances, control action x P, changing the material or heat flows of the object using an actuator. Thus, during the control process, impacts are applied to the object that compensate for disturbances and ensure the maintenance of its normal operating mode.
Regulationcalled maintaining the output values of an object near the required constant or variable values in order to ensure the normal mode of its operation by applying control actions to the object.
An automatic device that ensures that the output values of an object are maintained near the required values is called automatic regulator.
According to the principle of regulation ASRs are divided into those operating by deviation, by disturbance and by a combined principle.
By deviation. In systems that operate by deviation of the controlled variable from the set value (Fig. 1-2, A), indignation z causes deviation of the current value of the controlled variable at from its set value And. The automatic regulator AR compares the values u and and, when they mismatch, it generates a regulatory effect X the corresponding sign, which through the actuator (not shown in the figure) is supplied to the control object OR, and eliminates this mismatch. In deviation control systems, mismatch is necessary to form regulatory influences; this is their drawback, since the regulator’s task is precisely to prevent mismatch. However, in practice, such systems have become predominantly widespread, since the regulatory influence in them is carried out regardless of the number, type and location of the appearance of disturbing influences. Deviation control systems are closed.
Out of outrage. When regulating by disturbance (Fig. 1-2, b) regulator AR B receives information about the current value of the main disturbance z 1. When measuring it and not matching with nominal meaning and B the regulator forms the regulatory impact X, directed to the object. In systems operating on a disturbance, the control signal travels along the circuit faster than in systems built on the principle of deviation, as a result of which the disturbing influence can be eliminated even before a mismatch occurs. However, it is practically impossible to implement disturbance-based control for most chemical technology objects, since this requires taking into account the influence of all disturbances of the object ( z 1, z 2, ...) the number of which is usually large; in addition, some of them cannot be quantified. For example, measuring such disturbances as changes in the activity of the catalyst, the hydrodynamic situation in the apparatus, the conditions of heat transfer through the wall of the heat exchanger and many others encounters fundamental difficulties and is often impracticable. Usually the main disturbance is taken into account, for example, by the load of the object.
In addition, signals about the current value of the controlled variable are sent to the system control loop by disturbances at do not arrive, therefore, over time, the deviation of the controlled value from the nominal value may exceed the permissible limits. Disturbance control systems are open.
According to the combined principle. With such regulation, i.e., with the joint use of the principles of regulation by deviation and disturbance (Fig. 1-6, V), it is possible to obtain high-quality systems . In them the influence of the main disturbance z 1 is neutralized by the AR B regulator, which operates on the principle of disturbance, and the influence of other disturbances (for example, z 2 etc.) - an AR regulator that responds to the deviation of the current value of the reacted quantity from the set value.
According to the number of controlled quantities ASRs are divided into one-dimensional and multidimensional. One-dimensional systems have one adjustable variable, the latter have several adjustable quantities.
In its turn multidimensional systems can be divided into unrelated and coupled control systems. In the first of them, the regulators are not directly related to each other and act separately on the common object of regulation. Systems unrelated controls are usually used when the mutual influence of the controlled quantities of the object is small or practically absent. Otherwise, systems are used related regulation, in which regulators of various quantities of one technological object are interconnected by external connections (outside the object) in order to weaken the mutual influence of the controlled quantities. If in this case it is possible to completely eliminate the influence of the controlled quantities on one another, then such a system of coupled regulation is called autonomous.
According to the number of signal paths ASRs are divided into single-circuit and multi-circuit. Single-circuit are called systems containing one closed loop, and multi-circuit- having several closed circuits
By purpose(the nature of the change in the reference influence) ASRs are divided into automatic stabilization systems, program control systems and tracking systems.
Automatic stabilization systems are designed to maintain the controlled variable at a given value, which is set constant ( u=const). These are the most common systems.
Program control systems constructed in such a way that the specified value of the controlled variable is a function of time known in advance u=f(t). They are equipped with software sensors that form the value And in time. Such systems are used to automate batch chemical processes or processes operating in a specific cycle.
In tracking systems the set value of the controlled variable is not known in advance and is a function of an external independent technological variable u=f(y 1). These systems serve to regulate one technological quantity ( slave), which is in a certain dependence on the values of another ( leading) technological value. A type of tracking systems are systems for regulating the ratio of two quantities, for example, the costs of two products. Such systems reproduce at the output a change in the driven quantity in a certain ratio with the change in the leading one. These systems seek to eliminate the mismatch between the value of the leading quantity, multiplied by a constant factor, and the value of the driven quantity.
By the nature of regulatory influences There are continuous ASR, relay and pulse.
Continuous ACPare constructed in such a way that a continuous change in the input value of the system corresponds to a continuous change in the output value of each link.
Relay (positional) ACP contain a relay link that converts a continuous input value into a discrete relay value that takes only two fixed values: the minimum and maximum possible. Relay links make it possible to create systems with very high gain factors. However, in a closed control loop, the presence of relay links leads to self-oscillations of the controlled quantity with a certain period and amplitude. Systems with position controllers are relay-based.
Pulse ASRcontain a pulse element that converts a continuous input quantity into a discrete pulse value, i.e., into a sequence of pulses with a certain period of their alternation. The period of occurrence of pulses is set forcibly. The input value is proportional to the amplitude or duration of the output pulses. The introduction of a pulse link frees the system's measuring device from the load and allows the use of a low-power, but more sensitive measuring device at the output that responds to small deviations of the controlled value, which leads to an increase in the quality of system operation.
In the pulse mode, it is possible to construct multi-channel circuits, which reduces the energy consumption for actuating the actuator.
Systems with a digital computing device in a closed control loop also operate in a pulsed mode, since the digital device produces the calculation result in the form of pulses following certain time intervals necessary for the calculations. This device is used when the deviation of a controlled variable from a set value must be calculated from the readings of several measuring instruments or when, in accordance with the criteria for the best quality of system operation, it is necessary to calculate a program for changing the controlled variable.
Issues covered in the lecture:
1. What consequences does the equality of the dynamics of direct and cross connections in the ASR of unrelated regulation lead to?
2. What operating frequencies are desirable to have in uncoupled control loops.
3. What is the complex coefficient of connectivity.
4. The principle of autonomy.
5. Condition of approximate autonomy.
Objects with multiple inputs and outputs that are mutually interconnected are called multi-connected objects.
The dynamics of multi-connected objects is described by a system of differential equations, and in Laplace-transformed form by a matrix of transfer functions.
There are two different approaches to automating multi-connected objects: unconnected control of individual coordinates using single-loop ACP; coupled regulation using multi-loop systems in which internal cross-connections of the object are compensated by external dynamic connections between individual control loops.
Figure 1 - Block diagram of unrelated regulation
In case of weak cross-couplings, the calculation of uncoupled regulators is carried out as for conventional single-circuit ACS, taking into account the main control channels.
If the cross-links are strong enough, then the stability margin of the system may be lower than the calculated one, which leads to a decrease in the quality of regulation or even loss of stability.
To take into account all the connections between the object and the controller, you can find an expression for the equivalent object, which has the form:
W 1 e (p) = W 11 (p) + W 12 (p)*R 2 (p)*W 21 (p) / . (1)
This is an expression for the controller R 1 (p), a similar expression for the controller R 2 (p).
If the operating frequencies of the two circuits are very different from each other, then their mutual influence will be insignificant.
The greatest danger is the case when all transfer functions are equal to each other.
W 11 (p) = W 22 (p) = W 12 (p) = W 21 (p). (2)
In this case, the setting of the P-regulator will be two times less than in a single-circuit ACP.
For a qualitative assessment of the mutual influence of control loops, a complex connectivity coefficient is used.
K St (ίω) = W 12 (ίω)*W 21 (ίω) / W 11 (ίω)*W 22 (ίω). (3)
It is usually calculated at zero frequency and the operating frequencies of both regulators.
The basis for building connected regulation systems is the principle of autonomy. In relation to an object with two inputs and outputs, the concept of autonomy means the mutual independence of the output coordinates U 1 and U 2 during the operation of two closed control systems.
Essentially, the autonomy condition consists of two invariance conditions: the invariance of the first output Y 1 with respect to the signal of the second controller X P 2 and the invariance of the second output Y 2 with respect to the signal of the first controller X P 1:
y 1 (t,x P2)=0; y 2 (t,x P1)=0; "t, x P1 , x P2 . (4)
In this case, the signal X P 1 can be considered as a disturbance for Y 2, and the signal X P 2 as a disturbance for Y 1. Then the cross channels play the role of disturbance channels (Figure 1.11.1 and Figure 1.11.2). To compensate for these disturbances, dynamic devices with transfer functions R 12 (p) and R 21 (p) are introduced into the control system, the signals from which are sent to the corresponding control channels or to the controller inputs.
By analogy with invariant ACP, the transfer functions of the compensators R 12 (p) and R 21 (p), determined from the autonomy condition, will depend on the transfer functions of the direct and cross channels of the object and will be equal to:
; 
, (5)
; 
. (6)
Just as in invariant ASRs, physical feasibility and technical implementation of approximate autonomy play an important role in constructing autonomous control systems.
The condition of approximate autonomy is written for real compensators, taking into account the operating frequencies of the corresponding regulators:
at w=0; w=w P2 , (7)
at w=0; w=w P1 . (8)
(a) – compensation of the impact from the second regulator in the first control loop
(b) – compensation of the impact from the first regulator in the second control loop
Figure 2 - Block diagrams of autonomous automated control systems
Figure 3 - Block diagram of an autonomous two-axis control system
In chemical technology, one of the most complex multi-connected objects is the rectification process. Even in the simplest cases - when separating binary mixtures - several interconnected coordinates can be identified in a distillation column. For example, to regulate the process in the lower part of the column, it is necessary to stabilize at least two technological parameters that characterize the material balance in the liquid phase and in one of the components.
Questions for self-control:
1. Definition and tasks of automation.
2. Modern automated process control system and stages of its development.
3. Management and regulation tasks.
4. Basic technical means of automation.
5. Technological process as a control object, main groups of variables.
6. Analysis of the technological process as a control object.
7. Classification of technological processes.
8. Classification of automatic control systems.
9. Control functions of automatic systems.
10. Selection of controlled quantities and control influence.
11. Analysis of statics and dynamics of control channels.
12. Analysis of input influences, selection of controlled quantities.
13. Determination of the level of automation of technical equipment.
14. Control objects and their main properties.
15. Open-loop control systems. Advantages, disadvantages, scope, block diagram.
16. Closed control systems. Advantages, disadvantages, scope, block diagram and example of use.
17. Combined control systems. Advantages, disadvantages, scope, block diagram and example of use.
18. Theory of invariance of automatic control systems.
19. Combined ACP.
20. Typical compensators.
21. Calculation of compensator.
22. What is the condition of approximate invariance.
23. At what frequencies is the compensator calculated under the condition of partial invariance?
24. Condition for the physical realizability of invariant ATS.
25. Cascade control systems.
26. What is an equivalent object in a cascade ACS.
27. What explains the effectiveness of cascade automated control systems.
28. Methods for calculating cascade automated control systems.
29. ASR with additional impulse based on the derivative from an intermediate point.
30. Scope of application of ASR with additional impulse on the derivative.
31. Calculation of ASR with additional impulse based on the derivative.
32. Interconnected regulatory systems. Decoupled regulatory systems.
33. What consequences does the equality of the dynamics of direct and cross connections in the ASR of unrelated regulation lead to?
34. What operating frequencies are desirable to have in uncoupled control loops.
35. What is the complex coefficient of connectivity.
36. Associated regulation systems. Autonomous ACP.
37. The principle of autonomy.
38. Condition of approximate autonomy.
o i i s l i n e viols
Union of Soviets
Socialist
Wrestblick
Automatic dependent certificate no.
Declared on November 11, 1965 (No. 943575/24-6) with the addition of application No.
UDC 621.165.7-546 (088.8) Committee on Affairs of Inventions and Discoveries under the Council of Ministers
V. B. Rubin, G. I. Kuzmin and A. V. Rabinovich;
Chg n,b, All-Union Thermal Engineering Institute named after. F. E. Dzernvzshchsky
Applicant
METHOD FOR REGULATING HEATING TURBINES
There is a known method of unrelated regulation of heating turbines, in which static autonomy is achieved by installing isodromic (or with low unevenness) regulators of each parameter.
This method cannot be used during parallel operation of several objects according to at least one of the parameters, because the parallel activation of isodromic regulators is unacceptable and, in addition, during parallel operation it is necessary to stabilize not the parameters, but the generalized forces of the objects acting on the parallel parameters. Therefore, when operating turbines in parallel, a more complex method of coupled control is used.
Coupled systems in principle provide not only static but also dynamic control autonomy in all conditions. However, achieving dynamic autonomy in most cases is associated with significant design difficulties, so in real systems, for economic reasons, complete BBTOHQM is rarely ensured. In addition, and from an operational point of view, it is only in very rare cases that the dynamic autonomy of the control loops must be observed. The transition from simpler uncoupled systems to more complex coupled systems is often dictated only by the impossibility of obtaining static autonomy in known uncoupled control schemes if parallel operation is necessary on any of the parameters. This transition leads not only to the complication of the scheme. In systems built using the method of coupled regulation, autonomy is achieved parametrically - by selecting the gain coefficients (transmission ratios) of cross connections between regulators. If the transmission ratios are constant, autonomy is not maintained in all modes. In unrelated regulation, autonomy is ensured compensatory (by regulators). In addition, the use of a coupled control system significantly complicates the methods of changing the structure of the circuit when transferring the turbine to special modes (for example, to work with back pressure, etc.). Stability issues are resolved satisfactorily with coupled and uncoupled regulation.
The proposed method allows to achieve
25 static autonomy in uncoupled control systems, both in isolated and parallel operation, and thereby eliminates the need to use complex non-compensation coupled control systems in heating turbines.
The essence of the invention lies in the fact that regulators of the derivative (mechanical) power of the turbine and the steam flow rate are introduced into the unconnected speed and pressure control loops as tracking subsystems.
The diagram of the proposed method is shown in the drawing. An executive circuit 2 for regulating the derivative (mechanical) power is introduced into the speed control loop 1 of the turbines, i.e., a control loop for the generalized internal force of the object acting from the turbogenerator on the system frequency.
The power control circuit is made in isodromes. The power regulator 8 receives tasks from the speed regulator 4, from the manual sensor 5, from the system regulators o and acts only on the high-pressure valves 7. An executive circuit 9 for stabilizing the steam flow is introduced into the pressure control circuit 8, i.e. the circuit is also introduced regulation of the generalized internal force of the object, acting from the side of the turbogenerator on the pressure in the selection. The flow regulator 10 receives tasks from the pressure regulator 11, from the manual set point 12, from the system regulators 18 and acts only on the low pressure channels 14.
The rest of the designations adopted in the drawing 1b - the produced (mechanical) power of the turbine, 1b - the steam flow directed by the turbine regulators to the extraction, 17 - we give out the (electrical) power of the generator, 18 - the steam consumption of the thermal consumer, 19 - the frequency (for isolated operation) or the phase angle of the generator (for parallel operation), 20 - pressure in the extraction (for isolated operation) or the pressure drop between the extraction chamber and the consumer (for parallel operation with steam).
When the unit operates in isolation according to the electrical and thermal load, static independence of regulation is ensured in the circuit in the same way as in conventional systems of uncoupled regulation of heating turbines. When there is disturbance from the heat consumer and the movement of the low-pressure valves, the speed of the turbogenerator is stabilized by the speed regulator (the power regulator makes this task easier, since it stabilizes the power of the turbine). In case of disturbance from an electrical consumer5
40 When moving high-pressure valves, the pressure in the outlet is stabilized by a pressure regulator; the flow regulator makes this task easier, as it stabilizes the flow.
Static independence is maintained in the circuit even during parallel operation of the turbogenerator under electrical load and thermal load. In this case, the circuit works as follows. In the event of disturbance from the electrical consumer (frequency change) and manual adjustment of the high-pressure control valves, the flow regulator maintains a constant pressure in the selection statically. In the event of disturbance from the heat consumer and rearrangement of the low-pressure valves, the constancy of the electrical load is ensured statically by the power regulator. The connections inherent in coupled control circuits (between the speed controller and the low pressure valves and between the pressure regulator and the high pressure valves) are absent in the system. Input of power and flow pulses into the turbine control system can be carried out through electro-hydraulic converters commercially produced by turbine-building plants.
With the most common operating mode of heating turbines - parallel operation of the electrical load and isolated operation of the thermal load (on isolated boilers) - the control method is simplified. In this case, the flow control loop 9 is not needed and only a power control loop is introduced.
Using the same principle, instead of pressure and flow control circuits, circuits for regulating the temperature of network water and flow rates can be introduced.
Subject of the invention
A method for regulating heating turbines equipped with unrelated speed and pressure control systems, characterized in that, in order to ensure static autonomy both in isolated and parallel operation, a power control circuit is introduced into the turbine speed control system, and a power control circuit is introduced into the pressure control system. ” control circuit for steam flow into the selection to neutralize the mutual influence of loads in static conditions.
Compiled by M. Mirimsky
Editor E. A. Krechetova Technical editor A. A. Kamyshnikova Proofreader E. D. Kurdyumova
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