KR800000720B1 - Control system for a nuclear power producing unit - Google Patents

Abstract

A control system for a nuclear power producing unit comprises a pressurized water reactor(1), a once-through steam generator(3) provided with feedwater supply means, a turbine generator (13) supplied with steam from the steam generator, means for maintaining a flow of pressurized water(7,8) through the reactor, the second means for adjusting the reactor heat release, and the third means for adjusting the rate of flow of feedwater to the steam generator.

Description

Control system for nuclear power plant

FIG. 1 is a schematic diagram of a nuclear power plant using a pressurized water reactor, and the first controller and the final control elements in the control system shown in FIG. 2 and FIG.

2 is a logic diagram specifically showing the control system of the present invention applied to the nuclear power plant shown in FIG.

3 is a logic diagram showing a typical arrangement for determining the deviation of critical system parameters from a fixed point.

The present invention is directed to a control system for a nuclear power plant having a nuclear reactor for supplying steam to a prime mover such as a turbine generator after heating a coolant such as pressurized water at high pressure to pass and circulate several steam generators in parallel. It is about. Depending on the size, the reactor of such a device may have a heat output of more than 3,400 megawatts (Mw) and a pure electrical output of 1,200 megawatts (Mw).

According to the present invention, the main feed water forward control signal corresponding to the desired power output or demand power output includes the reactor heat output required to meet the power demand and the water supply amount to the steam generator required to maintain the critical system parameter at a fixed point. The total speed of the steam and the total speed of the steam flow from the steam generator are adjusted in parallel through separate discrete control loops.

According to the present invention, the feedwater forward control signal going to each discrete control loop is a reactor heat output required to meet the power demand due to a change in cycle efficiency by correcting the difference between the demand power output and the actual power output by time integration. Changes consistent with the flow rate at the steam generator and the flow rate from the steam generator to the steam generator required to maintain the critical system parameters at fixed points are continuously adjusted under steady-state conditions.

In addition, according to the present invention, the feed water forward control signal to each discrete control loop is modified to be proportional to the temporary change in the demand power output and the actual power output and the critical system parameter difference.

In addition, according to the present invention, the state speed of the water supply amount up to the steam generator is further adjusted in proportion to the change in the relative speed of the coolant flow rate through the steam generator, and the relative speed of the water supply amount up to the steam generator is adjusted by the water supply temperature difference introduced into the steam generator. The relative speed of feedwater up to the steam generator is further adjusted by time integration of the average coolant temperature difference in the steam generator.

The object of the present invention will be described in detail with reference to the following drawings.

1 shows a pressurized water reactor 1 maintained at a predetermined operating pressure by a pressurizer 2. Reactor coolant, such as pressurized water, is circulated separately through once reactor steam generators 3 and 4 through reactor 1 and into parallel coolant flow loops A and B. The amount of coolant flow through the loop A is set and maintained by the circulation pumps 7 and 8 arranged in parallel.

Steam from generators 3 and 4 passes through conduit 11 and is transported to a turbine device indicated by the sign 12, which is in the middle of the high pressure (HP) device or the sign 14. It consists of voltage and low voltage (IP & LP) devices. The high pressure device 13 and the medium and low pressure device 14 operate only one generator 15 to generate electrical power and to be transmitted by the conductors 16, 17 and 18 therefrom. Optionally, each turbine unit may be arranged to operate a generator individually connected to each turbine to supply all power to the common bus.

The steam enters the high pressure device 13 through a conventional flow control valve device schematically shown at 11 and passes through a conduit 20 into the reheater 21, which is reheated 21. Heated steam from the conduit (11) is provided through the branch pipe (22).

The hot reheat steam is then passed through conduit 23 to the medium and low pressure apparatus, from which it enters the condenser 24.

The plurality of water coming out of the condenser 24 is pumped by the plurality of pumps 25 and passed by the low pressure heater string 26 and heated by the extraction steam from the medium and low pressure devices 14. The feed water is sorted out in parallel from the low pressure heater string 26 by the boiler feed pumps 27 and 28.

The water discharged from the boiler feed pump 27 passes through the high pressure heater 29 which is heated by the extraction steam from the high pressure device 13 and enters the steam generator 3. The water discharged from the boiler feed pump 28 also enters the steam generator 4 through the high pressure heater 30 which is heated by the extraction steam from the high pressure device 13.

2 is a logic diagram of the control system. The load demand of the nuclear power generation facility is set by an automatic load supply system shown by reference numeral 32 or another kind of automatic and manual device to generate a main water feed forward control signal. The feedwater main control signal determined by the apparatus 33A (with the maximum limit) corresponding to the reactor's capability at full load due to all auxiliary devices of the actual cost of nuclear power generation in operation, is a signal conductor (34). To the steam flow to the high-pressure turbine device (13), to the feedwater supply to the steam generators (3) and (4), and to the nuclear or heat output (Nd) of the reactor (1). Through parallel adjustment, the actual power output of the nuclear power plant is substantially maintained.

The feedwater main control signal is input to the discrete control loop individually through the function generators 61A, 62A and 63A. The purpose of this signal is to modify the main feedwater advance control signal at the time of normal operation and cycle efficiency. Determine the total speed of feedwater up to the steam generator required to maintain the reactor heat generation and critical system parameters required to meet existing demand power and the steam flow from the steam generator. In addition, each control loop is individually provided with a correction signal, as described in detail later, so that the actual power output must remain somewhat the same as the demand power output, and the critical system parameters can be changed in cycle efficiency and operating conditions. Remains at a fixed point despite single or multiple changes.

In the drawing, a conventional control logic circuit is used. Control components, commonly referred to as hardware, represented by these codes are commercially available and their operation is well known. Conventional logic codes have also been used to avoid homogeneity with control systems consisting of pneumatic, hydraulic, electric digital and combinations of these with special types of control, which may be incorporated into any one of these types. Because there is. It is further noted that the main controllers shown in the logic diagram are also associated with FIG. 1, with the final control elements.

Horizontal signals in one or more of the second degrees, separately applied to each discrete control loop, include megawatt error (MWe), throttle pressure error (TPe), feed water temperature error (FWTe) and reactor coolant temperature error. (RCTe).

3 is a logic diagram of a sub-loop for the generation of these correction signals. The feed water forward control signal is transmitted to the function generators 35, 36, 37, and 39 through the entirety of the signal diagram 34, and the purpose of the function generator is to adjust the feed water advance control signal and output it therefrom. The signal then causes a correction or fixed value of variability associated with the magnitude of the existing main water forward control signal. The function generator 35 generates a fixed point signal corresponding to the pressure of the calibration trolley for the existing main feed water forward control signal, which is compared with the signal generated by the regulating pressure transmitter 41 and the comparison device 40. Is compared to generate an output signal corresponding to the throttle pressure error (TPe).

The error signal corresponding to the time wattage error MWe is generated by comparing the output signal from the function generator 36 with the output signal generated by the megawatt transmitter 42 in the comparator 43.

A signal coinciding with the mean feed water temperature error FWTe is generated by averaging the feed water temperature errors FWTeA and FWTeB in loops A and B, respectively. Therefore, as shown in the drawing, the output signal from the function generator 37 having the normal feed water temperature in relation to the load demand and having all the extracted feed water heaters operates in the loop A generated by the feed water temperature transmitter 46 The signal corresponding to the actual water supply temperature is compared in the comparison device 44A. In the same way, the output signal from the function generator 37 is compared in the comparison device 44B with a signal corresponding to the actual feed water temperature in the loop B generated by the feed water temperature converter 47. The output signals from the comparators 44A and 44B are input to the summing device 45 which generates an output signal FWTe corresponding to the average water supply temperature error.

The signal coinciding with the coolant temperature error (RCTe) entering or exiting the reactor is generated by comparing the output signal from the function generator 39 with the signal corresponding to the average coolant temperature in the comparator 50 and entering or exiting the reactor. The average coolant temperature coming out is generated in the summation device 51 which averages the signals generated in the summation devices 52 and 53. The adder 52 averages the signals generated by the temperature transmitters 54 and 55 that correspond to the temperatures of the coolant entering or exiting the reactor 1 in the loop A.

In the same way, the summation device 53 also averages the signals generated by the temperature transmitters 56 and 57 corresponding to the temperature of the coolant entering or exiting the reactor 1 in the coolant loop B.

Item-specific error signals of FIG. 2 are applied to one or more calculation devices. In order to avoid the complexity in the drawings, the error signals from the comparators 40, 43, 45, and 50 are not shown in their entirety. For example, it is apparent that the signal TPe generated by the comparison device 40 is applied to the calculation device shown as this input.

Regarding the discrete control loop in FIG. 2 for the turbine steam flow, feed water and reactor heat output, an error signal is introduced through the integrators 58, 59 and 60 from which the output signals are multiplied. It is transmitted to the devices 61, 62 and 63 to actuate the correction of the steady state correction to match the main water feed forward control signal.

As shown, other signals are also introduced into summing devices 64, 66 and 66 to actuate the bias correction to match the main water feed forward control signal proportional to the temporary change in the luncheon signal.

This particular error signal, applied to correct steady state correction, bias correction, or temporary correction, depends on the discrete control loop in question. For the reactor heat output control loop, the quartz feed forward control signal set by the function generator 63A operates the control rod drive 102 to maintain the reactor heat output equal to the output required to meet the load demand under steady state conditions. .

In order to correct the steady state correction, a megawatt error is introduced through the integrator 6 and the multiplier 63. The throttle pressure error and megawatt error, signals that provide bias correction and temporary correction to match the coolant temperature error entering or exiting the reactor, are introduced via summing device 66. Positioning the control rod drive device 102 in place to maintain the heat output to the real atom corresponding to the control signal from the summing device 66 by the local feedback loop forming the comparator 103, from the summing device 66 The output signal coming out is compared in the comparison apparatus 103 with a signal corresponding to the actual nuclear power Ni generated in the nuclear transmitter 48. The output signal from the comparator 103 through the proportional integral device 104 controls the operation of the control rod drive device 102 to maintain the power output of the power generation facility at the output value set by the summing device 66. Maintain an actual nuclear power output equal to the required power.

For the turbine steam flow control loop, the quartz feedwater forward control signal actuates the turbine control valve 19. The control signal transmitted to the control valve 19 is applied to any particular type of turbine control valve mechanism via an A / D circuit or the like.

The throttle pressure error introduced through the integrator 58 reduces the turbine valve position and thus reduces the steam pressure below the fixed point, thereby reducing the demand for steam flow rate and vice versa. The signal proportional to the megawatt error is subtracted from the throttle pressure error in the comparator 70 to prevent inadequate steady state calibration of the steam flow.

Signals proportional to the average coolant temperature error, feed water temperature error, throttle pressure error, and megawatt error are applied to the feed water forward control signal in the summing device 64 with appropriate gain bias correction. A decrease in the average coolant temperature during operation results in a reduction in the turbine steam flow, and a decrease in the feed water temperature due to the shutdown of the feed water heater reduces the steam flow and compensates for the reduction in the extraction flow and thus may result from other means. Avoiding a temporary increase in the throttle pressure decreases the turbine steam flow, while a decrease in power output results in a reduction corresponding to the turbine steam flow. The proportional correction applied through summing device 64 serves to stabilize the operation of the nuclear power plant when in a temporary state. The control signal from the summing device 64 is transmitted to the turbine control valve 19 which is the final control element. In order to survive the unchanged relationship between the control signal from the summing device 64 and the speed of the turbine steam flow, a localized loop is provided. The signal corresponding to the actual turbine steam flow rate is generated in the first stage pressure transmitter 71 and compared with the output signal from the summing device 64 in the comparison device 72. The signal generated by the proportional integration device 73 adjusts the turbine control valve to keep the signal generated by the transmitter 71 the same as the output signal from the summing device 64.

As described in detail above, the turbine steam flow control valve 19 is positioned to maintain the turbine steam flow required by the output signal from the summing device 64. If necessary, as described in US Pat. No. 3,894,396, issued July 15, 1975, limiting control may be introduced into the steam flow control loop, whereby the rate of steam flow to the turbine may be throttled from a fixed point exceeding a predetermined limit. Adjust to prevent pressure runaway.

With regard to water supply control, the total water supply is maintained in proportion to the individually corrected water supply control signal, and the water supply to the steam generator 3 is equal to the loop (A) as long as it is related to the water supply to the other steam generator (4). In (B), the average coolant temperature is adjusted to remain the same.

The water feed forward control signal modified in the water generator 62A operates the valve 75 for adjusting the water supply amount to the steam generator 3 and the valve 76 for adjusting the water supply amount to the steam generator 4 in parallel. The total water supply to the steam generators 3 and 4 remains the same as the demand by the feedback loop, which consists of the flow transmitter 77, the comparator 78 and the proportional integral device 79. The output signal generated by the proportional integration device 79 is transmitted to the summing devices 82 and 83 through the conductors 80 and 81, respectively, and the same steam flow rate to the steam generators 3 and 4, respectively. Is adjusted to achieve. Therefore, the steam output from the steam generator in the steady state remains the same. The local feedback loop is provided for the steam generator 3 composed of the flow rate transmitter 84, the comparator 85 and the proportional integral device 86.

Similarly, the same feedback loop was provided for the steam generator 4 composed of the flow transmitter 87, the comparator 88 and the proportional integral device 89. Therefore, the amount of water supplied to the steam generator 3 is maintained in proportion to the output signal from the summing device 82, and the amount of water supplied to the steam generator 4 is maintained in proportion to the output signal from the summing device 83. Summarizing what has been described so far, the water supply control operates to maintain the total amount of water supplied to the steam generators 3 and 4 proportional to the signal generated by the adding device 65, and simultaneously from the adding device 82. The water supply amount to the steam generator 3 proportional to the output signal coming out and the water supply amount to the steam generator 4 proportional to the output signal coming out from the summing device 83 are maintained. However, the equivalence of the water supply to the steam generators 3 and 4 means that modifications are continuously made to keep the average cooling temperatures in loops A and B equal.

As shown in FIG. 3, the output signal from the adder 52 is proportional to the average coolant temperature in the loop A entering and exiting the reactor 1, and the output signal from the adder 53 or the reactor 1 Is proportional to the average coolant temperature at loops (B) entering and exiting As shown in FIG. 2, an output signal proportional to the coolant temperature difference in the loops A and B is generated in the comparator 90, and is added to the summation device through the proportional integration device 91 and the summation device 92. As shown in FIG. It is input to a multiplier 93 which receives an output signal from 65. Therefore, the feedwater forward control signal for determining the speed of the feedwater amount to the steam generator 3 is modified according to the average coolant temperature difference in the loops (A) and (B).

If the average coolant temperature in the loop A is less than the average coolant temperature in the loop B, the water supply to the steam generator 3 will be reduced, and vice versa.

At the same time, the control according to the change in the water supply amount to the steam generator 3 operates to cause the same change to occur rather than the opposite change in the water supply amount to the steam generator 4. The output signal indicating the demand of the water supply amount to the steam generator 3 and output from the multiplication device 93 is applied to the comparator 95 through the signal conductor 94, and thus the output signal from the summing device 65. Subtract the quantity corresponding to the water supply demand for the steam generator (3).

Therefore, the output signal from the comparator 95 proportional to the difference between the demand of the total water supply and the water supply acceptance of the steam generator 3 is the fixed water supply demand for the steam generator 4.

The over ride control due to the average coolant loop temperature difference is very precise, but the response is relatively slow because of the dependence on the temperature measurement, which has a relatively long time constant. Compared to other steam generators 4, it is possible to sufficiently adjust the changes in average coolant temperature caused by the gradual neutralization of the steam in the steam generator 3.

Moreover, in order to adjust for a potentially rapid and violent catastrophic change in average coolant temperature that may be caused by a stop of the coolant pump, the present invention pushes the immediate changes in the relative speed of the feedwater flow rate to the steam generator. A push-pull approach is used to approach the final change in mean coolant loop temperature difference. Continuing with this approach, this control, operating due to the mean coolant loop temperature difference, introduces continuous changes relatively slowly until the mean coolant loop temperature recovers equally.

This principle in FIG. 2 shows the adaptation to a drastic change in coolant flow that may be caused by the loss of coolant pump in loops (A) or (b). Any change in the coolant flow rate in the loop A compared to the coolant flow rate in the other loop B results in a change in proportion to the relative velocity of the feedwater to the steam generator, resulting from the change in the relative coolant loop flow rate. Average coolant temperature changes can be expected. The function generator 96 generates an output signal corresponding to the coolant flow rate through the loop A as determined by the flow rate transmitter 97. The function generator 98 generates an output signal corresponding to the coolant flow rate passing through the loop B as determined by the flow transmitter 99. These two output signals are compared in the comparator 100, and the output signal from the comparator is input to the summing device 92. For example, with a decrease in the coolant flow rate through the loop A caused by the stop of the coolant pump 7, this control operates to proportionally reduce the water supply to the steam generator 3, It causes an increase in proportion to the water supply for (4), and vice versa. This control, which then uses the mean loop temperature difference, corrects for changes in the relative velocity of the water supply based on the fundamental principles that continue until equal to the mean loop temperature. This principle is shown in FIG. 2, which is applied to predict the mean coolant loop temperature difference caused by the change in the relative feedwater temperatures for the steam generators 3 and 4 resulting from the stop of the feedwater heater. For example, the expected result when the feedwater heater 29 is stopped is that the coolant temperature entering the reactor 1 from the steam generator 3 decreases, so that the average coolant temperature of the loop A is lowered. .

The present invention anticipates this change by causing an immediate change in the rate of feedwater up to the steam generator. The bias control action from the comparator 101 acting on the summing device 92 to the booster 93 increases the water supply to the steam generator 4 and reduces the water supply to the steam generator 3.

For simplicity of the present specification, drawings and descriptions related to well-known types that are not in close proximity to the present invention are omitted. Thus, the steam generators 3 and 4 in FIG. 1 were provided with multiple parallel tubes which are routinely used in single-use steam generators. Likewise, the control rod drive 102 and the reactor power transmitter 48 are shown in block diagrams to indicate that any of several types of control systems are available for adjusting the nuclear levels and their associated measurements. Also included are conventional defense systems and limiting controls used in nuclear power plants. These systems and controls do not form part of the present invention and are therefore omitted from the drawings and description.

The illustration and description are only one example of a control system, the invention being defined in the appended claims.

Claims (1)

As shown and described in detail in this text, the reactor uses pressurized coolant, a once-throug steam generator equipped with a water supply device, a turbine generator supplied with steam from the steam generator, and a coolant flow through the reactor and the steam generator. In the control system for a nuclear power plant consisting of devices for maintaining the power supply, it is a feedwater forward control signal generator that is proportional to a constant nuclear power output of the nuclear power plant, the rate of supply to the reactor heat generation and steam generators A nuclear power plant characterized in that the reactors are operated in parallel in response only to the forward control signal, and are constituted by devices in which the heat generation of the reactor to the steam generator and the water supply rate are combined so as to maintain a separate functional relationship with the feedwater forward control signal. Control system.

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