JPH03111602A - Turbine controller - Google Patents

Abstract

PURPOSE:To avoid an unnecessary quick closing operation of a regulating valve due to a transient system disturbance or the like by providing a timer circuit for delaying the quick closing operation of the regulating valve by a set time when a load is interrupted during partial load running. CONSTITUTION:The output of a turbine 3 from an output detector 11 and the load of a generator 4 from a load detector 12 are inputted in a subtracter 13 to calculate the deviation of the turbine output from the generator load. The result of the calculation is sent through a comparator 14 to a timer 15. When the certain value or more deviation of the turbine output from the generator load is kept for at least the set time, the load interruption is judged to have occurred, so that an electromagnetic valve 10 is changed over to the fully closing direction of a regulating valve 2. The time set in the timer 15 is set by the output of a function generator 16 for receiving the output from the output detector 11. Thus, an unnecessary quick closing operation of the regulating valve 2 due to a transient system disturbance or the like can be avoided as long as the closing operation does not become inoperative when it is needed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a turbine control device, and more particularly to a turbine control device that quickly closes a regulating valve to prevent overspeed during load shedding. .

(Prior Art) A conventional turbine control device will be described with reference to FIG.

Steam generated in the steam generator 1 flows into the turbine 3 via the control valve 2, and rotates the turbine 3 and the generator 4 that is axially connected to the turbine 3.

The speed of the turbine 3 is detected by a speed detector 5 and the result is sent to an amplifier 6. The amplifier 6 operationally amplifies the deviation between the input speed signal and the rated speed, and outputs the result to the servo valve 7. The servo valve 7 controls the amount of oil supplied from the oil pump 8 based on the input signal, thereby controlling the position of the hydraulic cylinder 9 and controlling the opening degree of the adjustment valve 2.

When the opening degree of the regulating valve 2 is controlled, the amount of steam flowing into the turbine 3 from the steam generator 1 is controlled so that the turbine speed is equal to the rated speed, which is a constant value. The above is the speed control during steady state.

On the other hand, when load shedding occurs, the generator 4 becomes unloaded before the steam flowing into the turbine 3 is throttled, and the turbine speed increases rapidly. In that case, if the load before load shedding is above a certain value, the normal servo control will
The speed at which the regulator valve 2 is suddenly closed cannot keep up with the rapid increase in turbine speed, and as a result of the speed increase of the turbine 3, the emergency governor is activated and a turbine trip occurs. In order to avoid this, a solenoid valve 10 is usually installed in addition to the servo valve 7, and when load cutoff occurs from a load exceeding a certain value, the solenoid valve 10 is switched to rapidly drive the hydraulic cylinder 9. Adjustment valve 2 is suddenly closed.

In other words, an output detector 11 is attached to the turbine 3, and a load detector 12 is attached to the generator 4, and a subtracter 13 calculates the deviation between the two, which is input to a comparator 14 to detect a value exceeding a certain value. In this case, it is determined that a load cutoff has occurred from a load exceeding a certain value, and the solenoid valve 10 is switched to rapidly supply the oil supplied by the oil pump 8 to the hydraulic cylinder 9, thereby quickly closing the regulating valve 2. The speed increase of the turbine 3 is suppressed. The control logic is shown in FIG.

Further, FIG. 4 shows the relationship between the load immediately before load shedding and the turbine speed increase when controlled by such a speed control method.

(Problem to be Solved by the Invention) Generally, when a load shedding occurs and the regulator valve 2 suddenly closes, the plant must have sufficient bypass capacity (steam generated in the steam generator 1 bypasses the turbine 3 and is directly condensed). If there is no capacity for discharging into a vessel, there will be nowhere for the steam to go,
Steam generator 1 also needs to be tripped. Particularly in the case of a nuclear power plant, once the steam generator 1 trips, it takes a long time to restart it, so it is desirable to not operate the solenoid valve 0 as long as it does not cause any problems.

In addition, there may be cases where the operating conditions for the solenoid valve 10 are instantaneously established due to a temporary system disturbance, etc., rather than a true load shedding, and the solenoid valve 10 is immediately reset, or even if it is a true load shedding. Depending on the size of the steady load, the solenoid valve 10
If the speed does not rise to the operating point of the emergency governor even if the operation is slightly increased, there is no need to immediately operate the solenoid valve 10. In the conventional turbine control device, the solenoid valve 10 operates too quickly, so there is a problem that the solenoid valve 10 operates even when unnecessary, such as in the case of the above-mentioned transient system disturbance.

The present invention has been made in consideration of the above circumstances, and is a turbine control device that is capable of avoiding unnecessary operation of a solenoid valve during a temporary system disturbance to the extent that it does not become inoperable when necessary. The purpose is to provide

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a means for solving the problems when load shedding occurs during turbine operation.
In a turbine control device that maintains the turbine overspeed below a certain value by rapidly closing the regulator valve that controls the flow of steam into the turbine, if a load shedding occurs during partial load operation, the regulator Equipped with a timer circuit that delays the valve sudden closing operation by a set time determined as a function of the turbine output at the time of load shedding, to avoid unnecessary adjustment valve sudden closing operations due to temporary system disturbances, etc. It is.

(Function) By causing the timer circuit to rapidly close the regulator valve for a period of time set by the turbine output, unnecessary rapid closing operations of the regulator valve during transient system disturbances are prevented. The setting time of the timer is preset to a time such that even if a true load shedding occurs at that time, the speed increase of the turbine will not reach the operating point of the emergency governor.

(Example) An example of a turbine control device according to the present invention will be described with reference to the accompanying drawings.

In Fig. 1, the steam generated in the steam generator 1 is transferred to the control valve 2.
The water flows into the turbine 3 via the turbine 3 and rotates the turbine 3 and the generator 4 coaxially connected to the turbine 3. A speed detector 5 is attached to the turbine 3, and a turbine speed signal detected by the speed detector 5 is sent to an amplifier 6.

The amplifier 6 calculates the difference between the input turbine speed signal and the rated speed of the internal turbine, and sends the speed deviation to the turbo valve 7. Based on the input speed deviation, the servo valve 7 controls the amount of oil sent from the oil pump 8, controls the position of the hydraulic cylinder 9, and controls the opening degree of the adjustment valve 2. When the opening degree of the regulating valve 2 is controlled, the amount of steam flowing into the turbine 3 from the steam generator 1 is controlled so that the turbine speed is equal to a constant control speed.

On the other hand, an output detector 11 is attached to the turbine 3, and a load detector 12 is attached to the generator 4. Turbine output from output detector 11 and load detector 1
The generator loads from 2 are each input to a subtractor 13,
A subtracter 13 calculates the turbine output minus the generator load.

The calculation result is sent to the comparator 14, and the output of the comparator 14 is sent to the timer 15, and load shedding occurs when the deviation between the turbine output and the generator load continues to be a certain value or more for a set time or more. It is determined that the solenoid valve 10 is switched. By switching the solenoid valve IO, the oil supplied by the oil pump 8 is switched in the direction of fully closing the regulating valve 2 and sent to the hydraulic cylinder 9.

The output of the output detector 11 is input to the function generator 16 so that the set time can be variably set according to the turbine output, and the set time of the timer 15 is set by the output of the function generator 16. Incidentally, the relationship between the settings of the turbine output upper timer 15 during load interruption, that is, the characteristics of the function generator 16, is shown in FIG.

Next, the operation will be explained with reference to FIG.

A subtractor 13 calculates a deviation between the turbine output detected by the output detector 11 and the generator load detected by the load detector 12, and a comparator 14 determines whether the deviation is larger than a certain value ( SL). As a result, if the speed is below a certain value, normal speed control is performed by the servo valve 7 (S2). Further, if the turbine output is above a certain value, the set time of the timer 15 is set using the function generator 16 based on the turbine output detected by the output detector 11 (S3). In this way, it is determined whether the deviation between the turbine output and the generator load continues to be greater than the specified value within the set time (S4), and if so, it is assumed that a true load shedding has occurred. The control valve 2 is suddenly closed by switching the electromagnetic valve 10 (S5), and if not, normal speed control is continued as it is not a true load shedding but a temporary system disturbance (S2).

Next, we will discuss the settings of the comparator 14 and the timer 15 in the fourth section.
This will be explained based on the diagram.

FIG. 4 shows the relationship between the turbine speed increase after load shedding and the turbine output at the time of load shedding when load shedding occurs. Regardless of the prior art or the present invention, when a load cutoff occurs from an output smaller than the solenoid valve operating point shown in FIG. 4, the solenoid valve 10 is not switched and the servo valve 7 is
The speed increase is suppressed by normal speed control. As the turbine output increases at the time of load shedding, the energy held within the turbine at that point also increases, so if normal servo control is used, the speed increase after load shedding increases and approaches the emergency governor-like operating point. According to the Ministry of International Trade and Industry's ``Technical Standards for Thermal Power Facilities for Power Generation,'' turbines must have a speed governor that can suppress the speed increase during load shedding to below the emergency governor-like operating point. There is. Therefore, the solenoid valve 10
This is to suppress the increase in speed. However, in the case of a conventional control device, when load interruption occurs (large deviation between turbine output and generator load), the solenoid valve
Since we are operating 0, as shown by the solid line in Figure 4,
When a load shedding occurs from a load near the solenoid valve operating point, the speed increase is much lower than the emergency governor-like operating point. The amount of speed increase increases as the load immediately before load shedding increases. On the other hand, as in the above embodiment, the function generator 1 having the characteristics shown in FIG.
By delaying the operation of the solenoid valve 10 by the set time of the timer 15 set by 6, the relationship between the load shedding turbine output and the speed increase after the load shedding becomes as shown by the chain line in FIG. Even in this case, the speed increase is controlled below the emergency governor-like operating point.

According to the conventional device, when the deviation between the turbine output and the generator load exceeds a certain value even momentarily, the solenoid valve 10 operates and the control valve 2 is suddenly closed. That is, there is a problem in that even a temporary system disturbance causes the control valve 2 to suddenly close, which is not originally necessary. In contrast, according to the above embodiment, by delaying the operation of the solenoid valve 10 as much as possible from the viewpoint of preventing a speed increase during load shedding, unnecessary operation of the control valve 2 is avoided during a temporary system disturbance. This has the effect of reducing the probability of sudden closure.

〔Effect of the invention〕

The present invention is equipped with a timer circuit that delays the quick closing operation of the regulator valve by a set time determined as a function of the turbine output at the time of load shedding when a load shedding occurs during partial load operation. Unnecessary sudden closing of the control valve due to disturbance etc. can be avoided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a turbine control device according to the present invention, FIG. 2 is a characteristic diagram showing the characteristics of the function generator in the above embodiment, and FIG. 3 is a control logic of the above embodiment. Flowchart, FIG. 4 is a characteristic diagram showing the relationship between the turbine output at load shedding and the speed increase after load shedding in the present invention and the conventional device, FIG. 5 is a configuration diagram showing the conventional turbine control device, and FIG. 6 is a flow diagram showing control logic in a conventional device. DESCRIPTION OF SYMBOLS 1... Steam generator, 2... Control valve, 3... Turbine, 4... Generator, 5... Speed detector, 6... Amplifier,... Servo valve, 8... ...Oil pump, 9...Hydraulic cylinder, 10...Solenoid valve, 11...Output detector, 12...Load detector, 13...Subtractor, 14...
-Comparator, 15...Timer, 16...Function generator.

Claims (1)

[Claims] A turbine control system that maintains the turbine overspeed below a certain value by rapidly closing the regulator valve that controls the flow of steam into the turbine when a load shedding occurs during turbine operation. When a load shedding occurs during operation, the control valve is equipped with a timer circuit that delays the sudden closing operation by a set time determined as a function of the turbine output at the time the load shedding occurs, to prevent unnecessary adjustment due to temporary system disturbances, etc. A turbine control device characterized in that a sudden valve closing operation is avoided.