JPS62162703A - Turbine control device - Google Patents

Abstract

PURPOSE:To reduce pressure fluctuation, by providing a change rate restricting unit for restricting an opening of a turbine bypass valve to a rate less than a change rate corresponding to a response property of a system regulating valve provided with a system for regulating the opening of the turbine bypass valve. CONSTITUTION:Steam pressure d is compared with a set value 7 and a first opening command of a steam regulating valve 2 is applied to a pressure control unit 8. A turbine speed a is compared with a set value 11 and a command for opening the steam regulating valve 2 corresponding to a valve obtained by adding its deviation to a load set value 13 is produced. A change rate restricting unit 19 is interposed between a low value selecting unit 15 and a deviation calculating unit 17 and its output is subtracted from a steam flow rate command for pressure control for obtaining an opening command for a bypass valve 4. With such an arrangement, a difference between a steam regulating valve and a turbine bypass valve can be corrected for reducing pressure fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a turbine control device that controls the flow rate of steam in a turbine plant that includes a steam control valve and a turbine bypass valve.

[Technical background of the invention and its problems] In recent years, in steam power generation systems such as thermal power plants and yK sub-furnaces, the independence of the steam generator and turbine has been increasing when there is a significant change in operating conditions such as when starting up the plant or cutting off the system load. A turbine bypass system has been installed to enable operation of the plant and reduce the time required to start up and rejoin the plant.

FIG. 5 shows a conventional example, in which steam generated by the nuclear reactor 1 normally passes through the control valve 2 and drives the turbine 3, but when the load is cut off, etc.

When the turbine 3 becomes unable to receive steam.

The bypass valve 4 is configured to release this steam to a condenser (not shown). Here, the pressure d in the reactor l is
It is detected by the pressure generator 5 and input to the deviation calculator 6, where the deviation from the pressure setting value output from the pressure setting device 7 is calculated. The pressure control unit 8 receives this deviation signal, suppresses the expansion of the deviation, and calculates and outputs a steam flow rate command that keeps the pressure constant.

On the other hand, the speed a of the turbine is detected by the speed detector 9 and added to the deviation calculator 10, where the deviation from the speed setting value given by the speed setter 11 is calculated. The speed control unit 12 receives the deviation signal and calculates a steam flow rate command that suppresses the expansion of the deviation and keeps the speed constant. The sum of this steam flow rate command and the load setting signal from the load setting device 13 is calculated and outputted from the adder 14.

The low value selector 15 receives the two steam flow rate commands, selects the algebraic low value thereof, and applies it to the adjustment valve opening command and the adjustment valve opening controller 16. As a result, the opening degree of the regulating valve 2 is controlled. Further, the opening degree command of the bypass valve 4 is calculated and outputted in the deviation calculator 17 as the difference between the steam flow rate command for pressure control and the adjustment valve opening degree command, and the valve opening degree controller 1
8 controls the opening degree C of the bypass valve 4.

Generally speaking, in a boiling water type nuclear coupler, controlling the pressure in the reactor 1 is the first requirement for plant control, and therefore in normal operation, the load setting device 13
By setting the value relatively high, the low value selector 15 selects the pressure control side.

Therefore, the regulating valve 2 performs pressure control, and the opening degree command for the bypass valve 4 is O, so that the bypass valve 4 is fully closed.

At this time, the speed of the turbine 3 is changed by connecting a generator (not shown) connected to the turbine 3 to the grid.
The speed is controlled to the rated speed determined by the system frequency. Therefore, under normal turbine control conditions, the speed control side shown in the figure has no effect.

However, when there is no longer anything that restricts the generator speed due to system load cutoff, etc., and the speed a of the turbine 3 increases, the steam flow rate command for speed control is narrowed down, and the low value selector 15
selects the speed control side and uses this as the opening command for the control valve 2. At this time, the steam flow rate command for pressure control becomes greater than the adjustment valve opening command, and the deviation calculator 17 calculates and outputs the opening command for the bypass valve 4.

The configuration and operation of conventional control systems have been explained above.
This operation can only be achieved by assuming exactly the same response for the regulator valve 2 and the bypass valve 4. If there is a difference in response, the main steam flow rate will temporarily be too high or too short, causing pressure fluctuations. I may be invited. That is, as shown in Figure 6,
When the closing speed of the load disconnection and adjustment valve opening C is slow and the opening speed of the bypass valve opening C is fast, the sum of the flow rates of the adjustment valve 2 and the bypass valve 4 temporarily becomes an overflow, and the pressure d fluctuations occur.

In particular, in nuclear power plants, bypass valve 4 is mechanically designed to have a faster opening/closing speed than other steam valves in order to suppress fluctuations in I7I reactor pressure as much as possible. In the event of an abnormality such as a shutdown, the pressure d in the reactor 1 fluctuates, posing a safety problem for the reactor.

[Object of the Invention] The present invention provides a turbine control device that corrects the difference in response characteristics between a steam control valve and a turbine bypass valve without reducing the responsiveness of normal pressure control and speed control, thereby reducing pressure fluctuations. The purpose is to provide

[Summary of the Invention] The present invention applies a change rate limit to the steam control valve opening command according to the responsiveness of the steam control valve, and calculates the turbine bypass valve opening command based on this signal. be.

[Embodiments of the invention] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration diagram of a turbine control device according to an embodiment of the present invention, and the same reference numerals as in FIG. 5 indicate the same or corresponding parts. The difference from the configuration in FIG. 5 is that a change rate limiter 19 is provided between the low value selector 15 and the deviation calculator 17, and its output is subtracted from the steam flow rate command for pressure control, thereby reducing bypass. The point is that the structure is configured to obtain the opening degree command of 4.

FIG. 2 is a configuration diagram showing an example of the rate of change limit value 19.
A negative bias 22 or a positive bias 23 is constantly applied to the two integrators 20 and 21, and a change in the direction of decrease or increase at a constant rate of change is calculated. This rate of change limiter 1
The opening command e inputted to the opening command 9 is first compared with a decreasing direction signal at a constant rate of change in a high value selector 24, and by selecting the high value, the rate of change in the decreasing direction is limited. Thereafter, the low value selector 25 compares the increasing direction signal with a constant rate of change, and by selecting the low value, the rate of change in the increasing direction is limited. Further, the output of the low value selector 25 is fed back to the two integrators 20, 21 by two sample switches 26, 27, and the starting value of the integration in the next step is made to match the current output value. Here, the rate of change in the increasing direction and decreasing direction, that is, the bias 22.23 is set in advance according to the response characteristics of the regulating valve 2.

With the above configuration, 1 In the normal control state, the opening command e output from the low value selector 15 changes within the change rate limit range set in the change rate limiter 19, so that the change rate limit 1j
There is no effect due to the provision of l19, and the responsiveness of valve opening/closing control is no different from that of the conventional device. on the other hand,
In response to a sudden increase in the rotation speed of the turbine 3 due to system load cutoff, the low value selector 15 selects the speed control side and outputs the opening command e, but this opening command e causes the control valve 2 to suddenly increase. Therefore, the rate of change is limited by the rate of change limiter 19. As a result, the bypass valve opening degree C is
As shown in the time chart of Fig. 3, the total steam flow rate of the regulator valve 2 and bypass valve 4 is controlled to be just the right amount, and pressure fluctuations are controlled in order to respond at the same rate of change as the response of the regulator valve opening. It can be kept to a minimum.

Note that the configuration of the rate of change limiter 19 is not limited to that shown in FIG. 2, and may be configured as shown in FIG. 4, for example. That is, the opening degree of the regulating valve 2 is detected by the valve opening pressure regulator 28, the negative bias 22 is added thereto by the adder 29 to obtain the lower limit value, and the positive bias 23 is similarly added to this by the adder 30 to determine the upper limit value. The rate of change in the decreasing direction and increasing direction can be limited as in the above-mentioned embodiment, and the same effect can be expected.

[Effects of the Invention] As explained above, according to the present invention, normal pressure control,
The difference in responsiveness between the control valve and the bypass valve can be corrected without reducing the responsiveness of speed control, thereby providing a turbine control device with less pressure fluctuation.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a turbine control device according to an embodiment of the present invention, FIG. 2 is a block configuration diagram showing an example of the rate of change limiter of FIG. 1, and FIG. 3 shows the operation of FIG. 1. A time chart for explanation, FIG. 4 is a block diagram showing another example of the rate of change limiter shown in FIG. 1, FIG. 5 is a block diagram of a conventional turbine control device, and FIG. FIG. 2 is a time chart for explaining the operation of FIG. 1...Nuclear reactor, 2...Adjustment valve, 3...Turbine. 4... Bypass valve, 5... Pressure detector, 6... Deviation calculator, 7... Pressure setting device, 8... Pressure control unit,
9... Speed detector, 10... Deviation calculator, 11...
・Speed setter, 12... Speed control unit, 13... Load setter, 14... Adder, 15... Low value selector, 1
6... Valve opening controller, 17... Deviation calculator, 18.
Valve opening controller, 19... Rate of change limiter, 20.21
... Integrator, 22 ... Negative bypass, 23 ... Positive bypass, 24 ... High value selector, 25 ... Low value selector, 26.27 ... Sample switch. r−−=−−−−−−−−−−−−−−−−−−−−
---1------------------------1121 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A system that compares the steam pressure with a set value and outputs the first opening command for the steam control valve according to the deviation, and a system that compares the turbine speed with the set value and outputs a first opening command for the steam control valve according to the deviation and the sum of the deviation and the load set value. a system that outputs a second opening command for the steam control valve; a low value selection circuit that selects the lower value of the first and second opening commands and outputs it as a third opening command; A system that adjusts the opening of a steam control valve according to a third opening command; and a system that adjusts the opening of a turbine bypass valve according to a deviation between the third opening command and the first opening command. 1. A turbine control device comprising: a system for controlling the opening of the turbine bypass valve; and a rate-of-change limiter provided in the system for limiting the opening degree adjustment of the turbine bypass valve to a rate of change that corresponds to the response characteristics of the steam control valve.