JPH0329963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine control device that prevents damage caused by turbine thermal stress and the like due to a sudden increase in turbine output.

Power generation turbines normally control the speed of the driving medium by adjusting the drive medium using a signal that amplifies the deviation between the setter output and the actual speed, but when the turbine is connected in parallel to the grid and is operating synchronously, the turbine speed is determined by the grid frequency. The vehicle is forced to operate. Therefore, at this time, the actual speed is usually constant, so by operating the setting device, a corresponding deviation is obtained, the driving medium is adjusted accordingly, and the turbine output is controlled.

However, even in this parallel state, if the frequency suddenly drops due to a system failure, for example,
The speed deviation rapidly increases, and the speed governor operates to rapidly increase the turbine output by rapidly increasing the driving medium. This phenomenon occurs, for example, in the case of a steam turbine, where a large amount of high-temperature steam energy suddenly flows in, which not only disrupts the temperature balance inside the turbine and increases thermal stress, but also puts stress on the controlled turbine. There is a risk of disturbing the steam pressure and steam flow control of the boiler supplying steam, making the entire plant unstable.

Therefore, in order to prevent such a phenomenon, measures have been conventionally taken to prevent a sudden increase in the speed regulating signal (output control signal), which will be explained based on the example shown in FIG.

In FIG. 1, 1 is a turbine, 2 is a generator directly connected to the turbine, and 3 is a turbine speed detector.
Reference numeral 4 denotes a regulating valve for controlling the driving medium, which is controlled by the output signal of the output amplifier 12. 5 is a setter, which is compared with the actual speed by an adder 9.
The compared signals are calculated by the control calculator 10 and sent to the low value selector 11 as a speed regulating signal (output control signal). 6 is a control setting device for limiting the speed control signal, which is driven by the limit setting device operating motor 7, and its output is sent to the low value selector 1.
Sent to 1.

Reference numeral 8 denotes a tracking width setting device for causing the output of the limit setting device 6 to follow the output of the control calculator 10. 13 is an adder, 14 is a limiter, and 15 is an integrator, the output of which slowly follows the value obtained by adding the setting of the tracking width setting device 8 to the output of the control calculator 10.
The limiter 14 determines the following speed. 16 is an adder that compares the follow-up signal produced by this integrator 15 and the output of the limit setter 6; 17 is an output amplifier that calculates the deviation signal of the adder 6 and drives the operating motor 7; be.

In FIG. 1, when the output of the limit setter 6 is larger than the output of the control calculator 10, the speed regulating signal is used as the output control signal to control the regulating valve 4, so there is an output deviation between the setter 5 and the speed detector 3. The regulating valve 4 opens and closes depending on the increase or decrease in the number, and the turbine speed is controlled during independent operation, and the output is controlled during system parallel operation. On the other hand, if the output signal of the tracking width setter 8 is b, the output of the control calculator 10 is a, and the output of the integrator 15 is c, then a+b
>c, the output of the integrator 15 increases in the direction of a+b
When <, the output of the integrator 15 changes in the decreasing direction, and a
At the point when +b=c, the output of the integrator 15 stops increasing or decreasing, so c always slowly follows (a+b). This following speed is (a+b) and c
The deviation of is determined by the speed stored in the integrator, but since the magnitude of the deviation between (a+b) and c is limited to the maximum value d by the limiter 14, the integrator 15 determined by the input of this value The output change rate will be limited to Further, the limit setter 6 is operated by the operation motor 7, and this operation is performed by controlling the output amplifier 17 depending on the positive or negative difference between the output of the integrator 15 (a+b) and the output of the limit setter 6. It is increased or decreased through. Therefore, the output of the limit setter 6 always slowly follows the speed regulating signal, ie, the output of the control calculator 10, in the increasing direction by the output value b of the follow width setter 8.

Therefore, if a system accident or the like occurs and the turbine speed decreases at this point, the output of the control calculator 10 will increase rapidly, but the output of the limit setter 6 will follow the governor signal before the accident and the output of the width setter 8. Therefore, the output control signal is increased by the following width at most by the low value selector 11, and a large amount of driving medium than the setting does not flow into the steam turbine.

The above is an explanation of the prior art, but this also has the following drawbacks. That is, in order to always follow the speed regulating signal, it is necessary to provide a follow-up device with a rate of change limit such as shown in 13 to 17 in FIG. In addition, reliability decreased, and there was a high risk of sudden failure due to failure of the follow-up part.

Also, 6, 7, etc. are mechanical parts, and not only do maintenance of bearing oil be required due to frequent operations, but if 6 is made with a potentiometer when the load is frequently operated, the slider part may wear out. There was a fear that the output would suddenly increase due to wire breakage, etc.

Also, when the frequency suddenly decreases, the output will temporarily settle by increasing by the following width, but if this is left as is, as time passes, the output of the integrator 15 will follow the regulating signal after the system fault. As a result, the output increases to a value different from the initial target output, so in order to prevent this, the limiter 14 detects that the output of the low value priority circuit 11 is switched to the limiting signal.
Further, an interlock was required to set the limit value of 0 to zero and hold the output of the integrator 15.

Furthermore, in the conventional control device, there are three setting devices operated by the operator: the setting device 5, the limit setting device 6, and the following width setting device 8, which is cumbersome. For example, when you try to increase the output by more than the tracking width in a short time using the setting device 5, you must manually increase the limit setting device, but if you return the tracking to automatic, the value of the integrator 15 will change. Since the value before the operation is stored, it is necessary to wait for the tracking to be completed or to take measures such as increasing the tracking speed during manual operation.

An object of the present invention is to provide a control device that is highly reliable, easy for an operator to operate, and capable of limiting sudden changes in a speed regulating signal (output control signal).

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing one embodiment of the present invention. In Figure 2, 1, 2, 3, 4, 8, 1
0, 11, and 12 are the same as in FIG. 1, so their explanation will be omitted. 18 is a speed load setting device, 19, 20,
21 is an adder, 19 is a tracking width adder, 20
21 is a speed deviation adder, and 21 is a speed regulating adder.
Further, α is a reference speed, and during normal operation when no system fault occurs, the output of the speed detector 3 is equal to α, so both the input and output of the control calculator 10 are zero.

In FIG. 2, the output of the adder 19 is a limiting signal, which is the sum of the output e of the speed load setting device 18 and the output b of the following width setting device. The output of the adder 21 is a speed regulating signal, and the output e of the speed load setting device 18
and the output of the control calculator 10.

If the turbine is operating in synchronization with a healthy grid, the grid frequency is at the rated value and the actual turbine speed is also equal to the reference speed. Therefore, the input and output of the control calculator 10 are both zero, and the output of the adder 21, that is, the speed regulating signal, is equal to the output signal of the speed load setter 18. Therefore, if the output b of the following width setter 8 is positive, the speed regulating signal is selected by the low value selector 11, so that the output is controlled by the speed regulating signal. Therefore, the actual output decreases or increases around the value equivalent to the output of the speed load setter 18 as the actual speed, that is, the system frequency increases or decreases. If a system fault occurs in this state and the actual speed suddenly decreases, the speed governor signal increases rapidly, but if the increase exceeds the value set by the following width setting device 8, the low value selector 11
Since the limiting signal is selected by , an excessively rapid increase in turbine output is prevented.

Although the above explanation prevented a sudden increase in turbine output,
According to FIG. 2, there are further advantages as follows.

First, it eliminates the need for a follow-up device with a complicated change rate limiter and an operation motor as in the conventional technology, which not only reduces costs, but also improves reliability and maintains maintenance of mechanical parts by greatly reducing the number of parts. becomes unnecessary. In particular, the frequency of sudden output decreases and failures due to failures in the follow-up device section, wear of the follow-up width setting potentiometer, etc. can be greatly reduced, and safer plant operation can be expected.

Second, even if the allowable range of fluctuation at the time of a system accident occurs immediately after the accident or after a period of time has elapsed, unless the operator operates the following range setting device 8 or the speed load setting device 18 of his own will, the target value will not change. It is something that can be maintained.

Thirdly, only two setting devices are required for the operator to operate.
One example is that driving has become easier. That is, once the following width is determined, both the set value and the limit value can be changed at the same time simply by operating the speed load setting device 18, and there is no need to manually operate the limiter to follow each time and the follow-up speed of the follow-up device as in the past. Interlocks such as changes are not required.

Fourthly, if the following width setter is set to a negative value, limiter operation, that is, constant output operation that is not affected by the system frequency, is also possible by operating the speed load setter without changing the setting. For example, in a steam turbine, etc.
When the characteristics of the boiler are poor and frequent output fluctuations are not possible with so-called governor-free operation according to the system frequency, by setting the output b of the following width setting device 8 to be negative,
The output of adder 19 will be selected. In this case, the system frequency increases and the output of the control calculator becomes −
Until it goes down to |b|, it will be controlled by the output of the adder 19 regardless of the system frequency fluctuation, so the output in both the speed control operation and opening limit operation modes can be adjusted while operating the speed load setter 18. Control becomes possible.

Here, since α in FIG. 2 is a fixed value, the adder 21 multiplies α by the gain of the control calculator 10.
2, the block in FIG. 2 can be equivalently changed in terms of signal processing, such as eliminating the need for the adder 20.

Further, even if the output of the following width setter 8 is inputted in the subtractive direction to the regulating adder 21 on the regulating signal side rather than on the limiting signal side, the magnitude relationship between the limiting signal and the regulating signal does not change. During the restrictor operation shown in the above-mentioned fourth effect, this is rather preferable to the operator because the output of the speed load setting device 8 does not include the bias value and corresponds to the turbine output value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example, and FIG. 2 is a block diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Turbine, 2... Generator, 3... Speed detector, 4... Adjustment valve, 5... Setting device, 6... Limit setting device, 7... Limit setting device operation motor, 8...
Following width setter, 9, 13, 16, 19, 20, 2
1... Adder, 10... Control calculator, 11... Low value selector, 12... Output amplifier, 14... Limiter, 15... Integrator, 17... Output amplifier, 18
...Speed load setting device.

Claims (1)

[Scope of Claims] 1. A speed and load setting device for setting the speed or load setting value of the turbine according to the operating state of the turbine, and a permissible change in the driving medium for adjusting the steam supplied to the turbine. a following width setter for setting the width; a following width adder for adding the output signal of the speed load setter and the output signal of the following width setter; a speed regulating adder that adds a signal based on the deviation between the actual speed and the reference speed, and selecting the smaller of the output signal of the following width adder and the output signal of the speed regulating adder. A turbine control device comprising: a low value priority circuit that outputs an output to a driving medium of the turbine. 2. A speed/load setting device for setting a set value of the speed or load of the turbine according to the operating state of the turbine, and a speed/load setting device for setting an allowable change range of the driving medium for adjusting the steam supplied to the turbine. a following width setting device; and a regulating adder that adds a signal based on the deviation between the actual speed of the turbine and a reference speed to the output signal of the speed load setting device, and subtracts the output signal of the following width setting device. and a low value priority circuit that selects the smaller one of the output signal of the speed load setter and the output signal of the speed regulating adder and outputs it to the driving medium of the turbine. Turbine control device.