JPH024762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine control device, and more particularly to a turbine control device having a plurality of valves.

Generally, a turbine control device can be roughly divided into two components: a speed control section and a valve opening control section.

That is, as shown in FIG. 1, the turbine control device 1 includes a speed control section 2, a valve opening degree control section 3,
A speed command a is input to the speed control section 2 . On the other hand, the speed of the turbine is detected by a speed detector 5 and inputted to the speed control section 2 as an actual speed signal b. The speed control unit 2 compares and calculates the speed command a and the actual speed signal b, and sends a valve opening command c to the valve opening control unit 3 so that the two match. On the other hand, the opening degree of the valve 6 is detected by a valve opening degree detector 7 and inputted to the valve opening degree control section 3 as an actual opening degree signal d. The valve opening degree control section 3 compares and calculates the valve opening degree command c and the actual opening degree command d, and outputs an opening degree adjustment signal e so as to make both coincide.
is output to the valve drive section 8. The valve drive unit 8 increases or decreases the valve opening according to the opening adjustment signal e, and uses the valve 6 to adjust the flow rate of steam flowing into the turbine 4. Thereby, the turbine 4 is accelerated or decelerated according to the amount of incoming steam and the actual load, and finally enters steady operation in a state where both are balanced.

Although only one valve 6, that is, a steam control valve is shown in the figure, a plurality of valves 6 are normally provided for reasons such as improving reliability and accuracy in turbine control.

By the way, conventionally, the turbine control device 1,
In particular, since the valve opening control section 3 was composed of an analog operational amplifier, and a plurality of valve opening control sections 3 were provided in one-to-one correspondence with the plurality of valves 6, (a) 1
If one valve opening degree control section 3 fails, that valve 6 becomes unusable. (b) During a valve test in which the valve is periodically opened and closed momentarily to check the function of the valve 6, speed fluctuations occur because there is no mutual compensation function. (c) There were problems such as drift due to temperature changes, etc.

Therefore, the applicant has previously proposed an all-digital turbine control device that eliminates such problems and is also compatible with the recent trend of digital processing using computers.

This turbine control device will now be explained in more detail with reference to FIGS. 2 to 6.

FIG. 2a shows a configuration diagram of the valve opening control section 3 of the turbine control device, and the speed control section 2
is omitted because it is equivalent to an analog type speed control section except that it is constituted by a digital arithmetic processing unit.

The valve opening degree control section 3 consists of m digital arithmetic processing devices 31, n (n≧m) adder circuits 32, and a power amplifier 33, and the m digital arithmetic processing devices 31 include a speed control section. 2, the valve opening command c is input. On the other hand, each of the n valves 6 has a valve drive section 8 and a valve opening degree detection section 7,
Opening adjustment signal ei (i=1 to n) from the valve opening controller 3
Based on this, the valve opening degree is adjusted, and an actual opening degree signal di (i=1 to n) is sent from the valve opening degree detector 7 to the digital arithmetic processing device 31.

Each digital arithmetic processing device 31 has a second
It is configured as shown in Figure b. That is, the actual valve opening signal d _i sent from each valve opening detection section 7 is added by an adder 311 and then converted to 1/n by an arithmetic circuit 312.
is converted into an actual opening signal _o 〓 ⁱ⁼¹ d _i /n for one valve, which is averaged considering all valve openings. Next, this actual opening signal is compared with the valve opening command C by a comparator 313 to calculate a deviation. The valve opening command C at this time is given to the digital arithmetic processing device 31 as individual valve opening commands obtained by averaging the overall valve opening command from the speed control unit 2. The deviation from the comparator 313 is integrated by an integrator 314, and then added to the valve opening command C by an adder 315 to calculate a corrected valve opening command C'. That is,
Individual valve opening command C given from speed control unit 2
is compared with the average valve opening considering all valve openings, and in order to eliminate the deviation, the value obtained by integrating the deviation is added as a correction value to calculate the corrected valve opening command C'. be done. Next, this corrected valve opening command signal C' is converted into an individual actual valve opening signal by each comparator 316.
d _i ( _i =1 to n), and the deviation thereof is outputted to each adding circuit 32 as an opening adjustment command signal fji (i=1 to n).

Each digital arithmetic processing device 31 is activated every cycle T, executes the above arithmetic processing, and sequentially outputs an opening degree adjustment command signal fji (j=1 to m, i=1 to n). For example, when the j-th digital arithmetic processing device 31 is activated, as shown in the flowchart of FIG.
The opening adjustment command fji is sequentially calculated and updated while taking into account the total opening of each valve. When all n opening degree adjustment commands fji have been updated, the j-th processing is completed, and the j+1-th digital arithmetic processing device 31 is activated next. Such arithmetic processing is performed for each digital arithmetic processing device 31, and when time T has elapsed, the j-th digital arithmetic processing device 31 is activated again. During this time, the opening adjustment command fji is held constant. Further, in this way, the n opening adjustment commands fji output from each digital arithmetic processing device 31 are input to the n addition circuits 32, respectively.

Each adder circuit 32 receives m opening adjustment commands fji output from m digital arithmetic processing units 31.
The opening adjustment command fi is calculated by averaging ( _o 〓 ⁱ⁼¹ fji/m)
Output. For example, as shown in FIG. 4, the i-th addition circuit 32 receives m opening adjustment commands output from m digital processing units 31
fji input. At this time, each opening adjustment command fji is
Since the calculation period of each digital calculation processing device 31 is T and there are m digital calculation processing devices 31,
It will be input every T/m. This opening adjustment signal fji is multiplied by 1/m and the previous opening adjustment signal fi
will be added to. As a result, the opening adjustment signal fi is sequentially updated at a cycle of T/m as shown in the figure.

In this way, the opening adjustment signal fi outputted from each adding circuit 32 is amplified by each power amplifier 33, and is inputted to each valve drive unit 8 as an opening adjustment signal ei to adjust the opening of each valve 6. The adjustment provides control of the turbine.

Therefore, according to the above configuration, an all-digital turbine control device can be obtained which eliminates the problems of the conventional device described above.

However, the above configuration has a problem in that it is not satisfactory in terms of quick response.

That is, when a step signal is input as the valve opening command c, the actual opening signal di (i=1
~n) response dia and one control group in FIG. 2 as shown in FIG. 5, and the actual opening signal d when the update period of the opening adjustment command f is T.
When comparing the response dis and the results shown in FIG. 6, the results were obtained.

As is clear from the results shown in FIG. 6, the response dia in the configuration shown in FIG. The response dis of the single valve opening controller 3 shown in FIG. 6 is more vibratory, and
The settling time is getting longer.

This phenomenon can be explained as follows.

That is, in the case of FIG. 2, the valve opening control section 3 uses the addition circuit 32 to create the opening adjustment command fi from m opening adjustment commands fji, so the valve opening adjustment command fji This phenomenon is caused by the fact that when the signal is updated, the compensation effect is only 1/m of the maximum signal level of the opening adjustment command fi, and all other opening adjustment commands fji that are not updated become offsets. It is the cause of

Therefore, as m becomes larger, in the case of Fig. 2,
There was a problem with poor response dia.

It is an object of the present invention to further improve the previously proposed turbine control system and to provide an all-digital turbine control system that is extremely responsive and reliable.

In order to achieve this object, the present invention uses a switching circuit in place of the adding circuit in the turbine control device proposed earlier, and each time the opening adjustment command is calculated and updated in each digital processing device, By directly amplifying the signal and using it as a valve drive signal,
It is characterized in that the influence of the outputs of other digital arithmetic processing devices is removed.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 7 is a configuration diagram of the main parts of a turbine control device showing an embodiment of the present invention, where the same reference numerals as in FIG. 2 indicate the same or corresponding parts, and the speed control section 2 is omitted for the same reason as in FIG. 2. It has been done.

The difference in the configuration of the diagram from that of Figure 2 is that the adder circuit 3
2 is replaced by a switching circuit 34.

This switching circuit 34 receives m opening adjustment signals fji and m switching request signals gji from m digital processing devices 31, and according to the switching request signals gji, the opening adjustment command fji that has just been updated is sent to the switching circuit 34. is selected and output to the power amplifier 33 as the opening adjustment command fi.

That is, each digital arithmetic processing device 31
As in the case of the figure, as shown in the flowchart of Fig. 8, the opening adjustment command fji is calculated and updated based on the input valve opening command c and the actual opening signal di, but the opening adjustment command fji is updated. Afterwards, a switching request signal gji is output. As a result, the first switching circuit 34 has the ninth
As shown in the figure, the opening adjustment command fji and the switching request signal gji outputted from each digital arithmetic processing device 31 every T/m are input. This switching request signal gji
As a result, the opening adjustment command fji is switched and output as is to the power amplifier 33 as the opening adjustment command fi. Therefore, in the case of FIG. 2, for example, even if the valve opening command c changes, one opening adjustment command
Whereas fji exerted only a compensation effect of 1/m on the opening adjustment command fi, in the case of this embodiment, it exerts a compensation effect of 100% and the control calculation period T/m.
A result equivalent to controlling m is obtained.
In other words, the signal levels of the opening adjustment command fji and the opening adjustment command fi are the same, and only one opening adjustment command fji is selected within a certain T/m time.
Unlike the case shown in FIG. 2, there is no offset effect from other opening adjustment commands.

Here, a step signal is input as the valve opening command c, and the response of the actual opening signal d when the update cycle of the opening adjustment command f is T in the single system valve opening controller 3 in FIG. When dis was compared with the response die of the actual opening degree signal di in this embodiment, the results shown in FIG. 8 were obtained.

As can be seen from this result, the response die of this example is
It can be seen that this is significantly superior to the response dis in terms of less overshoot and shorter settling time. In other words, the response die in this example is
While the response dis performed control with the control period T,
The response is the same as when control is performed at a control cycle of T/m. Therefore, in this embodiment, sufficient rapid response can be obtained by setting an appropriate control period T/m.

Furthermore, in this embodiment, even if one of the digital processing devices 31 fails, the switching request signal gji is generally not sent from the faulty digital processing device 31. The opening adjustment command fji is also ignored, and the opening adjustment command from the digital arithmetic processing unit 31 is at most normal.
As long as fji remains the opening adjustment command fi for a period of 2T/m, there is no problem in operation due to the control characteristics of the valve opening controller 3.

Furthermore, even in the event of a failure of the digital arithmetic processing device 31 that causes the switching request signal gji to be output continuously, the switching request signal gji is monitored, and if the switching request signal gji continues for a certain period of time, the corresponding faulty digital arithmetic processing unit 31 is output. If the switching circuit 34 is configured to disable the selection of the opening adjustment command fji from the processing device 31, there will be no problem with operation at all.

In addition, since the total opening is managed within the valve opening control for disturbances during a valve test, prompt correction can be made without affecting the speed.

In the above embodiment, for simplicity, each digital arithmetic processing device 31 calculates n opening adjustment commands, but it is not necessary to calculate all n opening adjustment commands, and it is assumed that k (k<n) The opening adjustment command may be calculated. In this case, the switching circuit 34 receives l opening adjustment commands (l<m), and k×m=
The relationship l×n may be maintained. however,
For k, it is necessary to have sufficient redundancy for compensation during valve testing, and for l, it is necessary to have sufficient redundancy so that the control cycle at the time of failure does not have a large effect on valve opening control. .

As described above, according to the present invention, it is possible to configure a configuration according to the performance and cost of the digital arithmetic processing device used, and it has sufficient quick response in terms of control.
A highly reliable all-digital turbine control device with a simple configuration can be obtained.

[Brief explanation of drawings]

Figure 1 is a general configuration diagram of a turbine control device.
FIG. 2a is a block diagram of the main parts of the turbine control device previously proposed by the applicant, FIG. 2b is a detailed block diagram of the digital arithmetic processing device, and FIG. 3 is a flowchart for explaining its operation. Fig. 4 is a timing chart to explain its operation, Fig. 5 is a block diagram of a single valve opening degree control section showing a part of its structure, and Fig. 6 shows its response characteristics. 7 is a configuration diagram of a turbine control device showing an embodiment of the present invention, FIG. 8 is a flow chart for explaining its operation, and FIG. 9 is a diagram for explaining its operation. FIG. 10 is a waveform chart showing the response characteristics in comparison with FIG. 5. 1... Turbine control device, 2... Speed control section,
3... Valve opening degree control section, 4... Turbine, 5... Speed detector, 6... Valve, 7... Valve opening degree detector, 8...
... Valve drive section, 31 ... Digital arithmetic processing device,
32...Addition circuit, 33...Power amplifier, 34
...Switching circuit.

Claims (1)

[Claims] 1. A speed control section that receives a turbine speed command and an actual turbine speed signal as input, outputs a valve opening command, and controls the speed of the turbine, and adjusts the opening using the valve opening command and the actual valve opening signal as input. In a turbine control device comprising a valve opening control unit that outputs a signal and controls a valve opening, the valve opening control unit receives the valve opening command and each actual opening signal from a plurality of valves. a plurality of digital arithmetic processing devices that sequentially output opening adjustment commands for the plurality of valves; 1. A turbine control device comprising a plurality of switching circuits that switch a degree adjustment command for each input and output the degree adjustment signal as the opening degree adjustment signal.