JPS59122708A - Speed control device for steam turbine - Google Patents

Abstract

PURPOSE:To open an unused steam valve to the full and prevent a speed variation from occurring, by installing both of a bias setter biasing a revolution command to a low value and a selector device in a speed control device being set up at each position of plural steam valves of a steam turbine which has plural steam sources. CONSTITUTION:A steam turbine 1 driving a feed water pump 14 is supplied with low and high pressure steam from a low pressure steam control valve 2 and a high pressure steam control valve. At the forestage of each of comparators 17a and 17b comparing signals out of a turbine revolution command and a revolution detector 4, those of a bias setter 16 giving a bias to the revolution command, a selector 17, adders 15a and 15b are all installed. When low pressure steam is used, a switch (a) is turned on while a switch (b) is off, and a valve 2 is opened or closed according to a deviation between the desired value and the actual revolution, while high pressure control valve 3 is given the revolution command whose value is lowered down by th bias and thereby fully opened so that a speed variation is prevented even if steam pressure in the high pressure steam source varies.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a steam turbine speed control device that controls the rotational speed of a steam turbine.

[Technical Background of the Invention] Fig. 1 shows a speed control device for a steam turbine for driving a feedwater pump, which has conventionally been generally used in a power generation plan 1-, and in the figure, the symbol -C 1 is not shown. Boiler, -
A steam turbine for driving a water supply pump (B
FP-T) and -C.

This feedwater pump driving steam turbine 1 is driven by extracted steam from a power generation steam turbine (not shown), and its rotational speed is controlled by controlling the opening degree of a low-pressure steam control valve 2, thereby controlling the flow of feedwater to the boiler. controlled.

However, if the power generation load suddenly decreases due to an accident in the electric power system, most of the air extracted from the power generation steam turbine disappears, so there is no steam source for the feed water pump driving steam turbine 1, and at this time, the water pump driving steam turbine 1
Since the rotational speed of the engine decreases, the steam source is switched to a high-pressure steam source such as boiler outlet steam, the high-pressure steam control valve 3 is opened, and the rotational speed is controlled by the high-pressure steam source.

That is, in the conventional steam turbine speed control device, the rotation speed command signal and the rotation speed signal from the rotation speed detector 4 that detects the rotation speed of the steam turbine 1 for driving the feed water pump are input to the deviation calculation bag @5, and the rotation speed signal is inputted to the deviation calculation bag @5. The deviation between the rotational speed command signal and the rotational speed signal is calculated, and this calculated deviation signal is corrected by the deviation corrector 6, and then converted into a hydraulic signal by the electro-hydraulic converter 7 and output to the cylinder 8. be done.

The cylinder 8 moves a piston 9 up and down in response to a hydraulic signal from an electro-hydraulic converter 7, and a camshaft 11 via a gear 10.
is rotated, and as a result, the cam 12 is fixed to the camshaft 11.
．． 13 rotates, and the opening degrees of the low-pressure steam regulating valve 2 and the high-pressure steam regulating valve 3 are controlled, and the steam turbine 1 for driving the water supply pump is rotated.
The rotation speed of the feed water pump driving steam turbine 1 changes due to a change in the amount of steam flowing into the boiler, and the rotation speed of the feed water pump 14 connected to the feed water pump driving steam turbine 1 is controlled, thereby controlling the flow rate of water feed to the boiler. be done.

In the conventional steam turbine speed control device configured as described above, the horizontal axis represents the cam angle, and the vertical axis represents the opening degree of the low-pressure steam control valve 2 or the high-pressure steam control valve 3, as shown in FIG. According to the angle of the camshaft 11, first, the low pressure steam control valve 2 begins to open as shown by curve a, and after the low pressure steam control valve 2 is fully opened, the high pressure steam control valve 3 begins to open as shown in curve A.

In other words, when the power generation load suddenly decreases due to an accident in the electric power system, almost no air is extracted from the power generation steam turbine, and the actual rotation speed of the water supply pump driving steam turbine 1 decreases. The deviation from the rotational speed command signal is calculated, and this deviation signal is sent to the camshaft 1 via the deviation corrector 6, the electro-hydraulic converter 7 and the cylinder 8.
1, the low-pressure steam control valve 2 is first fully opened, and then the high-pressure steam control valve 3 is opened, so that the rotation speed of the water supply pump driving steam turbine 1 is controlled by the other high-pressure steam source. .

[Problems in the Background Art] However, in the conventional steam turbine speed control device configured as described above, when the high pressure steam control valve 3 is opened, the low pressure steam control valve 2 is also fully opened. Therefore, the feedwater pump driving steam turbine 1 is directly affected by fluctuations in extracted steam from the power generation steam turbine, which causes fluctuations in the amount of water supplied to the boiler.

[Object of the Invention] The present invention has been made in response to such conventional circumstances.
An object of the present invention is to provide a speed control device for a steam turbine that can eliminate fluctuations in the rotational speed of a steam turbine 1 for driving a water supply pump due to extracted steam flowing in from the control valve by fully opening the control valve on the side that is not in use. It is something to do.

[Summary of the Invention] That is, the present invention provides a speed control device for a steam turbine that controls the rotation speed of a steam turbine driven by low pressure steam from a low pressure steam control valve or high pressure steam from a high pressure steam control valve. a low pressure side deviation calculation device that inputs a rotation speed signal indicating the actual rotation speed and a rotation speed command signal indicating the required rotation speed and outputs a difference signal between the two as a low pressure side difference signal, and the low pressure side difference signal. 1. A low pressure steam control valve opening control device that inputs and controls the opening degree of the low pressure steam control valve; a high pressure side deviation calculation device that inputs a rotation speed signal indicating the actual rotation speed of the steam turbine and a rotation speed command signal indicating the required rotation speed and outputs a difference signal between these as a high pressure side difference signal; High-pressure steam regulating valve opening degree control I that inputs a side difference signal and controls the opening degree of the high-pressure steam regulating valve.
a bias setting device that adds a bias signal to either the rotation speed command signal input to the low pressure side deviation calculation device or the rotation speed command signal input to the high pressure side deviation calculation device; This is a steam turbine speed control device characterized by comprising a switching device that switches the output of a bias signal.

[Embodiment of the Invention] The details of the present invention will be described below with reference to an embodiment shown in the drawings. In FIG. 3, parts common to those in FIG. 1 are given the same reference numerals.

FIG. 3 shows a steam turbine speed control device according to an embodiment of the present invention, and in the figure, reference numeral 1 indicates a water supply pump driving steam turbine 1 that drives a water supply pump. Low-pressure steam from a power generation steam turbine flows into the feedwater pump driving steam turbine 1 via a low-pressure steam control valve 2, and high-pressure steam, such as boiler outlet steam, flows into the feedwater pump drive steam turbine 1 via a high-pressure steam control valve 3. It is composed of C. The low-pressure steam control valve 2 and the high-pressure steam control valve 3 are driven by different cylinders 8a and 8b, respectively, and cams 12a and 12b fixed to gears 10a and 101), camshafts 11a and 11b, and camshafts 11a and 111b, respectively.

In the figure, reference numerals 15a and 15b indicate deviation calculation devices, and a rotational speed command signal and a bias signal from a bias setting device 16 are inputted to the deviation calculation devices 15a and 15b via a switching device 17.

That is, the bias setting device 16 is for giving a low command signal to one of the deviation calculating devices 17a, 17b when giving the rotation speed command signal to the next stage deviation calculating devices 17a, 17b, and also for providing a low command signal to one of the deviation calculating devices 17a, 17b. is composed of a pair of interlocking switches a and b, and when switch a is connected to the bias setting device 16, switch b
is not connected to the bias setting device 16, and when the switch 1 is connected to the bias setting device 16, the switch a is configured not to be connected to the bias setting device 16.

The deviation calculation devices 17a and 17b at the next stage input the deviation signals from the deviation calculation devices 15a and 15b, respectively, and the rotation speed signal from the rotation speed detector 4 disposed in the steam turbine 1 for driving the feed water pump, and calculate the deviation. The signals are outputted to deviation correctors 6a and 6b, respectively.

The correction signals from the deviation correctors 6a, 6b are converted into -C hydraulic signals by electro-hydraulic converters 7a, 7b, and output to the cylinders F3a, 8b.

In the steam turbine speed control device configured as described above, as shown in FIG. If there is no rotation speed command signal, the rotation speed command signal is directly input to the next-stage deviation calculation device 17a, where the deviation amount between the rotation speed signal from the rotation speed detector 4 and the rotation speed command signal is calculated, and the deviation corrector 6a The operating amount of the low-pressure steam control valve 2 is calculated, and this signal is sent to the electric-hydraulic converter 7
a is converted into a hydraulic signal, and the operation of the cylinder 8a rotates the camshaft 11a and the cam 12a, thereby controlling the opening degree of the low-pressure steam control valve 2.

On the other hand, in this case, switch my bias setting device 1
6, the value of the deviation signal output from the deviation calculation device 15b is subtracted by the bias signal from the bias setting device 16, and the deviation calculation device 15b outputs a signal indicating a lower rotation speed than the rotation speed command signal. It is output to the next stage deviation calculation device 17b.

The deviation calculation device 17b is the steam turbine 1 for driving the water supply pump.
The difference signal between the rotational speed signal from the rotational speed detector 4 disposed in The signal is converted into a hydraulic signal by the electro-hydraulic converter 7b, and then output to the cylinder 8b.
-C through the cam shaft 11b and cam 12b by the drive of
The opening degree of the high pressure steam control valve 3 is controlled.

However, in this case, when comparing the rotational speed signal indicating the actual rotational speed of the steam turbine 1 for driving the water supply pump and the value of the deviation signal output from the deviation calculation device 1.5b,
Since the rotational speed signal is "C", the high pressure steam control valve 13 is closed.

Then, from this state, switches a and b of the switching device 17 (
7) When ON-OFF is switched, the deviation calculation device 15b
Since the bias signal from the bias setting device 16 is not input to the deviation calculation device 17b, the rotation speed command signal is inputted as it is to the deviation calculation device 17b, and the value of this rotation speed command signal is the same as that of the rotation speed signal input from the rotation speed detector 4. The high pressure steam control valve 3 is closed.

On the other hand, since the value obtained by adding the bias signal from the bias setting device 16 to the value of the rotation speed command signal is input to the deviation calculation device 17a, the rotation speed signal input to the deviation calculation device 17a is The value becomes larger, and the low pressure steam control valve 2 is closed.

That is, in the steam turbine speed control device configured as described above, when the steam source on the low-pressure steam control valve 2 side is sufficient, the high-pressure steam control valve 3 is fully opened, and the steam turbine 1 for driving the feed water pump is in the low-pressure The rotation speed is controlled by the steam control valve 2, and conversely, if the steam source on the high pressure steam control valve 3 side is sufficient, the high pressure steam control valve 3 controls the feed water pump driving steam turbine 1, and the low pressure steam control valve 2 remains fully open.

[Effects of the Invention] As described above, according to the steam turbine speed control device of the present invention, when one steam source is lost due to an accident in the electric power system, it is possible to switch to another steam source. In addition, since the control valve on the side that is not in use can be fully opened, disturbances to the control and abnormal steam from the steam generation source can be prevented from flowing into the turbine.
Damage to the turbine due to rapid cooling etc. can be prevented.

In addition, in the steam turbine speed control device configured as in the embodiment described above, the control section on the low rotation speed target value side is always in a controlled state, so there is a shortage of steam sources on the high rotation speed target value side. However, when the rotational speed decreases and reaches a low rotational speed target value, the control section on the lower rotational speed side works to prevent the rotational speed from decreasing, so that the same effect as provided with a backup speed device can be achieved.

In the embodiments described above, the case where there are two steam sources is shown, but the present invention is not limited to such embodiments, and it goes without saying that it is effective as long as there are two or more steam sources. .

Furthermore, in the embodiments described above, an example was described in which a bias signal was added to the rotation speed command signal, but the same effect can be obtained by adding a bias signal to the rotation speed signal. It goes without saying that the control may be controlled not by signals but by setting the speed adjustment rate provided in each speed control section, or by a mechanical method using a banner or the like.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional steam turbine for driving a water supply pump, Fig. 2 is a graph showing the relationship between the cam angle and the opening of the conventional steam turbine for driving a water supply pump, and Fig. 3 is a graph showing the relationship between the cam angle and opening of the conventional steam turbine for driving a water supply pump. FIG. 1 is a block diagram showing a steam turbine speed control device according to an embodiment. 1......Steam turbine for driving water supply pump 2...Low pressure steam control valve 3...
......High pressure steam control valves 6a, 6b...
Deviation corrector 7a, 7b...Electro-hydraulic converter 8a, 8b...Cylinder 15a, 1'7a...Deviation calculation device (low pressure side) 15b
, 17b... Deviation calculation device (high pressure side) 16...
......Bias setting device 17...
・・・・Patent attorney representing the switching device Tomo Suyama −

Claims (1)

[Claims] (1) In a steam turbine speed control device that controls the rotation speed of a steam turbine driven by low pressure steam from a low pressure steam control valve or high pressure steam from a high pressure steam control valve,
a low pressure side deviation calculation device that inputs a rotation speed signal indicating the actual rotation speed of the steam turbine and a rotation speed command signal indicating the required rotation speed, and outputs a difference signal between these as a low pressure side difference signal; A low-pressure steam regulator opening control device inputs a low-pressure side difference signal to control the opening of the low-pressure steam regulator, and a 1-rpm signal indicating the actual rotational speed of the steam turbine and the required rotation. a high pressure side deviation calculation device which inputs a rotation speed command signal indicating the number of revolutions and outputs the difference signal as a high pressure side difference signal; and a high pressure side deviation calculation device which inputs the high pressure side difference signal and controls the opening degree of the high pressure steam control valve. A bias signal is added to the steam control valve opening control device and either the rotation speed command signal input to the low pressure side deviation calculation device or the rotation speed command signal input to the high pressure side deviation calculation device. 1. A speed control device for a steam turbine, comprising: a bias setting device for switching the output of the bias signal; and a switching device for switching the output of the bias signal.