JP2011144732A - Turbine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch over a valve during warming-up of a turbine owing to the no-load, rated speed operation. <P>SOLUTION: Calculation is made for the changing amount by time of a first stage post pressure of a turbine during the no-load, rated speed operation at starting the turbine, and the point of time at which the calculated changing amount by time becomes greater than the prescribed value, is sensed as the valve switching point. At the valve switching point, the openings of a main steam stop valve and a steam governor valve are controlled so that valve to control the steam flowing into the turbine is switched over from the main steam stop valve to the steam governor valve. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a turbine control device, and more particularly to a turbine control device that controls a turbine by a main steam stop valve when the turbine is started and switches to a steam control valve during load operation.

  A turbine control device that controls steam flowing into a turbine controls the amount of steam flowing into the turbine by a main steam stop valve to start the turbine. In the load operation, the valve switching control from the main steam stop valve to the steam control valve is performed, and the amount of steam flowing into the turbine is controlled by the steam control valve.

  The valve switching control is a control for narrowing down the steam control valves so that the valve opening degree of the main steam stop valve and the valve opening degree of the steam control valve are equal when the turbine is started. Since this valve switching control needs to be performed with the load kept constant, it is not desirable for a thermal power plant that frequently starts and stops according to power demand.

  For this reason, a technique has been considered in which load fluctuation during valve switching control is suppressed as much as possible, and time required for valve switching control is shortened. Such a technique is described in Patent Document 1, for example. In the valve switching control device described in Patent Document 1, an appropriate valve opening degree at which the steam control valve does not generate output fluctuation is calculated based on the main steam pressure, the main steam temperature, and the generator output immediately before the start of the valve switching control. To do. Then, by controlling the steam control valve in the closing direction continuously up to the calculated valve opening degree + α, the fluctuation of the generator output, that is, the load is suppressed.

JP-A-5-195713

  However, in the valve switching control device described in Patent Document 1, the valve switching control is performed during load operation, and it is necessary to keep the load constant in order to safely perform the valve switching. There was a problem in terms of.

  For example, if valve switching control is performed during turbine warm-up by no-load rated speed operation before entering the system, the time required for valve switching can be reduced and the startup pattern of the entire plant can be simplified. However, during no-load rated speed operation, the steam volume and valve opening are extremely small, so the most important switching point between the main steam stop valve and the steam control valve (hereinafter referred to as the “valve switching point”) is detected. It was difficult to do. The valve switching point can also be said to be a turning point where the valve that controls the amount of steam flowing into the turbine is changed from the main steam stop valve to the steam control valve.

  The present invention has been made in view of such points, and an object of the present invention is to provide a turbine control device that performs valve switching control by detecting a valve switching point during turbine warm-up by no-load rated speed operation.

In order to solve the above problems, the present invention calculates a temporal variation amount of the pressure after the first stage of the turbine detected by the pressure detector after the first stage of the turbine during no-load rated speed operation at the time of starting the turbine. And a valve switching point detector for detecting when the calculated amount of temporal fluctuation is greater than a predetermined value as a valve switching point, and a valve for controlling steam flowing into the turbine at the valve switching point. An operation amount output unit that controls the valve opening degree of the main steam stop valve and the steam control valve so as to switch from the valve to the steam control valve is provided.
According to the above configuration, it is possible to detect the point at which the valve is switched based on the change in the pressure after the first stage of the turbine.

  According to the present invention, since valve switching control can be performed during turbine warm-up by no-load rated speed operation, there are effects that the plant start-up time can be shortened and the plant start-up pattern can be simplified.

It is a block diagram which shows the structure of the turbine control apparatus which concerns on one Embodiment of this invention. It is a wave form diagram which shows the relationship between the turbine 1st post-stage post pressure detection signal at the time of a no-load rated speed driving | operation, and the 1st post-stage post pressure regulation value. It is a flowchart which shows the flow of operation | movement of the turbine control apparatus which concerns on one Embodiment of this invention. It is a wave form diagram which shows the operating characteristic of valve switching control.

  Embodiments for carrying out the present invention will be described below. The embodiments described below are preferable specific examples of the present invention. Therefore, various technically preferable limitations are attached. However, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description. For example, the numerical conditions of each parameter given in the following description are only suitable examples, and the dimensions, shapes, and arrangement relationships in the drawings used for the description are also schematic.

The description will be made in the following procedure.
<Description of an embodiment of the present invention>
1. 1. Configuration of turbine control device Operation of the turbine controller

<Description of an embodiment of the present invention>
An example of an embodiment of the present invention will be described with reference to FIGS.
[1. Configuration of turbine control unit]
FIG. 1 is a block diagram showing a configuration of a turbine control device according to an embodiment of the present invention.
The turbine control device 3 controls the operation of the steam control valve 4 and the main steam stop valve 5 provided between the boiler 7 and the steam turbine 2 in order to adjust the amount of steam sent from the boiler 7 to the steam turbine 2. Control each one. The steam control valve 4 adjusts the amount of driving steam to the steam turbine 2 directly connected to the generator 1, and the main steam stop valve 5 disperses local heating when the steam turbine 2 is started. 2 adjusts the amount of steam sprayed around the entire circumference. In this example, these valves are switched when the generator 1 is operating at no load and at a rated speed (hereinafter, “no-load rated speed operation”).

  The turbine control device 3 includes a peak hold circuit 10, a valve switching point detection circuit 101, and an operation amount output circuit 102.

  The peak hold circuit 10 is connected to the turbine first stage post-pressure detector 8. This turbine first stage post-pressure detector 8 detects the turbine first stage post-pressure, which is the pressure in the steam turbine 2, and uses the detection result as the turbine first stage post-pressure detection signal 31 to the peak hold circuit 10. Output.

  As shown in FIG. 2, the peak hold circuit 10 detects an envelope using the maximum value of the turbine first-stage post-stage pressure detection signal 31 input from the turbine first-stage post-stage pressure detector 8. Then, the detected envelope of the turbine first stage post-pressure detection signal 31 is output to the valve switching point detection circuit 101 as the turbine first stage post-pressure pressure prescribed value 32.

  The valve switching point detection circuit 101 detects a valve switching point, which will be described later with reference to FIG. 4, based on the turbine first stage post-stage pressure regulation value 32 input from the peak hold circuit 10, and valve switching according to the detection result. It is a circuit that generates a point detection signal. The valve switching point detection circuit 101 includes a temporary delay circuit 18, a previous value output circuit 11, and a comparator 12.

  The first-order lag circuit 18 generates a first-order lag element for delaying the turbine first stage post-stage pressure regulation value 32 input from the peak hold circuit 10 for a predetermined period. Then, the turbine first-stage post-stage pressure regulation value 32 is output to the previous value output circuit 11 together with the generated first-order lag element.

  The previous value output circuit 11 delays the turbine first-stage post-stage pressure regulation value 32 input from the first-order lag circuit 18 by a period corresponding to the first-order lag element input from the first-order lag circuit 18, and after the first turbine stage. The pressure is output to the comparator 12 as the previous specified value 34.

  The comparator 12 is connected to the previous value output circuit 11 and receives the turbine first stage post-pressure pre-specified value 34. Furthermore, the peak hold circuit 10 is also connected, and a real-time turbine first stage post-pressure regulation value 32 is also inputted. The comparator 12 compares the previous turbine first stage pressure pre-specified value 34 with the turbine first stage post-pressure predetermined value 32. Then, when the deviation between both signals is larger than a predetermined specified value, the valve switching point detection signal 33 indicating “ON” is indicated. When the deviation between both signals is within a predetermined specified value, the valve switching indicating “OFF” is indicated. The point detection signal 33 is output to the operation amount output circuit 102.

  The manipulated variable output circuit 102 controls the valve opening degrees of the steam control valve 4 and the main steam stop valve 5 based on the valve switching point detection signal 33 input from the comparator 12. In particular, in order to control the amount of steam flowing into the steam turbine 2 by the steam control valve 4 when the valve switching point detection signal input from the comparator 12 becomes “ON”, that is, when the valve switching point is detected. Then, valve switching control from the main steam stop valve 5 to the steam control valve 4 is performed.

  The manipulated variable output circuit 102 includes switches 13, 14, 15 and speed control circuits 16, 17.

  The switch 14 is connected to the comparator 12, and based on the valve switching point detection signal 33 input from the comparator 12, a signal for adjusting the valve opening degree of the steam control valve 4 is sent to the steam control valve. 4 is output. Specifically, when the valve switching point detection signal 33 indicating 'OFF' is input, the output from the switch 13 is output to the steam control valve 4 and the valve switching point detection signal 33 indicating 'ON'. Is input, the output from the speed control circuit 16 is output to the steam control valve 4.

  The speed control circuit 16 generates a signal that keeps the valve opening degree of the steam control valve 4 constant and outputs the signal to the switch 14.

  Based on the valve switching control start command 20, the switching unit 13 selects one of the steam control valve full opening operation amount 21 and the steam control valve narrowing operation amount 22, and outputs the selected one to the switching unit 14.

  The valve switching control start command 20 is a signal for controlling which one of the steam control valve narrowing operation amount 22 and the steam control valve full opening operation amount 21 is output from the switch 13 to the switch 14. For example, when outputting the steam control valve narrowing operation amount 22 from the switch 13, the valve switch control start command 20 indicating “ON” is output to the switch 13. On the other hand, in the case of outputting the steam control valve fully open operation amount 21 from the switch 13, a valve switch control start command 20 indicating “OFF” is output to the switch 13.

  The steam control valve narrowing operation amount 22 is a signal for narrowing the steam control valve 4 by a predetermined amount, that is, reducing the valve opening degree of the steam control valve 4 to a target value.

  The steam control valve fully-opening operation amount 21 is a signal for causing the steam control valve 4 to open fully, that is, for setting the valve opening degree of the steam control valve 4 to 100%.

  On the other hand, the switch 15 is also connected to the comparator 12 in the same manner as the switch 14, and the valve opening degree of the main steam stop valve 5 is determined based on the valve switching point detection signal 33 input from the comparator 12. A signal for adjustment is output to the main steam stop valve 5. Specifically, when the valve switching point detection signal 33 indicating “OFF” is input, the output from the speed control circuit 17 is output to the main steam stop valve 5 and the valve switching point detection indicating “ON” is detected. After the signal 33 is input, the main steam stop valve full opening operation amount 23 is output to the main steam stop valve 5.

  The speed control circuit 17 generates a signal for controlling the valve opening degree of the main steam stop valve 5 so that the rotational speed of the steam turbine 2 becomes the rated speed, and outputs the signal to the switch 15.

  The main steam stop valve full opening operation amount 23 is a signal for causing the main steam stop valve 5 to be fully opened, that is, setting the valve opening degree of the main steam stop valve 5 to 100%.

  It is assumed that the valve switching control start command 20, the steam control valve full opening operation amount 21, the steam control valve narrowing operation amount 22, and the main steam stop valve full opening operation amount 23 are generated by a control unit (not shown).

[2. Operation of turbine control unit]
Next, the operation of the turbine control device will be described with reference to FIGS.
FIG. 3 is a flowchart showing an operation flow of the turbine control device according to the embodiment of the present invention.
FIG. 4 is a waveform diagram showing operating characteristics of the valve switching control.
FIG. 4A is a waveform diagram showing time-series fluctuations in the rotational speed of the steam turbine.
FIG. 4B is a waveform diagram showing time-series fluctuations in the specified pressure value after the first stage of the turbine calculated by the peak hold circuit.
FIG.4 (c) is a wave form diagram which shows the time series fluctuation | variation of each valve opening degree of a steam control valve and a main steam stop valve. The vertical axis of each waveform chart indicates the size of each parameter, and the horizontal axis is a common time axis.

  First, in order to cause the steam turbine 2 to start at time T0 shown in FIG. The steam control valve full opening operation amount 21 input to the switch 13 is output to the switch 14. At this time, the specified pressure value 32 (see FIG. 4B) after the turbine first stage is substantially constant. Therefore, the comparator 12 generates the valve switching point detection signal 33 indicating “OFF”, and the switching device 14 and 15. Therefore, at this time T0, the steam control valve full opening operation amount 21 input from the switch 13 is output from the switch 14 to the steam control valve 4, and the steam control valve 4 starts to open.

  When the steam control valve 4 is fully opened at time T <b> 1 (step S <b> 1), the switch 15 outputs the output from the speed control circuit 17 to the main steam stop valve 5. Then, the main steam stop valve 5 is gradually opened so that the valve opening degree of the main steam stop valve 5 (see FIG. 4C) becomes the target value (step S2). As a result, the rotational speed of the steam turbine 2 (see FIG. 4A) starts to rise at a rate corresponding to the opening of the main steam stop valve 5 at time T1, and the main steam stop valve 5 is opened. The rated speed is reached at time T2 immediately after the degree reaches the target value (step S3).

  When a predetermined time elapses from time T2 and time T3 is reached, a valve switching control start command 20 indicating "ON" is input to the switch 13 (step S4). Then, in the switcher 13, the steam control valve narrowing operation amount 22 is output to the switcher 14 instead of the steam control valve fully open operation amount 21. In the switching device 14, the valve switching point detection signal 33 indicating “OFF” is still input from the comparator 12, so that the steam control valve narrowing operation amount 22 input from the switching device 13 is output to the steam control valve 4. The Then, the steam control valve 4 is gradually closed, and the valve opening degree of the steam control valve 4 is gradually reduced (step S5).

  When the valve opening degree of the steam control valve 4 becomes substantially equal to the valve opening degree of the main steam stop valve 5 at time T4, the amount of steam flowing into the steam turbine 2 is not only determined by the steam stop valve 5 but also by the steam control valve 4. Will also be limited and decrease. At this time, the peak hold circuit 10 detects a rapid decrease (see FIG. 4B) of the turbine first-stage post-stage pressure regulation value 32 as the steam amount decreases, and the valve switching point detection circuit 101. Is output. Then, a valve switching point detection signal 33 indicating “ON” is generated and output from the valve switching point detection circuit 101 to the switches 14 and 15.

  As a result, in the switch 14, the output from the speed control circuit 16 is output to the steam control valve 4 instead of the output from the switch 13, and the valve opening degree of the steam control valve 4 is determined by the output from the speed control circuit 16. Be controlled. On the other hand, in the switch 15, the main steam stop valve full opening operation amount 23 is output to the main steam stop valve 5, and the main steam stop valve 5 is fully opened at time T5 (step S6). Then, the rotational speed of the steam turbine 2 after time T5 can be controlled only by the steam control valve 4, and a load operation is performed.

  As described above, in the present embodiment, it is possible to detect the point at which the valve is switched based on the change in the turbine first stage post-pressure. Thereby, valve switching control can be performed even during turbine warm-up by no-load rated speed operation. As a result, there is an effect that the plant activation time can be shortened and the plant activation pattern can be simplified.

  In the above-described embodiment, the electrohydraulic governor that directly controls the main steam stop valve position and the steam control valve position is taken as an example, but the application target is replaced by the main steam stop valve position control and the governor motor. Application to governors is possible as well.

  In the above-described embodiment, the specified pressure value after the first stage of the turbine during the no-load rated speed operation is obtained by an envelope using the maximum value of the detected pressure value after the first stage of the turbine. It is also possible to use an envelope using the minimum value of the pressure detection value after one stage.

  Further, in order to shorten the valve switching time, if the steam control valve position does not clearly reach the valve switching point immediately after the start of the throttle of the steam control valve 4 (time T3 shown in FIG. 4), the conventional steam It is also possible to change the steam control valve throttle speed by using the control valve position signal, the main steam stop valve front-rear differential pressure, and the like.

  As mentioned above, although the example of embodiment of this invention was demonstrated, this invention is not limited to the said embodiment example, Unless it deviates from the summary of this invention described in the claim, other modifications Needless to say, application examples are included.

  DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Steam turbine, 3 ... Turbine controller, 4 ... Steam control valve, 5 ... Main steam stop valve, 7 ... Boiler, 8 ... Turbine 1st stage post pressure detector, 10 ... Peak hold circuit, DESCRIPTION OF SYMBOLS 11 ... Previous value output circuit, 12-15 ... Comparator, 16, 17 ... Speed control circuit, 18 ... Primary delay circuit, 20 ... Valve switching control start command, 21 ... Steam control valve full-open operation amount, 22 ... Steam control valve Narrowing operation amount, 23 ... Valve fully open operation amount, 31 ... Turbine first stage post pressure detection signal, 32 ... Turbine first stage post pressure regulation value, 33 ... Valve switching point detection signal, 34 ... Turbine first stage post pressure Specified value, 101 ... Valve switching point detection circuit, 102 ... Manipulation amount output circuit

Claims (3)

In the turbine control device that controls the steam flowing into the turbine by a main steam stop valve at the time of starting the turbine, and controls the steam by a steam control valve at a stage subsequent to the main steam stop valve at the time of load operation,
A time fluctuation amount of the first stage post-pressure of the turbine detected by a turbine first stage post-pressure detector during no-load rated speed operation at the time of starting the turbine is calculated, and the calculated temporal fluctuation quantity is predetermined. A valve switching point detector that detects a point when the value becomes larger than the value as a valve switching point;
Operations for controlling the valve openings of the main steam stop valve and the steam control valve so that the valve for controlling the steam flowing into the turbine is switched from the main steam stop valve to the steam control valve at the valve switching point. A turbine control device comprising: a quantity output unit. The turbine control device according to claim 1, further comprising a peak hold unit that removes a vibration component from the turbine first stage post-pressure detected by the turbine first stage post-pressure detector. The turbine control device according to claim 2, wherein the peak hold unit calculates an envelope of the first-stage post-pressure detected by the turbine first-stage post-pressure detector.

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