JPH108914A - Turbine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain load variation at the time of a valve test, by installing a limitter, for restricting a correcting valve closing direction speed to a normal plant load-pressure correcting signal, to restrain the load dropping at the time of testing valve closing action, in a device equipping a valve action test circuit for testing the closing action of a principal control valve. SOLUTION: In the case where closing action is tested one by one about four valves 44-47 by a principal valve action test circuit 201, at first, an opening directive value 104 is sent to the governing valve 44 by a CV $1 valve control circuit, to execute a valve closing test. Since variation is caused in a flow rate at this time, in a flow rate lowering compensating circuit 90, a switch is closed, and deviation, between a steam flow rate from a steam flow rate directing part and an actual flow rate, is calculated by a subtractor, and this resultant deviation value is gain-adjusted by an adjustor, to correct correcting quantity 38 by a correction signal lowering direction change ratio limitter 80. Modified correcting quantity 81 is outputted to an adder, and a signal from the steam flow rate directing part is added to the correcting quantity 81, moreover signals 101-103, before a directive value, wherein functions 71-73 are multiplied, are sent to the governing valves 45-47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for a main control valve of a steam turbine, and more particularly, to a turbine control device for controlling a main control valve during a main valve test.

[0002]

2. Description of the Related Art In conventional valve control, taking a valve operation test as an example, as described in Japanese Patent Application Laid-Open No. 7-19007,
In the control valve operation (open / close) test for turbine control,
Only the flow reduction compensation by the pressure or pressure model after the first stage, that is, the load correction by other valves that do not perform the valve operation test, and the like are performed. The speed in the opening direction of the correction valve is limited from the viewpoint of preventing turbine overspeed, and there is a drawback that stable load correction is hindered.

It is also disclosed that a limiter for opening and closing the valve is provided separately from a normal valve control device when the valve is restored after the valve test, and the opening and closing of the valve is controlled using the limiter.

[0004]

However, no special control is added during the valve test.

At the time of the test, load compensation is performed by the other main control valves that have not been subjected to the valve operation test in order to compensate for the decrease in the flow rate by the first-stage post-pressure and pressure model, thereby suppressing the load fluctuation during the test. doing. However, there is a limit to suppressing load fluctuations and the like that occur at the time of testing alone.

[0006] Therefore, an object of the present invention is to provide a turbine control device that can further suppress load fluctuation during a valve test.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a turbine control apparatus having a valve operation test circuit for performing a close operation test of a main control valve for controlling a flow rate of steam flowing from a boiler into a turbine. This can be realized by installing a limiter for limiting the speed of the correction valve in the closing direction with respect to the correction signal and suppressing a drop in load during a valve closing operation test. Specifically, in a steam turbine control device that controls a plurality of control valves that adjust a steam flow supplied to a steam turbine driven by steam, a load required for the steam turbine to control the steam flow flowing through the control valve The correction amount of the steam flow rate signal is calculated from a steam flow rate signal set according to the set value of the steam turbine and the shaft rotation speed of the steam turbine, and a signal from a steam pressure measuring unit in the steam turbine provided in the steam turbine. A regulator, and a limiter for limiting a rate of change of a component in a downward direction of the correction signal of the steam flow rate from the regulator, and a steam flow rate from another control valve to the steam turbine during an operation test of one control valve. Is controlled to bear the required load of the steam turbine, and in response to the start of the operation test of the one control valve, a steam flow signal that has passed through the restriction unit is output to the other control valve. It is intended.

The steam turbine control device further comprises a steam flow rate command section for issuing a steam flow rate signal so that a steam flow rate corresponding to a load request value of the steam turbine and a shaft rotation speed of the steam turbine flows through the control valve. A subtracter for calculating a difference by comparing the steam flow rate flowing through the control valve based on the signal from the flow rate command section with the actual steam flow rate flowing through the steam turbine based on the signal of the steam pressure measuring means in the steam turbine provided in the steam turbine; A controller that outputs a correction signal for the steam flow rate flowing through the control valve so as to reduce the difference calculated by the subtractor; and a rate of change of a component in a downward direction of the correction signal for the steam flow rate from the regulator. A restriction section for restricting, and a path through which the correction signal passing through the restriction section and the steam flow rate signal are communicated to a control circuit for adjusting the opening of the control valve.

Further, in a turbine control method for an operation test of a control valve of a turbine for controlling a plurality of control valves for adjusting an amount of steam supplied to a steam turbine, one control valve is closed and another control valve is closed. The steam flow rate of the other control valve is increased so as to bear the load required for the steam turbine by the steam flow rate from the steam flow rate, and the steam flow rate flowing through the control valve corresponding to the load request value of the steam turbine and the shaft rotation speed of the steam turbine. The actual steam flow rate in the steam turbine based on the steam pressure in the steam turbine by the measuring means provided in the steam turbine,
And a correction signal for the steam flow rate of the other control valve is issued so as to reduce the difference, and a rate of change of a component of the correction signal in a direction in which the steam flow rate is reduced is limited to a predetermined value. It is.

[0010] Flow rate (load) correction at the time of valve closing operation test By limiting the valve closing direction speed, coordination with the valve opening direction speed limit for preventing turbine overspeed can be achieved, and suitable load correction, i.e. Stable plant operation can be realized.

Further, it is possible to reduce the load fluctuation at the time of the valve operation test by controlling so as to increase the steam flow rate of the other control valve at the time of one valve operation test.

FIG. 1 is a schematic diagram of a reheat turbine to which the present invention is applied. The steam generated in the boiler 1 is guided to a main steam pipe 2, passes through a control valve 3, and generates a torque in a high-pressure turbine 4. The steam discharged from the high-pressure turbine 4 returns to the boiler 1 again, and is heated again by the reheater 5. The reheated steam is led to a re-steam pipe 6, passes through an intercept valve 7, and generates torque in a low-pressure turbine 8. The high-pressure turbine 4 and the low-pressure turbine 8 generate electric power in a generator 9. Steam from the low-pressure turbine 8 is supplied to the condenser 1
At 0, it is condensed to become water, and is sent to the boiler 1 again through the condensing pump 11, the low pressure heater 12, the water suction pump 13, and the high pressure heater 14. Water sent to boiler 1 is furnace water wall 1
Heated at 5, generating steam. The generated steam is further heated by a superheater 17 from a drum (in the case of a drum boiler) 16 and sent out of the boiler. Such load and speed control of the turbine generator is generally performed by adjusting the control valve 3 and the intercept valve 7 using a turbine control device (electro-hydraulic governor control device) 200. Other detailed valves and the like are omitted. Note that 50
Denotes a reheat steam chamber pressure detector, 27 denotes a pressure detector after the first stage of the turbine, and 55 denotes a turbine shaft speed detector.

[0013]

FIG. 2 shows the overall configuration of a turbine control device 200 according to the present invention, and 201 denotes a control valve operation test circuit. The main valve operation test circuit 201 is assigned the same reference number as in FIG. As shown in FIG. 2, the main valve operation test circuit 201 of the present invention is characterized in that a rate-of-change limiting device 80 for limiting the rate of change of the load correction signal 38 in the downward direction at the time of the up-down valve operation test is provided. is there. The detailed operation will be described with reference to FIG. In FIG. 2, reference numerals 40, 41, 42, and 43 denote CV #, respectively.
1, CV # 2, CV # 3, CV # 4.

FIG. 3 shows an outline of a valve operation control method using the control valve 200 as an example in the control device 200. The figure shows a turbine control device according to the present invention. Although four control valves 3 shown in FIG. 1 are provided, the steam flow rate, that is, the load fluctuates when performing the closing operation test one by one, so the flow rate (load) correction (an example of the control valve CV # 1 test). I do. First, the correction method
From the CV # 1 test signal generator 39, the valve test (CV #
1) When the signal 40 is issued, the CV # 1 valve control circuit in which the signal 40 is input has a higher CV priority than other signals 100 before the opening command value.
An opening command value 104 is issued to CV # 1 so as to fully close # 1 at a constant speed, and a valve closing test is performed. At this time, CV #
When 1 is fully closed, the flow rate (load) fluctuates. Therefore, in the flow rate reduction compensating circuit 90, the switch 48 is closed, and the steam flow rate is calculated from the steam flow rate commanding section 60 in which the steam flow rate is calculated based on the turbine rotation speed and the load request value using the turbine first stage pressure 27. The difference between the signal and the actual flow rate detected and obtained by the turbine first-stage pressure detector (PX) 27 is calculated by the subtractor 23, and this difference is adjusted by the adjuster 29 for gain (K). The correction amount 38 for compensating so as to suppress the actual flow (load) fluctuation is corrected by a correction amount 81 of the steam flow rate corrected by the correction signal decreasing direction change rate limiter.
Is output to the adder 26, the signal from the steam flow rate command unit 60 is added to the adder 26, and the pre-command value signals 101 to 103 multiplied by the functions 71 to 73 are added to the control valves CV # 2, CV # 3, CV #
Emitted to V # 4. In the above description, the correction amount 81 is obtained using the pressure after the first stage of the turbine where the pressure fluctuation is remarkable. However, if the pressure in the turbine at the time of the valve test can be obtained, the pressure may be obtained using other means. . Thus, the CV # for which the valve operation test has not been performed by the flow rate reduction correction circuit 90
2, the flow rate (load) fluctuation is suppressed by applying the correction amount 81 to CV # 3 and CV # 4. At this time, CV #
The CV # 3, CV # 4, CV # 4 valve control circuit limits the opening direction speed of the pre-command value signals 101 to 103 to prevent turbine overspeed, so that the amount of change in the valve opening direction is suppressed and load reduction is corrected. Although the power valve could not operate sufficiently, there was a limit in suppressing the load fluctuation during the test, but with the present invention, the amount of change in the valve closing direction was also limited, so the average value of the flow command was relatively increased. Since a larger valve opening command can be issued to the valve control circuit, load fluctuation can be further suppressed.

When setting the compensating steam flow rate command value decreasing direction change rate limiter, an optimum value is estimated from the opening direction change rate limit value of the valve opening command value and the function of the first stage post-pressure during the valve test. can do.

For example, it can be obtained from the maximum rate of change (gradient) G of the upward component to be corrected in FIG.

The set value is set so that the central value of the opening of the correction valve does not excessively decrease with respect to repetition of up / down of the correction signal.
Limiting the rate of change in the correction signal lowering direction so that the operating speed in the closing direction of the compensating valve (downward direction, steam flow decreasing direction) has almost the same limit as the limit value of the opening direction operating speed (upward direction, steam flow increasing direction). You can set a value.

For example, when the operating speed of the valve in the opening direction is limited to + 10% / sec, the correction signal lowering direction change rate limit value is-
The operation speed is limited to 10% / sec.

If the change in the opening of the valve and the corresponding load change correspond in the same direction in the upward direction and the downward direction, the limit value is adjusted so that the upward / downward load change rates are the same. Is preferred. As a result, the valve opening can be further increased.

If the change in the opening of the valve and the change in the load associated therewith do not correspond in the same manner in the upward direction and the downward direction, the upward / downward correction valve opening due to the upward / downward direction of the correction signal indicates that the load is high / low. The correction signal lowering direction change rate limit value is set so that the degree of influence of the correction signal on the upper and lower sides is substantially the same.

FIG. 5 shows the characteristics of the valve opening command value (including the correction amount) during the CV # 1 valve test. FIG. 4 shows a circuit diagram substantially the same as the control device of the present invention except that the load correction amount decreasing direction change rate limiter 80 is not provided as a comparative example. When the CV # 1 valve test is started, the CV # 1 starts the closing operation in response to the fully-closed signal 104 from the CV # 1 valve control circuit. As a result, as shown in (a), the signal before the opening degree command value (the correction value 3
8 (including the dotted line 8) (shown by the dotted lines) also increases while moving up and down. In the control signal, a component in a rising direction (increase in steam flow rate or opening direction of a valve) is limited so as not to exceed a predetermined rate of change in order to prevent a sudden change in the rotation speed of the turbine. Even during the test, the signal before the normal opening command value is CV #
2, CV # 3 and CV # 4 restrict the rate of change in the opening direction. Opening command values (shown by solid lines) 104 to 107 are obtained through a control circuit for this purpose. Since the obtained opening degree command values 104 to 107 are limited only in the opening direction change rate, valves CV # 2, CV # 3, CV # 4 for which load reduction should be corrected in a control device not using the present invention. Cannot perform a sufficient operation, and there is a limit in suppressing the amount of load drop.

Here, the upward direction component refers to, for example, from a minimum point to a next maximum point in the waveform of the correction signal which fluctuates up and down of the steam flow rate command signal as shown in FIG. Also,
The downward component refers to a portion from one maximum point to the next minimum point in the waveform of the correction signal that fluctuates up and down of the steam flow rate command signal.

The amount of increase in the valve opening is, for example, a local maximum such as D1 or D2 with respect to a reference line (X) drawn with respect to the vertical amplitude of the correction signal of the steam flow rate command signal as shown in FIG. It is the amount of change up to the value.

The valve opening reduction amount is defined as a reference line (X) drawn with respect to the vertical amplitude of the correction signal of the steam flow rate command signal.
In contrast, the amount of change up to one minimum value such as E is referred to.

On the other hand, in the present embodiment, the correction amount signal 38 itself obtained by the comparison circuit is provided with a change rate limiter 80 for limiting the change rate of the component in the lowering direction. By limiting the change rate only for the directional component,
As shown in (b), the rate of change of the downward component is limited as compared with the case where the change rate limiter of (a) is not provided. Further, the amount of decrease in the valve opening can also be suppressed. As a result, valves CV # 2, CV # 3, CV
By suppressing the rate of change of the opening degree of V # 4 in the decreasing direction, it is possible to relatively reduce the drop in load during the valve test.

FIG. 6 shows the CV # 1 opening (a), correction amount (b), CV # 2, CV # 3, CV # 4 opening (c) and load (d) at this time. In the comparison circuit, during the valve test, the load correction amount reduction direction change rate limitation is not provided, so that CV # 2, CV # 3, and CV # 4 are limited only by the valve control circuit as in the normal case. , A drop in load occurs during the CV # 1 valve test as indicated by the dashed line. On the other hand, in the present embodiment, the rate of change in the component in the downward direction of the correction amount during the valve test is limited, so that the amount of load drop is relatively reduced as indicated by the solid line. Therefore, the lowering amount (opening degree or flow rate of the valve) can be suppressed to be smaller than that of the comparative example.

[0027]

According to the present invention, since the amount of change in the closing direction of the valve whose flow rate (load) is to be corrected in the operation test of the main control valve is limited, the load fluctuation in the valve opening / closing test can be suppressed. , Stable load correction can be realized.

[Brief description of the drawings]

FIG. 1 is a system diagram of a reheating turbine of a generator.

FIG. 2 is a schematic diagram of the overall configuration of a turbine control device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of an embodiment of a control device according to the present invention.

FIG. 4 is a schematic diagram of a comparative control device.

FIG. 5 shows characteristics of a valve opening command value (including a load correction amount).

FIG. 6 shows an operation characteristic at the time of a control valve operation test.

[Explanation of symbols]

28 ... Compared flow reduction compensation circuit, 40 ... Valve test (CV
# 1) signal, 44: control valve (CV # 1), 60: steam flow command unit, 70: valve opening converter (CV # 1), 80: change rate limiter, 90: flow rate after application of the present invention Drop compensation circuit,
100: signal before opening degree command value; 104: command value for opening degree.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadahiko Iijima 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Omika Plant, Hitachi, Ltd. (72) Inventor Takashi Tomura 5-chome, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd., Omika Plant (72) Inventor Shintaro Tsuji 5-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Omika Plant

Claims (4)

[Claims] 1. A steam turbine control device for controlling a plurality of control valves for adjusting a steam flow supplied to a steam turbine driven by steam, wherein a load required for the steam turbine for controlling a steam flow flowing through the control valve is provided. A steam flow rate signal set according to the set value of the steam turbine shaft speed, and a signal of a steam pressure measuring means in the steam turbine provided in the steam turbine,
And a limiter for calculating a correction amount of the steam flow rate signal, and a limiter for limiting a rate of change of a component in a downward direction of the steam flow rate correction signal from the adjuster. Controlled to carry the required load of the steam turbine by the steam flow from the other control valve to the steam turbine, in response to the start of the operation test of the one control valve,
A steam flow rate signal having passed through the restriction section is output to the other control valve. 2. A steam turbine control device for controlling a plurality of control valves for adjusting a flow rate of steam supplied to a steam turbine driven by steam, the steam corresponding to a load request value of the steam turbine and a shaft rotation speed of the steam turbine. A steam flow rate command section for issuing a steam flow rate signal so that the flow rate flows through the control valve; and a steam flow rate flowing through the control valve based on a signal from the steam flow rate command section and a steam pressure measuring means provided in the steam turbine. A subtractor for comparing the actual flow rate of the steam flowing through the steam turbine based on the subtraction signal to calculate the difference, and a regulator for outputting a correction signal for the steam flow rate flowing through the control valve so as to reduce the difference calculated by the subtractor. A limiting unit that limits a rate of change of a component in a downward direction of the steam flow correction signal from the regulator; a correction signal that has passed through the limiting unit; and the steam flow signal. Steam turbine control device characterized by comprising: a path to be contacted to the control circuit for adjusting the degree of opening of the control valve, the. 3. The steam turbine control device according to claim 1, wherein the steam pressure in the steam turbine is a pressure after the first stage of the steam turbine. 4. A turbine control method for an operation test of a control valve of a turbine for controlling a plurality of control valves for adjusting an amount of steam supplied to a steam turbine, wherein one control valve is closed and another control valve is closed. The steam flow rate of the other control valve is increased so as to bear the load required for the steam turbine by the steam flow rate from the steam flow rate, and the steam flow rate flowing through the control valve corresponding to the load request value of the steam turbine and the shaft rotation speed of the steam turbine. And comparing the actual steam flow rate in the steam turbine based on the steam pressure in the steam turbine by the measuring means provided in the steam turbine with a correction signal for the steam flow rate of the other control valve so as to reduce the difference. Controlling a rate of change of a component of the correction signal in a direction of decreasing the steam flow rate within a predetermined value.