JP2006002571A - Turbine control device, its control method and turbine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a conventional control requires to acquire a steam flow rate characteristic by combination of valves not to be tested when controlling a valve on the basis of a steam flow rate characteristic formed by combining flow rates of valves other than a test valve. <P>SOLUTION: A turbine control device for controlling a control valve by converting a demand flow rate signal from a flow rate command section into opening signals of a plurality of control valves for adjusting a fluid flow of one turbine, is equipped with functions for calculating a flow rate flowing in the turbine on the basis of openings of one valve to be tested and the other control valves, for calculating a correction amount with respect to a fluctuation portion of the test valve based on the calculated flow rate and for adding the correction amount to the demand flow rate signal during executing a valve test of one of the control valves. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for controlling fluctuations in the flow rate of a fluid supplied to a turbine that occurs during a valve test for confirming the operation function of a valve.

  Control of the turbine is controlled by controlling a plurality of control valves of one turbine and adjusting the flow rate of fluid flowing into the turbine. The control flow rate signal from the flow rate command unit that determines the flow rate of the turbine is converted into opening signals of a plurality of control valves to control the control valves.

  About this control valve, in order to confirm whether the valve has failed, one valve of the plurality of control valves provided for one turbine is opened and closed while operating the turbine and maintaining the flow rate. The valve test is carried out. In this valve test, it is necessary to compensate so as not to fluctuate the flow rate of the turbine.

  Japanese Patent Application Laid-Open No. 9-189204 discloses a flow rate for calculating a corrected opening degree command by previously obtaining a steam flow rate characteristic of a combination of valves that are not subjected to a valve test and storing them in respective corrected opening degree command setting means. The compensation technique ([0027], [0028], FIG. 3) is described. This is because when one turbine has four valves, the steam flow characteristics of three valves other than the test valve are separately created to compensate for one test valve, and other valves are tested. Since the steam flow characteristics vary depending on the flow rate maintained during the test, it is necessary to obtain a large number of steam flow characteristics in advance.

JP-A-9-189204

  In the above conventional valve test, it is described that the valve is controlled based on the steam flow characteristics obtained by combining the flow rates of valves other than the test valve. It is necessary to obtain the characteristics.

  The purpose is to compensate the flow fluctuation of the test valve with a simple configuration based on one steam flow characteristic.

  The present invention calculates the flow rate flowing into the turbine based on the opening degree of the valve test target valve and the other control valves during the valve test of one of the plurality of control valves, and performs the test based on the calculated flow rate. A correction amount for the variation of the valve is calculated, and the correction amount is added to the required flow rate signal from the flow rate command unit.

  With a simple configuration based on one steam flow rate characteristic, it is possible to achieve control capable of compensating for the flow rate variation of the test valve.

  The present invention will be described below with reference to the drawings.

  FIG. 1 shows a turbine control circuit provided with a valve test required flow rate compensation circuit according to the present invention, which is characterized in that a valve test required flow rate compensation circuit 1 is additionally provided. In the figure, valves CV-A to D (adjustment valves A to D) for adjusting the flow rate of steam flowing into the turbine are provided. When one valve starts operation in the closing direction during the valve test, The supplied steam flow fluctuates. In the present invention, fluctuation of the steam flow rate is compensated by the valve test required flow rate compensation circuit 1 additionally provided.

The steam flow rate command unit 6 obtains and outputs a CV required steam flow rate signal 29 based on the load and the turbine rotational speed. Functions f _{1 (x) to} f _{4 (x)} 10 to 13 defined for each of CV-A to D convert the CV steam required flow rate signal 29 into opening command value signals 20 to 23. During normal operation, not during the valve test, the valves CV-A to D are controlled by the converted opening command value signals 20 to 23. At the time of the test, when the CV-A valve test is started, the test signal generator 9 has a CV-A valve test signal 28 having a command value for operating the CV-A to the fully closed position at a constant speed. Is output. The valve test required flow rate compensation circuit 1 adds a correction amount to the CV steam required flow rate signal 29 based on the opening command value signal of each valve of CV-A to D, and suppresses fluctuations.

The valve test required flow compensation circuit 1 includes an ON signal generator 24, a switch 5, a function f5 _(x) to
f _{8 (x)} 14 to 17, an adder circuit 18, a holding circuit 2, a comparator 3, a subtracter 8, and an integrator 4.

  The ON signal generator 24 outputs an ON signal when the CV-A valve test signal 28 inputs a command value other than 0, and the holding circuit 2 and the switch 5 are operated by the ON signal.

  The switch 5 is a switch for operating the valve test required flow rate compensation circuit 1.

The functions f _{5 (x) to} f _{8 (x)} 14 to 17 convert the valve opening command value into the steam flow signal of each valve and calculate the steam flow for each valve to the CV steam required flow signal 29. To do. Details will be described later.

The adding circuit 18 outputs a total flow rate obtained by adding the steam flow rate signals of the respective valves, which are outputs from the functions f _{5 (x) to} f _{8 (x)} 14 to 17. This is the current control valve steam flow signal 30. The holding circuit 2 is operated by the ON signal of the generator 24 and holds the current control valve steam flow signal 30 obtained by calculating the steam flow signal of each control valve before starting the valve test.

  The comparator 3 compares the held control valve steam flow signal 33 (FH) with the current control valve steam flow signal 30 (Fn) by the comparator 3, and if both signals are not equal to the integrator 4. Output a signal.

  The subtractor 8 calculates a deviation between the retained control valve steam flow signal 33 (FH) and the current control valve steam flow signal 30 (Fn). A deviation 34 (ΔFn) between the control valve steam flow signal 33 (FH) and the current control valve steam flow signal 30 (Fn) represents a correction amount for the variation of the test valve. That is, when the deviation 34 (ΔFn) is 0, this means that the fluctuation of the test valve is compensated by a control valve other than the test valve, and the deviation 34 (ΔFn) does not become 0. In this case, the compensation of the valves other than the test valve is insufficient, and the correction amount for the variation of the test valve remains.

The integrator 4 receives the signal from the comparator 3, that is, the control valve steam flow signal 33.
If (FH) and the current control valve steam flow signal 30 (Fn) are not equal, the deviation 34 (ΔFn) of both signals obtained by the subtractor 8 is integrated and corrected until both signals are equal. The amount 35 (FS) is added to the CV steam request flow rate signal 29.

The CV steam required flow rate signal 29 to which the correction amount 35 (FS) is added is expressed as a function f _{1 (x)} to
By controlling the control valve by converting the opening signal of each valve at f4 _(x) 10 to 13, valves other than the test valve are controlled with respect to the fluctuation flow rate of the test valve. It is possible to control with a simple configuration with only one steam flow characteristic of each valve for one turbine, and it is possible to control without obtaining the steam flow characteristics of other valves other than the test valve separately for testing. .

  An operation flow of the flow compensation circuit of FIG. 2 will be described.

  In Step 1, the switch is turned on when the valve test is started, and the steam flow compensation circuit functions to maintain the control valve steam flow immediately before the start of the test. When the CV-A valve test is started, the test signal generator 9 generates a CV-A valve test signal 28 having a command value for operating the CV-A in the closing direction to the fully closed position at a constant speed. The CV-A control circuit containing the valve test signal 28 used for the valve test controls the CV-A according to the command of the valve test signal 28 of the CV-A regardless of the original opening command value signal 20, Perform CV-A valve test. At the same time, the generator 24 that emits an ON signal when the CV-A valve test signal has a command value other than 0 is used, and the holding circuit 2 operates in response to the ON signal. The current control valve vapor flow signal 30 (Fn) obtained by calculating the valve opening is held in the holding circuit 2, and the switch 5 for operating the valve test required flow compensation circuit 1 is turned on. The holding circuit 2 may be configured to hold the CV steam required flow rate signal 29 immediately before starting the valve test. The holding circuit 2 holds the CV steam request flow signal 29 or the current control valve steam flow signal 30 as the flow before the test as the held control valve steam flow signal 33 (FH).

In Steps 2 and 3, the held control valve steam flow signal 33 (FH) is compared with the current control valve steam flow signal 30 (Fn). In the control valve, the CV steam required flow rate signal 29 obtained from the load and the turbine rotational speed is changed to functions f _{1 (x) to} f _{4 (x)} 10 to 13 determined for each of CV-A to D. Are converted into opening command value signals 20 to 23, and valve control is performed. The opening command value signal of each adjusting valve is converted into a steam flow signal flowing from each control valve into the turbine by functions f _{5 (x) to} f _{8 (x)} 14 to 17, and the sum is obtained by the adding circuit 18. The current control valve steam flow signal 30 (Fn) is obtained. As the opening command value signal 20 when the test signal 28 is input during the test, the opening command value signal transmitted from the test signal generator is used. The held control valve steam flow signal 33 (FH) is compared with the current control valve steam flow signal 30 (Fn) by the comparator 3.

  In steps 4, 5 and 7, if both signals are not equal in step 3, the deviation 34 (ΔFn) of both signals obtained by the subtractor 8 is integrated by the integrator 4 until both signals become equal (Step 4, 5) It is added to the CV steam required flow rate signal 29 as a correction amount 35 (FS) (Step 7).

  In Steps 6 and 7, when both signals become equal in the comparator, the integrator 4 ends the integration operation, and feeds back the output signal to the integrator (B) to hold the correction amount 35. It adds to the CV steam demand flow signal 29 (Steps 6 and 7).

When both signals are not equal again in the comparator (Steps 2 and 3), the value obtained by integrating the deviation 34 is added and output, and this value is output as a correction amount 35. (Steps 4, 5, and 7).

  After CV-A is fully closed, the command value of CV-A valve test signal 28 will cause CV-A to move in the open direction to the pre-test position at a constant speed, and CV-A will operate in the open direction. Similarly, in the valve test required flow rate compensation circuit 1, the above operation is repeated.

  In Step 8, when the command value of the valve test signal 28 becomes 0 thereafter, the CV-A returns to the position before the test, and the output of the ON signal generator 24 is turned OFF. The switch of the valve request flow rate compensation circuit is also turned OFF, and the valve test is finished (Step 8).

  For the sake of easy understanding, the comparator 3 is described. However, since the integrator 4 always adds the previous correction amount and the current deviation, the previous correction amount is similarly calculated even when the current deviation is zero. In order to output, the determination device 36 may be omitted.

  Details of the integrator 4 will be described. The integrator 4 integrates the deviation 34 (ΔFn). This improves the followability to the offset in the steady state. When the integrator 4 is not provided, an offset is generated when compensation is performed by proportional control and a steady state is reached. By providing the integrator 4, it is possible to correct this offset and follow the CV steam required flow rate signal 29 that is a target value. If there is no need to correct the offset amount as being minute, the integrator 4 is unnecessary.

The functions f _{1 (x) to} f _{4 (x)} 10 to 13 will be described in detail. Functions f _{1 (x) to} f _{4 (x)} 10
13 converts the CV steam required flow rate signal 29 into a valve opening command value of each valve. An example of the conversion is shown in FIG. FIG. 4 shows the relationship between the steam flow rate request signal and the valve opening degree in the partial injection method. In the partial injection method, where the control valves of multiple valves have individual nonlinear characteristics, correct the inflow of each other between multiple valves, and determine the turbine steam flow in a comprehensive manner, correction at the time of valve test for each valve The amount will vary greatly. As an example, when a CV-A valve test is started at a point T1 indicated by a dotted arrow in FIG. 4, CV-C and D operate in the closing direction even if the steam flow request signal changes in the increasing direction. The relationship between the opening of each valve and the output flow rate at that opening is determined in a one-to-one relationship. In FIG. 4, the CV steam request flow rate signal and the opening degree of each valve are associated with each other. However, if this valve opening degree is converted into a flow rate, the CV steam request flow rate corresponds to the flow rate of each valve.

The functions f _{5 (x) to} f _{8 (x)} 14 to 17 will be described in detail. Function f _{5 (x) to} f _{8 (x)} 14 to
17 is a function for converting the valve opening command value into a steam flow signal of each valve. Since the relationship between the opening degree of the valve and the output flow rate at the opening degree is determined one-to-one as the specification of each valve, a function f _{5 (x)} ~ Set as f _{8 (x)} 14-17.

  FIG. 3 shows the opening degree of the valve to be tested (CV-A), the opening degree of the other valves (CV-BD), the correction amount, and the current control valve steam when the valve test having the characteristics shown in FIG. Indicates the required flow rate and load status.

  First, a valve test is started at T1, and CV-A starts to operate in the closing direction at a constant rate. At this time, CV-C and D also operate in the closing direction due to their characteristics, so that a large deviation occurs between the held control valve steam request flow rate signal and the current control valve steam request flow rate signal. The correction amount increases rapidly until T2 when C starts operating in the opening direction. Since CV-C starts to move in the opening direction at T2, the increase in the correction amount becomes somewhat gentle. Further, after C4-D starts to operate in the opening direction, the correction amount follows the deviation. Therefore, the correction amount increases constantly. The control valve steam required flow rate and load return to the original state even when T3 is exceeded, and remain constant.

  At T4, CV-A is fully closed, and then from T5, CV-A starts to move in the opening direction at a constant rate from the original opening. At this time, various states show changes opposite to those in the case where the CV-A operates in the closing direction, and after the CV-A returns to the position before the test, the valve test is terminated.

  When compensating as shown in FIG. 1, a display device for displaying the turbine control result is provided, and the retained control valve steam flow signal 33 (FH) and the current control valve steam flow signal 30 (Fn) are displayed. If a control system for monitoring these is used, it is possible to grasp the followability of the total flow rate as the entire current valve with respect to the flow rate before the test.

  FIG. 5 shows another example of the compensation circuit. Different points from FIG. 1 will be described.

  The holding circuit 2 does not hold the flow rate before the test, but holds the opening signal of each test valve before the test. The holding circuit 2 operates by the ON signal generator 24 as in FIG.

  The subtracter 37 is a subtractor for the test valve CV-A, and converts the opening signal held before the test by the holding circuit 2 and the opening signal of the valve test signal 28 which is the current opening signal. Then, subtraction is performed to calculate the CV-A fluctuation flow rate 40 during the test.

  The subtractor 38 is a subtractor for valves other than the test valve, and after subtracting the flow rate of each valve opening signal held by the holding circuit 2 before the test and the current valve opening signal, the subtraction is performed. Then, the fluctuation flow rate 41 of CV-B to D during the test is calculated.

  The subtractor 39 calculates the deviation 34 (ΔFn) by subtracting the fluctuation flow rate 40 of CV-A and the fluctuation flow rate 41 of CV-B to D. When this deviation 34 is not 0, the increase in CV-B to D is not compensated for the decrease in CV-A of the test valve. It is added to the signal 29. When the deviation 34 is 0, the increase in CV-B to D is compensated for the decrease amount of CV-A of the test valve, so that the correction is sufficient.

  In this figure, the test valve CV-A is described. However, when testing the test valve CV-B, the signal input to the subtractor 37 is changed to the signal of the test valve CV-B and input to the subtractor 38. The signal to be changed may be changed for the CV-A, C, D valves other than the test valve CV-B. This change may be switched based on the valve test signal.

When compensating as shown in FIG. 5, a display device for displaying the control result of the turbine is provided, and the variable flow rates 40 and 41 are displayed. The followability of the variable flow rate 41 can be grasped.

  Also in FIG. 5, as in FIG. 1, an integrator 4 can be further provided to improve the followability with respect to the offset in the steady state.

  As a common turbine control device having the configuration described in FIGS. 1 and 5, the control flow rate signal from the flow rate command unit is converted into opening signals of a plurality of control valves that adjust the fluid flow rate of one turbine. In the turbine control device that controls the engine, a function for calculating the flow rate flowing into the turbine based on the opening signals of the valve test target valve and the other control valve during the valve test of one of the plurality of control valves, and the calculation And a turbine control device having a function of calculating a correction amount for the variation of the test valve based on the flow rate and a function of adding the correction amount to the required flow rate signal. Thereby, it is possible to control with a simple configuration based on one steam flow rate characteristic.

  Further, by applying the turbine control device of the present invention to a turbine, the turbine can be controlled with a simple configuration based on one steam flow rate characteristic without using a separate flow rate characteristic for testing, and the valve opening is used. Therefore, the fluctuation of the test valve can be compensated at an early stage before being reflected in the measured value actually measured as the turbine output, and the followability to the required flow rate of the turbine can be improved.

  This example is the best mode for carrying out the invention, and the conventionally used steam pressure amount and the generator output in the steam turbine may be further added as correction amounts.

  Moreover, although the steam turbine was demonstrated in the said Example, it is applicable also to turbine control by other fluids, such as a gas turbine.

  Moreover, in the said Example, although the opening degree command value signal is used, you may use the opening degree signal which measured the opening degree of the valve. The use of the opening command value signal has better followability because no valve response is involved. However, using the measured valve opening signal can be more in line with the actual turbine output. Both of these are used as the opening signal.

  Further, the control device, the compensation circuit, etc. of the present invention can also be used by making a computer a program for causing the computer to achieve its function or a storage medium storing the program.

An example of the turbine control circuit provided with the valve test demand flow compensation circuit. Flow compensation circuit operation flow diagram. The operating state during the valve test. Relationship between steam flow request signal and valve opening in partial injection method. 6 is another embodiment of a turbine control circuit including a valve test required flow compensation circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Valve test request | requirement flow compensation circuit, 2 ... Holding circuit, 3 ... Comparator, 4 ... Integrator, 5 ... Switch, 6 ... Steam flow command part, 7 ... Adder, 8 ... Subtractor, 9 ... Test signal generation vessel, 10 to 13 ... function _{f 1 (x) ~f 4 (} x), 14~17 ... function _{f 5 (x) ~f 8 (} x), 18 ... adding circuit, 20 to 23 ... opening command value signal , 24 ... ON signal generator, 28 ... Valve test signal, 29 ... CV steam demand flow signal, 30 ... Current control valve steam flow signal, 31 ... Reset, 33 ... Control valve steam flow signal held, 34 ... Deviation 35: Correction amount.

Claims (10)

  In a turbine control device for controlling a control valve by converting a required flow signal from a flow command unit into opening signals of a plurality of control valves for adjusting a fluid flow rate of one turbine, one valve of the plurality of control valves During the test, a function for calculating the flow rate flowing into the turbine based on the opening degree of the valve test target valve and other control valves, and a correction amount for the variation of the test valve based on the calculated flow rate are calculated. A turbine control device comprising a function and a function of adding the correction amount to the required flow rate signal. The turbine control device according to claim 1,
The function of adding the correction amount to the required flow rate signal has a function of adding, to the required flow rate signal, a correction amount obtained by integrating the correction amount for the variation of the test valve. .   2. The turbine control device according to claim 1, wherein the function of calculating a correction amount for a variation of the test valve based on the calculated flow rate is a steam flow signal before a valve test signal used for the valve test is input. And a subtractor for calculating a difference between the total flow rate of the calculated flow rate and the held steam flow rate signal as a correction amount.   2. The turbine control device according to claim 1, wherein the function of calculating a correction amount for a variation of the test valve based on the calculated flow rate is provided for each valve before a valve test signal used for the valve test is input. A holding circuit for holding an opening signal, a subtractor for calculating a deviation between the calculated flow rate for the valve test target valve and a flow rate before the valve test, and the calculated flow rate and other values before the valve test for other control valves. A turbine control device comprising: a subtractor that calculates a flow rate deviation; and a subtractor that calculates a difference between the two deviations as a correction amount.   In a control valve test method for testing one of a plurality of control valves of a turbine, an opening signal is input to the valve test target valve, and the valve test target valve and other control valves are opened. The flow rate flowing into the turbine is calculated based on the degree signal, the correction amount for the variation of the test valve is calculated based on the calculated flow rate, the correction amount is added to the required flow rate signal, and the correction amount is added A control valve test method comprising: converting the required flow rate into opening signals of the plurality of control valves to control valves other than the test valves. The test method for a control valve according to claim 5,
When adding the correction amount to the required flow rate signal, a control valve test method comprising adding a correction amount calculated last time and a correction amount calculated this time as a correction amount to the required flow rate signal . The test method for a control valve according to claim 5,
When calculating the correction amount for the variation of the test valve based on the calculated flow rate, the flow rate immediately before the valve test signal input when performing the valve test is held, and the calculated flow rate is maintained. The control valve test method is characterized in that a difference between the total flow rate and the retained flow rate is calculated as a correction amount.   6. The control valve test method according to claim 5, wherein when calculating a correction amount for a variation of the test valve based on the calculated flow rate, a valve test signal input when the valve test is performed is input. The opening of each valve immediately before being held is maintained, the deviation between the calculated flow rate for the valve test target valve and the flow rate before the valve test is calculated, and the calculated flow rate for the other control valves and before the valve test are calculated. A control valve test method, comprising: calculating a flow rate deviation, and calculating a difference between the two deviations as a correction amount.   In a turbine control system comprising a turbine, a turbine control device that controls a plurality of control valves that adjust a fluid flow rate of one turbine, and a display device that displays a control result of the turbine, the control device includes the plurality of control devices. A function for calculating the flow rate flowing into the turbine based on the opening signals of the valve test target valve and the other control valves during one valve test of the control valve, and a function for calculating the total flow rate of the calculated flow rates And a function of displaying the calculated total flow rate and the flow rate before the test on the display device. The turbine control system according to claim 9, wherein the calculation for the valve test target valve is performed instead of the function of calculating the total flow rate of the calculated flow rate and the function of displaying the calculated total flow rate on the display device. A function for calculating a deviation between the calculated flow rate and the flow rate before the valve test, a function for calculating the deviation between the calculated flow rate and the flow rate before the valve test, and the two calculated deviations are displayed. A turbine control system having a function.

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