JP2004060496A - Steam turbine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam turbine control device including a control logic circuit structured simple so as to be free of malfunction, whereby an intercept valve is certainly closed quickly when the steam turbine is in an over-speed. <P>SOLUTION: The steam turbine control device is equipped with the intercept valve, an intercept valve factor means 43, and an intercept valve quick closing means 40, whereby part of an intercept valve speed load control signal 39 before being given from the factor means 43 to a low value selecting means 44 is branched, and the valve quick closing means 40 closes quickly the intercept valve on the condition that either of a power load unbalance signal 57 and a valve control signal 56 operated arithmetically on the condition that a valve closing direction deviation large signal 54 operated arithmetically on the basis of the branched valve speed load control signal 39 and a signal 55 to indicate as an actual load being no less than the predetermined value are both obtained is emitted. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steam turbine control device, and more particularly to a steam turbine control device that simplifies a control circuit and incorporates a logic circuit without malfunction to quickly close an intercept valve.
[0002]
[Prior art]
Generally, as shown in FIG. 3, a steam turbine plant applied to a thermal power plant or a nuclear power plant includes a steam generator 1, a high-pressure turbine 2, a reheater 5, a medium-pressure The steam generator 1 includes a turbine 5, a low-pressure turbine 9, a condenser 10, and the like. The steam generated by the steam generator 1 is supplied to the high-pressure turbine 2 via the main steam stop valve 3 and the steam control valve 4, where the steam is expanded. To remove the power, reheat the high-pressure turbine exhaust whose temperature has become low by the reheater 5, and supply it to the medium-pressure turbine 6 through the reheat steam stop valve 7 and the intercept valve 8 as reheat steam. ing.
[0003]
Further, the steam turbine plant supplies the medium-pressure turbine exhaust having completed the expansion work in the medium-pressure turbine to the low-pressure turbine 9 to perform the expansion work again, and supplies the low-pressure turbine exhaust having completed the expansion work to the condenser 10. , Where it is condensed and condensed.
[0004]
Further, in the steam turbine plant, during the start-up operation, if the temperature of the reheated steam coming out of the reheater 5 does not reach a predetermined temperature, the components such as the medium-pressure turbine 6 and the low-pressure turbine 9 have an adverse effect. For example, a so-called turbine bypass operation is performed in which the turbine bypass valve 11 is opened until the load becomes several tens%, and a part of the reheated steam discharged from the reheater 5 is supplied to the condenser 10.
[0005]
In this case, the flow rate of the reheated steam supplied from the reheater 5 to the condenser 10 is controlled by opening and closing the turbine bypass valve 11.
[0006]
Further, the reheat steam supplied from the reheater 5 to the intermediate-pressure turbine 6 is combined with the steam passing through the steam control valve 4 in which the valve opening of the intercept valve 8 is linked to the valve opening of the steam control valve 4. The flow ratio control to make the flow ratio with the steam passing through the intercept valve 8 2: 1 was performed.
[0007]
On the other hand, during the operation of the steam turbine plant, the steam turbine control device for rapidly closing the intercept valve 8 due to, for example, a system accident was initially only the speed load control circuit 12, as shown in FIG.
[0008]
The speed load control circuit 12 includes a speed control circuit 13, a steam control valve intercept valve flow ratio control unit 14, an intercept valve coefficient unit 15, a low value selection unit 16, and the like. When a deviation is found, a speed control signal is calculated by the speed control circuit 13 based on the deviation, a load setting signal is added to the calculated speed control signal, and a speed load control signal 17 is calculated. The steam control valve 4 is controlled using the load control signal 17 as a valve opening / closing command signal, and the signal is branched and supplied to the steam control valve intercept valve flow ratio control means 14 and the intercept valve coefficient means 15, respectively.
[0009]
The steam control valve intercept valve flow ratio control means 14 converts the speed load control signal 17 into, for example, a flow ratio control signal that makes the flow ratio between the steam flow through the steam control valve 4 and the steam flow through the intercept valve 8 2: 1. The calculated value is applied to the low value selecting means 16.
[0010]
Further, the intercept valve coefficient means 15 calculates the speed load control signal 17 into an intercept valve speed load control signal 19 so as to match the intercept valve stabilization rate, and supplies the calculated intercept valve speed load control signal to the low value selecting means 16. ing.
[0011]
The low value selecting means 16 selects any low value signal from the flow rate control signal from the steam control valve intercept valve flow ratio control means 14 and the intercept valve speed load control signal 19 from the intercept valve coefficient means 15. The intercept valve opening / closing signal 20 is given to the intercept valve 8.
[0012]
However, the steam turbine control device provided with such a control logic circuit has problems and inconveniences.
[0013]
For example, at the moment when the operation is switched from the normal operation to the turbine bypass operation, the flow rate control signal 18 from the steam control valve intercept valve flow ratio control means 14 is given to the intercept valve 8 via the low value selection means 16, The intercept valve 8 is to be closed from the fully opened state to the valve opening corresponding to the flow ratio control signal 18, but is not immediately closed to the set position because the valve is driven by hydraulic pressure. Therefore, the difference between the preset valve opening / closing signal and the actual valve opening, the so-called deviation, increases. As the deviation increases, a large intercept valve deviation signal is calculated, and the calculated large intercept valve deviation signal is given to the intercept valve 8 as a valve rapid closing signal. For this reason, the intercept valve 8 may be closed and the steam turbine may trip even though the turbine is at the rated speed and not at the abnormally high speed.
[0014]
In order to deal with such inconveniences and inconveniences, in a recent steam turbine control device, as shown in FIG. 2, the speed load control circuit 12 is provided with an intercept valve quick closing means 21.
[0015]
The intercept valve quick closing means 21 matches the intercept valve opening / closing signal 20 calculated by the speed load control circuit 12 with the actual intercept valve opening signal 23, and when a deviation occurs, a large deviation detector 23 based on the deviation. Calculates the large intercept valve closing direction deviation signal 24. A first valve control signal 27 calculated by a first AND circuit 26 on the condition that the calculated intercept valve closing direction deviation large signal 24 and the turbine bypass operation non-operation signal 25 are aligned, a turbine bypass operation signal 28, a load X% The second valve control signal 32 calculated by the second AND circuit 31 on the condition that the actual load signal 29, the rotation speed control signal 30 having a rotation speed of 102% or more are equal, and the power load unbalance signal 33 The OR circuit 34 calculates the intercept valve rapid closing signal 35 on condition that one of the control signals is prepared. Then, the intercept valve 8 is closed rapidly so that the intercept valve 8 is not affected by a valve closing signal given from a turbine bypass circuit (not shown) during the turbine bypass operation. That is, the intercept valve 8 is for preventing the overspeed of the steam turbine, and is affected by the valve closing signal given from the turbine bypass circuit even during the turbine bypass operation unless the rotation speed of the steam turbine abnormally increases. It was made not to be.
[0016]
[Problems to be solved by the invention]
However, the steam turbine control device shown in FIG. 2 requires the presence or absence of the turbine bypass operation. Therefore, even if there is a valve closing command from the turbine bypass circuit, the intercept valve 8 operates in a manner other than a signal necessary for preventing overspeed. Although no longer affected, the control signal circuit malfunctions because the control logic circuit is complicated by incorporating the steam control valve intercept valve flow ratio control means 14 and adding the condition of the turbine bypass operation. Even though the rotation speed of the steam turbine is not overspeed, a quick closing command may be input to the intercept valve 8.
[0017]
For example, during turbine bypass operation, when the steam control valve 4 is linked with the intercept valve 8 in a flow ratio control, for example, when the steam control valve passing flow rate is controlled at 2 and the intercept valve passing flow rate is controlled at 1, the frequency fluctuation or When the steam pressure fluctuates and the flow ratio control signal 18 given to the steam control valve 4 changes suddenly, or when switching from normal operation to turbine bypass operation due to a load drop, the intercept valve 8 is suddenly closed. When the turbine bypass operation is completed, the load becomes a preset value when the turbine bypass operation is completed.At this time, when the turbine bypass operation and the normal operation are intermittently repeated for some reason, the steam control is performed. Under the influence of the flow ratio control signal 18 from the valve intercept valve flow ratio control means 14, or The malfunction caused by Zatsuka, actually had to give rapid closing signal to the intercept valve 8 as steam turbines has become overspeed despite not been overspeed.
[0018]
The present invention has been made in view of the above circumstances, and a steam turbine control device for surely and rapidly closing an intercept valve when the steam turbine is overspeed so as to simplify a control logic circuit and prevent malfunction. The purpose is to provide.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, a steam turbine control device according to the present invention detects a speed signal from a preset turbine rotor speed using a speed detector provided in the turbine rotor, as described in claim 1. A first comparator for subtracting the signal of the actual rotation speed, a speed control means for inputting a signal from the first comparator to calculate a speed control signal, and the speed control signal being preset. An adder for adding a load setting signal to calculate a speed control signal; a steam control valve intercept valve flow ratio control means for inputting the speed load control signal and calculating a flow ratio control signal; and the speed load control signal. , An intercept valve coefficient means for calculating an intercept valve speed load control signal, a flow ratio control signal from the steam control valve intercept valve flow ratio control circuit, and the intercept Low value selecting means for selecting one of the low value signals from the intercept valve speed load control signal from the valve coefficient means and giving the low value signal to the intercept valve as an intercept valve opening / closing signal; and detecting the intercept valve opening provided in the intercept valve. A second comparator for calculating a deviation between an actual intercept valve opening signal from the interceptor and an intercept valve speed load control signal branched and input from the intercept valve coefficient means, and a deviation of the deviation from the second comparator. A large deviation detector that outputs a large intercept valve closing direction deviation signal when the signal exceeds a predetermined deviation, and an actual load that is equal to or greater than a predetermined value with the large intercept valve closing direction deviation signal. An AND circuit for calculating a valve control signal by performing an operation on condition that both of the signals are identical; A steam turbine controller having an OR circuit for calculating an intercept valve suddenly closing signal performs calculation on the condition that any of the signals of imbalance signals are aligned.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a steam turbine control device according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.
[0021]
FIG. 1 is a schematic control block diagram showing an embodiment of a steam turbine control device according to the present invention.
[0022]
In the steam turbine control device according to the present embodiment, for example, when switching from normal operation to turbine bypass operation, the flow ratio control signal 37 from the steam control valve intercept valve flow ratio control means 36 is selected, and the steam turbine is overspeeded. In spite of the fact that it is not, it aims to prevent the erroneous signal that the intercept valve issues a sudden close command and also to prevent the malfunction due to the complexity of the control logic circuit by including the condition of the existence of turbine bypass operation. Thus, the intercept valve speed load control signal 39 calculated by the speed load control circuit 38 is used as an intercept valve quick closing command, while the control logic circuit of the intercept valve quick closing means 40 is simplified.
[0023]
The speed load control circuit 38 includes a speed detector 41, a speed control circuit 42, a steam control valve intercept valve flow ratio control means 36, an intercept valve coefficient means 43, a low value selection means 44, and the like, and a turbine rotor (not shown). The first comparator 45 compares the actual rotational speed signal from the speed detector 41 provided in the first comparator 45 with a preset rotational speed, and determines a deviation corresponding to the speed adjustment rate by the speed control circuit 42. A control signal 46 is calculated, a load setting signal is added to the calculated speed control signal 46 by an adder 47 to calculate a speed load control signal 48, and the calculated speed load control signal 48 is branched to intercept the steam control valve intercept. The values are given to the valve flow ratio control means 36 and the intercept valve coefficient means 43, respectively.
[0024]
The steam control valve intercept valve flow ratio control means 36 calculates the flow ratio control signal 37 so that, for example, the flow rate of the intercept valve becomes 1 with respect to the flow rate 2 of the steam control valve, and the calculated flow ratio control signal 37 Is given to the low value selecting means 44.
[0025]
Further, the intercept valve coefficient means 43 calculates the intercept valve speed load control signal 39 corresponding to the intercept valve stabilization rate, branches the calculated intercept valve speed load control signal 39, and selects the low value selecting means 44 and the intercept valve quick closing means 40. Has given to.
[0026]
The low value selecting means 44 selects any one of the flow ratio control signal 37 and the intercept valve speed load control signal 39 and supplies an intercept valve opening / closing command signal 49 to the intercept valve to control the valve opening / closing. It is carried out.
[0027]
The intercept valve rapid closing means 40 includes an intercept valve opening degree detector 50, a large deviation detector 51, an AND circuit 59, an OR circuit 60, and the like, and outputs the intercept valve speed load control signal 39 from the intercept valve coefficient means 43 to the second. The comparator 52 matches the actual intercept valve opening signal 53 from the intercept valve opening detector 50, and when a deviation occurs, the deviation is detected by the large deviation detector 51 to calculate a large intercept valve closing direction deviation signal 54. A valve control signal 56 on condition that the calculated intercept valve closing direction deviation large signal 54 and a signal 55 indicating that the actual load is equal to or greater than a predetermined value are provided by an AND circuit 59, and a power load unbalance. An intercept valve rapid closing signal 58 on the condition that one of the signals 57 is input to the OR circuit 60 is interleaved. Giving the concept valve, it is made to rapidly close the intercept valve.
[0028]
As described above, in the present embodiment, a part of the intercept valve speed load control signal 39 calculated by the intercept valve coefficient means 43 is branched before being input to the low value selecting means 44, and the branched intercept valve speed load control signal 39 is branched. Is matched with the actual intercept valve opening signal 53. When a deviation occurs, a large intercept valve closing direction deviation signal 54 is calculated based on the deviation, and the calculated intercept valve closing direction deviation large signal 54 and a signal indicating that the actual load is equal to or greater than a predetermined value. When any one of the valve control signal 56 and the power load unbalance signal 57 having the same value 55 is output, the intercept valve is rapidly closed by the intercept valve quick close signal 58. Therefore, unlike the related art, the influence of the flow ratio control signal 37 from the steam control valve intercept valve flow ratio control means 36 is eliminated, and the control logic circuit of the intercept valve quick closing means 40 is further simplified to control the control signal. When the trip command is input to the steam turbine, the intercept valve can be surely and quickly and rapidly closed, and the overspeed of the steam turbine can be reliably prevented.
[0029]
【The invention's effect】
As described above, the steam turbine control device according to the present invention branches a part of the intercept valve speed load control signal calculated by the intercept valve coefficient means of the speed load control means before inputting it to the low value selection means. Then, the branched control signal is supplied to a large deviation detector of the intercept valve rapid closing means to calculate a large signal of the intercept valve closing direction deviation, and the calculated large signal of the intercept valve closing direction deviation, which is equal to or larger than a predetermined value, is calculated. When one of the load signal and the power load unbalance signal is output, the control signal is output to the intercept valve as an intercept valve rapid closing signal, and the intercept valve is rapidly closed regardless of the presence or absence of turbine bypass operation. Simplifies the control logic circuit and prevents the control signal from malfunctioning, It can be reliably quickly close the valve.
[Brief description of the drawings]
FIG. 1 is a schematic control block diagram showing an embodiment of a steam turbine control device according to the present invention.
FIG. 2 is a schematic control block diagram showing a conventional steam turbine control device.
FIG. 3 is a schematic system diagram showing a conventional steam turbine plant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steam generator 2 High pressure turbine 3 Main steam stop valve 4 Steam control valve 5 Reheater 6 Medium pressure turbine 7 Reheat steam stop valve 8 Intercept valve 9 Low pressure turbine 10 Condenser 11 Turbine bypass valve 12 Speed load control circuit 13 Speed control circuit 14 steam control valve intercept valve flow ratio control means 15 intercept valve coefficient means 16 low value selection means 17 speed load control signal 18 flow ratio control signal 19 intercept valve speed load control signal 20 intercept valve opening / closing signal 21 intercept valve rapid closing Means 22 Large deviation detector 23 Actual intercept valve opening signal 24 Intercept valve closing direction large deviation signal 25 Out of turbine bypass operation signal 26 First AND circuit 27 First valve control signal 28 Turbine bypass operation signal 29 Actual load signal 30 Revolution Control signal 31 second AND circuit 32 second valve Control signal 33 Power load unbalance signal 34 OR circuit 35 Intercept valve rapid closing signal 36 Steam control valve intercept valve flow ratio control means 37 Flow ratio control signal 38 Speed load control circuit 39 Intercept valve speed load control signal 40 Intercept valve rapid closing means 41 speed detector 42 speed control means 43 intercept valve coefficient means 44 low value selecting means 45 first comparator 46 speed control signal 47 adder 48 speed load control signal 49 intercept valve opening / closing command signal 50 intercept valve opening detector 51 Large deviation detector 52 Second comparator 53 Actual intercept valve opening signal 54 Large intercept valve closing direction deviation signal 55 Signal indicating that the actual load is equal to or greater than a predetermined value 56 Valve control signal 57 Power load unbalance signal 58 Intercept valve quick closing signal 59 A ND circuit 60 OR circuit

Claims (1)

A first comparator for subtracting a signal of an actual rotational speed detected by a speed detector provided on the turbine rotor from a preset rotational speed signal of the turbine rotor;
Speed control means for receiving a signal from the first comparator and calculating a speed control signal;
An adder that calculates a speed control signal by adding the speed control signal and a preset load setting signal;
A steam control valve intercept valve flow ratio control means for inputting the speed load control signal and calculating a flow ratio control signal,
Intercept valve coefficient means for inputting the speed load control signal and calculating an intercept valve speed load control signal,
Among the flow rate control signals from the steam control valve intercept valve flow ratio control circuit and the intercept valve speed load control signal from the intercept valve coefficient means, one of the low value signals is selected, and the intercept valve is used as an intercept valve opening / closing signal. Low value selecting means to give;
A second comparator for calculating a deviation between an actual intercept valve opening signal from an intercept valve opening detector provided in the intercept valve and an intercept valve speed load control signal branched and input from the intercept valve coefficient means. When,
A large deviation detector that outputs a large intercept valve closing direction deviation signal when the deviation signal from the second comparator is equal to or larger than a predetermined deviation,
An AND circuit that performs an operation on condition that both the large signal of the intercept valve closing direction deviation large signal and a signal indicating an actual load equal to or greater than a predetermined value are provided to calculate a valve control signal,
An OR circuit that performs an operation on the condition that one of the valve control signal and the power load unbalance signal is aligned to calculate an intercept valve rapid closing signal;
A steam turbine control device comprising:

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