JP2656363B2 - Steam turbine controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a steam turbine control device for switching a flow distribution of each control valve of a steam turbine in a power plant.

(Prior Art) FIG. 6 shows an example of a turbine control system.

The steam generated from the boiler 1 flows into the turbine 3 through flow distribution by two steam control valves (hereinafter, abbreviated as CV) 2A and 2B. The steam flowing into the turbine 3 rotates the turbine 3 and further drives the generator 4 to generate electric power. The actual speed of the turbine 3 is detected by the speed detector 5 and input to the governor control unit 6. The governor control unit 6 creates a flow command U from the speed signal and the output request of the generator, and sends it to the flow distribution control unit 7. Flow distribution controller 7 based on the flow command U, opening instruction W _A of the valve, and calculating the W _B, sends the CV opening control section 8A, the 8B. Each CV opening control unit controls the CV to a valve opening corresponding to the opening command.

FIG. 7 shows a configuration of a flow distribution control unit 7 of a conventional turbine control device for controlling such a turbine system.
The FA function generators 10A and 10B generate functions F _1A (X) and F _1B (X) for making the CV flow rate distribution an FA pattern, an example of which is shown in FIG. 8 (a). The purpose of this FA pattern is to reduce the thermal stress applied to the turbine by setting the opening of all valves to the same value so that the amount of steam flowing into the turbine is the same between the valves. Therefore, the function F _1A
(X) and F _1B (X) are the same as indicated by the solid line in FIG. In addition, these two functions F _1A (X), F _1B
(X) that shows a non-linearity is due to the nonlinearity of the valve opening versus flow characteristics of the CV, flow command U and CV inflow steam flow F _A, F
_B and the total sum of turbine inflow steam F
Is a non-linear function as shown by the solid line in order to make the relationship linear as shown by the one-dot chain line in FIG.

Similarly, the PA function generators 11A and 11B in FIG. 7 are functions F _2A (X) and F _2B (X) for making the CV flow rate distribution a PA pattern.
An example is shown in FIG. 8 (b). The purpose of this PA pattern is to reduce the energy loss at the valve by opening the valve sequentially with increasing flow requirements. Therefore, the functions F _2A (X) and F _2B (X)
Is FIG. (B) 50% of the valve opening command V ₁ as indicated by the solid line
A change characteristic in which the same pattern is repeated with the boundary as a boundary. Further, the pattern, the flow command U and CV inflow steam flow F _A, F _B
In order to make the relationship with the total steam amount F flowing into the turbine, which is the sum total thereof, linear as indicated by the one-dot chain line in FIG. 3B, the horizontal axis of the pattern is reduced to half.

The FA / PA switching bias generator 12 shown in FIG.
It is configured to generate the FA / PA switch bias V ₁ which varies in ~100% (PA), to start and end the FA / PA switch. FA bias function generator 13 and PA bias function generator
14 is the FA bias V ₂ and P according to the FA / PA switching bias V ₁
And it outputs the A bias V _3. These biases, V ₂ = 0% in FA pattern, V ₃ = 100%, the PA pattern V ₂ = 100
%, V ₃ = 0%. The purpose of these two function generators is F
FA bias to suppress fluctuations in steam volume during A / PA switching
V ₂ and PA bias V ₃ .

The adders 15 _A , 15 _B , 16 _A , and 16 _B apply the FA bias V ₂ ,
It adds a bias _{V 3, V 4A, V 4B} , V 5A, outputs the V _5B. FA
The value of V _5A is a large value by 100% bias component from the V _4A in the case of the pattern.

FA flow opening function generator 10A, 10B and PA flow opening function generator 11A, 11B converts the flow command signal input to the opening command signal, and outputs the _{V 6A, V 6B, V 7A} , V 7B .

Low value selector 17 _A, 17 _B selects towards the lower opening command signal input value, CV2A opening command W _A, CA2B, outputs the opening command W _B. For example, in the case of the FA pattern, V _4A = U, V _5A = U +
Since 100%, it becomes V _6A <V _7A, the low value selector 17 _A, V _6A is a opening signal FA pattern is selected.

(Problems to be Solved by the Invention) However, according to the above-described conventional configuration, the FA bias function generator 13 and the PA bias function generator 14 are set so that there is no flow rate fluctuation at the time of switching at a specific flow rate. Therefore, if switching is performed at a point deviating from a specific flow rate, there is a problem that flow rate fluctuation is caused and disturbance to boiler control is caused.

That is, when changing the FA / PA switch bias V ₁ from 0 to 100 (%), as shown in FIG. 9 (a), the output PA bias V ₃ of the function generator 14, a bias V ₁ is 0 to 50 (%), It changes from 100 to 0 (%). Then the bias V ₁ becomes 5
Output FA bias of function generator 14 while changing from 0 to 100 (%)
V ₂ is changed to 0 to 100 (%). This PA bias V ₃ , FA
With the change in bias V _2, flow opening function generator 10A, 11
The output FA opening command V _6A and the PA opening command V _7A of A change as shown in FIG. 9B, respectively, as is apparent with reference to FIG. In addition, the output F of the flow opening function generators 11A and 11B
The A opening command V _6B and the PA opening command V _7B also change as shown in FIG. 9 (c), respectively, as is apparent from FIG.

Therefore, the output valve opening instruction W _A obtained through opening command V _6A, V _7A of the low value selector 17A is as shown by the one-dot chain line in Figure No. 9 (b). Also, the opening commands V _6B and V _7B are set to the low value selector 17B.
Output valve opening instruction W _B obtained through is as shown by a chain line in FIG. (C).

As a result, the total turbine inflow steam amount F, which is the sum of the steam flow rates flowing through the two steam control valves 2A and 2B, becomes as shown in FIG.
(%) Change occurs.

As described above, the conventional steam turbine control apparatus has a problem in that, when the FA / PA pattern is switched, the opening / closing operation of the two steam control valves has a time lag, and the turbine inflow total steam amount F fluctuates. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a steam turbine control device capable of performing FA / PA switching without flow rate fluctuation at an arbitrary flow rate command value.

[Constitution of the Invention] (Means for Solving the Problems) The present invention relates to a flow rate distribution control unit, which is provided with a PA flow rate opening function generator and a FA flow rate opening function generator. A bias which changes so as to simultaneously switch from one to the other in the function value corresponding to the command value is applied to each function generator.

(Operation) With the above configuration, when switching from one pattern to the other pattern, the change in the opening degree of each CV starts and ends at the same time. Pattern switching is performed.

(Embodiment) FIG. 1 shows a configuration diagram of a flow distribution control unit in a steam turbine control device according to an embodiment of the present invention.

1, the same reference numerals as those in FIG. 7 denote the same or corresponding parts, and point bias opening generators 13, 14 different from FIG.
Instead of this, FA actual switching bias function generators 21A and 21B, PA actual switching bias function generators 22A and 22B, FA bias function generators 23A and 23B, and PA bias function generators 24A and 24B are provided.

Based on the flow command U, the FA actual switching bias function generators 21A and 21B and the PA actual switching bias function generators 22A and 22B provide bias amounts V _11A , V _11B , V _12A and V from the start of switching to the completion of switching.
_It generates _12B . Functions F _5A (U), F _5B (U), F _6A (U), F _5A set in these function generators
_6B (U) is the function F _1A (X), F _1B (X), F _2A (X),
This is set in consideration of F _2B (X) and the switching direction.

For example, when switching from the FA pattern to the PA pattern,
Function F _5A (U) is equal as shown in FIG. 2 (a), and F _2A obtained from U point on the V ₁ axis (U), in the F _2A (U)
Distance connecting the F _1A (U ') point parallel to the V ₁ axis F _5A (U), and becomes a function shown in FIG. 3 (a). The meaning of having this function is that CV2A is converted to FA pattern F while driving at V ₁ = U.
_The amount of bias required to switch from _1A (X) to the PA pattern F _2A (X), which is represented by F _2A (X) F _1A (X
+ Α), and α = F _5A (U). Given flow command U is uniquely determined with F _5A (U), for example, the F _5A (40) = 40 when the U = 40.

The function F _6A (U) is a PA opening input V _7A to the low value selector 17 _A.
Is set to a high value until the start of switching, and a constant value of 100 (%) is output so as to be selected when the switching is completed.

As shown in FIG. 2B, the functions F _5B (U) and F _6B (U) are such that the PA pattern F _2B (X) is always the FA pattern F _1B (X).
Therefore, in order to switch from the FA pattern to the PA pattern, it is necessary to set the F _2B (X) output V _7B side to a low value at the start of the switching so as to be selected by the low value selector 17B.
Therefore, the function F _5B (U) is a function that outputs a constant value of 100 (%), as will be clear from the description below. On the other hand, the function F _6B (U) are determined from point U on V ₁ axis F
_1B (U) and an F _2B (U ′) point equal to this F _1B (U)
V ₁ distance connecting in parallel to the axis F _6B (U), and becomes a function shown in FIG. 3 (b). This function F _6B (U) is given by V ₁ =
For switching the CV2B while driving in U from FA pattern F _1B (X) in the PA pattern F _2B (X), F _2B at switching start time (X)
Is selected by the low value selection base 17B, and when switching is completed, V ₁ = U and F
_It indicates the amount of bias to become _2B (U). If a flow rate command U is given, it is uniquely determined as F _6B (U). For example, U = 4
When it is 0, F _2B (40) = 30.

Next, FA bias function generator 23A, and 23B, PA bias function generator 24A, 24B, the function generator 21A, 21B, 22A, the output V _11A of 22B, V _12A, V _11B, and V _12B, FA / FA bias V _13A based on the PA switched bias V _1, V _13B and PA bias V _14A, generates a V _14B. Function F set for these function generators
_7A (X), F _7B (X), F _8A (X), F _8B (X) are used so that the change of the actual switching bias amount obtained above starts and ends simultaneously for each valve, for example, as shown in FIG. as shown in (a) and (c), 10~90 (%) of V ₁ main section is set between.

That is, the function F _7A (X) is the output V _11A of the function generator 21A =
V ₁ F _5A the (U) as the target value is a function that changes from 0 to F _5A (U) while the 10 to 90 (%) change.

The function F _8A (X) is the output V _12A of the function generator 22A = 100
While V ₁ = change 10% to 90% based on (%) 100-0
(%).

The function F _7B (X) is the output V _11B = 100 of the function generator 21B.
0% to 100% while changing V ₁ = 10 to 90% based on (%)
(%).

The function F _8B (X) is the output V _12B = F of the function generator 22B.
F _6B while V ₁ = 10 to 90% change with _6B (U) as the initial value
The function changes from (U) to 0 (%).

For example, switching from the FA pattern to the PA pattern when the flow rate command U = 40% will be described.

During the FA pattern operation, as shown in Fig. 2, CV2A, CV2
B is _V6A = _F1A (40) = 20 (%), _V7A = _F1B (40) = 2
Operating at 0 (%) opening. In this state, the switch to the PA pattern, CV2A side must be opened from _{F 1A (40) = 20 (} %) degree _{F 2A (40) ≒ 73 (} %) to the opening.
At the same time CV2B is _{F 1B (40) = 20 (} %) degree of F _2B (40) = 0
(%) It is necessary to close to the opening.

Therefore First, 73 (%) of CV2A from 20 (%) in the opening, it is necessary to the V _4A from 40% to 80%,
The bias amount _V11A for this is obtained from the function generator 21A in FIG. 1 as _V11A = _F5A (40) = 40. And with the function generator 23A, V while changing the V ₁ = 10~90 _13A = 0~40
(%). After the switching is completed, the bias amount _V13A is increased from 40 (%) to 100 (%) in order to prevent the FA pattern from being selected.

On the other hand, during the FA pattern operation before switching, the PA pattern is irrelevant, so the function generator 11A output V _7A has a high value of 100.
(%) Biased. In order to be selected as the W _A output at low value selector 17A is the same when switching completion, it is necessary to set _{V 7A = F 2A (40)} = 73 in the switching completion time point. Therefore, the function generator 24A generates the bias amount that varies V _14A = 100~0 (%) during the change in V ₁ = 10 to 90.

In this manner, the function generator 23A, from 24A, a bias V _13A shown in FIG. 4 (a), V _14A is generated. Based on the biases V _13A and V _14A , the function generators 10A and 11A generate valve opening signals V _6A and V _7A shown in FIG. 4 (b).

That is, the valve opening signal V _6A generated from the function generator 10A is
As shown in FIG. 3B, V _6A = 20 until V ₁ = 10, and then V
It increases linearly to V _6A ≒ 73 up to ₁ = 90 and then rapidly increases to V _6A = 100 (%) by V ₁ = 100. On the other hand, the function generator 11A
The valve opening signal _V7A generated from _V7A = 10 up to _V14A = 60
Maintaining 0, then decreases towards the switching point V _7A ≒ 73, V ₁
= 90 was reduced to V _7A ≒ 73 in retains its value.

This allows the low value selector 17A output W _{A to} V ₁ = 90
V _6A and thereafter V _7A are selected, and the switching on the CV2A side is completed.

Next, CV2B is changed from F _1B (40) = 20 (%) to F _2B (40) = 0.
(%) To set the opening, PA pattern F _2B at the start of switching
It is necessary to switch to (70) = 20. Therefore, the FA pattern
In order to make F _1B (X) irrelevant from the switching time, as shown in FIG. 4 (c), while changing from V ₁ = 10 to 90,
V _13B = 0 to 100% (%) is generated.

On the other hand, since the transfer source PA pattern F _8B (X) is 100 (%), for this to be selected by the switch at the same time as the start low value selector 17B, until V ₁ = 0 _V14B = 10
Reduce to 0-30%. Subsequently, a bias amount that changes to V _14B = 30 to 0 while changing to V ₁ = 10 to 90 is generated.

In this manner, the function generator 23B, from 24B bias V _13B shown in FIG. 4 (c), V _14A is generated. The bias V _13B, function based on V _14B generation group 10B, 11B the valve opening signal V _6B shown in FIG. 4 (d), to generate a V _7B.

That is, the valve opening signal V _6B generated from the function generator 10B is
As shown in FIG. 3D, V is not changed until the switching start time V ₁ = 10.
_6B = 20 and selected by the low value selector 17B. However, thereafter increases toward the 100 (%), V _13B is 60 (%)
At which point it reaches 100 and holds that value thereafter. On the other hand, the valve opening signal V _7B generated from the function generator 11B
When V ₁ = 10, V _7B = 20, and with the change of V ₁ = 10 to 90, V
_7B = 20-0. Therefore, after the start of switching, V
_7B is selected, whereby CV2B is switched to the PA pattern.

As described above, in the switching from the FA pattern to the PA pattern, the opening change of each CV starts and ends at the same time. In this, CV2A, CV2B inflow steam flow F _A, the change in F _B is, for the fifth start as simultaneously shown in Figure was completed at the same time, and straight, and the amount of change is to cancel each other, the turbine inlet No change in the total steam flow rate F occurs.

In the above embodiment, the case where there are two CVs has been described as an example, but the present invention is also applicable to the case where there are two or more CVs.

[Effects of the Invention] As described above, according to the present invention, it is possible to switch the FA pattern PA pattern without changing the total turbine inflow steam flow at an arbitrary flow command. Further, even when the flow rate command is changing, the switching can be performed while the flow rate command and the total flow rate are set to the same value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a flow distribution control unit of a steam turbine control device showing one embodiment of the present invention, and FIGS. 2 (a) and (b) show FAs.
FIG. 3 (a) and FIG. 3 (b) are pattern diagrams showing an example of a function set to generate an actual FA / PA switching bias function in FIG. 1, and FIG. Is
Examples of functions set in the FA and PA bias function generators are FA,
Pattern diagram showing the relationship with the PA flow rate opening function generator output,
FIG. 5 is an explanatory diagram of a flow rate change at the time of FA / PA switching, FIG. 6 is a configuration diagram of a general steam turbine control device, FIG. 7 is a configuration diagram of a conventional flow distribution control unit, and FIG. , (B) is FA, PA
FIG. 9 is a pattern diagram showing an example of a function set in the flow rate opening function generator and a flow rate change based on the function.
FIG. 7 is an explanatory diagram of an A pattern switching operation. 7: Flow distribution control unit, 10A, 10B: FA flow opening function generator, 11A, 11B: PA flow opening function generator, 12: FA / PA
Switching bias generator, 21A, 21B… FA actual switching bias function generator, 22A, 22B… PA actual switching bias function generator, 2
3A, 23B: FA bias function generator, 24A, 24B: PA bias function generator, 17A, 17B: Low value selector.

Claims (1)

(57) [Claims] 1. A lower value is selected for a lower value of the output from each of the function generators generated by changing a bias signal input together with a flow rate command to the FA flow rate opening function generator and the PA flow rate opening function generator. In the steam turbine control device including a plurality of circuits selected by the heater and a flow distribution control unit that uses the output of those circuits as the opening command of the plurality of steam control valves, the FA flow opening function generation is performed. And a PA flow rate opening function generator generate a bias for simultaneously shifting the value corresponding to the flow rate command from one function to the other function in accordance with a change in the bias signal. A steam turbine control device, wherein a bias function generator to be provided is provided for each flow rate opening function generator.