JPS6088803A - Steam turbine controller - Google Patents

Abstract

PURPOSE:To check a turbine output variation in time of testing a main steam control valve with an optional output, by compensating a first stage steam pressure signal of a turbine with a main steam pressure signal and thereby producing an actual flow signal, while opening or closing the main steam control valve according to a deviation between the flow signal and the flow setting value. CONSTITUTION:A first stage steam pressure signal R1 if a steam turbine 7 is compensated with a main steam pressure signal at an actual flow transducer 13 and then an actual flow signal Q3 is fed to a comparator 10. A deviation between a flow setting signal Q1 and the actual flow signal Q3 is taken up at the comparator 10 and inputted into a control valve opening functors 2A and 2B via a gainer 11. In time of testing, a valve test contact 4A of a valve to be tested is closed, giving it a bias, whereby a main steam control valve 6A is closed. And, another valve 6B increases its opening so as to compensate a portion for the decrement of steam flow whereby a variation in turbine output is checked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a steam turbine control device C for a steam turbine having a plurality of steam control valves.

[Technical background of the invention and its problems]

Generally, in the control and installation of a steam turbine, the rotation speed and output of the turbine are controlled by controlling the amount of high-temperature, high-pressure steam flowing into the turbine using a plurality of steam control valves. Furthermore, when a plurality of steam control valves are open, a valve test is generally performed to confirm that the valves open and close normally. This valve test method selects one of the multiple open valves, forcibly closes the valve, and confirms the valve's operation in the closing direction and opening direction. During this valve test, forcibly closing the relevant valve reduces the amount of steam flowing into the turbine, which in turn reduces the output of the turbine. Control device C: Additionally, it is designed to suppress a decrease in the output of the turbine.

FIG. 1 shows a conventional steam turbine control device having two steam control valves. The steam flow rate command Q, in which the steam flow rate value to the turbine is set, passes through the adder 1 and becomes q. Then, the steam flow rate command is input to the steam control valve opening command I: converting control valve opening function unit 2 and 2B, respectively, and is converted into the control valve opening command PIAJ knee Ptn. Then, the control valve opening command PIA is input to PIB adders 3A and 3B, and is added to the bias signal passed through contacts 4A and 4B, which are closed during the valve test, and P2A and P! B becomes the regulator valve driver 5
Enter in A and 5B. The opening degrees of the steam control valves 6A and 6B are adjusted by outputs from the control valve drivers 5A and 5B.

By adjusting the opening degree of the steam control valve iMI, the turbine 7
The output of the generator 8 connected to the turbine is changed by adjusting the amount of steam supplied to the turbine and changing the output of the turbine.

The steam pressure value P1 in one stage of the turbine 70η has a characteristic that it is proportional to the turbine output, and this pressure value is converted from a pressure signal to a flow rate signal by the flow rate converter 9 to become the actual steam flow iQ, and the steam pressure value P1 is proportional to the turbine output. The flow rate setting value is subtracted by the adder 10 to obtain the flow rate deviation Q4. The flow rate deviation Q4tl is amplified by the gain device 11 and becomes Q, and when any one of the contacts 48 or 4B closes during the valve test mentioned above, it closes at the same time, and 4A
The signal is input to the adder 1 through the contact point 1, which opens after a certain period of time after the contacts 4B and 4B are both opened.

In the above configuration, when I: contact 4A is closed for valve testing, the control valve opening commands P and A decrease and the steam control valve 6
In order to control A in the closing direction, the amount of steam flowing into the turbine 7 is reduced. At this time, the turbine first stage steam pressure P1
Since the output Q of the flow rate converter 9 also decreases, a difference occurs between the steam flow rate command q and the actual steam flow rate Q1.

Then, the deviation signal q is amplified by a gain unit 11 and sent to an adder 1.
is added.

And Q at this time was Q+=Qt, but now it is Ql + Qs I! :The result is increased by q and input to the regulator valve opening function unit.

For this reason, the output of the regulating valve opening function device is increased, but A I
Since the signal for forcibly closing the valve is input to II by the bias from contact 4N, only F'ta of B111l increases without increasing the P and A values, and the steam control valve 6
Only the B side changes to the opening direction, and the amount of steam flowing into the turbine increases. The increase at this time is the gain unit 11
The flow rate deviation Q, which is determined by the amplification degree, is set to be approximately zero, that is, the amplification degree is set such that the turbine steam inflow amount almost stops before and during the valve test.

Also, when the valve test contact 4A is returned from closed to open, the steam control valve changes in the open direction to its original position, but at this time, the amount of steam flowing into the turbine increases, so the turbine first stage steam pressure also increases. Therefore, the flow rate deviation q will decrease,
The steam control valve 6B changes in the closing direction. When the steam control valve 6A returns to its original position, the flow rate deviation Q4 becomes zero, and at this time the steam control valve 6B also returns to its original opening value. The time limit for changing the contact 12 from closed to open is set to be longer than the time required for the valve test contact 4A to change from closed to open and for the steam control valve opening to return to its original position from closed to open.

The above operation is effective only when the steam flow rate command Q and the actual steam flow rate Q converted from the turbine first stage steam pressure are in an equal relationship. That is, it is applicable only to so-called constant-pressure operation in which the main steam pressure or temperature is kept constant and the opening degree of the steam control valve is adjusted to change the amount of steam entering the turbine to adjust the turbine output.

However, in variable pressure operation in which the turbine output is adjusted by adjusting the main steam pressure value while keeping the steam regulator opening constant, the turbine first stage steam pressure changes due to the correlation between the throttled steam amount by the steam regulator and the main steam pressure. Therefore, a difference naturally occurs between the steam flow command Q and the actual steam flow rate Q.

FIG. 2 shows how the first stage steam pressure changes with respect to the above-mentioned main steam pressure and changes in the opening degree of the steam control valve.

Xl is the characteristic of the main steam pressure, so is the characteristic of the turbine first stage steam pressure when the main steam pressure changes as Xl,
, is the characteristic of the turbine first stage pressure when the rated main steam pressure is constant. As is clear from this figure, between c and d, where the main steam pressure is the rated pressure value, the turbine first stage steam pressure changes equally between the steam flow rate setting and the steam control valve opening C: but in other regions, It can be seen that the turbine first stage steam pressure changes depending on the main steam pressure.

In addition.

The horizontal axis in FIG. 2 is the steam flow rate setting or the opening degree of the steam control valve.

Based on the above, when the conventional method is used for valve testing in variable pressure operation, it is impossible to suppress turbine output fluctuations. I could not do it.

[Purpose of the invention]

The present invention aims to provide a steam turbine control device that can perform valve tests while suppressing turbine output fluctuations at any output without being affected by changes in the main steam pressure introduced into the turbine and the steam flow rate setting ζ. purpose.

[Summary of the invention]

The present invention corrects the turbine first stage steam pressure signal using the main steam pressure signal to create an actual steam flow rate signal that is equal to the steam flow rate setting at that time, and the difference between the steam flow rate setting and the actual steam flow rate is 1: It is characterized by adjusting the opening degree of the steam control valve so that the amount of steam flowing into the turbine is constant, so that the turbine output does not fluctuate due to the valve test (2).

[Embodiments of the invention]

FIG. 3 shows an embodiment according to the present invention. The circuits inside the dashed-dotted line in the figure are the circuits added according to the present invention, and the circuits other than the dashed-dotted line (two have the same configuration as the prior art in FIG. 1). Input the actual steam flow rate value q flowing into the turbine.
It calculates and outputs. This invention! An example of the internal configuration of the actual flow rate converter 13 that has been added is shown in FIG.

The main steam pressure signal is input to the coefficient unit 14C, which outputs a coefficient value of 1 based on the ratio of the current main steam pressure to the rated steam pressure, and this coefficient value is input to the multiplier 15.

Further, the turbine first stage steam pressure signal is also input to the multiplier 15, and the turbine first stage steam pressure signal is multiplied by the coefficient value to obtain the turbine first stage steam pressure signal I model corrected by the main steam pressure 1 word. , outputs. Then, this signal is input to the flow rate converter 9 and the pressure signal is converted into the flow rate (i
It is converted into the number Q.

The turbine first stage steam pressure is proportional to the valve opening degree of the steam control valves 6A and 6B, that is, the amount of steam flowing into the turbine.
It is also proportional to the main steam pressure. To quantify it with a simple hand wash, when the main steam pressure is constant at 100% of the rated pressure, and the steam control valve opening is set to 100% U'R degrees, the turbine first stage pressure is also 100%. becomes. In addition, the main steam pressure is set to 100% rated pressure, and the steam adjustment "opening degree is set to 5
0% opening (when it is 10 (1% main steam pressure x 50
% steam control valve opening becomes 50% of the turbine first stage steam pressure. Also, if the main steam pressure is the rated 5υch pressure and the steam control valve opening is set to 1'00% at once, the turbine first stage steam pressure will be 5u% with 50% main steam pressure x 100% steam control valve opening. (100% main steam pressure 1
When the coefficient unit 14 outputs a coefficient of 50% main steam pressure) = 2 times, and this coefficient is multiplied by the turbine first stage steam pressure by the multiplier 5, it becomes equivalent to 100% first stage steam pressure, and the 100-chi steam control valve A signal equal to the opening degree is output. This number 43 is then converted into a flow rate value by the flow ff1K converter 9.

After hand washing as above, the steam control valve 6B side Q is determined from the turbine first stage steam pressure and main steam pressure.

The actual flow rate converter 13 performs this calculation. Now, when the steam flow rate command Q is set to 50, the steam control valve 6A is at 6%.
B is also at 50% opening, and if the main steam pressure at this time is the rated 501 pressure, the turbine first stage steam pressure is (steam control valve opening x main steam pressure) = (50% opening x 5
0% pressure) = 5% pressure.

At this time, the output of the coefficient unit 14 is doubled, and the multiplier 15
The output R1 becomes 50% pressure, and the actual steam amount becomes a function. This actual steam flow rate Q, = 50% becomes equal to the steam flow rate command Q, and the flow rate deviation Q, f'i becomes zero.

In this state, close the valve test contact 4A and steam control valve 6A.
When the valve is closed to the opening degree of 04, the turbine first stage steam pressure decreases to half the pressure, 125%, and by correcting this signal with the main steam pressure signal, the actual flow rate Q3 becomes 5e.
s Totoru. And at this time, Q is +25%, so Q
The t value increases from 50% and the steam control valve 6B
The side changes to the opening direction, and from 50% to around 100 degrees opening (
: When the turbine first stage steam pressure #″t25
The pressure becomes high, and the s Qs value also becomes smooth and balanced.

In addition, balance at this time. Note that the balance value at this time is determined by the gain 1 of the gain unit 11, which is treated as an infinite gain here.

Even if the steam conditions change, one valve is forced to operate in the closing direction. Therefore, the remaining valves operate in the open direction, and the amount of steam inflow to the turbine is always constant, resulting in a change in turbine output. do not have. Furthermore, it is possible to adjust the steam control valve so that the amount of steam flowing into the turbine remains constant no matter how the main steam pressure or steam flow rate command changes. In the above description, only two valves have been described, but the present invention can be applied to an apparatus having a plurality of steam control valves.

〔Effect of the invention〕

According to the present invention I, a steam control valve test at any output C22 can be performed while suppressing turbine output fluctuations, regardless of constant pressure operation or variable pressure operation C2.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional steam turbine control device, Fig. 2 is a characteristic diagram of turbine first stage steam pressure versus steam flow rate setting or steam control valve opening C2, and Fig. 3 is a steam turbine control device according to the present invention. FIG. 4 is a block diagram of the actual flow rate converter. 1.3A, an, 10; Adder 2A, 2B; Adjuster valve opening function unit 4A, 4B, 12; Valve test contact s A + s B = Adjuster valve driver 6A, 6B; Steam adjuster valve 7; Steam turbine 8; Generator 9; Flow rate converter ll; Gain unit 13; Actual flow rate converter 14; Coefficient unit 15; Multiplier (7317) Agent: Patent attorney Norichika Kensuke (ζMaiki) 1 person) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a valve closing test of a steam turbine control device having a plurality of steam control valves, a calculator is provided that calculates the actual steam flow rate by inputting the turbine first stage steam pressure and main steam pressure, and the output of the calculator and the steam flow rate set value. an adder 1 for inputting and obtaining the difference, an amplifier for amplifying the output of the first adder, and a second adder for adding the output of the amplifier and the steam flow rate set value. A steam turbine control device, characterized in that a steam control valve is controlled by the output of an adder to maintain a constant amount of turbine steam inflow during a valve closing test of the steam control valve.