DE4344117A1 - Power regulation system for steam turbine generation block - Google Patents

Abstract

The power regulation system is operated with a turbine setting reserve, with regulation of the power to maintain a required power level (Ps), in dependence on the measured network frequency deviation. The turbine setting reserve is maintained for the primary support of the network frequency during a ramp variation in the power requirement matched by altering the fuel feed, with the resulting network frequency variation controlled by altering the turbine inlet valve setting in response to a turbine inlet valve control signal (S).

Description

The invention relates to a method for control and regulation of the output of a steam power plant block the preamble of claim 1.

Such a method is known both from DE 36 32 041 C2 and from DE 41 24 678 C2. The method according to DE 41 24 678 C2 differs from the previous method only by the partial method for restoring the turbine reserve after it has been claimed. The invention relates to a further development of the power control method known from the two publications, the details of which are shown in FIG. 4 with the associated description.

In this description, for simplification alone Parts reproduced from DE 36 32 041 C2, and this only insofar as it is necessary to understand the invention is such. Reference numerals and signal names that be have already been used in the cited patent, ha have the same meaning here too.  

The known method relates to the way in which the turbine reserve is used. It is released there for every type of power setpoint increase. In the known method, a distinction is already made according to low-frequency and higher-frequency power changes and corresponding power _{setpoint components} P _f1 and P _f2 , but the turbine reserve is also used when the power setpoint P _{S is} increased. This has the disadvantage that with a ramp-shaped increase in power, in particular with a large amplitude, the turbine reserve is even completely canceled. If a drop in network frequency occurs during such a process, the increase in power required per second is no longer possible or not to the full extent. The stability of the electrical supply network is at risk.

The invention is therefore based on the object known method for controlling and regulating a steam Power plant blocks to change so that the reserve during the transition to a higher block power remains for the regulation of mains frequency dips.

This task is carried out in a method according to the generic term of claim 1 by its characteristic features ge solves.

Preferred embodiments of the Ver driving specified.

Advantages of the method are that only marginally current changes to the ge to perform the procedure suitable control and regulating devices are required.

The invention is based on a in the drawing voltage illustrated embodiment explained in more detail.  

As stated at the beginning, the invention takes place within the scope of in the publications DE 36 32 041 C2 and DE 41 24 678 C2 described method for regulating the performance of a Steam power plant blocks application. This process works with a combined control and regulation of performance. The stationary and dynamic behavior of the power plant block is modeled with the help of a process model, so that the Response of the power plant block z. B. on a change of Fuel supply or a change in the position of the turbi inlet valves is predictable. This makes it possible Essentially controls changes in block power, to bring about with the help of control signals. The The control device only has to deal with small control deviations gels, remains largely inactive, which means overall a very stable regulation is achieved.

The method of operation of the control and regulating method described above is thus essentially determined by the control signals fuel control signal B and turbine control signal S be. The object on which the invention is based is achieved by a new method for forming these control signals B, S. The use of the control signals B, S in the entire system has not changed, so that a description of the entire system, in the drawing represents Darge as a power plant block with other parts of the control and regulating device 100 , is unnecessary.

The drawing shows power _setpoint signals P _S , P _f1 , P _f2 , which are input signals of the power control device. The power setpoint P _S is set on a power setpoint adjuster 6 . The power _setpoint components P _f1 and P _f2 are formed by filtering a frequency difference signal Δf = f-f₀. The frequency deviation Δf thus indicates the difference between the actual network frequency f and the target frequency f₀. The second power _{setpoint component} P _{f2 is} formed in the first filter device 14 and only takes into account low-frequency changes that can be transmitted by the steam generator. In the second filter device 15 , the first power setpoint component P _{f1 is} formed, which takes into account higher-frequency changes that can be transmitted by the steam turbine.

Another input signal is a signal P _NR supplied by a mains frequency controller as a power setpoint component.

The fuel control signal B is formed by adding three fuel control signal components B₁ to B₃ at egg ner addition point 86th

The first component B₁ is the output signal of a function generator 33 a, to which the second power setpoint component P _f2 is supplied as an input signal. The function generator 33 a provides a certain amount of reserve for the accelerated increase in output.

All functions designated here with function builder units have a dynamic behavior.

The second component B₂ is the output signal of a further function generator 33 b, the input signal of which is the power setpoint P _S , to which the signal P _{NR is} added at a thirty-ninth addition point 132 . The power set value at the output of summing point 132 is only a ramp shape changed during operation and b overridden by the Function generator 33rd

The third component B₃ is the output signal of a controller 63 , the input signal of which is the turbine valve control signal S. The controller 63 is preferably designed as a PD controller. It causes a fuel increase, which is necessary for the restoration of the turbine reserve.

The formation of the turbine control signal S is shown below purifies.

With the help of a function generator 90 , whose input signal is the second fuel control signal component B₂, the course of a performance component P _BS dependent on the power setpoint is simulated.

With the help of a function generator 22 , the input signal of which is the fuel control signal B, the power curve P _B to be expected from the fuel supply is simulated. The dynamic behavior of the function formers 90 and 22 is identical.

The function generator 90 is followed by a MIN selector 122, to which the output signal of the addition point 132 is supplied in addition to the component P _BS . With this measure it is achieved that the turbine reserve is maintained during the ramp-shaped power increase, while the reduction of the turbine valve position is released for better regulation of the power to its setpoint in the ramp-shaped power reduction. In the second case, this results in an even greater reserve capacity and thus a favorable condition for the even faster response of the power control than in the first case in the event of a sudden drop in the mains frequency. After the ramp-shaped power reduction has ended, however, the turbine control reserve, which is now dependent on the load level and is now reduced, is again set in the second case.

A difference signal (P _B -P _BS) is formed at a summing point 87, which a P _∈ limiter is fed 85th In the P _∈ limiter, the difference signal (P _B -P _BS ) is added to an input signal ΔP _{S ∈} . The signal ΔP _{S ∈} indicates the power increase that can be achieved with the existing throttling with a strictly monotonous curve. Another input signal of the P _∈ limiter 85 is the first power setpoint component P _f1 . The P _∈ limiter 85 has the task of limiting the increase in performance caused by the use of the turbine reserve so that at least one monotonous course is ensured if the existing turbine reserve is not sufficient to implement the strictly monotonous increase in performance. The P _∈ -Begren zer 85 is z. B. can be realized by the components 16 , 17 , 18 and 61 shown in DE 36 32 041 C1 in FIG. 4. In such a case, it forms an output signal which is a signal which limits the amplitude of the P _f1 signal and is fed to a downstream function generator 19 . The function generator 19 specifies a strictly monotonous curve of a power component on the basis of its limited power input signal.

At an addition point 88 , the output signal of the function generator 19 is added to the output signal of the MIN selection element 122 . The sum signal formed is fed as a preset signal P _v to an addition point 20 , at which the fuel-dependent power P _{B is} subtracted to form a signal P _∈ . This throttling-dependent power P _∈ is converted in a power / displacement converter 21 into the turbine valve control signal S to be formed.

It is essential to the invention that, in the event of a ramp-shaped increase in the power setpoint, the preset signal P _{v has} the same time profile as the fuel-dependent power P _B , so that the difference signal P _∈ at the addition point 20 retains the value zero. Thus the valve control signal S is also zero and the throttling remains.

In the case of a ramp-shaped reduction in the power setpoint, the signal P _v becomes smaller than the signal P _B , where the signal P _∈ becomes negative; this also makes the control signal S negative. The throttling temporarily becomes larger than would correspond to the new steady state of performance.

Reference list

6 power setpoint adjuster
14 first filter device
15 second filter device
19 first function builder
20 eighth addition point
21 Power / path converter
22 second function generator
33 a twenty-first function builder
33 b twenty-second function builder
85 P _∈ limiter
86 thirtieth addition point
87 thirty-first addition point
88 thirty-second addition point
90 twenty-third function builder
100 power plant block with further parts of the control and regulating device
122 MIN selector
132 thirty-ninth addition
B fuel control signal
B₁ first fuel control signal component
B₂ second fuel control signal component
B₃ third fuel control signal component
P _B fuel-dependent performance
P _BS fuel-dependent power component
P _S power setpoint
P _∈ androsselungsunabhängige performance
ΔP _{S ∈} achievable performance increase with strictly monotonous curve with existing throttling
P _v power input signal
P _f1 first power setpoint component
P _f2 second power setpoint component
S Turbine valve control signal
P _{NR Line} frequency controller signal.

Claims (5)

1. A method for controlling and regulating the power of a steam power plant block, which is operated with throttled turbine inlet valves (turbine reserve) and the energy thus stored for a monotonous, strictly monotonous course of the block power P in the event of a sudden power increase, where is used

• - The power is controlled and regulated depending on a predetermined power setpoint P _S and a measured Netzfre frequency deviation, and
• a second power _{setpoint component} P _{f2 is} formed from the grid frequency deviation by filtering, which takes into account low-frequency changes (which can be carried by the steam generator), and a first power _{setpoint component} P _f1 which takes into account higher-frequency changes (which can be transmitted by the steam turbine),

characterized in that to maintain the turbine reserve for the primary support of the network frequency during

• a) a merely ramp-shaped change in power is reacted to changes in the power setpoint P _S solely by changing the fuel supply and
• b) a change in the mains frequency Δf is reacted to changes in the power setpoint component P _f1 with a change in the turbine inlet valve position.

2. The method according to claim 1, characterized in that a fuel control signal B used to control the fuel supply is formed by adding the following control signals:

• - A first fuel control signal component B₁, the output signal of a function generator ( 33 a), the input signal is the second power setpoint component P _f2 ,
• - A second fuel control signal component B₂, the output signal of a further function generator ( 33 b), the input signal is a sum signal from the power setpoint P _S and a Netzfrequenzreg ler signal P _NR , and
• - A third fuel control signal component B₃, which is the output signal of a controller ( 63 ), the input signal of which is a valve control signal S.

3. The method according to claim 2, characterized in that the valve control signal S is formed as follows:

• a) with a function generator ( 90 ), the input signal of which is the second fuel control component B₂, a fuel-dependent power component P _{BS is} simulated,
• b) with a function generator ( 22 ), the input signal of which is the fuel control signal B, a fuel-dependent power signal P _{B is} simulated,
• c) a difference signal (P _B -P _BS ) is formed at a thirty-first addition point ( 87 ),
• d) a P _∈ limiter ( 85 ), which limits a power to be supplied from the turbine reserve, the input signals are first power setpoint components P _f1 , difference signal (P _B -P _BS ) and a signal ΔP _{S ∈} that the with existing throttling indicates achievable performance increase with a strictly monotonous course, supplied; the P _∈ limiter ( 85 ) supplies an input signal for a function generator ( 19 ) which outputs a partial amplitude of the first power setpoint component P _f1 ; this partial amplitude is added to the fuel-dependent power component ABS at a thirty-second addition point ( 88 ), the fuel-dependent power P _{B is} subtracted from the input signal P _v thus formed at an addition point ( 20 ) to form a throttling-dependent power P _∈ ;
• f) the signal P _∈ is fed to a power / displacement converter ( 21 ) which outputs the valve control signal S.

4. The method according to claim 3, modified in that

• - The output signal of the function generator ( 90 ), which outputs the fuel-dependent power component P _BS , is guided to a MIN selection element ( 122 ), the second input signal of which is the sum signal of the power setpoint value P _S and the mains frequency controller signal P _NR , and
• - The output signal of the MIN selection element ( 122 ) is the input signal of the thirty-first and thirty-second addition points ( 87 , 88 ), so that feature a) of claim 1 applies only to the ramp-shaped increase in power, but still applies to the ramp-shaped reduction in power is also reacted with the change in the turbine inlet valves.