DE3235557A1 - BYPASS SYSTEM FOR A STEAM TURBINE SYSTEM - Google Patents

Description

Bypass system for a steam turbine system

The invention relates to a bypass system for a steam turbine system with a high pressure and at least one low pressure turbine, a reheater in the steam line / between high and low pressure turbine and a bypass arrangement leading past the turbines, which V _1- at least high pressure valve J! Arrangements for introducing steam Included in the fiypass arrangement.

In power plants with a steam turbine, steam is generated by a boiler, which is fed to a high-pressure turbine via a large number of control valves. The steam emitted at the outlet from the high-pressure turbine is roughly heated before it is fed into the intermediate-pressure turbine, if one is present. The Zwlaohendruekturbine and, if this is not available, the high-pressure turbine is connected to a low-pressure turbine, at the outlet of which a condenser is connected, which converts the residual steam into water and feeds it back to the boiler.

The amount of steam discharged from the high pressure turbine is carried out with the help of a control valve, which can consist of a large number of individual valves and their Positioning is determined by a controller. In the turbines, the steam is expanded and the steam that is released in the process Energy used to drive an electric generator.

The steam generation needs the help of fossil fuels brings e «; with it that the kettle is not instantaneous

WS342P-2!> 34 · be switched off

can be switched off. If the turbine is running and a sudden drop in load occurs, the turbine must be shut down quickly. In this case, under normal conditions, the boiler would continue to generate steam, so that the pressure rises which, when a certain level is reached, triggers the safety valves. In view of the fact that the or / euqtt! Steam has a very high purity, on the order of 3/4 particles of impurities per billion, the loss of process steam through the safety valves represents a significant economic loss. Another economic impact on the operation of a steam turbine plant is the cost of the fuel. Because of the high fuel costs, some turbine systems are deliberately switched off during periods of low electrical power demand, e.g. overnight, so that there are difficulties with a warm start . B. on the next Moryrr », since the turbine position still unites; has a relatively high temperature, whereas the steam supplied by the Kossei during start-up operation is supplied at a comparatively lower temperature. If this relatively cool steam is fed to the turbine, it experiences a thermal shock which has a very significant effect on the service life. In order to avoid this thermal shock, the steam must be fed in relatively slowly so that the turbine temperature can cool down to the steam temperature. In the meantime, the turbine system is gradually ramped up to the desired operating level and load level. This start-up operation takes a relatively long time and is therefore always economically disadvantageous.

In order to deal with the dropping of load b / w. associated with the warm start To solve problems, it is already known to provide bypass systems, whereby the availability of the turbine

WS34ZP-2534 location for the

BATH ORIGINAL

location for normal operation improved and also a faster one New start can be achieved. With the help of bypass operation Ui (At you also the harmful «influence of passing through Minimize term cycles. In bypass operation is In principle, steam continues to be generated in the boiler, even if the RiMjH vent, 1 le, via which the steam is sent to the turbines supplied, is, are closed. A high pressure bypass valve in front of the lurblnenanlaqe is opened in bypass operation, to guide your steam around the turbine or turbine system, wöbe! it is carried out over a close relationship. Li η Niederdruekbypafiventi L, which is behind the reheater tinijcurdiK · t lsi, enables the steam to be used if necessary the Ml UeidruekturbJne and the low pressure turbine passed directly to the capacitor.

In normal operation, the steam is expanded in the turbine, with which mechanical energy can be obtained. During bypass operation, the steam is fed through the bypass line no Inerqle taken. However, since the steam l / it and the condenser can damage, cooling water will be in the steam flow both in the high pressure part and in the Low-pressure part canned, which means that the NaoherhI t / ers and the condenser is avoided »The Amount of the t'lrujedüsten water is determined with the help of a tempera turreqe i systems controlled, fell to a well-known temperature control system » The governor takes the temperature at the entrance of the closer and compares it with a certain one fie / utj temperature b / w. Target temperature. That kind of determination requires a relatively large amount of time and effort. In particular, various test runs must be provided to fix / uloqun the setpoint for a certain boiler system, whereby the setpoint determined thereby becomes a It is a compromise and is by no means optimal for all operating conditions. The throttle pressure of the output

of the BAD ORIGINAL boiler

of the boiler available steam can under different operating conditions are also regulated by the control of the bypass system: Jt. A friend The standard structure depends on the steam flow Lg and is not for different operating pressures / conditions, which on the boiler fit, insert / bar.

The invention is based on the object of creating a bypass system for a steam turblncfuui I β q <* / u , which, compared to known bypass systems, enables better temperature and / or pressure control in order to reduce the flow of air. I reduce the turbine system and the boiler / u by umjcit.

This task is used for the above-mentioned üypaHüy »! Cm according to the invention solved in that the BypaManordriumi Hegel devices for the actuation of the high pressure valve arrangement Depending on the given pressure conditions in the overall system, this includes temperature measurement at the entrance and exit of the Nacherh 1 i./cr;> are arranged, and that steam temperature Rcyelelnrlehtungen are available, with which the temperature of the over the Hoehdruekvent! 1 arrangement "ge 1 c! I et cif steam Depending! Gkc 1 I on the temperature at the entrance and "in the exit dc ·" Nticherhit / cr ;; is adjustable.

The invention becomes particularly advantageous in one embodiment realized in which in the bypass system a Hochdrijokbypdttvßntj 1 dngpendet Is that in dependence can be actuated by certain predetermined pressure conditions. A high pressure spray valve is also provided, with which cooling water in the ßypaßstrom clncjcdüsl if the bypass valve is opened Int., fm GccjcnSiil / In addition to the known provision of a fixed setpoint for the temperature, the difference has the advantage of

WS342P-2534 that they

that it is the temperature of the diverted steam stream regulate adaptively depending on both the temperature at the inlet and the outlet of the reheater can. The outlet-side throttle valve on the steam generator is set with the help of a control that also controls the Operation of the bypass valve affected. A set value generator for the throttle pressure is provided, which is independent compares this process-independent signal from the steam flow with the actually measured steam pressure, to further open or close the bypass valve accordingly. Under normal operating conditions the Turbine system, the regulator works as a pressure regulator that opens the bypass valve when the actual throttle pressure is reached exceeds the throttle pressure specified by the setpoint plus a preload value.

A further improvement in the steam temperature and / or Pressure control is achieved with the help of a control system that is both fast under certain specified conditions, d. H. coarse as well as slowly under other given conditions, i. H. fine, appealing. Thereby are all operating states, both in start-up mode as well as during normal full operation can be optimally controlled by the devices according to the invention.

The invention with its advantages and features will be explained in more detail with the aid of exemplary embodiments referring to the drawing. Show it

1 shows a simplified block diagram of a power plant with a turbine-driven generator and a bypass system;

FIG. 2 shows a known bypass system as a detail of the system according to FIG. 1;

WS342P-2534 Fig. 3

- 13 -

3 shows a bypass system according to the invention; 4 shows details of the bypass system according to FIG. 3;

FIG. 4A is a block diagram of an alternative embodiment of the tracking control according to FIG. 4; FIG.

FIG. 5 shows a functional explanation of a controller of the follow-up control according to FIG. 4; FIG.

6 is a block diagram for further explaining the initiation of a bypass operation;

Fig. 7 is a diagram showing the dependence of the throttle pressure on the boiler load for a sliding Printing operation explained;

8 shows a block circuit for setting the target value for the throttle pressure as a function of the load;

FIG. 9 shows a block diagram to explain the bypass operation according to FIG. 6 with an alternative biasing arrangement; FIG.

FIG. 10 shows a curve corresponding to the diagram according to FIG. 7 for the pretensioning arrangement according to FIG. 9;

11 is a block diagram of a further embodiment of the invention.

Referring to Fig. 1, in a simplified block diagram, there is a Turbine generator set for a fossil fuel power plant shown. The turbine system 10

WS342P-2534 · includes several

comprises a plurality of turbine sections, namely a high pressure turbine 12, a medium pressure turbine 13 and a low pressure turbine 14. The turbines all work on a common shaft to drive a generator 18, the releases energy to a load, not shown.

The steam can be generated with the aid of a conventional boiler 22 heated with fossil fuels, which heats the generated steam to the correct operating temperatures with the aid of a superheater 24. Of the Superheated steam is via a throttle line 26 of the high pressure turbine 12 supplied via control valves 28. Regardless of the embodiment explained, others can also Find boiler types use. The steam which leaves the high-pressure turbine 12 via a steam line 31, is fed to a reheater 32, which is usually assigned to the boiler 22. From the reheater is over a steam line 34 the medium pressure turbine 13 via control valves 36 acted upon. The steam is then passed on to the low-pressure turbine 14 via a steam line 39, the outlet of which is connected to a condenser 40 via the steam line 42 in order to recover water from the residual steam. This recovered water is the boiler 22 via the water pipe 44, the pump 46, the water pipe 48, the pump 50 and the water line 52 are supplied. Although not indicated in the illustration, is fundamental A device for water treatment is provided in the return line of the water in order to ensure a high level of water purity and maintain exact chemical composition.

A boiler control 60 ensures normal operation of the boiler 22, whereas the control valves 28 and 36 of one Turbine control 62 can be controlled from. Both the boiler control 60 and the turbine control 62 will monitored by a master controller 64.

WS342P-2534 To check availability

• *. λ m

- 15 -

To the availability and lifespan for boilers as well To enlarge the turbine system and also to ensure an optimal warm start, a turbine bypass is provided, so that steam can be continuously generated by the boiler 22 as if it were consuming in the turbine would, although this steam is only conducted through the turbine bypass. This turbine bypass includes a steam line 70, which is activated for bypass operation by actuating a high-pressure bypass valve 72. Of the Steam transmitted via this valve flows via line 74 to the inlet of the reheater 32 and from there from via the steam line 76 and a low-pressure bypass valve 78 and the steam line 80 to the steam line 42.

About the losses due to the heat consumption that normally results in the high pressure turbine 12 and about overheating of the reheater 32 is to avoid cold water from the water line 82 via the pump 50 in the Steam line 74 introduced via a high pressure spray valve 84. Other devices can also be provided to supply coolant directly to the valve assembly In a corresponding manner, relatively cold water from the water line 85 behind the pump 46 is used to to cool the steam in the steam line 80, thus reducing the losses due to the extraction of heat in the low-pressure turbine 14 is compensated and overheating of the capacitor 40 is avoided. A low pressure spray valve 86 is provided in the water line 85, through which the water is sprayed. To control the valves in the Various associated control devices are used by the bypass system. For example, with the help of the high pressure regulator 90 the high pressure bypass valve 72 and the high pressure spray valve 84 are controlled. Accordingly, with help a low-pressure regulator 92, the low-pressure bypass valve

WS342P-2534 and that

• if If · <·· * »*

- 16 - ■

and the low pressure spray valve 86 is controlled. Usable Low pressure spray valves are known from US patent application 321,160 dated November 13, 1981.

A typical known structure for the high pressure control is shown in Fig. 2 which is a more detailed one Shows a detail of part of the system according to FIG.

The bypass function is triggered by comparing the Throttle pressure with a throttle pressure setpoint, with a deviation between these two signals a control signal for the high pressure bypass valve 72 triggers. In particular, the pressure transducer located in the steam line generates 100 a signal proportional to the actual throttle pressure and transmits this signal via the Line 101 to a regulator 102. The actual pressure present on line 101 and describing the throttle pressure The signal is compared with the setpoint signal supplied by a calculation circuit 106 via the line 104. A signal is fed to the calculation circuit 106 via the line 108, which characterizes the steam flow, by detecting the pressure conditions at a constriction 110 in the steam line. The flow indicator is modified by various factors, the maximum being and minimum permissible pressure values are taken into account when deriving the setpoint. These modification factors are fed to the calculation circuit 106 via connections which are indicated by the arrow 112.

Depending on the deviations between the two input signals for the controller 102, the latter generates a Control signal which an actuating circuit 1 1A-for the high pressure bypass valve 72 is supplied. Because of this arrangement, the throttle pressure setpoint depends on the

WS34-2P-2534 steam flow.

- 17 -

Steam flow from. If the load ratios change, so will the steam flow and, accordingly, the Setpoint. A change in the steam flow can result both from the bypass operation and from the turbine and each have an influence on the throttle pressure setpoint, which in turn influences the repeated operation takes on the turbine system and the bypass system.

Regarding the operation of the high pressure spray valve 8A-ist provided that a controller 120 is compared to the actual temperature at the input of the reheater 32 responds with a temperature setpoint and a control signal to the actuation circuit 122 for the high pressure spray valve supplies to control the cooling by spraying water.

The inlet temperature of the reheater 32 is with

Using a temperature sensor 12 ^ - detects which one

Signal via line 126 to one input of the

Controller 120 supplies whose other input via the

Line 127 is supplied with a temperature setpoint from the main controller 64.

The setpoint calculation takes a considerable amount of time and, at best, gives an empirical one derived compromise value that does not necessarily ensure optimal operation. In contrast, should In the present invention, a target value can be derived as a function of certain system parameters in order to achieve the To improve temperature control. Reference is made to FIG. 3 for an explanation.

In the embodiment according to FIG. 3 is additionally to the one on the cold side of the reheater with the help

WS342P-253A- the temperature sensor

- 18 -

of the temperature sensor 12A- detected temperature signal a second temperature value is detected at the output of the reheater with the aid of a temperature transmitter 134 and over the line 126 is fed to an adaptation circuit 14-4-. A spray valve controller 14-0 is on the one hand with the temperature signal acted upon via line 126 and on the other hand with the setpoint signal via line 141 and ensures the temperature setting on the cold side of the reheater by actuating the high-pressure spray valve 84. This spray valve is actuated by the actuation circuit 122, which in turn has the line 142 is controlled by the spray valve controller 140. The spray valve can be used in any way as an electro-hydraulic, electromechanical or electric motor driven valve.

In contrast to the prior art, the setpoint signal on line 141 is not calculated in advance, but rather by Adaptation derived from the operating conditions with the aid of the adaptation circuit 144. This adaptation circuit can in addition to the application of the temperature signals via the lines 126 and 136 also from external Signals which are fed via lines 146 and 147 are influenced.

The spray valve regulator is activated depending on certain pressure conditions, so that for this purpose a Pressure control circuit 150 is provided. One example Embodiment of such a pressure regulating circuit 150 is described below with reference to FIG. Basically, when the system is running in bypass mode, a Output signal of the pressure control circuit 150 delivered via line 152 to trigger the temperature control.

WS342P-2534 A detailed

A detailed description of this operating state is given with reference to FIG.

The adaptation circuit 14-4 · for setting the setpoint includes a PI controller 160, which via line 136 with the high temperature signal after the reheater and a second signal from a summing circuit 164 is applied via line 162. There too the controller for the spray valves 140 includes PI controllers, a brief explanation is given below for these controllers given with reference to FIG. 5.

The PI controller receives two input signals A and B and determines the difference between these two Signals. The difference signal is amplified by the factor K. and adding the signal derived therefrom to the integral of this signal. The control signal is obtained as the result at output C. The schematic circuit according to FIG. 5 also includes an upper and lower limit value circuit 143, which the output signal to a maximum value corresponding to an upper limit value supplied via line D. limited and, furthermore, the output signal is limited to a minimum limit value in accordance with the limit value signal E. An alternative embodiment can provide that the upper and lower limit value is supplied by an internal circuit of the controller. If the line D the Voltage zero is effective, the output signal is held at the value zero volts. A correspondingly higher one The control signal on the output side can be set by adjusting the limit value applied via line D. has a higher signal value. In this case, the applied signal would act as an enable signal for the controller.

In a second operating mode, in which synchronization with a signal applied via line F is desired

WS342P-2534 appears

is, a corresponding signal appears at output C when an enable signal is applied via line G. In this case, the PI function effective on the difference between the two input signals via lines A and B. no longer effective at the output. Such PI controllers are used extensively and are commercially available. Of course, the PI function can also be used with the help of can be realized by microprocessors or other computers.

With reference to FIG. 4, the lines A and B of FIG. 5 correspond to the lines in the PI controller 160 and 162. Line 141 corresponds to output line C, line 166 to line D, line 168 to line G and the line 126 of the line F according to FIG. 5.

The adaptation circuit 144 also includes a memory 170, in which the high temperature signal from the reheater is stored when the system is in bypass mode transforms. The stored temperature signal is transmitted via line 172 to one input of the summing circuit 164 supplied, the other input signal via the Line 174 is derived from a functional circuit 176, which is a via line 178 from a differential circuit 180 applied signal can gradually increase. The differential circuit 180 provides an output signal, which is the difference between the stored high temperature signal on line 172 and a signal 182 illustrates which lower signal level selected by signal selector 184 over the lines 146 or 147 selects. A threshold circuit 186 is based on the output signal of the pressure regulating circuit 150 applied via line 152 and represents the enable signal for bypass operation in order to:

WS342P-2534 a) the memory

- 21 -

a) to cause the memory 170 to hold the high temperature value of the reheater,

b) to put the functional circuit 176 into operation and c} to put the PI controller 160 into operation.

When the release signal from the threshold circuit 186 is not present, a NOT circuit 188 supplies an overrun signal via line 168, whereas if it is present of an output signal at the threshold value circuit 126, this lag signal is suppressed.

For the purpose of further explanation it is assumed that in a certain operating condition of the turbines a quick shutdown makes the closing of the control valves and the initiation of a bypass operation necessary. It is also assumed that the low temperature on the cold side of the reheater is about 755 K and on the The hot side of the reheater is around 810 K.

When the bypass operation is triggered, a signal from the pressure control circuit 150 via line 152 that the threshold value circuit 186 emits a trigger signal and the memory 170 stores the high temperature of 810 K. Before the bypass operation, the PI controller 160 has followed the lower temperature on the line 126, so that the output signal on line 1 ή-1 the one on the cold Side of the reheater represents the temperature present and holds it until the input signals for the PI controller 160 can be changed. In this regard, the PI controller 160 acts like a memory for the low Temperature value. In this condition, the actual temperature signal for the temperature is on the cold side of the reheater on line 126 is identical to the setpoint signal on line 141, so that no output signal is supplied by the spray valve controller 140, whose

WS342P-2534 Functioning below

Function is explained below. The input signal for PI controller 160 on line 136 is this actual temperature signal for the temperature on the hot side of the reheater. The PI controller 160 additionally receives an input on line from summing circuit 164. The output of the Function circuit 176 does not change instantly, when the bypass operation is started, so that the summing circuit 164 has a signal available on the output side which is equal to the input signal on line 172; i.e., corresponds to the stored high temperature.

Considering the influence of the function circuit 176 of the differential circuit 180 and the signal selector 184 disregard, it is found that the input signals via the Lines 136 and 162 on PI controller 160 are identical, so that there is also no change for its output signal results. The setpoint value that has been set thus retains the value it had before the bypass operation was started up Value. When the turbines now start operating again, the temperatures would be the same as briefly before switching off so that normal operation can be continued. It is now assumed that changed the high or low temperature for whatever reason. For example, the increase in heat in the reheater be changed. When the low temperature changes, it is no longer consistent with the previously stored one Value on line 141 corresponds, so that the disturbed equilibrium puts the spray valve regulator 114 into operation, to effect a correction. When the high temperature changes, the input signal changes over the line 136 for the PI controller 116 and no longer agrees with the previously stored high temperature

WS342P-2534 of the line

of line 162 match. As a result of this change, the PI controller changes the setpoint by changing the The balance of the input signals to the spray valve controller 114 is disturbed and a correction is carried out accordingly will. The correction causes a change in the low temperature to match the high temperature on the previously saved one To be able to maintain value.

As a further example, the triggering of the bypass operation should be considered at a point in time at which the high temperature is approximately 800 K and not 810 K, which is desirable in the interests of better long-term efficiency. In this case, the temperature of 810 ° K is entered via the line 147 and can be entered automatically by the turbine control 62 according to FIG. 1 or by an operator manually. At this point in time, the signal on line 146 has risen to its maximum value, which characterizes the desired temperature of 810 ° K , for example, so that signal selector 184 emits an output signal via line 182 for the lower signal value, which indicates this desired temperature of 810 K indicates. In the example under consideration, the high temperature of 800 K was stored after the bypass operation was triggered, so that the associated temperature signal is fed via line 172 to both the summing circuit 64 and the differential circuit 180, which determines the difference of 10 C and a corresponding value via the line 178 to the functional circuit 176. Since the functional circuit is in operation, it will slowly increase the signal on the output side via the line 174 to the summing circuit 164, which is added to the previously stored value of 800 ° K. Since thermal loads are to be avoided, the signal on the

WS342P-2534 line 162 only

- 2k -

Line 162 increases in value only very slowly, so that the setpoint value on line 14-1 also increases only very slowly changes in order to raise the temperature on the cold side of the reheater to a value at which the outlet side The temperature of the reheater assumes the desired value of 810 ° K.

Two examples of temperature control are described. Both possibilities occur during a normal Operation of the turbines, in the first case maintaining the same temperature conditions and in in the second case, the approach to a new temperature corresponding to a via line 147 from the turbine control 62 provided setpoint is shown. A third situation should be considered in which a warm start is carried out.

It is assumed that the turbine system was turned off during the night and turned on again the next morning will. During such a so-called standstill, the turbines will rotate at a low speed sustained via a gear to avoid warping or adjusting the rotor. Towards morning the kettle is at a relatively low temperature cooled, whereas the turbines are above the temperature of the boiler due to their very large metallic mass. For example, in such a case the high temperature after the reheater can be around 580 K, whereas Due to the metal temperature of the turbine system, the steam temperature should be around 780 K.

In the morning, the bypass mode is therefore switched on first, with the memory storing the temperature of 590 ° K and the turbine control either automatically or by

WS34-2P-2534 manual input

Manual input specifies a setpoint which characterizes a temperature of 780 ° K and which is sent to the signal selector 184 via the line 147. During bypass operation, the signal on line 146 is raised to the maximum value, ie the value 780 ° K is fed into differential circuit 180, which outputs a signal to function circuit 176 that indicates a temperature difference of 190 ° C. On the basis of this difference signal, the setpoint output via line 141 is slowly increased in order to bring the steam to the correct temperature. When this temperature is reached, the control valves can be opened in order to let the turbine rev up, while at the same time the setpoint signal can be increased further via line 147 so that the temperature value of 810 ° K desired for normal operation is finally set.

Under certain operating conditions it may be necessary or desirable to modify the temperature on the warm side of the reheater in order to adapt to certain situations caused by the boiler. Correspondingly, a setpoint value for the reheater temperature is given via line 146 to signal selector 184, which can originate from boiler control 60 according to FIG. 1. This temperature setpoint signal is raised to its maximum value and held, as previously described, so that the setpoint signal on line 147 can be selected for control purposes. It should be noted that the latter signal is kept at the desired temperature and, although this temperature display in the present case is greater than the actual temperature at the outlet of the reheater, under certain operating conditions

WS342P-2534 the desired

~: "U" :: = O.:- .: 323SSS7

the desired temperature will be lower than the actual, so the differential circuit 180 is a negative Outputs the output signal to the function circuit 176, the output signal of which increases slowly in the negative direction, to subtract the value from the temperature signal supplied via line 172 from the memory.

The adaptation circuit 144 thus supplies an adapted setpoint value via the line 141 during bypass operation, around the temperature on the output side of the reheater ν at a certain predetermined value during normal operation to maintain this temperature or during start-up operation by actuating the spray valve regulator accordingly to adjust.

The spray valve controller 140 includes two PI controllers 200-1 and 200-2. The lower temperature signal from the input side of the reheater is applied via line 126 to both controllers, on which the adapted setpoint signal acts via line 141. For control operation only one is released of the PI controller 202-1 or 202-2 at a given time and, if this is the case, the PI controller 200-1 supplies an output signal ^Su ^ via line 202 and the controller 200-2 an output signal via the line 203. The line 202 leads to a summing circuit 206 as well as the line 203. The output signal of each of the two PI controllers is also fed to the other controller in order to control it to synchronize so that each of the controllers reproduces the output signal of the respective other controller in the follow-up mode.

Although the two PI controllers are identical to the controller explained with reference to FIG. 5, they have different

WS342P-2534 borrowed time constants.

> * 0 Λ

fc φ 4b «ν« tn «« »ν -»

- 27 -

borrowed time constants. If the PI controller 200-1 for the operation is selected, it delivers a signal on the output side as a function of non-matched input signals via the lines 126 and 141 much faster than is the case for the PI controller 200-2 when it takes over the control. Because the regulators as analog circuits are constructed, the integration part of the PI controller 200-1 is provided with a time constant TC1. The PI controller 200-2 has a time constant TC2 that is greater than the time constant TC1.

Instead of a single controller with a response time for all operating situations is described in the Embodiment provided that one of the two controllers can be selected depending on the operating status of the system, d. i.e. whether the system works in start-up mode or in full operating state. The PI controller 200-1 with the short time constant is intended for fully retracted operation, with a bypass operation not switched on, and in which a short response time to load changes should be possible. On the other hand, the PI controller 200-2 operates with the slow Response time used for the switch-on phase.

The selection of the controller used for the follow-up control and the controller responding to the input signals takes place with the aid of a signal via the connection terminal 210, which is activated manually or automatically can be. The application of a binary signal with a first logical signal level acts as a trigger signal via the line 212 and, due to the presence of the NOT circuit 214, switches the previously on the line effective signal, so that the PI controller 200-1 is caused to respond to a rapid change in load, the

WS342P-2534 an imbalance

:: .. · ^■: :::: .. - 'V.. 3235S57

- 28 -

an imbalance in the input signals on lines 126 and 141 would cause. Oer PI controller 200-2 follows the output signal on line 202 and repeats it on its output line 203. The application a binary signal of opposite signal levels to the terminal 210 reverses the ratios, so that the PI controller 200-1 follows the output signal on the line from PI controller 200-2 and it on its output line 200-2 reproduces.

None of the regulators will take effect until a trip signal is effective on line 220, which indicates a bypass operation and caused by an output signal of the pressure regulator circuit 150 via line 152 will. This latter output signal is passed through an amplifier circuit 222, which in turn emits the trigger signal.

For further consideration it is assumed that the bypass operation has been initiated in such a way that both PI controllers 200-1 and 200-2 are enabled for operation. If the bypass operation occurs during the start-up phase, the PI controller 200-1 takes over the control and the PI controller 200-1 K ^ the follow-up control, whereas when the turbines are fully switched on, the PI controller 200-1 takes over the control and the PI Controller 200-2 takes over the readjustment.

If either the low temperature on line or the adaptive setpoint on line 14-1, as before discussed, changes, the activated controller reacts to the difference between the two signals and delivers a Output signal that is used to either open or close the high pressure spray valve 84 to control the high temperature on the output side from the reheater

WS342P-2534 the setting

Setting the low temperature on the inlet side of the reheater by adding water to the steam line 74 set.

The summing circuit 206 provides an output signal which is half the size of the sum of the input signals Has. It is assumed that the PI controller 200-1 responds to a difference in its input signals and via the line 202 on the output side emits a signal of the value A. This signal is provided to both summing circuit 206 and also fed to the PI controller 200-2, which, after working in the follow-up mode, has the same signal A at its Output via line 203 is available. Half the sum of the input signals at the summing circuit 206 thus cause an output signal A on line 142. With this arrangement, the control function can be based on the other controller can be switched, with the same output signal on line 142 is maintained and ensures a smooth transition of the control function.

As an alternative, a circuit is shown in Fig. 4A with which the same follow-up control and bumpless Switching over the regulation is possible by connecting the output signal of the summing circuit 206 with that of the readjustment associated inputs of the PI controller is connected via line 208.

If it is desirable, the initiation of the bypass operation can also be used to start from the beginning adjust the spray valve 84 to a specific position so that spray water is quickly supplied for temperature control can be. This predetermined position may not be set precisely enough for fine temperature control to make possible. Because of this, will

WS342P-2534 the position

the position of the spray valve is readjusted with the aid of the output signal of the spray valve regulator 114. To this The purpose is a summing circuit 22A and a proportional amplifier 226 provided. The proportional amplifier responds to any output signal from the pressure control circuit 150 via line 152 and supplies a correspondingly scaled signal to summing circuit 224 to make a rough adjustment of the spray valve. The output signal available on line 142 is also fed to summing circuit 224 and. added to or subtracted from a signal there,

which is applied by the proportional amplifier 226, in order to fine-tune the spray valve 24 for precise temperature control.

The pressure control circuit is shown in Fig. 6 and determines on the one hand when the system is to go into bypass operation and on the other hand it adjusts the throttle pressure of the boiler to a desired value, which it does independently of process feedback or intervention. It should be noted that the throttle pressure of the boiler is equal to the pressure at the inlet of the bypass system and at the control valves 28.
W.

This pressure control circuit 150 includes a first and a second PI controller 240-1 and 240-2, both of which have an output signal on the associated lines 242 and 243, which are connected to two inputs of a summing circuit 246 which correspond to the structure according to FIG can. In addition, as is also true of FIG. 4, the output of each of these controllers becomes the in each case fed back to the other controller, so that it corresponds to the applied output signal to the other

WS342P-2534 controller readjusted

- 31 -

Controller is readjusted when it is in overrun mode is located.

The determination of which of the two controllers takes over the follow-up operation and the control is made with the help an appropriate signal applied to terminal 248. This signal can be switched on manually or automatically will. The application of a binary signal with a first logical signal level acts as a trigger signal via line 250, whereas a binary signal with the opposite signal level due to the NOT circuit 252 a trigger signal for the follow-up control is applied via line 254 to the other controller.

The PI controller 240-1 is constructed in such a way that it has a Has time constant TC3, which is different from the time constant TC4 of the PI controller 240-2. In the present Case, TC4 is greater than TC3. For this reason, the PI controller 240-2 can be used for control purposes in such situations be selected in which a relatively slow Response is desirable for start-up operation applies. The PI controller 240-1 with its relatively fast response behavior is used in situations which require a quick response, as z. B. can be the case with rapid load changes.

In contrast to the controller structure according to FIG. 4, the controllers according to FIG. 6 are not subjected to identical input signals. Only one entrance at a time a same input signal is supplied via line 101 from pressure transducer 100, which is the actual Throttle pressure signal is. The setpoint of the desired throttle pressure signal is at the other input of the PI controller 240-2 via line 260, which is from a generator

WS342P-2534 262 is delivered,

3235 * 57

262 is supplied, which determines the setpoint signal independently of the process. To prevent the high pressure bypass system is opened during normal turbine operation, another input of the PI controller 240-1 is on the line 264, via which a setpoint signal is supplied which corresponds to the desired throttle pressure and a Bias is superimposed. This bias can, for. B. introduced by means of a bias amplifier 268 which is acted upon by the setpoint signal via line 260 according to the desired throttle pressure V ^, - becomes and a predetermined bias voltage B for this signal added up.

After ignition, many boiler systems work with a fixed throttle pressure, regardless of the boiler load. In a fixed pressure system, the throttle pressure can be on the order of about 170 kg / cm ² . Any load change that tends to change this pressure leads to more or less fuel being fed to the boiler in order to maintain a constant pressure as a function of the load. In such a system with a fixed pressure, any device can be used as the setpoint generator 262 which is capable of supplying a constant output voltage indicative of the desired constant throttle pressure. In a rudimentary form, this function can be fulfilled by a simple potentiometer.

Other boiler systems, on the other hand, provide for operation with sliding pressure, with the throttle pressure between a maximum and a minimum value can be changed depending on the load. This type of operation leads to better fuel economy and to a

WS342P-2534 better fuel economy

- 33 -

better fuel economy and more even Turbine temperature. A work characteristic that these classic relationships of the sliding printing process is shown in FIG. 7.

The solid curve 280 according to FIG. 7 represents the throttle pressure profile of the boiler as a function of the boiler load, the boiler load being plotted as a ^{percentage on the abscissa and the throttle pressure in kg / cm 2 on the ordinade.} The boiler is operated in such a way that the throttle pressure maintains a certain minimum value up to a certain load L. The inflection point 282 is located at this point. The pressure then rises linearly as a function of the load up to the inflection point 283, which is assigned to a load. Following this break point, the pressure is again kept constant at a maximum value. If a constant preload B is added to the throttle pressure profile, the result is curve 286, which is entered in dashed lines. This profile assigned to the boiler or this characteristic boiler curve is used in a conventional manner to establish the setpoint value for the throttle pressure. A ^ way by which this is accomplished in known steam turbine power plants, will be explained with reference to FIGS, 8th

In Fig. 8, 290 denotes a circuit which supplies an output signal via a line 293 which the correct setpoint for the throttle pressure as a function of an input signal characterizing the load via the Line 294 supplies. In this way, the setpoint value is determined in accordance with the characteristic curve according to FIG. 7. The correct load signal is in turn supplied by a computer 295 which detects the load requirement, although

WS34-2P-2534 others too

323SSS7

other regulating or control devices can also be used to provide a corresponding load signal to deliver.

A limiter circuit 296 is typically provided and can provide decoupling during a rapid change in load of the setpoint for the throttle pressure from the load index to cause the process to speed up Adapts load changes, with pressure changes nevertheless! be maintained within acceptable limits.

The setpoint generator 262 for the throttle pressure generates the desired setpoint in a sliding pressure curve corresponding to the profile according to FIG. 7, the setpoint value being a predetermined one that is completely independent of the steam flow Is worth. The generation of a process-independent setpoint can also be used in another boiler operation, e.g. B. with fixed pressure, with an increasing time dependency or in an operation with economic efficiency set valve position, as described in US-PS A-178 762, be provided.

It is now assumed that a warm start operation is initiated, the z. B. requires a 30% boiler load, so that the desired temperature for the turbine is obtained. To achieve this operation, it is necessary to a certain target value for the desired throttle pressure using the characteristics of FIG. 7 for the to select the given boiler load. Initially, the control valves 28 and the bypass valve 72 are closed, see above that by heating the boiler the throttle pressure rises and is measured with the help of the pressure transducer. When on the line 101 starting from the pressure transducer the throttle pressure

WS342P-2534 signal the

::: \ ϋ * :: ^; "· \ Λ ::. 323SSS7

signal approaches the desired value present on line 260, the PI controller 240-2 selected for the control process via terminal 248 provides an output signal which causes the bypass valve 72 to open into a position in which there is a balance between the desired and the actual throttle pressure, and the 30 % of the boiler steam capacity is routed through the bypass system.

If for any reason the setpoint for the throttle pressure needs to be changed, the opens or closes PI controller 240-2 the bypass valve 72 in such a way that the actual throttle pressure changes accordingly. Although the two PI controllers 240-2 and 240-1 were described as being of the same type, there are minor differences in the Operating mode due to the limitations superimposed on the output signal. The input lines 101 and 260 of the PI controller 240-2 are provided with a positive and a negative sign. When the input signal is on the with the line marked positive is greater than that on the line marked negative, the PI controller delivers 240-2 a positively directed output signal which is limited at a predetermined positive voltage. When the signal on the negative input line predominates, the output of PI controller 240-2 will drop to one lower limit of zero volts, d. This means that the output signal of this controller is not in the negative range transforms. The same functional sequence also applies to the PI controller 240-1.

If the desired setpoint for the throttle pressure drops, the PI controller 240-2 supplies an output signal, which tends to open the bypass valve 52, so that

WS342P-2534 the actual

: " ^: 'ü ^{*:; *:} * O.- .:'. 3235SI7

the actual throttle pressure drops, whereas with one If the setpoint signal rises, the output signal of the PI controller 240-2 falls, towards zero, and that Tries to close the bypass valve in order to increase the actual oil throttle pressure.

After a certain time in start-up operation, the Turbine is supplied with steam to finally bring it to a synchronous speed. This can e.g. B. take place in such a way that steam is first fed to the medium-pressure turbine 13 via the control valves 36. After this the turbine has reached a specified speed, the control valves are switched to associated controller. As the control valves slowly open, the actual throttle pressure slowly drops. The PI controller 240-2 detects this imbalance and provides an output signal which the bypass valve tries to close in order to keep the actual throttle pressure at the setpoint. This process continues until finally the bypass valve 72 is closed and all the steam generated by the boiler of the turbine is fed. The closing of the bypass valve 72 can be scanned with the aid of a limit switch (not shown) will. Depending on this, the throttle pressure control can either be applied to the boiler control or the turbine control transferred and a corresponding signal applied to terminal 248 to control the PI controller 240-1 to activate the regulation and the follow-up control with the PI controller 240-2.

Recall that PI controller 240-1 has a shorter time constant and therefore bypass valve 72 is faster can open if any kind of overpressure causes the

WS342P-2534 given constant

.:. ^{O'L: ::: "".} 323S5S7

predetermined constant preload B exceeds. This bias ensures that the bypass valve during normal Changes in pressure is not opened prematurely.

If one examines the input signals to PI controller 240-1, one finds that the signal on line 101 at a given load is in a state of equilibrium with the throttle pressure generated by the on the curve is represented according to Fig. 6 predetermined setpoint. In contrast, the signal on line 264 corresponds to a certain point on the dashed curve 298 of FIG. 10. Although the signal on line 264 by one constant amount B is greater than on the line 101, the bypass valve remains in the closed state, since the output signal of the PI controller 240-1 has the value zero Volt is held. As long as the normal deflections of the actual throttle pressure have this preload value B do not exceed, the bypass valve remains closed. However, if z. B. this predetermined by a load drop If the preload is exceeded by a pressure surge, the PI controller 240-1 quickly supplies an output signal on this imbalance to open the bypass valve 72 and thereby drain steam into the bypass system allow. As a result, the throttle pressure can remain at the setpoint value, which has only been changed by one bias value, for as long be held until normal operating conditions are restored. After a specified time delay the control is switched back to the PI controller 240-2 to reduce the throttle pressure again from the to regulate the higher value caused by the retention of the preload back to the setpoint. This switchover is bumpless because the PI controller 240-2 tracks the output signal of the PI controller 240-1 due to the follow-up control and thus at the time of the switchover

WS342P-2534 immediately before

supplies the same output signal immediately before switching. After correcting the difficulty and the complete switching of the steam flow to the turbine, the PI controller 240-1 is released again, so that it can perform its function of overpressure regulation again.

Referring to Figure 9, there is an alternative embodiment of the invention shown to provide the setpoint signal for the throttle pressure with a bias. In contrast to a fixed bias B, which is supplied by the amplifier 268 according to FIG. 6, the arrangement according to FIG 9 shows a multiplier circuit 297 which shows a certain predetermined percentage of the on the line applied signal value to the amplifier 268. If z. B. the desired preload should be 5%, What is needed is a multiplier circuit which multiplies the signal value on line 260 by 0.05. For a smooth pressure transition, the dashed curve 298 according to FIG. 10 should be maintained, from which one it can be seen that a first bias B1 is provided up to the inflection point 282, whereas after the second At the inflection point 283, a second, larger prestressing B2 is used. The bias in the inclined section the curve between the break points 282 and 283 increases continuously from the minimum value B1 to the maximum Value B2 to.

In the device described above, there is pressure control circuit 150 and spray valve regulator 140 a double regulator arrangement is provided in each case, one regulator for a short response time and the other Controller for a long response time is used.

In Fig. 11 a further embodiment is shown, where only one controller is used at a time.

WS342P-2534 In the pressure control circuit

In the pressure control circuit 150 only a single PI controller 240 is provided, which has a relatively slow response time corresponding to the PI controller 240-2 according to FIG. This PI controller 240 has two input signals applied to it, one characterizing the actual throttle pressure via line 101 and the other characterizing a function of the operating state of the turbine via line 264. Furthermore, a signal selector 300 is provided which emits either a bias signal B or a percentage bias signal as in the embodiment according to FIG. 9 via line 302 or a zero bias voltage via line 303 as a function of the selection signal via line 304. So z. B. during the start-up phase, the zero bias voltage is applied via line 301 so that amplifier 268 transmits the setpoint signal for the throttle pressure, as supplied by setpoint generator 262, and the amplifier sends a corresponding output signal to PI controller 240 via line 264 .

If the turbine is operating normally without bypass operation, the preload via line 302 is selected in such a way that that the amplifier 268 supplies the setpoint signal increased by the bias voltage to the PI controller 240 and thus the pressure control circuit works in the functional mode of the overpressure control. During this operation, for example a turbine shutdown take place, which would make the rapid connection of the bypass system necessary. An override circuit is used to enable this for situations in which a quick reaction is necessary 310 is provided, which is constructed in such a way that it normally receives the output signal of the PI controller 240 on the line 243 transmits if a signal is not applied from the outside via the line 312. In this

WS342P-2534 case supplies

I = '= .. ":: = Ό. · .:'. 323SS57

If so, the control circuit 310 supplies a signal which causes the actuation circuit 114 to open the bypass valve 72 can be opened quickly to a predetermined maximum position. When the operating load is on a predetermined is the minimum value, the signal applied via line 312, for. B. depending on a turbine shutdown or by opening a circuit breaker in the generator's line system.

The signal used for valve actuation is fed back to PI controller 240 via line 314 and serves as a Reference variable for the follow-up control. If a quick Valve actuation is initiated, a corresponding signal acts on the PI controller 240 and via line 316 switches this to the follow-up mode to the actual To copy valve actuation signal. When the valve is fully open and there is no signal on line 312 acts, the trigger signal for the follow-up control on the line 316 is switched off, resulting in a bumpless Transition back to the control mode for the PI controller results, which then opens the bypass valve 72 accordingly regulated according to the throttle pressure conditions.

The spray valve controller 140, which comprises a single PI controller 200, has a relatively long response time, such as B. the PI controller 200-2 according to FIG. 4. The controller works as a Did controller 200-2 during bypass operation and receives the same signals as the Did controller 200-2, namely the low temperature signal from the input side of the reheater via line 126 and the adapted setpoint signal via line 141 Bypass operation, the spray valve 84 remains closed and opens quickly to a predetermined maximum position, if the bypass operation is suddenly switched on, what

WS342P-2534 also the case

»* MK

- 41 -

is also the case when a signal is given to the override circuit 310 via the line 312. That The signal resulting therefrom for the rapid opening of the bypass valve 72 is also sent to the proportional amplifier 226 applied, which in turn sends a proportional signal via the summing circuit 224 to the actuating circuit 122 which causes the spray valve 24 to open rapidly. The controller 200 then provides the necessary Control signals for maintaining an accurate Temperature control.

The pressure regulating circuit 150 according to FIGS. 6, 9 or 11 thus serves to regulate the operation of a high-pressure bypass valve during the start-up phase of the turbine, so that the actual throttle pressure is kept at the desired value. Furthermore, the regulation works in normal operation of the turbine without a connected bypass overpressure regulator in order to quickly switch on the bypass system if unusual pressure conditions occur. The setpoint for the throttle pressure is generated completely independently of the steam flow, which also eliminates process feedback, which tends to inevitably change the setpoint. This dual function of the pressure control circuit is compatible with different, pressure-related operating modes and can be used both with a fixed pressure, with sliding pressure, with modified sliding pressure and with a programmed striking pressure and the like.

WS342P-2534

Claims (1)

Claims 1. J bypass system for a generator driving steam turbine system with a high pressure and at least one low pressure turbine, a reheater in the steam line between the high and low pressure turbine and a bypass arrangement leading to the turbines, which comprises at least high pressure valve arrangements for introducing steam into the bypass arrangement, thereby marked, - That the bypass arrangement comprises control devices (90) for the actuation of the high-pressure valve arrangement (72) as a function of predetermined pressure conditions in the overall system, - That temperature measuring devices (124, 134 ·) at the input and are arranged at the outlet of the reheater (32), - and that steam temperature control devices (84, 122, 140, 144) are present, with which the temperature of the passed through the high pressure valve arrangement (72) Steam can be set as a function of the temperature at the inlet and outlet of the reheater. FS / B 2. bypass system according to claim 1,
characterized, - That the steam temperature control devices with a Are connected to a source of cooling liquid and comprise a high pressure spray valve (84) with which the Cooling liquid can be introduced into the steam line of the bypass arrangement, - And that steam temperature control devices as a function Activate the high pressure spray valve based on the temperature at the inlet and outlet of the reheater. 3. bypass system according to claim 2,
characterized, - That the steam temperature regulating devices have an adaptation circuit (14-4) for setting a setpoint as a function the temperature at the inlet and outlet of the reheater and also a spray valve controller (140) includes which, depending on the temperature at the input of the reheater and the adapted setpoint, the actuation the high pressure spray valve (84) controls, 4. bypass system according to claim 3,
characterized, "» - - that the adaptation circuit (144) comprises: a controller (160), a memory (170) in which the temperature at the outlet of the reheater after the initiation of the bypass function is saved, - That the controller (160) responds to the temperature at the inlet of the reheater and this temperature supplies an identifying signal prior to the initiation of bypass operation in order to determine the setpoint, - and that the controller depends on the temperature at the output of the reheater as well as the stored Temperature signal after initiation of bypass operation WS342P-2534 provides the setpoint signal on the output side. 5. bypass system according to claim 4,
characterized, - that at least one input signal can be fed to a signal selector (184) which defines a predetermined temperature value, - That the output signal of the signal selector of a differential circuit (180) can be supplied, which is also supplied with the stored temperature signal from the memory (170) can be charged, - That the output signal obtained by forming the difference the differential circuit can be fed via a functional circuit (176) to a summing circuit (164) in which the signal modified in the functional circuit to the stored high temperature signal for the control of the controller (160) is added and that the functional circuit (176) the applied difference signal only during the bypass operation can gradually increase. 6. bypass system according to claim 3,
characterized, - That the spray valve controller (140) comprises a first PI controller (200-1) and a second PI controller (200-2), - That the first PI controller (200-1) with the low temperature tapped at the input of the reheater on the one hand and on the other hand the adapted setpoint signal is applied, - That the first PI controller (200-1) for the case that the turbine system is in normal operation, a first response time with which it responds to a deviation between the two input signals, - That the second PI controller (200-2) also with the low temperature tapped at the inlet of the reheater and the adapted setpoint signal can be applied WS342P-2534 and has a second, longer response time when the turbine system is in start-up operation, - and that there are also devices (210, 212 and 21A-) with which one of the two controllers is selected for the control process, the two controllers only can be switched on for bypass operation. 7. bypass system according to claim 6,
characterized, - That the spray valve regulator (140) also has facilities includes to the output signal of the respective PI controller as the signal to be tracked to the other PI controller to feed - That each of the two PI controllers is in a first operating mode for supplying an output signal as a function of the input signals and can be used in a second operating mode for replicating the signal to be tracked is, - That a summing circuit (206) can be acted upon with the output signals of the two PI controllers and one of the half Output signal corresponding to the sum of the input signals to an actuation circuit (122) for the high-pressure spray valve (8A-) applies. 8. Bypass system according to one of claims 1 to 7, characterized in that - That the control devices (90) for the actuation of the high pressure valve arrangement (72) have a generator (262) which provides a setpoint signal independent of the steam flow for the desired throttle pressure, - that measuring devices (100) are available to determine the steam pressure at the steam generator, - And that a pressure control circuit (150) as a function of the actual throttle pressure and the setpoint of the Throttle pressure, the high-pressure bypass valve (72) is actuated. WS342P-2534 9. Bypass system according to claim 8, characterized in that - That the pressure control circuit (150) is in normal operation the bypass valve (72) opens when the actual throttle pressure is equal to the throttle pressure determined by the setpoint plus a bias. 10. Bypass system according to claim 9, characterized in that - That the preload has a constant value. 11. Bypass system according to claim 9, characterized in that - That the bias voltage has a predetermined percentage value of the throttle pressure determined by the setpoint Has. 12. Bypass system according to claim 8, characterized in that - That the nominal value of the throttle pressure is determined depending on the load of the generator. 13. Bypass system according to claim 9, characterized in that - That the pressure control circuit (150) comprises a first PI controller (240-1) and a second PI controller (240-2), - That the first PI controller with the actual throttle pressure and the throttle pressure specified by the setpoint plus the preload can be applied and has an initial response time, - That the second PI controller with the actual throttle pressure and the throttle pressure determined by the setpoint can be applied without the preload and a second, has a longer response time, WS342P-2534 - and that there are facilities for one or the other Reyler for the control function in operation gain weight. H. bypass system according to claim 13, d a d it r ti h characterized, - That each of the two PI controllers is in a first operating state and a / wide operating state can be used - that the PI controller, which is in the initial operating state, outputs a control signal as a function of the FI ngangss 11 | ηa \ en II e Per t, - UaM dft- iHidfr «, working in / wide operating state! ¹ I-Regier follows an applied signal and replicates this signal at the output, - That the pressure control circuit also includes devices, um <! <is Auagamjssigndl of each of the two PI controllers use / u as a subsequent / u3t.controlling signal for the other PI controller / u, - ύΛ ^ the two output signals of the two controllers of a summing circuit (2 ^ 6) are fed, which output Ot) ItJg half the sum of the applied signals for the actuation circuit (114 ·) for the bypass valve (72) is available. 15. BypaUsystem according to claim 9,
characterized, - That the back control circuit (150) has a single PI controller (240), which can be acted upon on the input side with the actual throttle pressure signal and a second input signal is, - That the second input signal of the PI controller is the setpoint signal for the throttle pressure 1st, if the turbine system In a first operating state, - that there;; / wide input signal the set value signal of the BATH ORIGINAL Throttle pressure plus a bias signal is when the turbine system is running in a second operating state, - That the actuation circuit (114) for the bypass valve this as a function of the output signal of the PI controller opens and closes, - And that an override circuit (310) is also provided, which the output signal of the PI-Rogler overridden and activates the actuation line (114), if the bypass valve is to be opened quickly up to a predetermined maximum position. 16. Bypass system according to claim \ b,
characterized, - That the PI controller (Ζή · Ο) Jm the first operating state Control parameters depending on the input gas requirements and in a second operating state in narhiritifbet rleb replicates an applied signal, - and that the output signal of the overdrive unqsüehaltumj as an override signal to the PI controller as / u ropti / lerendps Signal is supplied until the BypalAvent! I dia given maximum position taken h.jl.