Method for operating an internal combustion engine coupled with a generator

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<td colspan="2"> (12)</td><td colspan="3">Patent specification</td>

<td> (21)</td><td>Application number:</td><td>A 775/2013</td><td>(51) Int. CI .: F02D29 / 06</td><td> (2006.01)</td>

<td> (22)</td><td>Registration date:</td><td> 09.10.2013</td><td>F02B 37/18</td><td> (2006.01)</td>

<td> (45)</td><td>Published on:</td><td> 15.02.2015</td><td>F02B 37/16</td><td> (2006.01)</td>

<td></td><td></td><td></td><td>H02P9 / 04</td><td> (2006.01)</td>

<td>(56) Citations:</td><td> (73)</td><td>Patent holder:</td>

<td>WO 2011088483 A1</td><td></td><td>GE JENBACHER GMBH &amp; CO OG</td>

<td>JP2000257511 A</td><td></td><td>6200 JEN BACH (AT)</td>

<td>US 2012175876 A1</td><td> (72)</td><td>Inventor: Thalhauser Josef 83191 Nussdorf (DE) Perktold Michael</td>

<td></td><td></td><td>6633 Biberwier (AT) Hirzinger-Unterrainer Johann 6345 Kössen (AT) Schaumberger Herbert 6232 Munster (AT)</td>

<td></td><td> (74)</td><td>Representative: Torggler Paul Mag. Dr., Hofinger Stephan Dipl.Ing. Dr., Gangl Markus Mag. Dr., Maschler Christoph MMag. Dr. innsbruck</td>

(54) Method for operating an internal combustion engine coupled to a generator

AT 514577 B1 2015-02-15 (57) A method for operating an internal combustion engine (2) coupled to a generator (1) in the event of a network fault in an energy supply network (3) connected to the generator (1), in particular in the event of a dynamic network voltage dip, the Internal combustion engine (2) comprises a turbocharger (4), which has a compressor (5) in an air supply line (6) of the internal combustion engine (2) and an exhaust gas turbine (7) coupled to the compressor (5) in an exhaust gas line (8) of the internal combustion engine (2), at least one bypass valve (9, 10) is provided to bypass the compressor (5) and / or to bypass the exhaust gas turbine (7), the at least one bypass valve (9, 9, 10) is actuated at least temporarily and with or after detection of the network fault an ignition (11) in the internal combustion engine (2) is deactivated, the ignition (11) in the internal combustion engine (2) being activated again after the network fault has subsided, at least a bypass valve (9, 10) has a first position (S1) before the detection of the network fault, with or after the detection of the

In the event of a network fault, the at least one bypass valve (9, 10) is set to an actuation position (O) that differs from the first position (S1), the at least one bypass valve (9, 10) after the network error has subsided to an actuation position (O) that differs from the actuation position (O) Position (S2, S1) is set.

Fig. 3

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DVR 0078018

AT 514 577 B1 2015-02-15 Austrian patent office

description

The invention relates to a method for operating an internal combustion engine coupled to a generator in the event of a network failure of a power supply network connected to the generator, in particular in the event of a dynamic mains voltage dip, the internal combustion engine comprising a turbocharger, which has a compressor in an air supply line of the internal combustion engine and one with has the exhaust gas turbine coupled to the compressor in an exhaust line of the internal combustion engine, at least one bypass valve is provided for bypassing the compressor and / or for bypassing the exhaust gas turbine and with an ignition in the internal combustion engine being deactivated upon or after the detection of the network fault, the ignition in the internal combustion engine being reactivated after the network fault has subsided.

When connecting power generation systems with a generator that is to be connected to an energy supply network, the prevailing network and system rules of the respective energy supply network operator must be observed. These network and system rules, also known as the “Grid Code” or “Transmission Code”, stipulate, among other things, minimum technical requirements and procedures for energy generation systems in the event of a network fault in the energy supply network. Grid faults in the form of dynamic grid voltage drops, which are also known as "low voltage ride through" (LVRT) events, are also of relevance. When such a dynamic mains voltage dip occurs, it is desirable that the electrical phase angle, which is also referred to as the load angle or pole wheel angle, remains within specified limits, since otherwise there will be a pole slip on the generator and, subsequently, an uncontrolled acceleration of the generator coupled to the generator Internal combustion engine can come. In addition, when the network returns after the network fault has subsided, the mechanical loads on the generator, internal combustion engine and coupling between internal combustion engine and generator increase as the phase angle change increases.

A conventional measure to keep the phase angle change within predefined limits is to deactivate the ignition in an internal combustion engine coupled to the generator. In the case of an internal combustion engine with a turbocharger, however, switching off the ignition shifts the operating point in the compressor map in the direction of the surge limit. If the surge limit is exceeded, there is a stall on the compressor blades of the turbocharger and so-called compressor pumping occurs, which can subsequently lead to an unstable operating state of the internal combustion engine.

[0004] WO 2011/088483 mentions that “through the targeted positioning of the actuators, a rapid reduction in the boost pressure is possible without the risk of reaching the surge limit of the compression device”. No statement is made as to when and how the “targeted” positioning of the actuators takes place. The aim in WO 2011/088483 is to reduce the boost pressure as quickly as possible, that is to say to reduce the engine power.

JP 2000257511 describes a method for operating an internal combustion engine with a generator, a first operating mode being described (mode 1) which is suitable for an operating mode of the engine in which no rapid changes in the output power are required. In this operating mode 1, the throttle valve is held in its fully open position, thereby avoiding pumping loss.

The object of the invention is to avoid the disadvantages described above and to provide a method, which is improved over the prior art, for operating an internal combustion engine coupled to a generator in the event of a network fault in the energy supply network. In particular, it should be made possible, taking into account the prevailing network and system rules, to avoid compressor pumping when a network fault occurs, in particular a dynamic network voltage dip.

According to the invention, this object is achieved by the features of claim 1. Advantageous configurations in the invention are specified in the dependent claims.

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According to the invention it is provided that upon or after detection of the network fault the at least one bypass valve is actuated at least temporarily, the at least one bypass valve having a first position before detection of the network fault, with the at least one during or after detection of the network fault The bypass valve is set to an actuation position that differs from the first position, wherein the at least one bypass valve is set to a position deviating from the actuation position after the network fault has subsided.

As a bypass valve, a compressor bypass valve for bypassing the compressor can be provided in a compressor bypass line which connects a compressor inlet with a compressor outlet. It can also be provided, for example, that a charge air cooler is arranged downstream of the compressor, the compressor bypass line connecting the compressor inlet to an outlet of the charge air cooler.

Alternatively or additionally, an exhaust gas turbine bypass valve for bypassing the exhaust gas turbine can also be provided in an exhaust gas bypass line as a bypass valve, which connects an exhaust gas turbine inlet with an exhaust gas turbine outlet.

The internal combustion engine can be a gas engine (eg a stationary gas engine) in which a fuel (eg fuel gas) is burned in the presence of air. The generator can be an alternating current generator that is driven by the internal combustion engine and feeds electrical current into an energy supply network connected to the generator.

The occurrence of a network fault can be detected in a known manner, for example in that the speed of the internal combustion engine or the generator rises above a predeterminable maximum value due to a failure of the power supply network, or by monitoring a generator voltage, a generator frequency or a generator current of the generator, a network fault being detected if, for example, the generator voltage drops out and / or the generator frequency exceeds a specifiable limit value rises and / or the generator current rises above a specifiable limit value.

By at least intermittently actuating at least one bypass valve (e.g. the compressor bypass valve and / or the exhaust gas bypass valve), compressor pumps can be avoided in the event of a network fault and the ignition may be switched off and the internal combustion engine coupled to the generator is stabilized accordingly become.

It can preferably be provided that the at least one bypass valve (for example compressor bypass valve) is opened to an actuating position that is more open than the first position.

According to a particularly preferred embodiment it can be provided that the at least one bypass valve is held in the actuating position during a predeterminable actuation time.

It can preferably be provided that the at least one bypass valve is set again essentially to the first position after the predefinable actuation time, that is to say to the position as before the dynamic mains voltage dip. In principle, however, it is also possible for the at least one bypass valve to be essentially completely closed after the predefinable actuation time.

It has been found to be particularly advantageous if the at least one bypass valve is closed after the predeterminable actuation time up to a second position that is further closed compared to the first position and is held in the second position for a predeterminable time, preferably the at least one bypass valve is opened again essentially to the first position after the predeterminable time. By closing the bypass valve further up to the second position, which is further closed compared to the first position, it can be achieved that the engine output of the internal combustion engine reaches its initial value again more quickly than before the network fault.

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It can also be provided that a fuel is supplied for ignition in the internal combustion engine, the supply of fuel being prevented to deactivate the ignition in the internal combustion engine. The ignition device can be, for example, an electrode spark plug or a laser spark plug. At least one fuel metering device, for example in the form of a port injection valve, can be provided for the fuel supply.

By actuating the at least one bypass valve and deactivating the ignition in the internal combustion engine, an extended period of time with deactivated ignition can be achieved without compressor pumping occurring.

It can be provided that the ignition in the internal combustion engine is reactivated when a speed of the internal combustion engine or the generator reaches a predefinable speed value and / or a relative phase angle change of the generator reaches a predefinable value.

The ignition in the internal combustion engine is usually only switched on again when the dynamic mains voltage dip is over. The point in time at which the ignition is switched on again can be determined from the speed of the internal combustion engine or generator and / or from the value of the relative phase angle change. In particular, by resetting the bypass valve to its starting position as before the network fault - that is, to its first position - it can be achieved that the internal combustion engine continues to run stably with the same power as before the network fault.

In principle, it can also be provided here that the at least one bypass valve is closed after the network fault has subsided up to a second position that is further closed compared to the first position and is held in the second position for a predeterminable time, with the at least one bypass valve preferably after the predefinable time is essentially opened again to the first position.

According to a particularly preferred embodiment it can be provided that after the network fault has subsided, the activation of the ignition and the setting of the at least one bypass valve to a position deviating from the actuation position take place essentially at the same time. Switching on the ignition again can be the triggering event to activate the bypass valve.

It can also be provided that after the network fault has subsided, the setting of the at least one bypass valve to a position deviating from the actuation position takes place after activating the ignition, preferably after a predeterminable second time after activating the ignition.

Further details and advantages of the present invention are explained with reference to the following description of the figures. It shows or shows:

1 shows a schematic block diagram of a generator which is connected to an energy supply network and can be driven by an internal combustion engine.

FIG. 2 shows the time profile of the valve position of a bypass valve according to an exemplary embodiment of the proposed method, and FIG

3 shows the time profile of the valve position of a bypass valve and the time profile of an ignition of the internal combustion engine according to a further exemplary embodiment of the proposed method.

1 shows, in a schematic block diagram, an electrical generator 1 which is connected to an energy supply network 3. The electrical generator 1 can be an alternating current generator which is connected to a three-phase power supply network 3. The generator 1 is coupled to an internal combustion engine 2, which in this example is designed as a stationary gas engine. The generator 1 can be driven by the internal combustion engine 2 in order to produce electrical current which is fed into the energy supply network 3. Charge air L is supplied to internal combustion engine 2 via an air supply line 6 3/10

AT 514 577 B1 2015-02-15 Austrian

Patent office leads. The charge air L can be, for example, a fuel-air mixture (eg for mixture-charged internal combustion engines) or essentially only air (eg for air-charged internal combustion engines). Exhaust gas from internal combustion engine 2 is discharged via an exhaust gas line 8. The internal combustion engine 2 is equipped with at least one turbocharger 4 which, in a known manner, comprises a compressor 5 in the air supply line 6 and an exhaust gas turbine 7 coupled to the compressor 5 in the exhaust gas line 8. The compressor 5 is coupled to the exhaust gas turbine 7 via a turbocharger shaft 14. A charge air cooler 18 for cooling the compressed charge air L is arranged in the air supply line 6 downstream of the compressor 5. The charge air L is fed via the air supply line 6 to a compressor inlet 5 a of the compressor 5. A compressor outlet 5b of the compressor 5 opens into the charge air cooler 18.

To bypass the compressor 5 and / or exhaust gas turbine 7, two bypass valves 9, 10 are provided in this example. A compressor bypass valve 9 for bypassing the compressor 5 is arranged in a compressor bypass line 12, which connects the compressor inlet 5a with the air supply line 6 downstream of the charge air cooler 18 arranged in the air supply line 6. An exhaust gas turbine bypass valve 10 for bypassing the exhaust gas turbine 7 is arranged in an exhaust gas bypass line 13 which connects an exhaust gas turbine inlet 7a directly to an exhaust gas turbine outlet 7b.

To detect a network fault, a control device 15 is provided which can monitor various operating parameters of the internal combustion engine 2 and / or the generator 1 and / or the energy supply network 3 by reporting corresponding values ​​of these operating parameters to the control device 15 via signal lines 16. For example, one or more of the following operating parameters can be monitored: speed of internal combustion engine 2, speed of generator 1, electrical voltage of generator 1 and / or energy supply network 3, voltage frequency of generator 1 and / or energy supply network 3, electrical current of generator 1 and / or the power supply network 3.

If a network fault is detected by detecting a deviation of the at least one monitored operating parameter, the control device 15 reports control signals to the compressor bypass valve 9 and / or to the exhaust gas turbine bypass valve 10 via corresponding control lines 17, in order to with or after detection of the Network failure to operate at least one of these bypass valves 9, 10 at least temporarily.

In addition, a control signal can be reported to the internal combustion engine 2 via a further control line 17 in order to deactivate an ignition in the internal combustion engine 2 when the network fault is detected.

Fig. 2 shows the course of a valve position V of a bypass valve 9, 10 over time t, and the course of an ignition 11 in the internal combustion engine 2 over time t. A network fault, for example a dynamic network voltage dip, is detected at time T1. At this point in time, a bypass valve 9, 10 is in a first position S1. After the network fault has been detected, the bypass valve 9, 10 is opened, for example, into an actuation position O at time T2. After a predefinable actuation time Tv, the bypass valve 9, 10 is closed again. In the example shown, the bypass valve 9, 10 is closed up to a second position S2 which is further closed compared to the first position S1. After a predefinable time T_s the bypass valve 9, 10 is brought back from its second position S2 to the first position S1 at time T5, which the bypass valve 9, 10 had before the network fault occurred. During this entire course, the ignition 11 in the internal combustion engine 2 remains on unchanged.

Fig. 3 shows the timing of valve position V and ignition 11 in the internal combustion engine 2 similar to FIG. 2, in this example, in addition to opening the bypass valve 9, 10, the ignition 11 in the internal combustion engine 2 is temporarily deactivated. After the network fault has been detected, in this example the ignition 11 in the internal combustion engine 2 is deactivated at time T3 and activated again at time T4 after the network fault has subsided

AT 514 577 B1 2015-02-15 Austrian

Patent Office fourth. The closing of the bypass valve 9, 10 and the activation of the ignition 11 take place in this example essentially at the same point in time T4. In comparison to the time curve of the valve position V according to FIG. 2, the bypass valve 9, 10 in this example remains in the actuating position O until the ignition 11 in the internal combustion engine 2 is switched on again. After a predefinable time T_s the bypass valve 9, 10 is brought back from its second position S2 to the first position S1 at time T5, which the bypass valve 9, 10 had before the network fault occurred.

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