Verfahren zum Betreiben eines mit einem Energieversorgungsnetz verbundenen Generators

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The invention relates to a method of operating a generator connected to an energy supply network, in particular synchronous generator, during a net error in the power network, in particular during an electrical short circuit.

In an energy supply network net error During a, in particular during an electrical short circuit and the associated drop in the line voltage in the power network, can occur on a connected electric generator with the power network, in particular synchronous generator, such as the speed or undesirable changes of operating variables of the generator load angle. As load angle is the angle between the vector of the rotating magnetic field in the stator of the generator, as we know, and the vector of the rotating magnetic field in the rotor of the generator means.

The waste of the mains voltage leads to a significant reduction in the output of electric power from the generator to the power network. In conventional configurations, in which a rotor of the generator (e.g. gas engine) with a the rotor driving motor shaft is connected an internal combustion engine, this electrical power degradation can lead to a corresponding increase in speed of the internal combustion engine and thus of the rotor. This the synchronization with the power network can be lost or even damage the generator are caused in the generator.

The net error in the power network can take place, for example, thereby detecting a that the supply voltage of the power supply network and/or the electric current fed into the power network by the generator and/or the rotational speed of the generator or of the internal combustion engine and/or the torque on the motor shaft of the internal combustion engine or to the rotor shaft of the generator is or are monitored, wherein, upon occurrence of a change of at least one of these monitored operating variables over a predeterminable threshold value is detected a network failure may include excessive. This may include be provided, only that occurring changes are detected as a network failure may include excessive, if more of these operating variables via preselectable threshold values have corresponding changes that is, if, for example, both the mains voltage, the electric current and also the rotational speed deviations have corresponding. The net error with the power network can remain connected during the generator.

The conventional approach, to take to respond to counteract in such a network failure may include excessive is, it, corresponding measures, such an increase of the rotational speed and an associated increase in the load angle of the generator. Thus usually measures are being taken, which reduce the rotational speed and the load angle. Such acceleration moment is reducing the exemplary action is connected to the generator by a throttled internal combustion engine accordingly.

It has, however, shown that the conventional measures are disadvantageous in the case of a network failure may include excessive in certain situations. So it can occurrence that the rotational speed of the generator in the event of a net error not increased, but firstly drops away. The person skilled in the art by its English technical term "Baking [...] " this known effect can lead under certain circumstances, lead to pole slip of the generator. pole slip in turn leads to a instability of the generator, wherein a of an internal combustion engine on the motor shaft into the rotor no longer as desired in electric power introduced mechanical power can be converted by the generator.

It is the purpose of the invention, the previously described disadvantages to avoid State of the Art improved method of operating a generator and a opposite the indicate net error in the energy supply network during a.

This problem is solved according to the invention by the features of claim 1. Advantageous configurations of the invention are recited in the dependent claims.

Under of the invention is therefore provided that an electrical excitation of the generator as a function of the value before the network failure may include excessive and/or at least an operation amount of the generator is reduced at least temporarily during the net error.

The electrical excitation of a generator and the level of output voltage of the generator determines the transferable electric power and thereby the height of the electrical reactive power is fed into the power network from the generator. The higher the generator output voltage during a mains voltage break-down , the higher the electric power is fed into the power network the. By reducing the electrical energization of the generator is therefore the height of the electric power is fed into the power network during a reduced mains voltage break-down the,. This is particularly advantageous in the energy supply network during a net error , [...] has the consequence of a Baking effect. In configurations, in which an internal combustion engine drives the generator, which, in the event of a network failure may include excessive-particularly in a can thereby Baking [...] -occurring imbalance between the mechanical power of the internal combustion engine and the output electric current from the generator advantageously be counteracted.

The proposed procedure is advantageous in particular for generators, a 1.5 Ws/ inertia constant of less than or equal to the VA, preferably less than or equal

1 Ws/VA have, since the more impact on generators with small inertia constant[...] Baking effect.

In a preferred embodiment of the generator is, preferably by means of a coupling device, coupled with an internal combustion engine. In of the internal combustion engine it can be, e.g., a otto-motor operated Reciprocating gas engine, a diesel engine or a gas turbine act.

Deviations from operating variables of the generator therefore frequently occur during a net error on, because an imbalance between the mechanical power, by said engine is introduced into the generator, and the electric power that occurs in the power network is fed by the generator,. In the case of a can as a result of this imbalance caused [...]net error occurring Baking effect that the electric power is greater than the mechanical power. By a lowering of electrical energization of the generator and the associated reduction of the output electric current can be countered this imbalance.

Preferably, it can be provided that the excitation of the generator by reducing an excitation voltage for the generator exciting current supplied to the generator is reduced by reducing a or. For the excitation of the generator will be obtained an excitation device for use can is located on or outside of the generator. The excitation device can be acted upon with the excitation voltage and to subsequently provide a field current, which, in a known manner is supplied to corresponding windings of the generator, so as to cause the excitation of the generator.

In accordance with a preferred embodiment of the invention it can be provided that a variable electrical power delivered by the generator to the power network is detected before the network failure may include excessive, wherein the excitation is reduced depending on the output electric current before the network failure may include excessive. Heat to excitation can output electric current substantially proportional to a difference to a predeterminable reference value-preferably before the network failure may include excessive the nominal power-be reduced.

Preferably, it can be provided that a variable during the transient speed of the generator and/or of the clutch device a net error and/or of the internal combustion engine is detected, wherein the excitation substantially proportional to a difference between the transient rotational speed to the rotational speed is reduced before the network failure may include excessive.

For example, 100% with respect to a predeterminable denominator active tension of a percent excitation voltage can be determined according to the following formula F1:

S3 = 100%-(_{re f-} S1 S1)* P_{S [...]},

wherein a percent excitation voltage with respect to a 100% denotes denominator active tension of S3, S1_{re f} a percent rotational speed of the generator or of the clutch device or of the internal combustion engine with respect to a rated speed of 100% denotes before the network failure may include excessive, S1 the percentage of the internal combustion engine during the transient speed of the generator or of the coupling device or with respect to a rated speed of 100% denotes [...]net error and a positive proportionality factor, can be influenced by the reduction of the intensity of the excitation voltage.

In accordance with another embodiment, it can be provided that a variable to change the speed of the rotation speed of the generator, and/or during the net error of said fitting and/or of the internal combustion engine is detected, wherein the excitation is dependent on the size of the change in rotational speed reduced.

It may also be provided that a variable net error a torque on a motor shaft of the internal combustion engine during the attached to a rotor shaft of the generator is detected and/or, wherein the excitation is reduced as a function of the torque.

In another preferred embodiment it can be provided that a variable which is a load angle of the generator is detected during the net error , wherein the excitation is proportional to the magnitude of the detected reduced substantially indirectly load angle.

For example, a reduced excitation voltage at a negative load angle F2 are determined according to the following formula:

S3 = 100% + | [...] (S2/180)* 100% * P

wherein reduced in percentage terms with respect to the 100% denotes denominator active tension of S3 corresponding to the excitation voltage, the measured negative load angle in degrees designated S2 [...]_{a positive proportionality factor and P |} 0, can be influenced by the reduction of the intensity of the excitation voltage.

Preferably, it can be provided that the excitation to a predeterminable minimal minimum is reduced to a maximum. For a minimal minimum be ensured can of the generator. For example, e.g. a minimum value for the size of the above formulae F1 or S3. F2 are specified is to be lowered, the percentage not under the exciting voltage. Through this safety measure critical operating conditions can be avoided of the internal combustion engine.

In accordance with a particularly preferred embodiment it can be provided that detects an operation amount of the generator during the vibrations are net error , wherein the excitation of the generator is reduced, if the vibrations exceed a predefinable intensity. This may be provided that vibrations are detected load angle of the generator a, wherein the excitation of the generator is reduced, if the vibrations an amplitude of more than 2 degrees, preferably more than 10 degrees, have.

net error In the case of a, the one results in [...] Baking effect, it is advantageous, to increase the mechanical power of the internal combustion engine, so as to compensate for the increase of electrical power feeds, the the generator in the power network,. Falls the reaction time of the corresponding adjusting members of the internal combustion engine is too large with respect to the duration of the net error , may be held in your positions preferably the actuators of the internal combustion engine, so that at least the mechanical power from the internal combustion engine introduced at the level remains, has prevailed before the network failure may include excessive.

Additional details and advantages of the present invention are explained by means of the following description of the figures. It show:

1 a schematic block diagram of a generator electrically connected to an energy supply network Fig., and is driven by an internal combustion engine

Fig. net errorload angle a generator during a 2 the time course of the in the power network.

Figure 1 shows in a schematic block diagram of an electric generator 2 is electrically connected with a three-phase power network formed 1. The generator 2 is in the form of a synchronous generator and a stator 6 and a rotor rotatably disposed within the stator 6 points 7 on. The three phases of the power supply network are in a known manner with windings on the stator 1 6 of the generator 2 connected. When will be a public energy supply network it can act 1 power network, the predetermines the power supply frequency, or, for example, a local power network in isolated operation, in which the power supply frequency by the generator 2 is being created. The rotor 7 or. Rotor of the generator 2 via a coupling device 4 is substantially non-rotatably connected with a motor shaft 3 8 of an internal combustion engine. In e.g it may be a 4 of the internal combustion engine.

for a stationary gas engine may be designed to act, the as externally ignited, otto-motor operated reciprocating piston engine.

A mechanical power delivered by the internal combustion engine via the motor shaft 4 is introduced into the generator 8 P_{me ch} 2, 2 in the electric energy P_{e i} converted in the generator, and to subsequently the electrical power is delivered to the power network 1 P_{e i}.

In the shown example are at the generator 2, 3 and 4 on the coupling device to the internal combustion engine 9 disposed in the State of the Art known speed sensors, through which the rotational speed n of the motor shaft 7 via corresponding signal lines 8 or of the rotor 11 detected and can be reported to a control device 10. Furthermore, 8 and 7 to the rotor shaft on the motor shaft are here 'of the rotor 12 arranged 7 torque sensors, with which the mechanical torque on the motor shaft 3 and in front of the coupling device 8 ml to the rotor shaft 7' after the coupling device 10 via corresponding signal lines 11 to the control device 3 is detected and can be reported. The control device 11 can, for example, from the detected number of revolutions n to subsequently in a known manner the prevailing load angle 5 (see Fig. 2) identify 7 of the rotor. The generator reactances 5 load angle also based on measured electrical quantities calculation method can (e.g. voltage, current, power factor) and are identified.

Furthermore, 2 an equally be charged on the generator 13 disposed in the State of the Art known power measurement, which notifies the electric power fed into the power network 2 by the generator 1 via a further signal line 10 determined and P_{e i} 11 to the control device 15 and to a voltage regulator. The [...] 13 can here in known manner from the electrical current measurements power measurement P_{e i} determine power.

The rotor 7 of the generator has not shown on field windings, by an excitation device in the form of a synchronous machine with an electrical excitation current l_{E 14 are} acted upon. The excitation device is acted upon by a voltage regulator 14 15 with an excitation voltage to S3, whereby a corresponding excitation current for_{the field windings S3 the excitation voltage on the rotor 7 of the generator 2 adjusts} E l.

net error During a in the energy supply network 1, in particular during a net error , [...] has the consequence of a Baking effect, the control device 2 as a function of the value of at least one operating variable of the generator 11 determined before the network failure may include excessive S3s net error a correspondingly reduced and/or during the maximum voltage, as maximum excitation voltage S3 of the tension controller 15 is to be dispensed, and this maximum voltage to the voltage regulator 16 notifies S3s viaa control line 15.

By S3s maximum excitation voltage S3 limited by maximum voltage, which now can be output from the voltage regulator 15, a reduction can be achieved the resulting excitation of the generator 2, by which the field windings by the excitation device 14 provided on the rotor 7 of the generator field current l_{E for} 2 is accordingly reduced. In the excitation voltage is a percent S3 it can act denominator active tension of 100% with respect to an excitation voltage. The denominator active tension reduced with respect to the, percentage excitation voltage by the control device 11 and/or the voltage regulator S3 can here 15 according to the above formulae F1 or. F2 are identified.

engine expensive line Via a 4 17 can not shown in detail are driven adjusting members of the internal combustion engine, so as to change the mechanical power delivered by the internal combustion engine 4. In the actuator systems it may be a, for example, around a throttle valve, a turbocharger-bypass valve or a wastegate act. In the case of a 17 the mechanical power can thus engine expensive line Baking [...] be increased over the 4 of the internal combustion engine, so as to compensate for the increase of electrical power feeds, the the generator 1 into the power network 2,. Falls the reaction time of the corresponding adjusting members of the internal combustion engine is too large with respect to the duration of the 4 net error , 4 can be held in your positions preferably the actuators of the internal combustion engine, so that at least the mechanical power from the internal combustion engine remains at the level 4 introduced, has prevailed before the network failure may include excessive.

Figure 2 shows the time course of the 5 of the rotor 7 of the generator 2 in degrees load angle t over time in seconds during a net error , [...] has the consequence of a Baking effect. As in the Figure is to detect, during the 5 to enter load anglenet error vibrations of the. The dotted course shows the vibrations of the 5 conventional tax measures with respect to the network failure may include excessive load angle in use and the solid line shows the curve of the 5 upon application of the proposed method load angle. As is plain to see is reduced upon application of the proposed method the amplitude of the oscillation of the 5 load angle , whereby a total of 2 results in a higher stability of the generator during the net error. Concerning this Figure should be noted that a load angle 180 degrees the slip limit which represents 5 of + or-and therefore, can be seen, the generator is already very close to the slip limit which 2 without the proposed procedure brought up.

Due to the proposed method, the stability of electrical generators or can Total. Power plants comprising at least one of an engine-driven electric generator are increased in situations, where a by a network failure may include excessive [...] initiated Baking effect occurs.

During [...] conventional tax measures are counterproductive with Baking effect such error situations, since conventional tax measures to reduce, for example, do not respect the Baking effect and the excitation of the generator increase [...] instead of these.

Preferably, the proposed procedure can only during the occurrence of a baking effect at a network failure may include excessive [...][...] can be used again and after the decay of the Baking effect are conventional control measures are taken.