• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Method for operating a generator (2), in particular a synchronous generator, connected to a power supply network (1) during a network fault in the energy supply network (1), in particular during an electrical short circuit, wherein electrical excitation of the generator (2) depends on the value of at least one operating variable of the generator Generator (2) is at least temporarily reduced before the network error and / or during the network error.
    公开号:AT515058A2
    申请号:T833/2013
    申请日:2013-10-30
    公开日:2015-05-15
    发明作者:
    申请人:Ge Jenbacher Gmbh & Co Og；
    IPC主号:
    专利说明:

    The invention relates to a method for operating a generator connected to an energy supply network, in particular a synchronous generator, during a network fault in the energy supply network, in particular during an electrical short circuit. During a network fault in a power supply network, in particular during an electrical short circuit and the associated drop in the mains voltage in the energy supply network, undesired changes in operating quantities of the generator, such as the rotational speed or the load angle, can occur at an electrical generator, in particular a synchronous generator, connected to the energy supply network. As the load angle, it is known to designate the angle between the vector of the rotating magnetic field in the stator of the generator and the vector of the rotating magnetic field in the rotor of the generator.
    The drop in line voltage results in a significant reduction in the delivery of electrical power from the generator to the power grid. In conventional configurations in which a rotor of the generator is connected to a rotor driving motor shaft of an internal combustion engine (e.g., gas engine), this electrical power loss may result in a corresponding increase in speed of the internal combustion engine and thus of the rotor. This can cause the synchronization of the generator with the power grid to be lost or even damage to the generator.
    The recognition of a network fault in the energy supply network can be effected, for example, by the mains voltage of the energy supply network and / or the electric current fed by the generator into the energy supply network and / or the rotational speed of the generator or the internal combustion engine and / or the torque at the engine shaft of the internal combustion engine or at the rotor shaft the generator is monitored, wherein upon occurrence of a change of at least one of these monitored operating variables over a specifiable
    Threshold a network error is detected. In this case, it can also be provided that changes occurring are only detected as network errors if a plurality of these operating variables have corresponding changes over predefinable threshold values, ie if, for example, both the mains voltage, the electrical current and also the rotational speed have corresponding deviations. The generator may remain connected to the power grid during the power failure.
    The traditional approach to responding to such network faults is to take appropriate measures to counteract such an increase in speed and associated increase in the load angle of the generator. Thus, measures are usually taken which reduce the speed and the load angle. One such exemplary measure is the reduction of the acceleration torque by correspondingly throttling an internal combustion engine connected to the generator.
    However, it has been found that the conventional measures in the event of a network failure are disadvantageous in certain situations. Thus, there may be occurrences that the speed of the generator does not increase when a network fault occurs, but initially drops. This known to those skilled in the art under the technical term "back-swing" effect may even lead to pole slippage of the generator under certain circumstances. Pole slip, in turn, results in instability of the generator in which mechanical power from an internal combustion engine via the motor shaft into the rotor can no longer be converted by the generator into desired electrical power as desired.
    The object of the invention is to avoid the disadvantages described above and to provide over the prior art improved method for operating a generator during a network fault in the energy supply network.
    This object is achieved by the features of claim 1. Advantageous embodiments of the invention are indicated in the dependent claims.
    According to the invention, it is thus provided that an electrical excitation of the generator is at least temporarily reduced depending on the value of at least one operating variable of the generator before the network fault and / or during the network fault.
    The electrical excitation of a generator determines the transmittable electrical power as well as the magnitude of the output voltage of the generator and thus the level of reactive electric power fed from the generator into the power grid. The higher the
    Generator output voltage during a mains voltage dip, the higher the electrical power that is fed into the power grid. Thus, by reducing the electrical excitation of the generator, the amount of electrical power that is fed into the power grid during a mains voltage dip is reduced. This is particularly advantageous during a network fault in the power grid, which results in a back-swing effect. In configurations in which an internal combustion engine drives the generator, this can advantageously counteract the imbalance between the mechanical power of the internal combustion engine and the electrical power output by the generator in the event of a network fault, in particular during a back-swing.
    The proposed method is particularly advantageous for generators having an inertia constant of less than or equal to 1.5 Ws / VA, preferably less than or equal to 1 Ws / VA, since the back-swing effect has a stronger effect on low inertia constant generators.
    In a preferred embodiment, the generator is coupled to an internal combustion engine, preferably by means of a coupling device. The internal combustion engine may be, for example, an Otto engine gasoline engine, a diesel engine, or a gas turbine engine.
    Deviations from operating quantities of the generator during a network fault frequently occur because of an imbalance between the mechanical power introduced by the internal combustion engine into the generator and the electrical power supplied by the generator into the power supply network. In the case of a back-swing effect occurring as a result of the network fault, this imbalance can be caused by the fact that the electrical power is greater than the mechanical power. By lowering the electrical excitation of the generator and the consequent reduction in the delivered electrical power, this imbalance can be counteracted.
    Preferably, it can be provided that the excitation of the generator is reduced by reducing an excitation voltage for the generator or by reducing an excitation current supplied to the generator. For the excitation of the generator, an excitation device can be used, which is arranged on or outside the generator. The excitation device may be energized with the excitation voltage and subsequently provide an excitation current supplied in a known manner to corresponding windings of the generator to effect the excitation of the generator.
    According to a preferred embodiment of the invention, it may be provided that the operating quantity is detected as an electrical power delivered by the generator to the power grid before the mains failure, whereby the energization is reduced depending on the electrical power delivered before the grid fault. In this case, the excitation substantially in proportion to a difference of the output electrical power before the network error to a predetermined reference value - preferably the rated power - can be reduced.
    Preferably, it can be provided that a transient rotational speed of the generator and / or the coupling device and / or the internal combustion engine is detected as the operating variable during the network fault, wherein the excitation is reduced in substantially proportional to a difference between the transient rotational speed and the rotational speed before the network fault.
    For example, a percent excitation voltage with respect to a predeterminable rated excitation voltage of 100% may be determined according to Formula F1: S3 = 100% - (S1 ref "S1) * Pspeed > where S3 denotes a percent excitation voltage with respect to a rated excitation voltage of 100%, S1ref denotes a percentage rotational speed of the generator or the coupling device or the internal combustion engine prior to the network error with respect to a nominal rotational speed of 100%, S1 the percentage transient rotational speed of the generator or the coupling device or the internal combustion engine during the network fault in Refers to a rated speed of 100%, and Pspeed denotes a positive proportionality factor by which the intensity of the excitation voltage reduction can be influenced.
    According to a further embodiment, it may be provided that a speed of change of the rotational speed of the generator and / or the clutch device and / or the internal combustion engine is detected as an operating variable during the network error, wherein the excitation is reduced depending on the amount of speed change.
    It may also be provided that a torque is detected at an engine shaft of the internal combustion engine and / or at a rotor shaft of the generator as an operating variable during the network fault, wherein the excitation is reduced as a function of the torque.
    In a further preferred embodiment, it may be provided that a load angle of the generator is detected as an operating variable during the network fault, wherein the excitation is reduced substantially in indirect proportion to the magnitude of the detected load angle.
    For example, a reduced excitation voltage can be determined according to the following formula F2 at a negative load angle: S3 = 100% + (S2 / 180) * 100% * P | oad_angle, where S3 designates the excitation voltage correspondingly reduced in relation to the rated excitation voltage of 100%, S2 the measured one denotes negative load angle in degrees and P | 0ad_angie denotes a positive proportionality factor by which the intensity of the excitation voltage reduction can be influenced.
    It can preferably be provided that the excitation is reduced to a maximum of a predeterminable minimum excitation. Thus, a minimum excitation of the generator can be ensured. Thus, e.g. a minimum value for the size S3 of the above formulas F1 and F2 are given, under which the percentage excitation voltage should not be lowered. By this safety measure, critical operating conditions of the internal combustion engine can be avoided.
    According to a particularly preferred embodiment, it can be provided that oscillations of an operating variable of the generator are detected during the network fault, wherein the excitation of the generator is reduced if the oscillations exceed a predefinable intensity. It can be provided that vibrations of a load angle of the generator are detected, wherein the excitation of the generator is reduced if the vibrations have an amplitude of more than 2 degrees, preferably more than 10 degrees.
    In the case of a network failure that results in a back-swing effect, it is advantageous to increase the mechanical performance of the internal combustion engine to compensate for the increase in electrical power that the generator feeds into the power grid. If the response time of the corresponding internal combustion engine governors is too great with respect to the duration of the network fault, it is preferable that the actuators of the engine be
    Internal combustion engine are held in their positions, so that at least the mechanical power introduced by the internal combustion engine remains at the level that prevailed before the network failure.
    Further details and advantages of the present invention will be explained with reference to the following description of the figures. Showing:
    Fig. 1 is a schematic block diagram of a with a
    Power supply network electrically connected generator, which is driven by an internal combustion engine andFig. FIG. 2 shows the time profile of the load angle of a generator during a network fault in the power supply network. FIG.
    FIG. 1 shows, in a schematic block diagram, an electrical generator 2 which is electrically connected to a three-phase power supply network 1. The generator 2 is designed as a synchronous generator and has a stator 6 and a rotor 7 rotatably disposed within the stator 6. The three phases of the power supply network 1 are connected in a known manner to windings on the stator 6 of the generator 2. The power grid 1 can be a public power grid that specifies the grid frequency or, for example, a stand-alone local power grid in which the grid frequency is set by the generator 2. The rotor 7 or rotor of the generator 2 is connected via a coupling device 3 with a motor shaft 8 of an internal combustion engine 4 substantially rotationally fixed. The internal combustion engine 4 may, for example, be a stationary gas engine, which may be designed as a spark-ignited, Otto engine-operated reciprocating engine.
    A mechanical power Pmech output from the engine 4 is input to the generator 2 via the motor shaft 8, converted into electric power Pei in the generator 2, and subsequently the electric power Pei is output to the power grid 1.
    In the example shown, speed sensors 9 known in the prior art are arranged on the generator 2, on the coupling device 3 and on the internal combustion engine 4, by means of which the rotational speed n of the motor shaft 8 or of the rotor 7 can be detected and reported to a control device 11 via corresponding signal lines 10. Furthermore, here on the motor shaft 8 and on the rotor shaft 7 'of the rotor 7 torque sensors 12 are arranged, with which detects the mechanical torque Ml on the motor shaft 8 in front of the coupling device 3 and on the rotor shaft 7' after the coupling device 3 and via corresponding signal lines 10 to the control device 11th can be reported. The control device 11 can subsequently ascertain the prevailing load angle 5 of the rotor 7 in a known manner, for example from the detected rotational speed n (see FIG. 2). The load angle 5 can also be calculated based on generator reactances and measured electrical quantities (e.g., voltage, current, power factor).
    Furthermore, a power measurement 13, also known in the state of the art, which determines the electrical power Pei fed into the energy supply network 1 from the generator 2 and reports another signal line 10 to the control device 11 and to a voltage regulator 15, is arranged on the generator 2. The power measurement 13 can determine the electric power Pei in a known manner from voltage and current measurements.
    The rotor 7 of the generator has here not shown excitation windings, which are acted upon by an excitation device 14 in the form of a synchronous machine with an electrical excitation current IE. The excitation device 14 is acted on by a voltage regulator 15 with an excitation voltage S3, whereby an excitation current IE corresponding to the excitation voltage S3 sets for the exciting windings on the rotor 7 of the generator 2. During a network fault in the power grid 1, in particular during a grid fault resulting in a back-swing effect, the controller 11 determines a correspondingly reduced maximum voltage S3s, which is the maximum, depending on the value of at least one operating quantity of the generator 2 before the grid fault and / or during the grid fault Exciter voltage S3 from the voltage regulator 15 is to be output, and reports this maximum voltage S3s via a control line 16 to the voltage regulator 15th
    By the maximum excitation voltage S3 limited by the maximum voltage S3s, which can only be output from the voltage regulator 15, a reduction of the resulting excitation of the generator 2 can be achieved by correspondingly reducing the excitation current Ie for the excitation windings on the rotor 7 of the generator 2 provided by the excitation device 14. The excitation voltage S3 may be a percent excitation voltage with respect to a nominal excitation voltage of 100%. In this case, the percentage excitation voltage S3 reduced with respect to the rated excitation voltage can be determined by the control device 11 and / or the voltage regulator 15 according to the above formulas F1 or F2. Via a motor control line 17, actuators, not shown, of the engine 4 can be controlled in order to change the mechanical power output by the engine 4. The actuators may, for example. to a throttle, a turbocharger bypass valve or a Wastegatehandeln. In the case of a back-swing, the mechanical control power of the internal combustion engine 4 can thus be increased via the engine control line 17 in order to compensate for the increase in the electrical power which the generator 2 feeds into the energy supply network 1. If the reaction time of the respective actuators of the engine 4 is too large with respect to the period of the power failure, the actuators of the engine 4 may preferably be held at their positions so that at least the mechanical power input from the engine 4 remains at the level prevailing before the power failure Has.
    Figure 2 shows the time profile of the load angle 5 of the rotor 7 of the generator 2in degrees over the time t in seconds during a network fault, which has a back-swing effect result. As can be seen in the figure, vibrations of the load angle 5 occur during the mesh failure. The broken line shows the oscillations of the load angle 5 using conventional control measures with respect to the network error and the solid line shows the course of the
    Load angle 5 using the proposed method. As can be clearly seen, using the proposed method, the amplitude of the oscillation of the load angle 5 is reduced, resulting in an overall higher stability of the generator 2 during the network failure. With reference to this figure, it should be noted that a load angle 5 of + or - 180 degrees represents the slip limit and therefore, as can be seen, the generator 2 is already brought very close to the slip limit without the proposed method.
    Overall, the proposed method can increase the stability of electrical generators including at least one electric generator driven by an internal combustion engine in situations where a back-swing effect is caused by a network failure. During such back-swing error situations, conventional control measures are counterproductive. because conventional control measures do not pay attention to the back-swing effect and, for example, increase the excitation of the generator instead of reducing it.
    Preferably, the proposed method may be applied to a network failure only during the occurrence of a back-swing effect, and after the back-swing effect has subsided, conventional control measures may again be taken.
    权利要求:
    Claims (13)
    [1]
    A method for operating a generator (2), in particular a synchronous generator, connected to a power supply network (1) during a network fault in the power supply network (1), in particular during an electrical short circuit, characterized in that electrical energization of the generator (2) depends on the value at least one operating variable of the generator (2) is at least temporarily reduced before the network fault and / or during the network fault.
    [2]
    2. The method according to claim 1, characterized in that the generator (2) has an inertial constant of less than or equal to 1.5 Ws / VA, preferably equal to 1 Ws / VA.
    [3]
    Method according to claim 1 or 2, characterized in that the generator (2) is coupled to an internal combustion engine (4), preferably by means of a coupling device (3).
    [4]
    A method according to any one of claims 1 to 3, characterized in that the excitation of the generator (2) is reduced by reducing an excitation voltage (S3) for the generator (2) or by reducing an excitation current (Ie) supplied to the generator (2) ,
    [5]
    5. The method according to any one of claims 1 to 4, characterized in that as an operating variable from the generator (2) to the power grid (1) output electric power (Pei) is detected before the network fault, wherein the excitation depending on the electrical power output (Pei ) before network error is reduced.
    [6]
    A method according to claim 5, characterized in that the excitation is reduced substantially in proportion to a difference of the delivered electrical power (Pei) before the network failure to a predeterminable reference value, preferably the rated power.
    [7]
    A method according to any one of claims 1 to 6, characterized in that a transient speed of the generator (2) and / or the coupling device (3) and / or the engine (4) is detected as an operating variable during the network error, the excitation being substantially proportional to a difference of the transient speed to the speed before the network error is reduced.
    [8]
    A method according to any one of claims 1 to 7, characterized in that a speed change of the speed of the generator (2) and / or the coupling device (3) and / or the internal combustion engine (4) is detected as an operating variable during the network error, the excitation being dependent on the amount of speed change is reduced.
    [9]
    9. The method according to any one of claims 1 to 8, characterized in that an operating variable during the power failure detected a torque (ML) on an engine shaft (8) of the internal combustion engine (4) and / or on a rotor shaft (7 ') of the generator (2) becomes, with the excitation is reduced depending on the torque (ML).
    [10]
    A method according to any one of claims 1 to 9, characterized in that a load angle (5) of the generator (2) is detected as an operating variable during the power failure, the energization being reduced substantially inversely proportional to the magnitude of the detected load angle (5).
    [11]
    11. The method according to any one of claims 1 to 10, characterized in that the excitation is maximally reduced to a predetermined minimum excitation.
    [12]
    12. The method according to any one of claims 1 to 11, characterized in that vibrations of an operating quantity of the generator (2) are detected during the network fault, wherein the excitation of the generator (2) is reduced if the vibrations exceed a predetermined intensity.
    [13]
    A method according to claim 12, characterized in that vibrations of a load angle (5) of the generator (2) are detected, whereby the excitation of the generator (2) is reduced if the oscillations have an amplitude of more than 2 degrees, preferably more than 10 degrees, exhibit.
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA833/2013A|AT515058B1|2013-10-30|2013-10-30|Method for operating a generator connected to a power supply network|ATA833/2013A| AT515058B1|2013-10-30|2013-10-30|Method for operating a generator connected to a power supply network|
    EP14003561.9A| EP2869459B1|2013-10-30|2014-10-17|Method for operating a generator connected to an energy supply network|
    JP2014213348A| JP6467189B2|2013-10-30|2014-10-20|Operation method of a generator connected to a power supply network|
    US14/523,048| US9733313B2|2013-10-30|2014-10-24|Method of operating a generator connected to a power supply network|
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