Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
  • H02P5/74—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more ac dynamo-electric motors
  • H02P5/747—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more ac dynamo-electric motors mechanically coupled by gearing
  • H02P5/753—Differential gearing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D15/00—Transmission of mechanical power
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H3/00—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion
  • F16H3/44—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion
  • F16H3/72—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion with a secondary drive, e.g. regulating motor, in order to vary speed continuously
  • F16H3/724—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion with a secondary drive, e.g. regulating motor, in order to vary speed continuously using external powered electric machines
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/70—Wind energy
  • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

• the invention relates to a method for connecting an electrical asynchronous machine of a drive train to an electrical network, wherein the drive train has a drive shaft of a work machine, the drive machine, a differential drive and a
• the invention also relates to a drive train with a drive shaft of a work machine, with a drive machine and with a differential gear with three drives and outputs, an output being connected to the drive shaft, a first drive to the drive machine and a second drive to a differential drive , with a clutch via which a drive is connected simultaneously to the other drive or to the output, with at least one device for detecting a speed of at least one input and / or output, and with a controller for controlling the differential drive and optionally opening the Coupling.
• WO 2016/172742 A1 describes a method for starting a drive train with a differential system with a drive shaft of a work machine, with a drive machine and with a differential gear with three drives and outputs, one output with the drive shaft and a first drive with the prime mover and a second drive can be connected to a differential drive.
• the differential system works in a first phase in an operating mode I, in which a Differential drive starts an electric drive machine and a work machine or drives it in the lower partial load range until the drive machine has reached its cut-in speed.
• the connection speed is the speed of a drive machine at which it is connected to the network and which can vary depending on the type.
• the simultaneous acceleration of the driven machine and the drive machine is realized by an additional connection.
• This additional connection is a gear via which, for example, the differential drive - in addition to its connection to the differential gear - can be connected to the drive machine by means of a clutch.
• the prime mover is connected to the grid.
• the system in a third phase, in operating mode II, the system is operated in differential mode up to a maximum torque or at maximum drive speed.
• a synchronous three-phase machine is used as the drive machine, it is brought to its connection speed and then, in accordance with recognized rules of technology, synchronized with the network and connected to the network without bumps.
• the differential drive helps to synchronize the prime mover with the network by regulating the speed and preferably also the phase angle of the prime mover and synchronizing it with the network.
• a synchronization device preferably measures the phase angle of the network and the drive machine and connects them as soon as the phase angles are essentially synchronous.
• the drive machine If the drive machine is designed as an asynchronous three-phase machine, it is brought to its connection speed, then a mains switch is closed and the drive machine is connected to the mains. As soon as it is connected to the mains, it briefly draws a high magnetizing current. In addition, the magnetization of the prime mover causes a brief drop in the speed of the prime mover, which subsequently increases again (due to the inertia of the prime mover's rotor) and levels off at its power or slip-dependent operating speed. Depending on the design and type of the drive machine, the magnetizing current can reach zero up to around 10 times the nominal current of the drive machine when starting from speed.
• the magnitude and duration of the magnetizing current also depend on whether a load (machine) is pulled up or at what speed the drive machine is connected to the mains. If, as in the method proposed in WO 2016/172742 A1, no load is pulled up by the drive machine, the level of the inrush current does not change significantly within the speed limits of, for example, 90% to 110% of the synchronous speed. It should therefore be understood that according to the prior art, when synchronizing or connecting asynchronous three-phase machines to the grid, no special precautions are taken with regard to the connection speed.
• a control unit of the differential system sends, for example, a message to a higher-level process control system as soon as the drive machine has reached its connection speed. Subsequently, the coupling in the additional connection is preferably not opened until the control unit has received a feedback from the process control system that the drive machine is connected to the network. In the meantime, however, the prime mover is already connected to the mains - this delay can last several 1/10 seconds, possibly several seconds. The shortest possible time span should preferably be implemented here.
• the differential drive works preferably with speed control for the purpose of connecting the drive machine. As soon as the prime mover switches on with the clutch closed, the differential system becomes tense.
• the servo speed is initially pulled down by the drive machine (due to the magnetization of the drive machine) and the driven machine (speed becomes lower) and the operating speed of the drive machine, which is dependent on the load and is lower than theirs due to slip, is subsequently set Is synchronous speed / nominal speed.
• connection speed is clearly oversynchronous, the operating speed of the drive machine will tend to decrease further. If the connection speed is undersynchronous, the operating speed of the drive machine will tend to increase.
• the synchronous connection speed is understood as the speed of the drive machine, which results from the number of pole pairs of the drive machine and a current network frequency.
• the synchronous cut-in speed at a nominal mains frequency of 50 Hz is 1,5001 / min, at a mains frequency of 49 Hz 1,4851 / min and at a nominal mains frequency of 60Hz 1,800 rpm.
• a subsynchronous cut-in speed is lower and an oversynchronous cut-in speed is higher than the synchronous cut-in speed.
• the deviation of the network frequency in networks with a synchronous connection may be + 1% of 50Hz.
• the grid frequency may vary between + 4% and -6% for a maximum of 0.5% of the year. In e.g. Asian networks, these deviations can be greater.
• the object of the invention is to improve the connection of the working machine to the network, i.e. to reduce the load on the differential system.
• the network frequency is detected and the drive machine is only connected to the network when the frequency resulting from the speed of the drive machine deviates by less than + 5% from the network frequency, whereupon the connection between one drive and the other drive or the Output is separated.
• the drive train has a device for detecting the network frequency and a comparator in the controller that checks whether the frequency resulting from the speed of the drive machine deviates from the network frequency by less than + 5%.
• the differential system becomes tense as soon as the prime mover is switched on, and large transient drive train loads can be avoided. In addition, it makes a difference which type of coupling is used in the additional connection.
• overrunning clutches the further the connection is within certain system-dependent limits in the subsynchronous range, the lower the load on the differential drive and clutch and the better the speed range of the differential drive can be used, since it starts at a lower speed when the drive machine is connected .
• the drive machine overtakes the part of the overrunning clutch on the differential drive side as soon as it is connected to the mains and thus automatically disconnects the additional connection between the drive machine and differential drive.
• the differential drive is preferably operated with so-called speed control - i.e. the process control system and / or the control device specify a speed, and the regulation and control unit of the differential drive tries to set this speed as precisely as possible.
• the speeds of the differential drive and the driven machine are also pulled down at the first moment.
• the control unit receives the feedback "Mains drive machine”
• the speed specified for the differential drive by its controller is reduced and the torque direction changes by means of the downstream torque controller (e.g. through field vector control of the converter) from a motor to a generator quadrant.
• monitoring and / or limitation of the design-specific maximum permitted current is preferably (but by no means mandatory) active.
• the speed specified for the differential drive by a controller is adapted accordingly when the speed of the drive machine is reduced as a result of its connection to the network, in order to ensure the lowest possible load on the differential drive. It is preferably recorded when the drive machine was actually connected to the network, and then the speed specified for the differential drive by the controller is adapted accordingly when the speed of the drive machine is reduced as a result of its connection to the network. Finally, the direction of the torque of the differential drive is changed and the clutch is opened.
• This embodiment of the invention can also be used in isolation from the present invention, i.e. the adaptation of the frequency of the drive machine to the mains frequency and the subsequent separation of the connection between one drive and the other drive or output and thus represents an independent invention and possibility to protect the drive train from inadmissibly high tension or transient vibrations.
• the torque (without further active influence on the resulting speed) can be controlled from a motor to a generator quadrant by means of torque control (i.e. the process control system and / or the control device specify a torque) and the differential system then works in Operating mode II.
• torque control i.e. the process control system and / or the control device specify a torque
• monitoring and / or limitation of the design-specific maximum permitted speed is preferably (but by no means mandatory) active. This, too, represents an independent invention and possibility of protecting the drive train from inadmissibly high tension or transient vibrations.
• a change from the control mode of a speed control to the control mode of a torque control or a change in parameterized speed and torque specifications / limits is typically implemented (ie with commercially available industrial drives) in around 20 to 40 milliseconds [ms].
• This time span results from the cycle times of the control unit of the differential system or the regulation of the Converter. This means that very fast transient changes in status can only be compensated for to a limited extent (ie depending on the cycle times that can be achieved) by changing the control mode. No limits are set here with regard to even shorter cycle times and a reasonable compromise must be achieved between the effort required for measurement and control and the load reduction that can be achieved.
• this clutch opens automatically as a result of the change in torque direction.
• a clutch is provided in the additional connection instead of an overrunning clutch, this clutch does not open automatically.
• a first approach to regulating the differential system is to continue the speed regulation which is active at this point in time. Due to a drop in the speed of the prime mover while it is being connected to the network, the differential drive changes the direction of the torque (e.g. through field vector control of the frequency converter) from a motor to a generator quadrant by means of its torque controller (downstream from the speed controller) and a generator torque is generated as a result a. The motor torque is first regulated towards zero before it changes to the generator quadrant.
• the speed of the drive machine and / or work machine and / or differential drive can alternatively be monitored and the speed of the differential drive can be "tracked" according to the connection-related fluctuation in the speed of the drive machine preferably "hold” - ie compensate for a drop in speed on the differential drive with a (+) delay typical of a clutch or drive machine.
• the torque (without further influencing the resulting speed) can be changed from a motor to a torque control by means of a torque control regenerative quadrants are regulated, the system then subsequently working in operating mode II.
• the direction of the torque of the differential drive is changed when the speed of the drive machine is reduced as a result of its connection to the network.
• it is preferably recorded when the drive machine was actually connected to the network, and then the direction of the torque of the differential drive is changed.
• the clutch is then opened.
• This embodiment of the invention can also be used in isolation from the present invention, i.e. the adaptation of the frequency of the drive machine to the mains frequency and the subsequent separation of the connection between one drive and the other drive or output, and thus represents an independent invention and possibility is to protect the drive train from inadmissibly high tension or transient vibrations.
• the torque of the differential drive is preferably kept essentially constant in the first moment of connection and, in yet another embodiment variant, is regulated to zero from the point in time of the receipt of the feedback in the control unit that the drive machine is connected to the network. This serves to keep the load in the additional connection and here in particular for the coupling as low as possible before it is opened.
• the clutch is also preferably designed to limit the torque (for example as a multi-plate clutch with friction linings).
• the permissible deviation of the connection speed or the resulting frequency of the drive machine is a maximum of + 5.0%, in a preferred embodiment it is a maximum of + 3.0%, in a particularly preferred embodiment it is a maximum of + 5.0% . + 2.0% and especially at max. + 1.0% of the current grid frequency. No limits are set here with regard to even higher accuracy and a reasonable compromise must be achieved between the effort required for measurement and control and the load reduction that can be achieved.
• the network frequency is recorded in an embodiment variant according to the invention.
• the following methods can preferably be used here.
• An exact detection of the network frequency can preferably take place on the one hand by means of a technically suitable measuring device (for example any type of network frequency measuring device) which forwards the currently measured network frequency to the control unit.
• a technically suitable measuring device for example any type of network frequency measuring device
• the network frequency detected by the converter of the differential drive is passed on to the control unit.
• the control unit can preferably carry out a very precise, situation-adapted calculation of the required connection speed of the drive machine. This means that the desired bandwidth of the cut-in speed of the drive machine can be selected to be very small.
• a desired connection speed of the drive machine can be determined in this case, for example, by using typical values of the mains frequency fluctuation range and on this basis a desired connection speed of the drive machine is determined.
• Typical values of the network frequency fluctuation range can be, for example, statistical values from historical databases, or they can be determined on the basis of measurement campaigns. From this statistical data, for example, a bandwidth is then determined within which, for example, 90% of the network frequencies occurring in the existing network are preferably located. This bandwidth is used to further determine the limit values for the connection speed of the drive machine.
• Examples of a typical network frequency fluctuation range (bandwidth) of + 1.0% are:
• the speed tolerance is determined, among other things, by a high resolution or accuracy of the measuring chain, starting with the frequency measurement or the speed detection through the processing of the measuring signal by means of the control unit up to the speed control of the differential drive.
• a maximum deviation (speed tolerance) between the currently measured mains frequency or speed and the A cut-in speed of + 0.1% that sets itself on the drive motor is desirable. No limits are set for an accuracy deviating from this, and a reasonable compromise must be achieved between the effort required in terms of measurement or control technology and the load reduction that can be achieved.
• the speed tolerance described has to be deducted from the limit values of the cut-in speed of the drive machine.
• the limit values in example (a) shown above decrease from + 2.0% to + 1.9% or in example (b) from -1.5 to -2.0 % to -1.6 to -1.9% of the synchronous speed of the drive machine.
• Fig. 1 shows the principle of a differential system with a
• FIG. 2 shows a diagram with a typical control system of a regulation and control unit of a variable-speed drive
• FIG. 3 shows an embodiment of a differential system according to the invention and FIG. 4 shows a sequence for connecting a drive machine of a differential system.
• Fig. 1 shows the principle of a differential system with an additional connection for a drive of a pump according to the prior art.
• the drive train shown consists of a driven machine 1 (in the present example the pump), one Drive shaft 2, a drive machine 4 and a differential drive 5, which are connected to the output or drives of a differential gear 3.
• the differential drive 5 is connected to a network 12 by means of a converter 6 (consisting of preferably a motor-side and line-side inverter or rectifier - shown here in simplified form as a unit) and a transformer 11.
• the drive machine 4 can be connected to the network 12 by means of a switch 23.
• the drive machine 4 is preferably a medium-voltage three-phase machine, which is connected to the network 12, which in the example shown is a medium-voltage network due to a medium-voltage three-phase machine.
• the selected voltage level depends on the application and, above all, on the performance level of the drive machine 4 and can have any desired voltage level without affecting the basic function of the system according to the invention.
• a design-specific operating speed range results in accordance with the number of pole pairs of the drive machine 4.
• the operating speed range is that speed range in which the drive machine 4 can deliver a defined or desired or required torque and in which the electric drive machine 4 is connected to the network or can be synchronized with the network 12.
• the differential drive 5 is preferably a three-phase machine and in particular an asynchronous machine or a permanent magnet synchronous machine.
• a hydrostatic adjusting gear can also be used.
• the differential drive 5 is replaced by a hydrostatic pump / motor combination, which is connected to a pressure line and is preferably adjustable in terms of the flow volume. As in the case of a variable-speed electrical differential drive 5, the speeds can thus be regulated.
• the core of the differential system in this embodiment is thus a simple planetary gear stage with three drives and outputs, one output with the drive shaft 2 of the machine 1 and a first Drive is connected to the drive machine 4 and a second drive to the differential drive 5.
• An essential advantage of this concept is that the drive machine 4 can be connected directly to the network 12, that is to say without complex power electronics.
• the compensation between the variable rotor speed and the fixed speed of the network-connected drive machine 4 is implemented by the variable-speed differential drive 5.
• the power consumption or output of the differential drive 5 is essentially proportional to the product of the percentage deviation of the speed of the work machine 1 from its basic speed, multiplied by the power of the work machine 1.
• the basic speed is the speed that is set at the work machine 1, when the differential drive 5 has the speed equal to zero. Accordingly, a large working speed range of the work machine 1 requires a correspondingly large dimensioning of the differential drive 5. If, for example, the differential drive 5 has a nominal output of around 20% of the total system output (nominal output of the work machine 1), this means that, using a so-called field weakening range of the differential drive 5, on the working machine 1, minimum working speeds of about 50% of the nominal working speed can be realized.
• the speeds at the input and output drives of the differential system are determined by the gear ratios of differential gear 3 and the matching gear (s) downstream thereof. On this basis and on the basis of the required working control range of the work machine 1, the required control speed range of the differential drive 5 and the converter 6 is then obtained.
• the control speed range is mainly determined by the parameters specified by the manufacturer, such as voltage, current and speed limits, field weakening range, overload capacity, etc.
• the drive shaft 2 is connected to the sun gear 13 and the drive machine 4 is connected to the ring gear 14 by means of a connecting shaft 19.
• the planet carrier 16 (with two or more planet gears 15) can be connected to the differential drive 5 ("Variant 5" in the following table) for example 2.5 to 7.5, in particular up to 6.5. With a stepped planetary set, for example, significantly higher gear ratios can also be achieved.
• a stepped planetary set is characterized in that the planetary gears 15 each have two gears which are connected to one another in a rotationally fixed manner and having different pitch circle diameters, one gear wheel cooperating with the sun gear and the second gear wheel cooperating with the ring gear.
• the planet carrier 16 can, for example, be made in one piece or in several pieces with components connected to one another in a rotationally test. Since the torque at the planetary carrier 16 is high, it is advantageous to implement a transmission stage 17, 18 between the planetary carrier 16 and the differential drive 5, for example.
• a matching gear e.g. in the form of a straight, helical or herringbone toothed spur gear stage, is available for this, whereby one gear 17 is connected to the planet carrier 16 and the other gear 18 is connected to the differential drive 5.
• a matching gear e.g. in the form of a straight, helical or herringbone toothed spur gear stage
• Adaptation gear stage 17, 18, for example, a multi-stage straight, helical or herringbone gear, a planetary or bevel gear, a chain drive, a V-belt drive, a gearbox, etc., or a combination of these types of gear can be used.
• a pump is shown symbolically as a working machine 1 in FIGS. 1 and 3 by way of example.
• the principles described above and below can also be used for drives for other work machines, such as compressors, fans, conveyor belts, mills, crushers and the like.
• Fig. 1 shows a differential drive 5 with a converter 6.
• several differential drives 5 can drive the planetary carrier 16, whereby the torque to be transmitted of the adaptation gear stage 17,
• Differential drives 5 can be distributed uniformly or asymmetrically around the circumference of gear 17.
• the differential drives 5 are preferably - but not necessarily - controlled by a common converter 6, in which case one differential drive 5 is preferably the so-called “master” and the other differential drive (s) 5 as so-called “slave (s)” s) "act.
• the differential drives 5 can also be controlled by several motor-side inverters 6 individually or in groups, these motor-side inverters 6 connected to the differential drives 5 preferably having a common network-side connected to the network 12 via a transformer 11 Have rectifiers to which they are connected via a DC voltage intermediate circuit.
• An additional connection 20 is connected to the connecting shaft 19 and subsequently to the drive machine 4 or the first drive of the differential system.
• This additional connection 20 can be connected to the differential drive 5 by means of a coupling 22.
• the clutch 22 can basically anywhere in the power flow between the differential drive 5 and the first drive of the
• the clutch 22 is preferably designed as a clutch, e.g. in the form of a claw clutch, tooth clutch or multi-disc clutch, or as a freewheel clutch.
• An overrunning clutch is a clutch that only acts in one direction of rotation.
• the overrunning clutch can also be designed in the form of a self-synchronizing clutch. This is an overrunning clutch in which, when fully activated, the torque is transmitted via a toothed clutch.
• the drive machine 4 can also be connected to a transmission intermediate stage of the additional connection 20, the connection of the additional connection 20 to the first drive remaining in place.
• differential drive 5 is preferably connected to the drive machine 4 via an additional connection 20.
• at least one second differential drive 5 drives the additional connection 20 via the planetary carrier 16 and the adaptation gear stage 17, 18.
• several differential drives can also be connected in parallel to, for example, the drive machine 4 by means of a separate additional connection 20.
• the drive machine 4 can also be connected to the drive shaft 2 by means of an additional connection.
• the differential drive 5 is connected to the additional connection 20 by closing the clutch 22. By subsequently starting up the differential drive 5, the working machine 1 and the drive machine 4 are also accelerated.
• the clutch 22 is designed in the form of an overrunning clutch, it automatically transmits the rotary movement of the differential drive 5 to the additional connection 20 or the drive machine 4.
• the differential system works in the so-called start-up mode (operating mode I).
• the drive machine 4 is preferably brought to operating speed and then the switch 23 is closed and the drive machine 4 is connected to the network 12. This draws a magnetizing current for a short time when it is connected to the network 12. Although this is higher than the rated current of the drive machine 4, it is only available for a few network periods and is below the current strength that the drive machine 4 would draw if it were connected to the network under load. If necessary, this magnetizing current can be additionally reduced by using recognized technical methods.
• the clutch 22 is opened and the differential system works in what is known as the differential mode (operating mode II). If the clutch 22 is designed as an overrunning clutch, the connection is released automatically as soon as the speed of the driving part (differential drive 5) is lower than the speed of the part to be driven (additional connection 20).
• both the drive machine 4 and the work machine 1 coast down in an uncontrolled manner.
• a brake (not shown) that acts on the second drive of the differential system or on the
• Differential drive 5 works, use.
• An alternative solution is to use a (not shown) implemented between the differential drive 5 and the second drive of the differential system. To open the clutch and thereby separate the differential drive (s) 5 from the rest of the differential system.
• the clutch 22 is designed as an overrunning clutch, its connection is automatically activated as soon as the speed of the driving part (additional connection 20) would be less than the speed of the part to be driven (differential drive 5), which inherently prevents overspeed of the differential drive 5.
• the clutch 22 is designed as a clutch, it is preferably activated in the event of a malfunction when the speed difference between the output shaft of the additional connection 20 and the differential drive 5 is a minimum (ideally at a speed difference of approximately zero).
• FIG. 2 shows a diagram with an exemplary regulation scheme of a regulation and control unit of a variable-speed drive of a differential system.
• a control unit 24 regulates and controls the functions of the differential system. This communicates with a higher-level process control system 25. Among other things, process-relevant status reports and target value specifications are exchanged via this communication interface.
• the control unit 24 communicates with the converter 6 via a further interface. This further communication interface is also used, among other things, to exchange process-relevant status reports and target value specifications.
• the control unit 24 preferably decides on the control mode (i.e. between speed control and torque control) or a change in parameterized torque specifications / limits.
• the control unit 24 can also be part of the converter 6. That is, the control and regulation unit of the converter 6 also takes over the functions of the control unit 24 and the communication with the process control system 25.
• Differential drive 5 maximum permitted current strength (s) and thus the maximum permitted torque monitored or limited.
• the converter 6 preferably detects the speed n of the differential drive 5 (for example by means of a
• Speed measuring device compares this in the speed controller with the speed specification and increases or reduces the torque by means of a downstream torque controller in order to achieve the specified speed.
• monitoring and / or limitation of the type-specific maximum permissible current intensity is preferably active here (but by no means mandatory). This means that if the maximum permissible current strength is reached (taking into account a possibly time-limited permissible overload), the specified speed cannot be achieved and a speed that can be achieved on the basis of the maximum permissible current strength is set.
• the control and regulation device of the converter 6 can regulate the torque of the converter 6 in four so-called quadrants, whereby a generator or a motor torque can be set depending on the direction of rotation.
• the differential drive 5 can also be operated over-synchronously in the so-called field weakening range by means of its converter 6. Typically, this oversynchronous range is limited due to mechanical limits of the differential drive 5, the overspeed limits usually decreasing with increasing system size.
• the differential system is constructed in the same way as described in FIG. 1.
• the drive train also consists of a work machine 1, a drive shaft 2, a differential gear 3, an additional connection 20, a motor shaft 19, a drive machine 4, a differential drive 5 and a converter 6.
• the differential drive 5 is by means of a particularly soft, ie torsional vibration damping , Coupling 31 is connected to the additional connection 20.
• Coupling 31 is connected to the additional connection 20.
• the system according to the invention also functions with one or more
• control device 24 communicates with the converter 6 and the process control system 25.
• the process control system 25 controls, among other things, the switch 23 in order to connect the drive machine 4 to the network 12 or to disconnect it from the network 12. Alternatively, this can also be controlled by the control device 24 or the converter 6. According to the invention, in the embodiment of FIG. 3, optionally different
• Measuring devices 26, 27 implemented for the detection of the network frequency of the network 12 (network frequency measuring device). These measuring devices can, for example, be integrated in the converter 6 (measuring device 26), but they can also be positioned at any other point where the current network frequency can be recorded, e.g. in the medium-voltage network 12 (measuring device 27). By precisely recording the current network frequency, it is possible to adapt the connection speed of the drive machine 4 as precisely as possible to the current network frequency and thus avoid unwanted high loads, e.g. drive train vibrations, when the drive machine 4 is connected.
• network frequency measuring device can, for example, be integrated in the converter 6 (measuring device 26), but they can also be positioned at any other point where the current network frequency can be recorded, e.g. in the medium-voltage network 12 (measuring device 27).
• one or more speed measuring devices 28, 29 and 30 are possible on the drives and drives of the differential system.
• only one speed measuring device - preferably the speed measuring device 30 - is required, since the other speeds can be derived therefrom.
• the speed measuring device 30 can be replaced by a calculation of the speed in the motor-side inverter of the converter 6 - for example on the basis of what is known as an encoderless speed control. 4 shows a sequence for starting up and subsequently connecting the drive machine 4 of a differential system to the network 12 using the example of a steam power plant.
• a steam power plant is typically controlled by a process control system 25.
• This process control system 25 also controls the connection of a drive machine 4 of a boiler feed pump as the work machine 1 and connects the drive machine 4 to the network 12 by means of the switch 23.
• the process control system 25 preferably communicates with the control unit 24.
• connection process can run according to the following chronology, for example:
• the drive machine 4 is first accelerated as described with the aid of the differential drive 5. After the drive machine 4 has reached its connection speed, the control unit 24 sends the command "Mains connection drive machine” to the process control system 25 at time 1. Due to a system-related delay in the communication interface, this command is received at time 2 in the process control system.
• this command is processed in the process control system up to time 3 and the command "close power switch” is sent to power switch 23.
• This "close power switch” process takes about 80 ms and is at time 4, ie after a total of 590 ms from the start of the connection process, completed.
• the process control system 25 then reports "Mains switch closed” to the control unit 24. This is done at time 5. This message is then processed in the control unit up to time 6 and a corresponding command is passed on to the coupling 22
• the clutch 22 will not begin to open until time 7 (after approx. 100 ms). If the clutch is, for example, a standard multi-plate clutch, the transferable torque will drop to approx. 1/3 by time 8 (after e.g. 100ms) and the The clutch must be completely open at time 9 (after, for example, another 300 ms). The complete connection process takes about 1.6 seconds.
• time sequences shown in FIG. 4 are an example and can differ significantly from the processes and time sequences shown, both as a result of the operation and of the system. This means that certain processes can take much longer, but can also be shortened or skipped according to the invention.
• the system control in the control device of the differential system
• the differential system does not know between times “1” and “6” whether or when exactly the drive machine is or has been connected. This means that the differential system remains "tense” for a longer or shorter period of time and is therefore burdened with transient drive train vibrations.
• an improvement can be achieved by measuring the speed of the drive train, ie of the work machine 1 and / or the drive machine 4 and / or the differential drive 5 in the connection phase by means of a speed measuring device 28, 29, 30 (and / or a speed from which one can derive the engagement-related drop in speed) monitored or a desired target speed for the differential drive 5 derived accordingly.
• This desired target speed is preferably calculated from the speed of the drive train and the gear ratios of the differential gear 3 plus any adaptation gear stages implemented.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Control Of Multiple Motors (AREA)
• Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
• Structure Of Transmissions (AREA)

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• 2019
  • 2019-12-16 AT ATA400/2019A patent/AT523332B1/de active
• 2020
  • 2020-12-16 EP EP20821101.1A patent/EP4078801A1/de active Pending
  • 2020-12-16 CN CN202080087023.4A patent/CN114830522A/zh active Pending
  • 2020-12-16 US US17/785,823 patent/US20230318494A1/en active Pending
  • 2020-12-16 WO PCT/EP2020/086392 patent/WO2021122724A1/de unknown

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