Patent Application
20190028050
The present invention relates to a driveline for supplying electrical energy. The energy market, especially the European energy market, changes from central power supply to decentral power supply. The electrical energy/electrical current is delivered by two different producers, controllable energy producer, like power plants, and non-controllable energy producers, like solar power suppliers or wind mill power suppliers.
The changes from the central power supply to decentral power suppliers and the non-controllable energy producer are creating the following electrical faults in the electrical network:
1-, 2- and 3-phase short circuits, electrical voltage fluctuations, micro interruptions in the grid. All these electrical faults can create overloads in the drivelines. The overloads can be between 7.5 times and 16.5 times of nominal torque. In order to prevent electrical voltage fluctuations and power failures, network and system rules for the electrical grid are instituted.
The rules comprise the obligation in case of an unstable network, that the electricity producer must stabilize the grid. For the electricity producers it is not allowed anymore to go off the grid for a specified amount of time. At the moment in dependence of the country it is the obligation to remain at the grid for 150-300 ms.
It is an object of the invention to provide electricity producer, which are able to stabilize the electrical grid.
Further it is an object of the invention to safeguard that after a failure the electricity producers are able to feed electrical power into the electrical grid over a predetermined time.
It is a further object of the invention to provide electricity producers, wherein the electricity producers are able to compensate fluctuations of supply with current of non-controllable current producers.
The object of the invention is solved by the features of claims 1, 10 and 11.
To provide a driveline comprising a controllable power unit, it is possible to stabilize a power grid by feeding electrical power into the electrical grid at times of high power consumption of end-users or low feeding of electrical power from non-controllable power units like home solar, solar forms and wind farms. The controllable power unit can be started to compensate the fluctuations of the non-controllable energy producer and at times of high power consumption. Especially a gas motor or a gas turbine is a preferred power unit which can be started on demand. Further a steam turbine can be used as power unit. A torque liming coupling is arranged between the power unit and the generator to avoid a destabilization of the grid in case of a fault. Especially the torque applied to the generator can be limited. Further in case of a fault on the side of the generator, the power unit is protected.
In a preferred embodiment a gearbox is arranged in the driveline between the power unit and the torque limiting coupling. The gearbox provides an adaption of the revolution speed of the driven shaft of the power unit to the needs of the generator and the electrical grid.
In a preferred embodiment the torque limited coupling limits the transmitted torque by slippage.
In a preferred embodiment a frictional coupling is used as torque limiting coupling, wherein the frictional coupling preferable comprises a cooling device. The cooling device supports leading off the heat generated by friction during slippage. In a preferred embodiment the cooling device comprises a liquid cooling unit.
In a preferred embodiment a multi-disc clutch is used as frictional coupling. A multi disc clutch is able to transfer a high torque and to be compact.
In a preferred embodiment the torque limiting coupling limits the transferrable load and comprises disconnecting safety coupling. The disconnecting safety coupling allows a slippage up to a predetermined slipping angle before disconnection. In a preferred embodiment the torque limiting coupling comprises a mechanism to reset the torque limiting coupling after a predetermined number of slippage events or after a predetermined time interval.
In a preferred embodiment the disconnecting safety coupling performs a disconnection in dependence of the rotational speed of the output shaft of the power unit or gearbox and the slippage angle. Thereby it is possible to allow at low speed a smaller slippage angle in comparison to slippage at high speed.
In a preferred embodiment a hysteresis coupling is used as torque limiting coupling. The advantage of a hysteresis coupling is that there is no contact between the surfaces of the interacting parts of the torque limiting coupling. So there is no wear and a slippage angles exceeding 360° and over minutes up to hours are allowable.
Controllable electricity power suppliers comprises a driveline with a controllable power unit, especially a gas motor or a gas turbine, and a generator connectable to an electrical grid for feeding electrical power into the electrical grid and a controller to start the power unit. A torque limiting coupling is arranged between the generator and the power unit to provide a limited torque to the generator.
Method for stabilization of an electrical grid can be used in an environment comprising an electrical grid comprising at least a controllable driveline. The driveline comprises a power unit and at least a generator and a torque limiting coupling arranged between the power unit and the generator. The method for stabilization the grid comprises the steps:
limiting the torque applied to the generator by slipping of the torque limiting coupling when a predetermined torque is exceeded and disconnecting the power unit from the generator by activation of a disconnecting safety coupling in dependence of the duration and/or frequency of slippage.
It is a preferred method to measure the duration and/or frequency of slippage by detection of the temperature increase of the torque limiting coupling. By this temperature measurement it is possible to activate a disconnection to disconnect the power unit form the generator.
Other aspects and advantages of the invention will become apparent from the following description.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the present preferred embodiments together with the accompanying drawings. The scope of this invention is not limited by these embodiments.
The driveline 1 comprises a gas motor 3 or a gas turbine 5 as power unit 2/power source. The rotational movement of the power unit 2 is transferred to a generator 15 to produce electrical current. A gearbox 13 is arranged between the generator 15 and the power unit 2 in the driveline 1 to adapt the rotational speed of the power unit 2 to the generator 15.
The changes from central power generation to decentralized power generation and non-controllable energy producer can create following electrical faults in the electrical network: —1-, 2- and 3-phase short circuits, electrical voltage fluctuations and/or micro interruptions in the grid. All these electrical faults can create overloads in the drivelines 1. The overloads can be between 7.5 times and 16.5 times of nominal torque. In the consequence to prevent electrical voltage fluctuations and power failures, the electrical driveline 1 must stabilize the electrical grid 12. To stay at the electrical grid 12 a slipping torque limiting coupling 16 is integrated in the driveline 1 as driveline protection between the gearbox 13 and the generator 15.
In the case the driveline does not comprise a gearbox 13 the slipping coupling 16 is arranged between the power unit 2 and the generator 15. By the slipping torque limiting coupling 16 the torque provided by the power unit 2 is limited to a predetermined maximal torque.
In the most cases the failures are of short durations, especially in the range of milliseconds. So the slippage will be only for a short time. By the slippage heat is produced. Because of the very short time of slippage, the time between the slipping events is sufficient long, so that an overheating of the slipping torque limiting coupling 16 will not occur.
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To compensate irregularities and overloads a slipping torque limiting coupling 16 is integrated in the driveline 1 as driveline protection between gas motor 3 or the gas turbine 5 and the generator. In the shown embodiment a gearbox is part of the driveline and the torque limiting clutch is arranged between the motor 3 or turbine 5 and the gearbox 13. This slipping torque limiting coupling also prevents the gear in the case of a fault of the gas turbine 5 or the gas motor 3.
When current is removed from the hysteresis coupling 61, the armature is free to turn and no relative force is transmitted between both the hysteresis sleeve 68 and the rotor 66. Therefore, the only torque seen between the input and the output is bearing drag.
It is possible to use a magnetic hysteresis coupling, which is equipped with permanent magnets. In the case the applied torque exceeds a predetermined torque the hysteresis sleeve 68 comprising the hysteresis elements 69 will slip and only a part of the applied torque is transferred. As there is no contact, no wear occurs. During slippage heat is generated in the hysteresis coupling 61. The heat can be lead away by cooling fins 63.
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The SmartSet 43 is a process improving coupling with controlled slip. It has the ability to slip without releasing to reduce short duration and dynamic torque peaks. SmartSet improves processes and maximizes the output of the application by functioning as an adjustable peak shaver. It can reduce system transient torques with short slippages, without releasing. It can be adapted for start-ups or continuous drives that experience many short peaks. The technology is the same as for the SafeSet coupling, but it is equipped with a centrifugal device 45 named Autoreset device that will give the coupling an additional slip feature. This centrifugal device 45 is activated by the rotational speed of the intended application. This enables the coupling to slip during high transient torques. If the torque peak is of long duration in an overload situation, like a complete blockage, the SmartSet coupling can fully release as a normal SafeSet coupling and subsequently save the driveline from catastrophic failure.
The centrifugal device 45 of the SmartSet comprises a shaft 57, a centrifugal unit 46 preloaded by a spring 59, a radial moveable sleeve 58, a main lever 55, a stop lever 56 rotatable mounted on the main lever 55 and preloaded by a spring. The rotational movement of the stop lever 56 is limited by a stop, wherein the stop is arranged at the main lever 55. Further the main lever 55 comprises an opening for receiving a shear tube 53. The main lever 55 is mounted pivotable and radial movable on the shaft 57 of the centrifugal device 45. In the case the main lever 55 pivots the shear tube 53 shears off and the oil pressure drops off and the frictional surfaces of the driven and driving elements separates. A pivot of the main lever 55 is activated by a shifting gate 51 with release projections. If the SmartSet device is mounted on the driving element, the shifting gate 51 with the release projection is fixed in respect of the driven element. So a shear off of the shear tube will take place in the case of slippage over a predetermined angle.
Further torque limiting couplings are well known in the market. For example the company MAYR offers torque limiting couplings named EAS.
| Number | Date | Country | Kind |
|---|---|---|---|
| EP15186024.4 | Sep 2015 | EP | regional |
| EP15198326.9 | Dec 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/072102 | 9/19/2016 | WO | 00 |
