Flywheel storage

Abstract

The invention relates to a flywheel mass storage device comprising a cylindrical rotating body and at least one energy converter for driving the rotating body.

Description

The invention relates to a flywheel mass storage device.These are fundamentally known in smaller embodiments, but are not suitable for use in large photovoltaic installations, for example solar parks.It is therefore an object of the invention to provide a flywheel mass storage device and a photovoltaic system with a flywheel mass storage device, in which / which safe operation is made possible even when the flywheel mass storage device is dimensioned to be large.This object is achieved by the subject matters of the independent claims.According to the invention, the flywheel mass storage device has a cylindrical rotary body. For example, the rotary body can be designed as a solid cylinder.The rotary body is preferably free of windings, i.e. it does not have, for example, any wire or stranded windings. Rather, the cylindrical rotary body is preferably made of a casting, i.e. of a material connected in the axial direction. In the radial direction, however, a plurality of layers can be provided.The rotary body can be between 1 m and 5 m, preferably 2 m, long, for example.The diameter of the rotary body can be, for example, between 0.5 m and 2 m, preferably 1 m.The rotary body preferably comprises or consists of a plastic material, e.g. glass fibre-reinforced plastic, and / or a metal material, e.g. steel.For example, the rotary body can be arranged in a, preferably cylindrical, housing.Preferably, a vacuum prevails within the housing. As a result, friction losses of the rotary body are minimized. For example, a vacuum pump for providing the vacuum can be provided.The flywheel mass storage device has at least one energy converter for driving the rotary body.Preferably, the speed is adjustable.For example, the energy converter can have a clutch, a transmission and / or a frequency converter.The energy converter preferably has a, for example dynamic, bearing, e.g. slide bearings and / or ball bearings, for the rotary body.The energy converter can comprise or consist of, for example, a variable transmission, a synchronous motor, a direct current motor and / or an alternating current motor.For example, the rotational speed can be between 1,000 and 10,000 revolutions per minute, preferably between 5,000 and 8,000 revolutions per minute, for example 7,000 revolutions per minute.The energy converter can be designed, for example, as a drive. Electrical energy can preferably be converted into kinetic energy, for example a rotational movement of the rotary body. Alternatively or additionally, the energy converter can convert kinetic energy, e.g. a rotational movement of the rotary body, into electrical energy.For example, the flywheel mass storage can be operated at 250 to 300 kWh.The energy converter enables safe operation even when the flywheel mass storage device is dimensioned to be large.Further developments of the invention can also be taken from the dependent claims, the description and the accompanying drawings.According to one embodiment, two energy converters are provided, which are arranged on opposite end sides of the rotary body.The rotary body can thus be driven on both sides or energy can be tapped off on both sides and current can be generated.The two energy converters can operate simultaneously or alternately. For example, an energy converter can jump in in the event of a defect in the other energy converter.The two energy converters make safe and / or variable operation possible.According to a further embodiment, both energy converters are based on alternating current.For example, one (or both) alternating current energy converter can set the rotary body in a rotary motion. The energy is thus stored in the flywheel mass storage. If the energy is required again, the same and / or the other energy converter can convert the rotational movement back into alternating current.At a favourable price of electricity, for example alternating current can be drawn from the power supply network and the rotary body can be set into a rotary movement via an energy converter. At a higher power price, the rotary movement can be converted again via the other energy converter into alternating current, which can be fed into the power grid. This is alternatively or additionally possible with a single energy converter which both sets the rotary body into a rotary movement and converts the rotary movement back into current.Alternatively, both energy converters are based on direct current.For example, one (or both) DC energy converter may set the rotary body in a rotary motion. The energy is stored in the flywheel mass storage in this way. If the energy is required again, the same and / or the other energy converter can convert the rotational movement back into direct current.According to a further embodiment, one energy converter is based on alternating current and the other energy converter is based on direct current.The flywheel mass storage device is extremely variable in this way and can be adapted to the respective circumstances.For example, an energy converter operated with alternating current can set the rotary body in a rotary movement. The energy is thus stored in the flywheel mass storage. If the energy is required again, the other energy converter can convert the rotational movement into direct current.Alternatively, an energy converter operated with direct current can set the rotary body in a rotary movement. The energy is stored in the flywheel mass storage in this way. If the energy is required again, the other energy converter can convert the rotational movement into alternating current.If a photovoltaic system generates direct current, for example, this can be converted via the energy converter into a rotational movement which, if required, is converted via the other energy converter into alternating current. The alternating current can be fed directly into the power grid. A separate inverter can consequently be dispensed with.According to a further embodiment, the rotary body has a shaft, a mass device which extends coaxially and / or concentrically around the shaft, and a connecting device which is arranged between the shaft and the mass device.The rotary body can thus have at least or exactly three layers.The shaft can be designed, for example, as a hollow shaft or solid shaft.At each of the two ends of the shaft, a bearing socket can preferably be provided.For example, the shaft comprises or consists of a plastic material, e.g. glass fiber-reinforced plastic, and / or a metal material, e.g. steel.Preferably, the shaft forms the axis of rotation of the rotary body.The shaft serves, for example, to reinforce the system.The mass device is preferably designed as a solid material, e.g. as a cylindrical sleeve. The mass is preferably distributed uniformly and / or at a uniform distance from the center of the axis of rotation.For example, the mass device comprises or consists of a plastic material, e.g. glass fiber-reinforced plastic, and / or a metal material, e.g. steel.The connecting device serves as a link between the shaft and the mass device. This transmits the forces that are generated.For example, the connecting device comprises or consists of a plastic material, e.g. glass fiber-reinforced plastic, and / or a metal material, e.g. steel.The tensile strength of the materials used for the rotary body and / or the rotational speed can preferably be selected in view of the centrifugal forces occurring.According to a further embodiment, the connecting device is designed to be rotationally symmetrical, e.g. with respect to the shaft and / or the axis of rotation.The design of the connecting device is preferably not geometrically defined, since it is dependent on the selected material.For example, the connecting device can be designed as a solid material, e.g. as a cylindrical sleeve.Alternatively, other rotationally symmetrical embodiments or geometries are conceivable. For example, the connecting device may comprise struts and / or disks which extend between the shaft and the mass device. The struts and / or disks can preferably taper from the shaft in the direction of the mass device.According to a further embodiment, the rotary body is arranged in a, preferably cylindrical, housing, wherein the housing is of double-walled design.Preferably, a vacuum prevails within the housing. In the event of a failure of the vacuum, high temperatures would occur on account of the high rotational speeds of the rotary body, which could lead to damage to the flywheel mass storage device and / or to the environment.This problem can be avoided by the double-walled embodiment. The inner region in which the rotating body is located and the intermediate region between the two housing walls can preferably be connected to one another via an opening. A pressure sensor can be provided in the region of the opening.If the pressure drops, for example due to a hole in the outer wall of the housing, e.g. caused by damage to the hair, the rotational movement of the rotary body can be shut down in a controlled manner and / or the pumping capacity of the vacuum pump can be increased.According to a further embodiment, an emergency bearing is provided.The emergency bearing can preferably be integrated into a bearing block in which the main bearing is also arranged, preferably centrally.The bearing block can be fastened to the housing, for example.The main bearing may be fixedly connected to the rotating body. In the event of a breakage and / or a bearing failure, the rotary body can break out. The emergency bearing now sets in and catches the rotary body.The emergency bearing is preferably designed such that sliding friction is used to conduct away the heat in a controlled manner.According to a further embodiment, a control device is provided which is designed to convert current into kinetic energy of the rotating body in the event of a current overflow of an energy system connected to the flywheel mass storage device and / or to generate current from the kinetic energy of the rotating body in the event of a lack of current of an energy system connected to the flywheel mass storage device.The energy system can be, for example, a photovoltaic system and / or the power grid.In the case of an overflow of current during great solar radiation, for example middays, the feed compensation is usually very low. Therefore, it is advantageous to temporarily store the generated current as kinetic energy in the rotating body. If the price of electricity increases, for example if solar radiation decreases, e.g. in the evening, electricity can be recovered from the kinetic energy and fed into the power grid.The power is thus always sold at times when a high price of power can be achieved or when there is a high power demand.Preferably, the control device can be connected to the power supply box. Thus, the current price of electricity can always be queried and / or the electricity can be negotiated.Protection is also claimed for a method for controlling a flywheel mass storage device according to the invention.In this case, a control device controls the flywheel mass storage device in such a way that, in the event of a current overflow of an energy system connected to the flywheel mass storage device, current is converted into kinetic energy of the rotary body and / or, in the event of a lack of current of an energy system connected to the flywheel mass storage device, current is generated from the kinetic energy of the rotary body.Finally, the invention relates to a photovoltaic system having a flywheel mass storage device according to the invention.It is especially in the case of large photovoltaic installations, for example field-land photovoltaic installations, it is advantageous to temporarily store the generated current in order to feed the current into the power grid when this is financially advantageous.All embodiments and components of the devices described here are preferably designed to be operated, for example by means of the control device, according to the method described here. Furthermore, all embodiments of the devices described here and all embodiments of the method described here can each be combined with one another, preferably also separately from the specific configuration in the context of which they are mentioned.The invention is described below by way of example with reference to the drawings. The following are shown: FIG. 1 is a partially transparent side view of an embodiment of a flywheel mass storage device according to the invention, FIG. 2 shows a perspective view of an embodiment of a rotary body of a flywheel mass storage device according to the invention, FIG. 3 shows a partially transparent side view of an embodiment of a rotary body of a flywheel mass storage device according to the invention, FIG. 4 is a partially transparent perspective view of the rotary body according to FIG. 3 , FIG. 5 shows a side view of an embodiment of a rotary body of a flywheel mass storage device according to the invention, FIG. 6 is a perspective view of the rotary body of FIG. 5 , FIG. 7 is a front view of the rotary body of FIG. 5; and FIG. 8 is a sectional view of the rotary body of FIG. 7 along A-A.First, it should be noted that the illustrated embodiments are merely exemplary in nature. Thus, individual features can be realized not only in the combination shown, but also alone or in other technically meaningful combinations. For example, the features of one embodiment can be combined with features of another embodiment as desired. Preferably, instead of two energy converters, only one energy converter can be provided.If a figure contains a reference sign which is not explained in the directly associated text of the description, reference is made to the corresponding preceding or following explanations in the description of the figures. Thus, the same reference numerals are used for identical or comparable components in the figures and these are not explained again.FIG. 1 shows a flywheel mass storage device with a cylindrical rotary body 10. The energy converters 12, 14 are omitted in the further figures for the sake of simplicity.The rotary body 10 has bearing stubs 16, via which a connection to the energy converters 12, 14 is produced.As shown in FIG. 2, the rotary body 10 can be formed in three layers: a connecting device 20 and a mass device 22 can extend coaxially and / or concentrically around a shaft 18.Alternatively, the rotating body 10 may also have only one or two layers or more than three layers.FIG. 3 shows a housing 24 in which the rotary body 10 is arranged.As can be seen in FIG. 4 (the upper half of the housing 24 has not been shown for reasons of better visibility), the housing 24 can be of double-walled design.FIGS. 5 to 8 show a housing 24 in which the rotary body 10 is arranged and to which a bearing block 26 is fastened on each side.An emergency bearing 28 is integrated into the bearing block 26.A main bearing formed by the bearing stubs 16 is arranged centrally in the bearing block 26 and is firmly connected to the rotary body 10.In the event of a breakage of a shaft 18 or of a bearing stub 16 or a bearing failure and a conditional failure of the rotary body 10, the emergency bearing 28 sets in and catches the rotary body 10. The run-flat bearing 28 is designed such that sliding friction is used to conduct away the heat in a controlled manner.The flywheel mass storage device according to the invention enables safe operation even with large dimensions.List of reference characters10 Rotating body 12 Energy converter 14 Energy converter 16 Bearing connection 18 Shaft 20 Connecting device 22 Mass device 24 Housing 26 Bearing block 28 Emergency bearing

Claims

Flywheel mass store, having a cylindrical rotary body (10) and at least one energy converter (12, 14) for driving the rotary body (10).Flywheel mass store according to Claim 1, characterized in that two energy converters (12, 14) are provided, which are arranged on opposite end faces of the rotary body (10).Flywheel mass store according to Claim 2, characterized in that both energy converters (12, 14) are based on alternating current or in that both energy converters (12, 14) are based on direct current.Flywheel mass store according to Claim 2, characterized in that one energy converter (12) is based on alternating current and the other energy converter (14) is based on direct current.Flywheel mass store according to one of the preceding claims, characterized in that the rotary body (10) has a shaft (18), a mass device (22) which extends coaxially and / or concentrically around the shaft (18), and a connecting device (20) which is arranged between the shaft (18) and the mass device (22).Flywheel mass store according to Claim 5, characterized in that the connecting device (20) is of rotationally symmetrical design.Flywheel mass store according to one of the preceding claims, characterized in that the rotary body (10) is arranged in a, preferably cylindrical, housing (24), the housing (24) being of double-walled design.Flywheel mass store according to one of the preceding claims, characterized in that an emergency bearing (28) is provided.Flywheel mass storage device according to one of the preceding claims, characterized in that a control device is provided which is designed to convert current into kinetic energy of the rotary body (10) in the event of a current overflow of an energy system connected to the flywheel mass storage device and / or to generate current from the kinetic energy of the rotary body (10) in the event of a lack of current of an energy system connected to the flywheel mass storage device.Photovoltaic system having a flywheel mass store according to one of the preceding claims.

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