Capacitive energy storage device for switchgear with energy flow control, a drive with such an energy storage device and a switchgear with such a drive

Abstract

Energy storage device (10) for an electromagnetic drive of a low-, medium-, or high-voltage switch, wherein the energy storage device (10) has one or more capacitors (201, 202, 203) of a first capacitor type and one or more further capacitors (301, 302, 303, 304, 305) of a second capacitor type, wherein the first capacitor type comprises ceramic, film, and / or electrolytic capacitors and the second capacitor type is a supercapacitor, and wherein the at least one capacitor (201, 202, 203) of the first capacitor type and the at least one further capacitor (301, 302, 303, 304, 305) of the second capacitor type are connected in parallel to one another via an energy flow control device (100).

Description

The invention relates to a capacitive energy store with an energy flow control for switchgears, a drive with such an energy store and a switchgear with such a drive.Switching devices for low-voltage, medium-voltage or high-voltage installations, such as power switches with electrical drives, that is to say for example magnetic drives, require an amount of energy for a switching operation, which is usually stored in capacitors, since the power required for a switching operation, that is to say the amount of energy, cannot be provided in a very short time from the auxiliary voltage supply of the switching device.Furthermore, the requirement is regularly to be fulfilled that in the event of an auxiliary voltage failure, i.e. a failure of the auxiliary voltage supply, a switching operation into the safe switching position OPEN, i.e. open or open, is ensured at least 5 minutes after the auxiliary voltage supply failure.These two requirements result in the need to design the energy store in such a way that, on the one hand, a low electrical internal resistance for the switching energy and a high storage capacity for the bridging time in the event of an auxiliary voltage supply failure are provided.Electrolytic capacitors are known from the prior art as energy stores for electromagnetic drives. These are used since the electrolytic capacitors can meet both requirements with appropriate dimensioning. Both low internal resistance for high short-term power for switching operation and a sufficient specific capacity for the required bypass times in the event of an auxiliary voltage supply failure.Since a correspondingly large number of electrolytic capacitors must be provided for a sufficiently long period of time in the event of an auxiliary voltage supply failure, the costs for such an electrolytic capacitor assembly are high, as are the installation space required.It is now the object of the invention to provide an alternative configuration of the energy store which overcomes the disadvantages from the prior art.The object is achieved by the independent claim 1 and by the claims dependent thereon.An exemplary embodiment relates to an energy store for electromagnetically driving a low-voltage, medium-voltage or high-voltage switch, wherein the energy store has one or more capacitors of a first capacitor type and one or more further capacitors of a second capacitor type, wherein the first capacitor type comprises ceramic, foil and / or electrolytic capacitors and the second capacitor type is a supercapacitor, and wherein the at least one capacitor of the first capacitor type and the at least one further capacitor of the second capacitor type are connected in parallel to one another via an energy flow controller.In other words, the energy store for an electromagnetic drive is a hybrid energy store comprising capacitors and supercapacitors, wherein the capacitors are connected to the supercapacitors via an energy flow control. In this case, the capacitors for the rapid energy output, i.e. high power output, are provided at the electromagnetic drive for operating the drive, and the supercapacitors serve as energy stores if the auxiliary voltage supply of a switching installation fails. In the event of a failure of the auxiliary voltage supply, the supercapacitors are designed to assume the function of the auxiliary voltage supply and preferably to provide a sufficient operating voltage for charging the capacitors, and thus for switching the switching device, over a period of at least 5 min and thus to be able to carry out at least one opening operation.The energy flow control is designed to control the energy flow between the capacitors of the first capacitor type and the further capacitors of a second capacitor type and preferably also the auxiliary voltage supply.The charging time for the capacitors of the first capacitor type is reduced compared to the total charging time of the hybrid energy store by the energy flow control, in particular since it is possible to charge only the capacitors of the first capacitor type first and only the capacitors of the second capacitor type subsequently in time.Supercapacitors are also referred to as electrochemical capacitors or ultracapacitors and are characterized in that they generally do not have a dielectric in the conventional sense, but rather the energy is stored in bilayers on the electrodes, storage taking place both in the form of charge separation in the bilayers and in the form of electrochemical storage.In particular, a short charging time until it is ready for switching operations is achieved first by charging the capacitors of the first capacitor type, then the capacitors of the second capacitor type are charged. The bypass time in the event of an auxiliary voltage failure is therefore only reached after the charging of the capacitors of the first capacitor type and after a short waiting time, which is not disadvantageous for the operation management, however.In addition, the use of supercapacitors ensures a higher bridging time in the event of an auxiliary voltage breakdown without increasing the charging times of the capacitors of the first capacitor type.At the same time, with the same installation space, a higher bridging time is likewise achieved in the event of an auxiliary voltage failure.It is preferred that the first capacitor type is an electrolytic capacitor.It is also preferred that the first capacitor type has an energy density of at most 0.5 Wh / l and the second capacitor type has an energy density of at least 3 Wh / l, and / or that the second capacitor type has an energy density which is at least 5 times higher than that of the first capacitor type, and wherein the first capacitor type has a lower internal resistance than the second capacitor type.It is further preferred that more than one capacitor of the first capacitor type are interconnected in parallel with one another.It is preferred that more than one further capacitor of the second capacitor type are connected in series with one another.In particular, it is preferred that the energy store further comprises a charge compensation circuit, wherein the charge compensation circuit is configured to transfer excess charges from supercapacitors with a higher voltage to supercapacitors with a lower voltage and / or to prevent the excess charge and / or to dissipate the excess charge. The charge balancing circuit is also referred to as a voltage balancing device. The charge balancing circuit prevents overcharging and thus damage to the individual supercapacitors, in particular if the cell voltages of the individual supercapacitors differ.An active charge balancing circuit is particularly preferred.It is further particularly preferred that each supercapacitor is connected in parallel with the charge balancing device.It is also particularly preferred that the charge compensation circuit of the energy store is constructed without highly integrated, inductive or capacitive components, in particular without coils and capacitors. Such a structure can be realized, for example, by means of a series connection of one or more Zener diodes and one or more resistors. Alternatively, such a construction is effected by means of a resistor network in combination with operational amplifiers as voltage followers.It is also preferred that the energy flow control is formed by one or more bidirectional DC-DC converters.It is also preferred that the energy flow control is formed by at least one unidirectional DC-DC converter per flow direction.A further exemplary embodiment relates to an electromagnetic drive for a vacuum interrupter of a low-voltage, medium-voltage or high-voltage switchgear, wherein the electromagnetic drive has an energy store according to one or more of the preceding embodiments.Another exemplary embodiment relates to a low-voltage, medium-voltage or high-voltage switchgear, wherein the low-voltage, medium-voltage or high-voltage switchgear has an electromagnetic drive according to the preceding explanations.It is preferred that the one or more further capacitors of the second capacitor type of the energy store store sufficient energy to serve as an auxiliary voltage source for the one or more capacitors of the first capacitor type 5 min or more after a failure of an auxiliary voltage source.It is also preferred that the one or more further capacitors of the second capacitor type of the energy store store sufficient energy to serve as an auxiliary voltage source for the one or more capacitors of the first capacitor type 5 min or more after a failure of an auxiliary voltage source and to enable a switching cycle of opening-closing-and renewed opening.A further exemplary embodiment relates to a method for operating a low-, medium- or high-voltage switchgear, wherein the low-, medium- or high-voltage switchgear has an electromagnetic drive according to one of the preceding explanations, and the one or more capacitors of the first capacitor type serve as a power source for carrying out switching operations, and the one or more further capacitors of the second capacitor type replace the auxiliary voltage source for 5 min or more of the auxiliary voltage source which has failed in the event of a failure of an auxiliary voltage source.It is also preferred that the one or more capacitors of the first capacitor type are charged by a controllable DC-DC converter present in the energy flow controller and the energy store does not have an additional charging device for the one or more capacitors of the first capacitor type.With regard to the device according to the invention, all the explanations given above and below with respect to the method according to the invention and vice versa apply in a corresponding manner, in particular the device according to the invention is set up for carrying out the method according to the invention in any desired embodiment or a combination of any desired embodiments. With regard to the advantages of the device according to the invention, reference is also made to the advantages described with respect to the method according to the invention.The invention is explained in more detail below with reference to an exemplary embodiment. The specific configuration of the exemplary embodiment is not to be understood as restrictive in any way for the general configuration of the method according to the invention and of the device according to the invention; rather, individual configuration features of the exemplary embodiment can be freely combined with one another and with the features described above in any desired manner.Regardless of the grammatical sex of a certain term, individuals with male, female or other sex identity are included.The invention is explained in more detail below with reference to figures. FIG. 1 : Schematic illustration of a switchgear assembly; FIG. 2 : Exemplary equivalent circuit diagram of an energy store according to the invention; FIG. 3 : Exemplary equivalent circuit diagram of a charge compensation circuit.FIG. 1 shows a schematic representation of a switching system 1 with displays 4 and a user interface 6.FIG. 2 shows an exemplary equivalent circuit diagram of an energy store 10 according to the invention. the energy store 10 in this case has an energy flow controller 100 for connecting the energy store 10 to an electromagnetic drive and an auxiliary voltage source of a switching system 1, wherein the energy flow controller 100 is further designed to control, i.e. to control, the energy flow between the capacitors 201, 202, 203 of a first capacitor type and the further capacitors 301, 302, 303, 304, 305 of a second capacitor type.Furthermore, FIG. 2 shows capacitors of a first capacitor type 201, 202, 203 connected in parallel, here by way of example three electrolytic capacitors, which are designed to supply the electromagnetic drive with electrical energy for at least one switching action. The energy flow controller 100 is connected to the parallel connection of the capacitors of the first capacitor type 201, 202, 203, in this case specifically to the last electrolytic capacitor 203, and supercapacitors 301, 302, 303, 304, 305 are connected in parallel via the energy flow controller 100, in this case five supercapacitors, by way of example. The supercapacitors are connected in series with one another. A charge compensation circuit 400 is optionally arranged in parallel with each capacitor here.FIG. 3 shows an exemplary equivalent circuit diagram of a charge compensation circuit 400 for five supercapacitors 301, 302, 303, 304, 305 here by way of example.The charge compensation circuit 400 has a voltage divider, here by way of example a resistor network having five resistors 410, 420, 430, 440, 450 as a voltage divider between a first potential 401, here by way of example a ground potential, and a second potential 402, here by way of example a positive voltage V +. Furthermore, the charge compensation circuit 400 has, by way of example, four operational amplifiers 415, 425, 435, 445. The voltage difference between the first potential 401 and the second potential 402 corresponds to the theoretical charging voltage of the supercapacitors 301, 302, 303, 304, 305. Since, however, the real capacitances in the case of capacitors can deviate from the nominal capacitances, deviations in the range from ± 5% to ± 20% are possible, the charge compensation circuit 400 is constructed in such a way that the theoretical charge voltage is divided by means of the resistor network comprising resistors 410, 420, 430, 440, 450 as a voltage divider, and, in the case of deviating capacitances of the supercapacitors 301, 302, 303, 304, 305, the operational amplifiers 415, 425, 435, 445 as voltage followers lead to a voltage compensation corresponding to the respective capacitances of the respective supercapacitors 301, 302, 303, 304, 305. For this purpose, the respective inverting input of an operational amplifier 415, 425, 435, 445 is connected directly to the output of the respective operational amplifier 415, 425, 435, 445. The operational amplifiers 415, 425, 435, 445 are each supplied with voltage by two cells, in this case supercapacitors 301, 302, 303, 304, 305.In this case, the operational amplifier 445, which is referred to here as the lowermost operational amplifier 445, is supplied with voltage by the ground contact 401 and the cell lying above it, that is to say at the output of the operational amplifier 435, here supercapacitor 302.The operational amplifier 435 located above is supplied with voltage by the cell with the output of the operational amplifier 445, here supercapacitor 301, and the cell with the output of the operational amplifier 425, here supercapacitor 303.The operational amplifier 425 is powered by the cell having the output of the operational amplifier 435, here supercapacitor 302, and the cell having the output of the operational amplifier 415, here supercapacitor 304.The top operational amplifier 415 is powered by the cell with the output of the operational amplifier 425, here 303, and the cell with the input voltage 402, here supercapacitor 305.If one or more supercapacitors 301, 302, 303, 304, 305 have a lower voltage than the desired capacitor voltage, the respective operational amplifier 415, 425, 435, 445 acts as a current source and charges the respective supercapacitor 301, 302, 303, 304, 305. The charge required for this is then taken from one of the adjacent supercapacitors 301, 302, 303, 304, 305.If one or more supercapacitors 301, 302, 303, 304, 305 have a higher voltage than the desired capacitor voltage, the operational amplifier 415, 425, 435, 445 acts as a current sink and discharges the respective supercapacitor 301, 302, 303, 304, 305. The excess charge is then taken up by one of the adjacent supercapacitors 301, 302, 303, 304, 305.The charge balancing circuit 400 thus reduces voltages of supercapacitor 301, 302, 303, 304, 305 with too high a voltage and thus increases voltages of supercapacitor 301, 302, 303, 304, 305 with too low a voltage. Charge balancing is thus achieved. In particular, such a charge compensation circuit 400 does not have any highly integrated, inductive or capacitive components, in particular no coils and further capacitors.List of reference characters1 Switching system; 4 display on the switching system 1; 6 user interface of the switching system 1; 10 energy storage devices; 100 energy flow regulation for connecting the energy storage device 10 to an electromagnetic drive and an auxiliary voltage source of a switching system 1 and for controlling the energy flow between the capacitors of a first capacitor type and the further capacitors of a second capacitor type; 201 capacitor of a first capacitor type, e.g. electrolyte capacitor; 202 capacitor of a first capacitor type, e.g. electrolyte capacitor; 203 capacitor of a first capacitor type, e.g. electrolyte capacitor; 301 capacitor of a second capacitor type, a supercapacitor; 302 capacitor of a second capacitor type, a supercapacitor; 303 capacitor of a second capacitor type, a supercapacitor; 304 capacitor of a second capacitor type, a supercapacitor; 305 capacitor of a second capacitor type, a supercapacitor; 400 charge compensation circuit; 401 first potential, for example ground potential; 402 second potential, for example positive voltage V +; 410 resistor of the voltage divider; 415 operational amplifier; 420 resistor of the voltage divider; 425 operational amplifier; 430 resistor of the voltage divider; 435 operational amplifier; 440 resistor of the voltage divider; 445 operational amplifier; 450 resistor of the voltage divider.

Claims

Energy store (10) for electromagnetic driving of a low-voltage, medium-voltage or high-voltage switch, characterized in that - the energy store (10) has one or more capacitors (201, 202, 203) of a first capacitor type and one or more further capacitors (301, 302, 303, 304, 305) of a second capacitor type, - wherein the first capacitor type comprises ceramic, foil and / or electrolytic capacitors and the second capacitor type is a supercapacitor, and wherein - the at least one capacitor (201, 202, 203) of the first capacitor type and the at least one further capacitor (301, 302, 303, 304, 305) of the second capacitor type are connected in parallel to one another via an energy flow controller (100).Energy store (10) according to Claim 1, characterized in that the first capacitor type is an electrolytic capacitor.Energy store (10) according to one of the preceding claims, characterized in that • the first capacitor type has an energy density of at most 0.5 Wh / l and the second capacitor type has a power density of at least 3 Wh / l, and / or • the second capacitor type has an energy density which is at least 5 times higher than that of the first capacitor type, and wherein the first capacitor type has a lower internal resistance than the second capacitor type.Energy store (10) according to one of the preceding claims, characterized in that more than one capacitor (201, 202, 203) of the first capacitor type are interconnected in parallel with one another.Energy store (10) according to one of the preceding claims, characterized in that more than one capacitor (301, 302, 303, 304, 305) of the second capacitor type are connected in series with one another.Energy store (10) according to claim 5, characterized in that the energy store (10) further comprises a charge balancing circuit (400), wherein the charge balancing circuit (400) is configured to transfer excess charges from supercapacitors with higher voltage to supercapacitors with lower voltage and / or to prevent the excess charge and / or to dissipate the excess charge.Energy store (10) according to Claim 6, characterized in that the charge compensation circuit (400) of the energy store is constructed without highly integrated, inductive or capacitive components, in particular without coils and capacitors.Energy store (10) according to one of the preceding claims, characterized in that the energy flow controller (100) is formed by one or more bidirectional DC-DC converters.Energy store (10) according to one of the preceding claims, characterized in that the energy flow controller (100) is formed by at least one unidirectional DC-DC converter per flow direction.Electromagnetic drive for a vacuum interrupter of a low-voltage, medium-voltage or high-voltage switchgear (1), characterized in that the electromagnetic drive has an energy store (10) according to one of the preceding claims.Low-voltage, medium-voltage or high-voltage switchgear (1), characterized in that the low-voltage, medium-voltage or high-voltage switchgear (1) has an electromagnetic drive according to the preceding claim.Low-voltage, medium-voltage or high-voltage switchgear (1) according to Claim 11, characterized in that the one or more further capacitors (301, 302, 303, 304, 305) of the second capacitor type of the energy store (10) store sufficient energy to serve as an auxiliary voltage source for the one or more capacitors (201, 202, 203) of the first capacitor type 5 min or more after a failure of an auxiliary voltage source.Low-voltage, medium-voltage or high-voltage switchgear (1) according to Claim 11, characterized in that the one or more further capacitors (301, 302, 303, 304, 305) of the second capacitor type of the energy store (10) store sufficient energy to serve as an auxiliary voltage source for the one or more capacitors (201, 202, 203) of the first capacitor type 5 min or more after a failure of an auxiliary voltage source and to enable a switching cycle of the vacuum interrupter from opening - closing - and renewed opening.Method for operating a low-, medium- or high-voltage switchgear (1), characterized in that the low-, medium- or high-voltage switchgear (1) has an electromagnetic drive according to one of the preceding claims, and the one or more capacitors (201, 202, 203) of the first capacitor type serve as energy source for carrying out switching operations, and the one or more further capacitors (301, 203, 303, 304, 305) of the second capacitor type replace the auxiliary voltage source for 5 min or more of the failed auxiliary voltage source in the event of a failure of an auxiliary voltage source.Method for operating a low-voltage, medium-voltage or high-voltage switchgear according to Claim 14, characterized in that the one or more capacitors (201, 202, 203) of the first capacitor type are charged by a controllable DC-DC converter present in the energy flow controller (100), and the energy store (10) has no additional charging device for the one or more capacitors (201, 202, 203) of the first capacitor type.

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