WO1999053593A1

WO1999053593A1 - Device and method for supplying an electric load with electric energy

Info

Publication number: WO1999053593A1
Application number: PCT/DE1999/000954
Authority: WO
Inventors: Michael Weinhold; Leon Voss; Ulrich Halfmann; Rainer Zurowski
Original assignee: Siemens Aktiengesellschaft
Priority date: 1998-04-09
Filing date: 1999-03-29
Publication date: 1999-10-21
Also published as: EP1070376A1; AU4131699A

Abstract

To supply an electric load (2) connected to a power supply network (4) with energy in case of a breakdown, especially an absolute drop in a voltage supplied by the power supply network (4), the invention provides for a device (1) comprising a power supply unit (12A) which is connected in series with the load (2), a switching element (8) and a controllable electric circuit (14, 21). Energy can be drawn from the power supply unit (12A) and fed to the load (2). The power supply network (4) can be disconnected by a switching element (8) and by means of the controllable electric circuit (14, 21) a closed circuit can be formed with the load (2) and the power supply unit (12A).

Description

description

Arrangement and method for the electrical energy supply of an electrical load

The invention relates to an arrangement for the electrical energy supply of an electrical load, which can be connected to and disconnected from an electrical power supply network via an electrical line. The invention further relates to a method for the electrical energy supply of an electrical load.

An arrangement for energy supply is known from US Pat. No. 5,514,915, which in practice is also referred to as “shunt-connected ^w ”. In the known arrangement, an energy storage cell is provided for supplying energy to the load, from which electrical energy is taken and can be delivered to the line and thus to the load via a transformer. The transformer has secondary windings that are connected in parallel to the load. The arrangement has a switching element with which the electrical power supply network can be separated from the line. The switching element is designed with controllable semiconductor valves which can be controlled by a control device via a control line. The arrangement is three-phase.

From US Pat. No. 5,329,222 an arrangement for supplying energy to an electrical load is known, which is connected to an electrical supply system. The arrangement has an energy source with an energy store, from which energy can be taken and fed to the load via a transformer. The transformer has a secondary winding that 2 serial m the line is switched. In practice, this arrangement is also referred to as “series-connected *.

The object of the invention is to provide an arrangement for the electrical energy supply of an electrical load, in particular in the event of a fault in the mains voltage provided by the energy supply network, which, based on a “senes-connected ^λ configuration, also masters a total failure of the energy supply network. Another object is to provide a method for supplying energy to an electrical load that is suitable for this purpose.

According to the invention, the object directed to an arrangement for energy supply is achieved by an arrangement for energy supply to an electrical load, which can be connected to and separated from an electrical energy supply network via an electrical line formed with at least two electrical conductors and via a switching element, with an electrical energy supply unit , which is used at least partially for the energy supply of the electrical load and is connected in series with the line, a controllable electrical path being provided via which the electrical conductors can be short-circuited at a location between the switching element and the energy supply unit.

In the event of a fault in the mains voltage delivered from the power supply network to the load via the electrical line, the fault operation of the arrangement is activated. A disturbance in the line voltage is understood to mean, for example, a drop in the line voltage or a deviation of the time profile of the line voltage from the sinusoidal shape. In fault mode, energy can be drawn from the energy supply unit, which acts as a compensating voltage on the line and thus on 3 the load can be released. Characterized in that the power supply unit ^¬ mt serially the line is connected, the offset voltage is added to the mains voltage. A disturbance in the mains voltage can thus be counteracted simply by adding the compensation voltage.

If the mains voltage drops sharply below a predetermined setpoint, particularly in the event of a total failure, the electrical power supply network can be disconnected from the line. In this case, the electrical energy supply of the load is carried out solely from the energy supply unit. After the electrical power supply network has been disconnected, the electrical line on the switching element is interrupted. The energy supply network can then no longer act as an undesirable additional load for the energy supply unit when supplying energy to the load. To supply energy to the electrical load from the energy supply unit, the electrical path can then be used to form a closed circuit with the load, the energy supply unit and the line, by which the conductors of the electrical line are short-circuited between the switching element and the energy supply unit. For this purpose, the controllable electrical path can be used, for example, to connect the electrical line on the switching element on the load side to a reference point of the load.

The switching element and / or the electrical path preferably each have at least one controllable valve, in particular a controllable semiconductor valve. The controllable valve can also be designed as a mechanical switch. The switching element and / or the electrical path, for example controlled by a control device, can be switched via the respective controllable valve. In particular controllable 4 semiconductor valves can be switched very quickly, so that the arrangement can be switched very quickly in a storage operation with a separate power supply network.

Further preferably, the switching member and / or the electrical ^¬ specific path each have at least one throttle. If necessary, such a choke serves to largely block interference signals which may be emitted from the power supply unit to the line and which could reach the power supply network via the line.

According to a further embodiment, the energy supply unit has an energy source. The energy source comprises an energy store which can be connected to the load via a power converter. For an energy supply, energy can be taken from the energy store in the form of a current, which can be converted via the converter and supplied to the load. Electrical power is delivered to the load. The electrical power can be varied and controlled by appropriately controlling the converter to convert the current.

The energy store is advantageously designed for storing electrical and / or mechanical energy. To store mechanical energy, the energy store can be designed, for example, as a flywheel store. The energy store preferably has a superconducting magnet for storing electrical energy. These types of memory are particularly suitable for the present application, and the superconducting magnet can be designed to store energy from 10 MVAs to 1000 MVAs. 5 The converter is further preferred via a filter with the

Connectable load. The filter can largely block or suppress any interference signals generated by the converter during the conversion. The filter largely prevents the interference signals from being transmitted through the

Transformer get to the load.

In a preferred embodiment, the energy source has a transformer, via which it is connected to the load, the transformer having a secondary winding connected in series with the line. The arrangement is galvanically isolated from the line by the transformer.

The switching element, the electrical path and optionally the transformer are preferably three-phase. As a result, the arrangement can advantageously be used in a three-phase low, medium or high voltage network.

The energy supply network can also be a single-phase AC network. The arrangement is then correspondingly single-phase.

According to the invention, the object directed to a method for electrical energy supply is solved by a method for electrical energy supply of an electrical one

Load, in which in normal operation the electrical load is connected to an electrical power supply network via an electrical line implemented with at least two electrical conductors, wherein the line is connected in series to an energy supply unit which serves to supply the load with energy, and m is a fault operation electrical power supply network is separated from the line by a switching element and a closed circuit with the load 6 and the power supply unit to which the

Conductors between the switching element and the power supply unit are short-circuited. In the method, the electrical energy supply of the electrical load takes place solely from the energy supply unit. This is advantageous for the disruption operation, in which a total failure of the energy supply through the energy supply network is assumed.

Advantageously, a frequency, an amplitude and a phase position of a voltage delivered by the energy supply unit to the load are synchronized with the network frequency, the amplitude and the phase position of the line voltage supplied by the energy supply network to the line, and the energy supply network with separation of the previously formed closed circuit connected to the line. If the electrical power supply network is disconnected from the line and a trouble-free power supply of the electrical load from the power supply network is possible, the method is used to reconnect the electrical power supply network to the line. A simple return to normal operation is thus possible. The advantages of the arrangement listed above apply mutatis mutandis to the method.

The arrangement and the method of energy supply are explained in more detail with reference to the exemplary embodiments shown schematically in the drawing. Show it:

1 shows an arrangement for the electrical energy supply of an electrical load,

2 shows an alternative embodiment of the electrical path for the arrangement according to FIG. 1, FIG. 3 shows a further arrangement for energy supply and 7 FIG 4 shows an arrangement for energy supply for a single-phase energy supply network.

Corresponding parts are provided with the same reference symbols in all figures. Unless otherwise stated, the voltages and currents referred to in the arrangements which are designed for a plurality of phases relate to one of the phases.

1 shows an arrangement 1 for the electrical energy supply of an electrical load 2. The electrical load 2 is connected via an electrical line 3 to an electrical power supply network 4, which can in particular be designed as a three-phase medium or low voltage network for energy distribution. The electrical load 2 can, for example, be a factory, in particular for the production of semiconductor components, which requires a stable, fail-safe energy supply. With such a load 2, a power failure can cause a running production process to be considerably disturbed. After a fault in the production process, it may be necessary to restart it. This can result in part of the results of the production process being unusable, so that great damage occurs. A safe power supply for load 2 is therefore of great importance. In the present case, line 3 is designed as a three-phase line, each with three conductors 5, 6 and 7. A switching element 8 is connected in line 3, with which the energy supply network 4 can be separated from line 3.

The arrangement 1 has an energy supply unit 12A with an energy source 12 and a transformer 13, via which the energy supply unit connects the line 3 in series. is switched. The energy supply unit 12 can also be designed without a transformer 13 and can be directly galvanically connected to the line 3. To supply power to the load 2, electrical energy can be taken from the energy source 12 and can be delivered to the load 2 via the transformer 13.

The transformer 13 has three secondary windings 9, 10 and 11, each of which is connected in series with an associated conductor 5, 6 and 7, respectively. An electrical path 14 can be connected to the conductors 5, 6 and 7 in such a way that they can be short-circuited to one another between the switching element 8 and the power supply unit 12A. The electrical path 14 is connected to the conductors 5, 6 and 7 via the terminals 50, 51 and 52. Both the switching element 8 and the electrical path 14 are designed with controllable valves 15 to 20.

The controllable valves 15 to 20 are in particular as controllable semiconductor valves 15 to 20, e.g. as thyristors or as shutdown thyristors (GTO). The controllable valves 15, 16 and 17 of the switching element 8 and the controllable valves 18, 19 and 20 of the electrical path 14 can each be controlled by a control device (not shown in more detail) (see also description of FIG. 4). Furthermore, the controllable valves 18 to 20 are connected as a star.

In normal operation, the energy supply network 4 outputs three phase voltages U 1, U 2 and U 3 to the load 2 via the line 3. In the event of a fault in one of the phase voltages U1 to U3, in particular a decrease or a deviation from the sinusoidal shape, the energy source 12 can supply a supply voltage UA1, UB1 or UC1 to the transformer 13, which acts as compensation voltages UA2, UB2 or UC2 the respective phase voltages Ul, U2 or U3 are added. 9 This causes a fault in one of the phase voltages Ul to

U3 can be counteracted by adding one of the compensating voltages UA2 to UC2.

Especially in the event of a total failure of the energy supply network 4, which is to be understood as a failure or a significant drop in one of the phase voltages U1 to U3, the electrical energy supply network 4 is separated from the line 3 by the switching element 8. To form a respectively closed circuit of one of the conductors 5, 6 and 7 with the respective secondary windings 9, 10 and 11 and the load 2, the conductors 5, 6 and 7 are connected via the electrical path 14 with the controllable valves 18, 19 and 20 can be short-circuited with one another between the switching element 8 and the power supply unit 12A. The load 2 is then supplied with energy from the energy supply unit 12A. The energy source 12 only delivers energy via the transformer 13 to the load 2.

The procedure for disconnecting the power supply network 4 and for shorting the conductors 5, 6 and 7 is as follows:

It is assumed in the following that all phase voltages U1, U2 and U3 each have a time course oscillating about a reference value and, for example, the voltage U1 is suddenly severely disturbed, including, for example, a sharp drop (possibly below a predetermined limit value) of the amplitude the voltage Ul is to be understood. At a time when the voltage Ul is less than the reference value, the valves 18 and 19 of the electrical path 14 are closed, whereby the conductors 5 and 6 are short-circuited. During this, the valve 15 of the 10 switching element 8 opened so that the conductor 5 is separated from the power supply network 4. The valve 20 is subsequently closed, so that all conductors are now short-circuited to one another. The valves 16 and 17 of the switching element are also opened so that the power supply network 4 is now completely separated from the line 3. The time sequence and sequence of opening valves 15-17 and closing valves 18-20 can be varied depending on the fault. This applies in particular to the resulting sequence of short-circuiting and the conductors 5, 6 and 7 and the sequence of disconnection of the conductors 5, 6 and 7 from the energy supply network 4.

To switch the electrical power supply network 4 back on to the line and to open the short circuits of the conductors 5, 6 and 7, the procedure is as follows:

It is assumed that the phase voltages U1 to U3 are again emitted undisturbed by the power supply network and each have a network frequency, amplitude and a phase sequence to one another. Furthermore, it is assumed that the compensation voltages UA2, UB2 and UC2 delivered by the energy source 12 to the load 2 each have a frequency, amplitude and a second phase sequence.

For re-connection, the frequency and the amplitudes of the compensating voltages UA2, UB2 and UC2 are first synchronized with the mains frequency, the amplitudes and the second phase sequence with the phase sequence of the mains voltages U1 to U3. For this purpose, generally known synchronizing devices with associated measuring devices are not shown. Following the synchronization, at a time when the voltage Ul is less than the reference value 11, the valves 15 and 16 of the switching element 8 are closed and the valve 18 of the electrical path 14 is opened. This eliminates the short circuit between conductors 5 and 6 and connects conductors 5 and 6 to the power supply network. Then, in time, the valves 19 and 20 of the electrical path are opened and the valve 17 of the switching element 8 is closed. As a result, the power supply network 4 is reconnected to the line 3 and the short circuit between the conductors 5, 6 and 7 is canceled again. The chronological sequence and sequence of the closing of the valves 15-17 and the opening of the valves 18-20 can be varied depending on the fault.

An alternative embodiment of an electrical path 21 is shown in FIG. The electrical path 21 has the controllable valves 22, 23 and 24. The valves 22 to 24 are connected as a triangle. The terminals 50, 51 and 52 can be short-circuited via the valves 22 to 24. The electrical path 21 can be switched to the terminals 50, 51 and 52 (see FIG. 1) instead of the electrical path 14 (see FIG. 1). The choice of delta or star connection for the electrical path 14, 21 depends on the respective application and on the properties of the components used to form the electrical path 14, 21.

FIG. 3 shows a further arrangement 1 a for the electrical energy supply of the load 2. In contrast to the arrangement 1 shown in FIG. 1, the star point 26 of the energy supply network 4 is connected to a reference point 27 of the load 2. The electrical path 14 is modified and likewise has a star point 25, which is connected to the star point 26 of the energy supply network 4 and the reference point 27 of the electrical load 2. 12

Furthermore, the conductors 5, 6 and 7 are each connected to the electrical power supply network 4 via a respective choke L1, L2 and L3. It can thus be avoided that possibly occurring fault signals US2 reach the power supply network 4 via the conductors 5 to 7. The chokes L1, L2 and L3 can also each be part of the switching element 8.

The energy source 12 of the energy supply unit 12A has an energy store 28 which is connected to the transformer 13 via a converter 29 and a filter 30. The energy store 28 supplies its electrical energy in the form of a current I or a voltage U to the converter 29 in order to supply the load 2 with energy. The delivered energy is converted by the converter 29 and, after filtering by the filter 30, is delivered to the load 2 via the transformer 13. The filter 30 is used to filter the currents IP1 to IP3 or voltages UPI to UP3 output by the converter 29.

The energy store 28 can be designed to store both mechanical and electrical energy and can be designed, for example, as a flywheel store or as a magnetic store. To store electrical energy, the energy store 28 can have a superconducting magnet 35, which is indicated schematically in FIG. 3.

A further arrangement 1 for the electrical energy supply of the load 2 is shown in FIG. 4, the electrical line 3 being designed as a single-phase line 3 with the conductors 31 and 32. The power supply unit 12A has a transformer 13, which is likewise of a single-phase design 13, via which it is connected to line 3 and thus to load 2. The transformer 13 has only one secondary winding 33, which is connected to the conductor 31 in series.

The switching element 8 is also connected in series with the conductor 31. The electrical power supply network 4 can be separated from the conductor 31 by the switching element 8. The switching element 8 is designed with controllable valves 34, which are designed as controllable semiconductor valves 34. The electrical path 14 serves to short-circuit the conductors 31 and 32 to form a closed circuit with the secondary winding 33 and the load 2. The electrical path 14 has the controllable valves 35a, which are designed in particular as controllable semiconductor valves 35a.

In normal operation, the energy supply network 4 outputs an electrical voltage UE to the load 2 via the line 3. In the event of a disturbance in the voltage UE, electrical energy can be drawn from the energy source 12 and can be supplied to the load as a compensating voltage UA via the transformer 13. Due to the serial connection of the secondary winding 33 m the line 31, the compensation voltage UA can be added to the voltage UE.

In the event of a total failure of the electrical power supply network 4, which means that there is no or a sharp drop in the voltage UE, the power supply network 4 is disconnected from the line 3 by the switching element 8 and the conductors 31 and 32 are short-circuited via the electrical path 14. The electric power supply of the load 2 is performed all from the power source 12 of the Energieversor ^¬ supply unit 12A. In the event of a total failure, the compensating voltage UA is used completely to supply the load 2. 14

The arrangement 1b furthermore has a control device 36. The control device 36 is connected to a measuring device 37 via a first measuring line 38, the measuring device 37 being connected to the line 31. The control device 36 is connected to the energy source 12 via a second measuring line 43. Furthermore, the control device 36 is connected to the switching element 8 via a first control line 40, to the electrical path 14 via a second control line 41 and to the energy supply unit 12 via a third control line 42. The control device 36 and the measuring device 37 and other measuring devices which are present in the energy source 12 and are not shown for better clarity are used to control the switching element 8 and the electrical path 14, or to measure the phase voltage UE and the compensation voltage UA emitted by the energy source.

The control device 36 and the associated measuring devices 37 for all the arrangements 1, 1a and 1b described here are shown by way of example in FIG. They therefore apply mutatis mutandis as a component of the arrangements 1 and la shown in FIGS. 1 and 3. The measuring devices have the task of measuring the phase voltages U1, U2 and U3 (see FIG. 1), their line frequency, amplitudes and phase sequence. Furthermore, they serve to measure the amplitudes of the compensating voltages UA2, UB2 and UC2, their frequency and their phase sequence as well as the acquisition of all measured quantities which are necessary for monitoring normal operation and fault operation.

The control device serves to control the switching element 8, the electrical path 14 and the energy source 12 in normal operation and in fault operation, in particular in one 15 Disconnecting and switching on the power supply network

4th

Claims

16 claims

1. Arrangement (1) for supplying electrical energy to an electrical load (2), which is connected to an electrical line (3) with at least two electrical conductors (5 and 6; 31 and 32) and a switching element (8) electrical power supply network (4) can be connected and separated from it, with an electrical power supply unit (12A) which serves at least partially to supply power to the electrical load (2) and is connected in series in the line (3), a controllable electrical path ( 14, 21) is provided, via which the electrical conductors (5 and 6; 31 and 32) can be short-circuited at a location between the switching element (8) and the power supply unit (12A).

2. Arrangement according to claim 1, wherein the switching element (8) and / or the electrical path (14, 21) each have at least one controllable valve (15, 16, 17 or 18, 19, 20), in particular a controllable semiconductor valve ( 15, 16, 17 or 18, 19, 20).

3. Arrangement according to claim 1 or 2, wherein the switching element (8) and / or the electrical path (14, 21) each have at least one inductance (L1, L2, L3).

4. Arrangement according to one of the preceding claims, wherein the energy source (12) has an energy store (28) which can be connected to the load (2) via a converter (29).

5. Arrangement according to claim 4, wherein the energy store (28) is designed for storing electrical and / or mechanical energy. 17

6. Arrangement according to claim 5, wherein the energy store (2!) Has a superconducting magnet (35).

7. Arrangement according to one of claims 4 to 6, wherein the converter (29) via a filter (30) with the load (2) can be connected.

8. Arrangement according to one of the preceding claims, wherein the power supply unit (12A) has a transformer (13), via which it is connected to the load (2), the transformer (13) having a secondary winding connected in series with the line (3) (9, 10, 11).

9. Arrangement according to one of the preceding claims, wherein the switching element (8), the electrical path (14, 21) and optionally the transformer (13) are three-phase.

10. Method for the electrical energy supply of an electrical load (2), in which the electrical

Load (2) is connected to an electrical power supply network (4) via an electrical line (3) formed with at least two electrical conductors (5 and 6 or 31 and 32), wherein the line (3) m serially an energy supply unit (12A ) is connected, which is used to supply power to the load (2), with the electrical power supply network (4) being separated from the line (3) by a switching element (8) in a fault mode and a closed circuit with the load (2) and the Power supply unit (15) is formed, m the conductors (5 and 6 or 31 and

32) between the switching element (8) and the power supply unit (12A) are short-circuited. 11. The method according to claim 10, wherein the frequency, amplitude and phase position of a voltage (U) emitted by the power supply unit (12A) via the transformer (13) to the load (2) with the mains frequency, the amplitude and phase position of that The power supply network (4) is synchronized to the line (3) and the power supply network (4) is connected to the line (3) by separating the previously formed closed circuit.