Electrical device comprising a gas-insulated apparatus, in particular a gas-insulated transformer or reactor

Abstract

The present invention relates to an electrical device comprising a gas-insulated transformer or reactor. The electrical device comprises a housing enclosing an interior space, at least a portion of which defining an insulation space containing a dielectric insulation fluid comprising an organofluorine compound, and an electrical component being arranged in the insulation space and being surrounded by the insulation fluid. The electrical component comprises at least one winding. The electrical device further comprises an electrical connector for bringing the apparatus from non-operational state to operational state by connecting at least one winding to a power grid. The device further comprises an auxiliary power source which is connectable to at least one winding when the apparatus is in the non-operational state.

Claims

1. An electrical device comprising an electrical apparatus including a gas insulation, the electrical apparatus is one of a gas-insulated transformer or gas-insulated reactor, comprising a housing enclosing an interior space, at least a portion of which interior space defining an insulation space containing a dielectric insulation fluid comprising an organofluorine compound, and an electrical component being arranged in the insulation space and being surrounded by the insulation fluid, said electrical component comprising at least one winding, the electrical device further comprising an electrical connector for bringing the electrical apparatus from a non-operational state to an operational state by connecting one or more of the at least one winding to a power grid, wherein the device further comprises an auxiliary power source which is connectable to one or more of the at least one winding when the electrical apparatus is in the non-operational state, wherein the auxiliary power source is an auxiliary alternating-current power source, and wherein the auxiliary alternating-current power source has an electrical power rating comparable to rated load losses of the electrical apparatus.

2. The electrical device according to claim 1, wherein the electrical apparatus is a gas-insulated transformer, specifically a gas insulated power transformer, the electrical component of which comprising at least two windings per phase, including a primary winding and a secondary winding per phase, and further comprising a magnetic core, and the electrical connector operable for bringing the transformer from a non-operational state to an operational state by connecting the primary winding to the power grid.

3. The electrical device according to claim 1, wherein the auxiliary power source is designed such to generate heat in the at least one winding that is connected to the auxiliary power source, during the non-operational state of the electrical apparatus.

4. The electrical device according to any one claim 1, wherein the auxiliary power source is operable to generate heat for evaporating the dielectric insulation fluid at least partially to increase the dielectric strength of the gas phase of the dielectric insulation fluid above an operational threshold dielectric strength value of the electrical apparatus.

5. The electrical device according to claim 1, which further comprises means for short-circuiting at least one winding, which is not to be connected to the auxiliary power source, when the electrical apparatus is off-grid.

6. The electrical device according to claim 5, wherein the means for short-circuiting comprise a circuit breaker for interrupting and keeping the electrical apparatus off-grid.

7. The electrical device according to claim 1, wherein the auxiliary alternating power source is rated such to induce a voltage in the at least one winding connected to the auxiliary alternating power source so that at most 200% of the rated current in the at least one short-circuited winding is generated.

8. The electrical device according to claim 1, wherein the auxiliary power source is a direct-current (DC) power source, in particular for supplying power to secondary equipment of the electrical apparatus, for generating ohmic losses in the at least one winding, that is connected to the auxiliary power source, during the non-operational state of the electrical apparatus.

9. The electrical device according to claim 1, wherein the auxiliary power source is a high-frequency power source.

10. The electrical device according to claim 2, wherein the auxiliary power source is a high-frequency power source for generating high-frequency magnetic losses in the magnetic core of the gas-insulated transformer during the non-operational state of the gas-insulated transformer.

11. The electrical device according to claim 1, wherein the electrical connector is an electrical switch for switching the at least one winding from being connected to the power grid to being connected to the auxiliary power source.

12. The electrical device according to claim 1, wherein the electrical connector comprises a circuit breaker, for interrupting and keeping the electrical apparatus off-grid, in particular for interrupting and keeping interrupted the primary side of the electrical apparatus from the grid, and further comprises contact means for connecting at least one of the at least one windings to the auxiliary power source when the electrical apparatus is off-grid, in particular when the electrical apparatus is separated on its primary side from the grid.

13. The electrical device according to claim 1, wherein the auxiliary power source is operable for further supplying power to at least one fan and/or to at least one additional thermal element attributed to the electrical apparatus.

14. The electrical device according to claim 1, wherein the organofluorine compound is selected from the group consisting of: fluoroethers, fluoroketones, fluoroolefins and mixtures thereof.

15. The electrical device (1) according to claim 1, wherein the insulation fluid comprises a hydrofluoromonoether containing at least three carbon atoms.

16. The electrical device according to claim 1, wherein the insulation fluid comprises a fluoroketone containing from four to twelve carbon atoms.

17. The electrical device according to claim 1, wherein the insulation fluid further comprises a background gas, the background gas selected from the group consisting of air, an air component, nitrogen, oxygen, carbon dioxide, a nitrogen oxide, and mixtures thereof.

18. An electrical apparatus including a gas insulation for use in an electrical device according to claim 1, the apparatus comprising a radiator for transferring heat from the interior space to the outside of the electrical apparatus, the radiator being designed to be passed by a heat transfer fluid carrying heat generated in any of at least one winding of the electrical apparatus and/or in a magnetic core of the electrical apparatus, the flow of the heat transfer fluid defining a heat transfer fluid path, wherein the electrical apparatus further comprises a bypass channel for the heat transfer fluid which upstream of the radiator branches off from the heat transfer fluid path, such that at least a portion of the heat transfer fluid is allowed to bypass the radiator.

19. The electrical apparatus according to claim 18, wherein the electrical apparatus is one of a gas-insulated transformer or gas-insulated reactor.

20. The electrical apparatus according to claim 18, wherein downstream of the branching off the bypass channel the heat transfer fluid path forms a radiator inlet channel, and at the branching off of the bypass channel a valve is arranged for at least partially opening and closing the bypass channel and the radiator inlet channel, respectively.

21. The electrical apparatus according to claim 18, wherein directly adjacent to and downstream of the radiator the heat transfer fluid path forms a radiator outlet channel, the bypass channel opening into the radiator outlet channel at a distance from the radiator.

22. The electrical apparatus according to claim 18, further comprising a fan for generating a flow of the heat transfer fluid, in particular a flow from the bypass channel and/or from the radiator outlet channel into the insulation space, and/or for homogenously mixing the fluid components contained in the heat transfer fluid.

23. The electrical apparatus a to claim 18, further comprising a collecting tank for collecting condensate of the insulation fluid.

24. The electrical apparatus according to claim 18, further comprising an additional thermal element for vaporizing condensate.

25. The electrical apparatus according to claim 22, wherein the additional thermal element and/or the fan is or are connected to the auxiliary power source for power supply.

26. The electrical apparatus according to claim 18, further comprising at least one control device for controlling electrical operation of the electrical apparatus and/or of the composition of the insulation fluid.

Description

(1) The present invention is further illustrated by way of the attached figures, which show in:

(2) FIG. 1 a purely schematic illustration of an exemplary electrical device of the present invention comprising an inventive gas-insulated transformer;

(3) FIG. 2 a switching configuration of a primary side of a transformer of the exemplary device according to the present invention; and

(4) FIG. 3 a switching configuration of a secondary side of a transformer of the exemplary device according to the present invention.

(5) According to FIG. 1, the exemplary electrical device 1 comprises an electrical apparatus 10 including a gas insulation, in the specific embodiment being shown a gas-insulated transformer 101. The transformer 101 comprises a housing 12 enclosing an interior space 14. The interior space 14 defines an insulation space 16 containing a dielectric insulation fluid comprising an organofluorine compound.

(6) In the insulation space 16, an electrical component 18 is arranged and surrounded by the insulation fluid. The electrical component 18 comprises a first winding 20, i.e. the primary winding 20, formed of a first conductor 19, and a second winding 22, i.e. the secondary winding 22, formed of a second conductor 21, both of which are arranged around a magnetic core 24 in the embodiment shown. For both the first conductor 19 and the second conductor 21, respective bushings 26a, 26b and 28a, 28b, respectively, are arranged in the wall 30 of the housing 12.

(7) The device 1 further comprises an electrical connector 32 for bringing the transformer 101 from a non-operational state to an operational state. According to the embodiment shown, this is achieved by the electrical connector 32 connecting the primary winding 20 to the power grid.

(8) The device 1 further comprises an auxiliary power source 34 which is connectable to the primary winding 20 when the transformer 101 is in the non-operational state, i.e. when the transformer 101 is galvanically isolated from the power grid. In the embodiment shown, the auxiliary power source 34 is an alternating power source and the electrical connector 32 is an electrical switch 321 for switching the primary winding 20 from being connected to the power grid to being connected to the auxiliary power source 34.

(9) According to the embodiment shown, the electrical device 1 comprises means 36, in particular a switch 361, for short-circuiting the secondary winding 22. As disclosed in FIG. 3 in conjunction with FIG. 1, the means 36; 361; 41a, 41b; 42a, 42b, 42c for short-circuiting can comprise a circuit breaker CB2, 42a, 42b, 42c for interrupting and keeping the electrical apparatus 10 off-grid, in particular for interrupting the electrical apparatus 10 on its secondary side and keeping it interrupted on its secondary side from the grid.

(10) An exemplary switching configuration of the primary side (here supply side) of the transformer 101 is shown in FIG. 2, while a specific configuration of the secondary side (here load side) is shown in FIG. 3. According to the specific embodiment, the transformer 101 is thus a three-phase power transformer 101 employing star-connected windings 20a, 20b, 20c on the primary side and delta-connected windings on the secondary side, the wires of the respective phase being abbreviated with L1, L2, L3 with the neutral wire of the star configuration being abbreviated with N.

(11) In the non-operational state shown, the contacts 38a, 38b, 38c, 38d in the circuit breaker CB1, or first three-phase circuit breaker CB1, attributed to the primary side are open and the transformer 101 is thus galvanically isolated from the power grid. In this state, the primary windings 20a, 20b, 20c can be connected to the auxiliary power source 34 by closing the respective contacts 40a, 40b, 40c, the corresponding wires being abbreviated by Aux.sub.1, Aux.sub.2 and Aux.sub.3.

(12) On the secondary side, the windings 22a, 22b, 22b can be short-circuited by means of the respective contacts 41a, 41b when the contacts 42a, 42b, 42c in the respective circuit breaker CB2, or second three-phase circuit breaker CB2, are open. Thus, the means 36; 361; 41a, 41b; 42a, 42b, 42c for short-circuiting can comprise a circuit breaker CB2, 42a, 42b, 42c for interrupting and keeping the electrical apparatus 10 off-grid, in particular for interrupting the electrical apparatus 10 on its secondary side and keeping it interrupted on its secondary side from the grid. Thereby, the contacts 41a, 41b function as shortcircuiting contacts between windings 20 or 22, here between secondary windings 22a, 22b, 22c.

(13) By the auxiliary alternating power source 34, a voltage can be induced in the windings 20a, 20b, 20c of the primary side to generate at least approximately the rated current in the windings 22a, 22b, 22c of the secondary side, ultimately allowing for an efficient heating of the insulation space 16 by power losses and thus for maintaining the insulation fluid, and in particular the organofluorine compound contained therein, in the gaseous phase.

(14) In exemplary embodiments, a sink 44 is arranged in the bottom wall 30 of the housing shown in FIG. 1, which sink 44 opens into a collecting tank 46. The sink 44 and the collecting tank 46 are designed for collecting condensate of the insulation fluid. To the collecting tank 46, an additional thermal element 48 in the form of a heat coil 481 is attached for vaporizing condensate contained in the collecting tank 46. The additional thermal element 48 is connected to the auxiliary power source 34 for power supply.

(15) In exemplary embodiments, the transformer 101 can further comprise a fan 50 which in the embodiment shown is arranged in the bottom region of the housing 12. Like the auxiliary power thermal element 48, also the fan 50 can for example be connected to the auxiliary power source 34 for power supply.

(16) The transformer 101 can further comprise a radiator 52 which is connected to the housing 12 in a distance from the electrical component 18. The radiator 52 is designed to be passed by a heat transfer fluid carrying heat generated in any of windings 20, 22 and/or the core 24, and to thereby transfer heat from the interior space 14 to the outside of the transformer 101.

(17) The flow of the heat transfer fluid defines a heat transfer fluid path 54, which is only schematically shown in FIG. 1 by means of arrows.

(18) The electrical apparatus 10 can further comprise a bypass channel 56 for the heat transfer fluid which upstream of the radiator 52 branches off from the heat transfer fluid path 54, such that at least a portion of the heat transfer fluid is allowed to bypass the radiator 52.

(19) Downstream of the branching off of the bypass channel 56, the heat transfer fluid path 54 forms a radiator inlet channel 58, which opens into the radiator 52. At the branching off of the bypass channel 56, a valve 60, specifically a three-port valve 60, can be arranged for at least partially opening and closing the bypass channel 56 and the radiator inlet channel 58, respectively.

(20) Directly adjacent to and downstream from the radiator 52, i.e. in direction of the downstreaming heat transfer fluid, the heat transfer fluid path 54 forms a radiator outlet channel 62, into which the bypass channel 56 opens at a distance from the radiator 52.

(21) By means of the fan 50, a flow of the heat transfer fluid, specifically from the bypass channel 56 and/or the radiator outlet channel 62 in particular into the insulation space 16, can be generated.

(22) The transformer 101 further comprises a temperature sensor 64, specifically a thermometer, a pressure and/or gas density sensor 66, specifically a manometer, and a chemical sensor 68, specifically a chromatographic sensor or an optical sensor, more specifically a UV sensor. By means of these sensors, the actual conditions in the insulation space 16 can be determined. In particular, the gas composition or gas density can be determined and compared to the nominal composition and/or nominal density.

(23) For example prior to operation of the transformer 101, i.e. in a starting phase in which the windings 20, 22 are still galvanically isolated from the power grid, the primary winding 20 is connected to the auxiliary power source 34 and the secondary winding is short-circuited. In the embodiment shown, the auxiliary power source 34 is an auxiliary alternating-current power source 341 that is rated such to induce in the primary winding 20 the voltage required for generating at most 100% of the rated current in the secondary winding 22. Due to the power losses, the windings 20, 22 are heated, thus effecting a temperature increase in the insulation space 16 allowing condensed insulation fluid to be brought in the gaseous state. Ultimately, an insulation gas of the nominal composition and, consequently, of a sufficiently high dielectric strength can thus be achieved prior to starting operation of the transformer 101.

(24) In other words, the auxiliary power source 34 is designed such to generate heat for evaporating the dielectric insulation fluid at least partially or fully to increase the dielectric strength of the gas phase of the dielectric insulation fluid above an operational threshold dielectric strength value of the electrical apparatus 10.

(25) Thus, preferably the windings 20, 22 of the transformer 101 act as a heating element generating the amount of heat required for evaporating any condensate of the insulation fluid present in the insulation space 16 prior to operation.

(26) During operation, a constant flow of heat transfer fluid is generated by means of the fan 50 described above, thus ensuring that the transformer 101 is constantly cooled. The fan 50 also serves to permanently mix the insulation fluid, in order to obtain a homogenous insulation fluid composition and heat distribution throughout the whole insulation space 16.

(27) By means of the above mentioned sensors 64, 66, 68, the conditions in the insulation space 16, in particular the temperature, the pressure as well as the composition and density of the insulation fluid, can be constantly monitored.

(28) If for example the temperature measured and/or a comparison of the partial pressure of organofluorine compound to the nominal value reveals that there is need for liquid organofluorine compound to be brought in the gaseous phase, this can be achieved by means of the valve 60 controlling the amount of heat transfer fluid bypassing the radiator 52. Specifically, the amount of heat transfer fluid to bypass the radiator 52 is increased.

(29) If, on the other hand, the temperature measured reveals that excess heat is generated also in consideration of the heat needed for maintaining the insulation fluid in fully gaseous state, said excess heat can be emitted by directing the respective amount of heat transfer fluid to pass the radiator 52. For this purpose, the bypass channel 56 can be closed.

(30) For controlling electrical operation of the transformer 101 and/or the composition of the insulation fluid, the transformer comprises a control device 70, which allows controlling for example the mode of the fan 50 and the degree to which the bypass channel is opened, for example by controlling the mode of the valve 60.

LIST OF REFERENCE NUMERALS

(31) 1 electrical device 10, 101 electrical apparatus; transformer 12 housing 14 interior space 16 insulation space 18 electrical component 19 first wire 20 first (primary) winding 21 second wire 22 second (secondary) winding 24 magnetic core 26a, 26b bushing for first wire 28a, 28b bushing for second wire 30, 30 housing wall; bottom wall of housing 32 electrical connector 321 electrical switch 34; 341 auxiliary power source; auxiliary alternating power source 36, 361 means for short-circuiting secondary winding; switch 38a-38d contacts in circuit breaker (primary side) 40a-40c contacts for connecting windings (primary side) to auxiliary power source 41a, 41b contacts for short-circuiting windings (secondary side) 42a-42c contacts in circuit breaker (secondary side) 44 sink 46 collecting tank 48, 481 additional thermal element, heat coil 50 fan 52 radiator 54 heat transfer fluid path 56 bypass channel 58 radiator inlet channel 60 valve 62 radiator outlet channel 64 temperature sensor 66 pressure and/or gas density sensor 68 chemical sensor 70 control device