Assembly having a DC circuit breaker
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SIEMENS ENERGY GLOBAL GMBH & CO KG
- Filing Date
- 2023-09-26
- Publication Date
- 2026-06-24
AI Technical Summary
The existing technologies for energy supply of DC power switches, especially in high-voltage applications, face challenges due to the need for large and costly transformers to handle potential differences, making the energy transfer inefficient and expensive.
An arrangement and procedure utilizing a DC power switch with first and second DC connections, a mechanical switching element, first and second capacitors for potential separation, and an energy decoupling construction element, which allows for the connection of alternating current into a mesh formed by the DC power switch, capacitors, and energy decoupling element, thereby reducing the need for large transformers.
This solution enables efficient and cost-effective energy supply to DC power switches by using capacitors for potential separation, reducing the reliance on expensive transformers and simplifying the energy transfer process, especially in high-voltage applications.
Smart Images
Figure EP2023076485_03042025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Arrangement with a DC circuit breaker
[0003] The invention relates to an arrangement with a DC circuit breaker and a method for supplying energy to a DC circuit breaker.
[0004] In the future, DC circuit breakers will be used more frequently to switch large direct currents, for example in direct current networks. One such DC circuit breaker is known, for example, from document W02016 / 003357A1 or W02017 / 116296A1. The DC circuit breaker requires electrical energy during operation, for example for a power electronic circuit of the DC circuit breaker or for driving a mechanical switching element of the DC circuit breaker. Since the DC circuit breaker is at the electrical potential of the DC electrical line to be switched, the electrical energy must be transferred to the DC circuit breaker in a potential-isolated manner. This energy transfer with potential separation can be complex, particularly when switching direct currents at high voltage levels.For example, it is conceivable to transfer the electrical energy from the ground potential to the potential of the DC circuit breaker using one or more transformers. These transformers would then have to be able to withstand the voltage differences that occur. For large voltage differences, such transformers are comparatively large and cost-intensive.
[0005] The invention is based on the object of specifying an arrangement and a method for supplying power to a DC circuit breaker that can be implemented cost-effectively. This object is achieved according to the invention by an arrangement and a method according to the independent patent claims. Advantageous embodiments of the arrangement and the method are specified in the dependent patent claims.
[0006] An arrangement is disclosed comprising a DC power switch, a first electrical capacitor, a second electrical capacitor and an energy coupling component, wherein
[0007] - the DC circuit breaker has a first DC connection, a second DC connection and a mechanical switching element,
[0008] - the mechanical switching element in its open state electrically separates the first DC terminal from the second DC terminal (and in its closed state electrically connects the first DC terminal to the second DC terminal),
[0009] - the first capacitor electrically connects the first DC terminal to an (electrical) reference potential,
[0010] - the second capacitor electrically connects the second DC terminal to the reference potential, and
[0011] - the energy coupling component is designed to couple an alternating current into a mesh formed by the DC power switch, the first capacitor and the second capacitor.
[0012] It is advantageous that the potential separation between the reference potential and the potential of the DC circuit breaker is achieved by means of the first capacitor and the second capacitor. Such capacitors are comparatively simple and cost-effective components.
[0013] The arrangement can be configured such that the energy coupling component is an alternating current source or an alternating voltage source, in particular a transformer or a transmitter. The energy coupling component does not need to be suitable for the potential separation between the reference potential and the potential of the DC power switch, because this potential separation is realized by means of the first capacitor and the second capacitor.
[0014] The arrangement can also be designed such that the energy coupling component is arranged substantially at the reference potential or is electrically connected to the reference potential.
[0015] This makes coupling the alternating current into the mesh particularly simple and cost-effective.
[0016] The arrangement can be designed so that the reference potential is the earth potential.
[0017] The arrangement can be designed such that the mechanical switching element is a vacuum interrupter.
[0018] By means of a vacuum interrupter, a particularly sustainable DC circuit breaker can be realized because, for example, no climate-damaging insulating gases are used.
[0019] The arrangement can be designed such that a main current path of the DC power switch is formed between the first DC connection and the second DC connection, and an inductive component, in particular an air choke, is arranged in the main current path.
[0020] The inductive component advantageously prevents the coupled alternating current from flowing through the main current path of the DC circuit breaker. As a result, the coupled alternating current has little or no effect outside the arrangement (in particular in a DC line or in a DC network in which the arrangement is arranged). The arrangement can be designed such that a second current path is electrically connected in parallel with the main current path.
[0021] The coupled alternating current advantageously commutates into this second current path.
[0022] The arrangement can be designed such that a capacitive component, in particular a capacitor, is arranged in the second current path.
[0023] The capacitive component is part of an oscillating circuit which, in particular, supports the switching off of the direct current by means of the direct current power switch.
[0024] The arrangement can be designed such that the capacitive component forms a series resonant circuit with the inductive component of the main current path.
[0025] This series resonant circuit particularly supports the switching off of the direct current by means of the direct current circuit breaker.
[0026] The arrangement can be designed such that the inductive component of the main current path is part of a parallel resonant circuit which is arranged in the main current path, and the capacitive component is part of a series resonant circuit which is arranged in the second current path.
[0027] This parallel resonant circuit (blocking circuit) advantageously prevents the coupled alternating current from flowing through the main current path of the DC circuit breaker. As a result, the coupled alternating current has little or no effect outside the circuit.
[0028] This series resonant circuit (absorption circuit) particularly supports the switching off of the direct current by means of the DC power switch by supporting the flow of the coupled alternating current into the second current path. The arrangement can be designed such that the series resonant circuit comprises the capacitive component and a second inductive component in a series circuit.
[0029] The arrangement can be designed such that the parallel resonant circuit has the inductive component and a second capacitive component.
[0030] The arrangement can be designed such that a rectifier and an electrical energy storage device are arranged in the second current path.
[0031] The energy storage device can advantageously be charged by means of the coupled alternating current, which is rectified by the rectifier. Advantageously, electrical energy can be extracted from the electrical energy storage device in order to supply the DC circuit breaker or components of the DC circuit breaker with electrical energy.
[0032] In particular, a switching device can additionally be arranged in the second current path, with which the energy storage device can be bridged if necessary without discharging it (i.e., the charging current can be bypassed by the energy storage device). In this case, the switching device can be designed, in particular, as a full-bridge circuit having four switches.
[0033] The DC circuit breaker may be a high-voltage DC circuit breaker.
[0034] Furthermore, a method for supplying energy to a DC circuit breaker is disclosed, wherein
[0035] - the DC circuit breaker has a first DC connection, a second DC connection and a mechanical switching element,
[0036] - the mechanical switching element in its open state electrically separates the first DC terminal from the second DC terminal (and in its closed state electrically connects the first DC terminal to the second DC terminal),
[0037] - a first capacitor electrically connects the first DC terminal to a reference potential, and
[0038] - a second capacitor electrically connects the second DC terminal to the reference potential, wherein in the method
[0039] - by means of an energy coupling component, an alternating current is coupled into a mesh formed by the DC power switch, the first capacitor and the second capacitor,
[0040] - the alternating current flows through the mesh to the DC circuit breaker, and
[0041] - the alternating current in the DC circuit breaker is used to supply energy to components of the DC circuit breaker.
[0042] The procedure can be carried out in such a way that
[0043] - the alternating current in the DC circuit breaker flows into a second current path electrically connected in parallel to a main current path,
[0044] - the alternating current is rectified by means of a rectifier arranged in the second current path, and
[0045] - an electrical energy storage device arranged in the second current path is charged by means of the direct current generated in this way.
[0046] The alternating current flows in the DC circuit breaker into the second current path, which is electrically connected in parallel with the main current path. In this second current path, a direct current is generated from the alternating current, and the energy storage device is charged with the direct current. The second current path thus enables energy extraction (particularly at the electrical energy storage device) at the electrical potential of the DC circuit breaker, in particular at the high-voltage potential.
[0047] The arrangement and the method have the same or similar properties and / or advantages. The invention is explained in more detail below using exemplary embodiments. The same reference numerals refer to the same or similarly acting elements.
[0048] Figure 1 shows an embodiment of a non-claimed arrangement with a DC circuit breaker, in
[0049] Figure 2 shows an embodiment of an arrangement with a DC power switch, a first electrical capacitor and a second electrical capacitor, and in
[0050] Figure 3 shows another embodiment of a
[0051] Arrangement with a DC circuit breaker, a first electrical capacitor and a second electrical capacitor shown.
[0052] Figure 1 shows a non-claimed exemplary embodiment of an arrangement with a DC power breaker 4. The DC power breaker 4 is supplied with electrical energy by means of a converter 12 arranged at earth potential 10. The energy is transferred from the converter 12 to individual parts of the DC power breaker 4 by means of a first transformer TI and a second transformer T2. The transformers TI and T2 must be able to withstand the electrical potential differences that occur. The voltage Ul occurs at the transformer TI, and the voltage U2 occurs at the transformer T2. With large potential differences / voltages, the transformers TI and T2 are comparatively large and expensive.Figure 2 shows an exemplary embodiment of an arrangement 1 according to the invention with the DC power switch 4, a first capacitor C1, a second capacitor C2 and an energy coupling component 8. The energy coupling component 8 is designed as a transformer. In other exemplary embodiments, the energy coupling component 8 can also be designed as an alternating current source, an alternating voltage source or as a transmitter. The energy coupling component 8 is electrically connected to an electrical reference potential 10. The reference potential 10 is the earth potential in the exemplary embodiment.
[0053] The DC circuit breaker 4 has a first DC connection 13 and a second DC connection 16. By means of the first DC connection 13 and the second DC connection 16, the DC circuit breaker 4 can be connected or is connected to a DC line 18. A DC current Ig flowing in the DC line 18 can be switched by means of the DC circuit breaker 4. The DC circuit breaker 4 is connected in series to the DC line 18. The DC line 18 can, for example, be part of a DC transmission line, in particular part of a high-voltage DC transmission line, or part of a DC transmission network, in particular part of a high-voltage DC transmission network.
[0054] The DC circuit breaker 4 generally has a plurality of identical switch units 17 which are electrically connected in series. In the exemplary embodiment, three switch units 17 are shown; however, the DC circuit breaker 4 can also have a different number of switch units 17. By connecting identical switch units 17 in series, the dielectric strength of the DC circuit breaker 4 is increased. However, the DC circuit breaker 4 also functions with just a single switch unit 17. The function of the DC circuit breaker 4 and the arrangement is explained below using a single switch unit 17, namely the switch unit 17 shown in detail on the right. The other switch units 17 function in a similar way.
[0055] The voltage Ul occurs across the first capacitor Gl, and the voltage U3 occurs across the second capacitor C2. The first capacitor Gl and / or the second capacitor C2 provide electrical isolation between the DC circuit breaker and the reference potential 10. The voltage U2 drops across the DC circuit breaker 4, i.e. across the series connection of the switching units 17 of the DC circuit breaker 4. The voltages Ul and U3 are often of a similar magnitude, particularly when the electrical potential of the DC line 18 is much greater than the reference potential 10. This is the case in high-voltage applications. In high-voltage applications (when the DC circuit breaker is switched on), the voltages Ul and U3 are significantly greater than the voltage U2. The vast majority of the voltages that occur then drop across the first capacitor Gl and the second capacitor C2.
[0056] The DC circuit breaker 4 has a mechanical switching element 19. In the exemplary embodiment, the mechanical switching element 19 is a vacuum interrupter. However, in other exemplary embodiments, the mechanical switching element can also be configured differently.
[0057] A main current path 22 of the DC circuit breaker 4 is formed between the first DC connection 13 and the second DC connection 16. The mechanical switching element 19 and an inductive component Lr are arranged in the main current path 22. The inductive component Lr is preferably designed such that it is not influenced as much as possible by the DC current flowing through it (DC current flow). The inductive component Lr can, in particular, be an air choke. An air choke advantageously has no significant magnetic saturation.
[0058] A second current path 24 is electrically connected in parallel with the main current path 22. A capacitive component Gr is arranged in the second current path 24. The capacitive component Gr can, in particular, be a capacitor. The capacitive component Gr forms a series resonant circuit with the inductive component Lr of the main current path 22. This series resonant circuit, in particular, supports the switching off of the direct current.
[0059] The second current path 24 thus forms a resonant unit or a resonant circuit. A surge arrester MOV is connected electrically parallel to the main current path 22 and / or electrically parallel to the second current path 24.
[0060] The surge arrester MOV forms a third current path. When supplying power to the DC circuit breaker, the surge arrester MOV protects the components of the respective switch unit 17 from overvoltage.
[0061] Four switching elements S1, S2, S3, and S4 are arranged in the second current path 24 and are electrically connected to form a full bridge. The full bridge is connected to an electrical energy storage device 25, which is arranged in particular diagonally of the full bridge. The full bridge with the electrical energy storage device 25 is connected in series with the capacitive component Gr.
[0062] The switching off process of a direct current is described below. Firstly, the electrical energy storage device 25 is charged, the mechanical switching element 19 is closed and the direct current Ig flows through the mechanical switching element 19 and thus through the main current path 22 of the direct current circuit breaker 4. At the start of the switching off process, the mechanical switching element 19 is opened. An arc begins to burn between the opening mechanical switching contacts of the mechanical switching element 19. Because the direct current does not have any zero crossings, the arc does not extinguish at first and the direct current Ig continues to flow. The switching elements S1, S2, S3 and S4 of the full bridge are then controlled in such a way that the electrical energy storage device 25 discharges and a current oscillation begins to flow through the series resonant circuit (formed from Lr and Gr).The switching elements SI, S2, S3 and S4 of the full bridge are controlled in particular with the resonance frequency of the series resonant circuit consisting of the inductive component Lr and the capacitive component Gr.
[0063] The amplitude of the current oscillation flowing through the series resonant circuit becomes increasingly larger and reaches the magnitude of the direct current to be switched off. This creates a zero current crossing in the direct current to be switched off, at which the arc at the mechanical switching element 19 is extinguished. Advantageously, the switching elements of the full bridge and the electrical energy storage device are used not only to switch off the direct current, but also to supply power to the DC circuit breaker. This is described below.
[0064] Each of the switching elements SI, S2, S3 or S4 of the full bridge has a transistor T1, T2, T3 or T4 (for example an IGBT) and an anti-parallel connected diode D1, D2, D3 or D4. Depending on the direction of the current flow in the full bridge circuit, either the transistors are conductive (if they are controlled accordingly) or the current flows through the anti-parallel connected diodes. If the current flows through the anti-parallel connected diodes D1, D2, D3 or D4, the full bridge works as a rectifier, more precisely as a rectifier bridge. A rectifier 26 and an electrical energy store 25 are therefore arranged in the second current path.In order to supply the DC power switch 4 with electrical energy, an alternating current I s is coupled into a mesh 28 formed by the DC power switch 4, the first capacitor G1 and the second capacitor C2 by means of the energy coupling component 8. For this purpose, the energy coupling component 8 is controlled by a power converter 12 with a control alternating current Ia. The frequency of the control alternating current Ia can be changed within a wide range by means of the power converter 12. For example, the resonant frequency of the series resonant circuit formed from the inductive component Lr and the capacitive component Gr can be used as the frequency of the control alternating current Ia.
[0065] The alternating current I s coupled into the mesh (formed by the DC power switch 4, the first capacitor Gl, and the second capacitor C2) flows through the mesh to the DC power switch 4. This alternating current I s is used in the DC power switch 4 to supply energy to components of the DC power switch 4.
[0066] The alternating current I s coupled into the mesh cannot flow through the main current path 22 in the switch unit 17 because the main current path 22 is either interrupted by the mechanical switching element 19 (when the mechanical switching element 19 is open) or the main current path 22 is blocked for alternating current by the impedance of the inductive component Lr. The alternating current I s must therefore flow into the second current path 24. (In the two switch units 17 shown on the left, the coupled alternating current I s also flows through the second current path 24; for reasons of clarity, this is not shown in Figures 2 and 3.)
[0067] In the second current path 24, the alternating current Is is rectified by the rectifier arranged in the second current path (in particular by the diodes D1, D2, D3 and D4 connected anti-parallel to the transistors). By means of the direct current generated in this way, the electrical energy store 25 arranged in the second current path 24 is charged to an energy storage voltage Us. As a result, a component of the direct current power switch 4, namely the electrical energy store 25, is supplied with electrical energy. This electrical energy is provided by a device 12 arranged at the electrical reference potential 10 (here ground potential) and transferred to the electrical potential of the direct current power switch 4.
[0068] To supply energy to other components of the DC circuit breaker 4, for example, to supply energy to a power electronic circuit of the DC circuit breaker 4 or a drive of the mechanical switching element 19 of the DC circuit breaker 4, electrical energy can be extracted from the electrical energy storage device 25. The energy storage voltage Us applied to the electrical energy storage device 25 can be further processed (smoothed, stabilized, voltage level changed, etc.) and made available to the other components of the DC circuit breaker 4.
[0069] Figure 3 shows a further exemplary embodiment of an arrangement 1 according to the invention with the DC power switch 4, the first capacitor Gl, the second capacitor C2 and the energy coupling component 8. This arrangement differs from the arrangement according to Figure 2 in that the inductive component Lr of the main current path 22 is part of a parallel resonant circuit which is arranged in the main current path 22. This parallel resonant circuit has the inductive component Lr and a second capacitive component Cr2. The capacitive component Cr is part of a series resonant circuit which is arranged in the second current path 24. This series resonant circuit has the capacitive component Cr and a second inductive component Lr2 in a series circuit.
[0070] The parallel resonant circuit (Lr parallel Cr2) is a blocking circuit and prevents the alternating current I s coupled into the mesh from flowing through the main current path 22. The series resonant circuit (Cr in series with Lr2) is an absorption circuit and supports the flow of the alternating current I s coupled into the mesh 28 into the second current path 24. The second current path 24 forms a supply unit or a supply circuit.
[0071] The parallel resonant circuit and the series resonant circuit can in particular have the same resonant frequency. This resonant frequency can in particular be selected as the frequency of the injected alternating current Is. For example, the output frequency of the power converter 12 arranged on the reference potential 10 can be set to this resonant frequency. The resonant frequency of the resonant circuit effective when the direct current is switched off (switch-off resonant circuit, which has the parallel resonant circuit and the series resonant circuit) and the resonant frequency of the second current path 24 (i.e. the power supply circuit, which only has the series resonant circuit) are not identical. The two resonant frequencies are preferably selected such that the two resonant frequencies are a significant distance from one another in order to avoid undesired mutual interference.Otherwise, the arrangement according to Figure 3 functions in the same way as the arrangement according to Figure 2 .
[0072] An arrangement with a DC power switch and a method for supplying power to a DC power switch have been described. The inductive component Lr, which forms the inductive component of the resonant circuit that supports the switching off of the DC current, is arranged in the main current path. Furthermore, coupling capacitors G1 and C2 are arranged before and after the DC switch 4 between the potential of the DC power switch 4 and the reference potential. By means of a power electronic circuit (e.g. a power converter) at reference potential 10, alternating current can be injected into the conductor loop that is taut (by the DC power switch 4, the first capacitor G1 and the second capacitor C2).This alternating current cannot flow through the main current path 22 at the potential of the direct current line 18, since this main current path 22 is either interrupted by the open mechanical switching element 19 or blocked by the impedance of the inductive component Lr.
[0073] For potential isolation between the potential of the DC power switch 4 (which essentially corresponds to the potential of the DC line 18) and the reference potential 10, purely passive components are advantageously used, namely the first capacitor 11 and the second capacitor C2. In contrast to a transformer or a pulse transformer, these capacitors C1, C2 are significantly simpler in construction, meaning the isolation barrier is simpler and / or less expensive to implement.
[0074] No additional components are required for the potential separation within the DC circuit breaker, or often existing components (such as the inductive component Lr) are used.
[0075] Reference symbol: 1 arrangement
[0076] 4 DC circuit breakers
[0077] 8 Energy coupling component 10 Reference potential
[0078] 12 power converters
[0079] 13 first DC connection
[0080] 16 second DC connection
[0081] 17 Switch unit
[0082] 18 DC line
[0083] 19 mechanical switching element
[0084] 22 Main current path
[0085] 24 second current path
[0086] 25 electrical energy storage
[0087] 26 rectifiers
[0088] 28 stitches
[0089] Gr capacitive component
[0090] Cr2 second capacitive component
[0091] Gl first capacitor
[0092] C2 second capacitor la control alternating current
[0093] Ig direct current
[0094] Is coupled alternating current
[0095] Lr inductive component
[0096] Lr2 second inductive component
[0097] MOV surge arrester
[0098] Dl, D2, D3, D4 diodes
[0099] Sl, S2, S3, S4 switching elements
[0100] TI , T2 , T3 , T4 Transistors Us Energy storage voltage
[0101] Ul , U2 , U3 voltages
Claims
Patent claims 1. Arrangement with a DC power switch (4), a first electrical capacitor (CI), a second electrical capacitor (C2) and an energy coupling component (8), wherein - the DC circuit breaker (4) has a first DC connection (13), a second DC connection (16) and a mechanical switching element (19), - the mechanical switching element (19) in its open state electrically separates the first DC connection (13) from the second DC connection (16), - the first capacitor (Gl) the first DC connection (13) electrically connects to a reference potential (10), - the second capacitor (C2) electrically connects the second DC terminal (16) to the reference potential (10), and - the energy coupling component (8) is designed to couple an alternating current (Is) into a mesh (28) formed by the direct current power switch (4), the first capacitor (Gl) and the second capacitor (C2).
2. Arrangement according to claim 1, characterized in that - the energy coupling component (8) is an alternating current source or an alternating voltage source, in particular a transformer or a transmitter.
3. Arrangement according to claim 1 or 2, characterized in that - the energy coupling component (8) is arranged substantially on the reference potential (10) or is electrically connected to the reference potential (10).
4. Arrangement according to one of the preceding claims, characterized in that - the reference potential (10) is the earth potential.
5. Arrangement according to one of the preceding claims, characterized in that - the mechanical switching element (19) is a vacuum interrupter.
6. Arrangement according to one of the preceding claims, characterized in that - a main current path (22) of the DC power switch (4) is formed between the first DC connection (13) and the second DC connection (16), and an inductive component (Lr), in particular an air choke, is arranged in the main current path (22).
7. Arrangement according to claim 6, characterized in that - a second current path (24) is electrically connected in parallel to the main current path (22).
8. Arrangement according to claim 7, characterized in that - a capacitive component (Gr), in particular a capacitor, is arranged in the second current path (24).
9. Arrangement according to claim 8, characterized in that - the capacitive component (Gr) forms a series resonant circuit with the inductive component (Lr) of the main current path (22).
10. Arrangement according to claim 8, characterized in that - the inductive component (Lr) of the main current path (22) is part of a parallel resonant circuit arranged in the main current path (22), and the capacitive component (Gr) is part of a series resonant circuit arranged in the second current path (24).
11. Arrangement according to claim 10, characterized in that - the series resonant circuit comprises the capacitive component (Cr) and a second inductive component (Lr2) in a series circuit.
12. Arrangement according to claim 10, characterized in that - the parallel resonant circuit comprises the inductive component (Lr) and a second capacitive component (Cr2).
13. Arrangement according to one of claims 7 to 12, characterized in that - a rectifier (26) and an electrical energy store (25) are arranged in the second current path (24).
14. Method for supplying energy to a DC circuit breaker (4), wherein - the DC circuit breaker (4) has a first DC connection (13), a second DC connection (16) and a mechanical switching element (19), - the mechanical switching element (19) in its open state electrically separates the first DC connection (13) from the second DC connection (16), - a first capacitor (Gl) electrically connects the first DC terminal (13) to a reference potential (10), and - a second capacitor (C2) electrically connects the second DC terminal (16) to the reference potential (10), wherein in the method - by means of an energy coupling component (8) an alternating current (Is) is converted into a current generated by the direct current circuit breaker (4), the first capacitor (Gl) and the second capacitor (C2) formed mesh (28) is coupled, - the alternating current (Is) flows through the mesh (28) to the direct current circuit breaker (4), and - the alternating current (Is) in the DC circuit breaker (4) is used to supply energy to components of the DC circuit breaker (4).
15. Method according to claim 14, characterized in that - the alternating current (Is) in the direct current circuit breaker (4) flows into a second current path (24) electrically connected in parallel to a main current path (22), - the alternating current (Is) is rectified by means of a rectifier (26) arranged in the second current path (24), and - an electrical energy store (25) arranged in the second current path (24) is charged by means of the direct current thus generated.