Arrangement of rc elements for medium voltage, for switching low inductive currents by means of high-voltage vacuum switching technology

Abstract

The invention relates to a circuit arrangement of RC elements for medium voltage, for implementing an RC filter circuit solution for switching low inductive currents by means of high-voltage vacuum switching technology in the high-voltage range of >= 72.5 kV. Advantageous further embodiments relate to specific arrangements for the limited installation space available in a sub-station.

Description

[0001] Description

[0002] Arrangement of medium-voltage RC elements for switching small inductive currents using vacuum switching technology at high-voltage level

[0003] The invention relates to an arrangement of RC elements designed for medium voltage for realizing an RC filter circuit solution for switching small inductive currents using high-voltage vacuum switching technology.

[0004] When switching small inductive currents, such as those encountered in choke applications in high-voltage networks (>= 72.5 kV), special protective measures are necessary. This switching task carries the risk that transient overvoltages could destroy substation components. The choke itself is particularly exposed to a certain risk. Gas switches and vacuum switching devices, for example, are suitable switching media.

[0005] SF6 circuit breakers are predominantly used in high-voltage networks. In these applications, the gas circuit breakers are not operated without additional protective measures. These measures serve to reduce the overvoltages that occur during the switching process.

[0006] To date, reactor switching applications in high-voltage networks (>= 72.5 kV) have been operated using a combination of an electronic control unit (which controls the exact moment of closing or opening) and an SF6 circuit breaker with a single-pole drive. This solution is costly, requires increased effort during commissioning and carries the risk that the circuit breaker data stored in the control unit, such as the breaker's operating times, may change over the course of operation - over decades. This could change the optimal switching time and impair the function of the arrangement of the single-pole driven circuit breaker and electronic control unit.The invention is based on the problem of providing a solution for using an RC filter circuit in high-voltage electrical power transmission, where the high voltage (HV) is greater than or equal to 72.5 kilovolts. Furthermore, the invention is directed to providing variants for the arrangement of the RC elements for efficient integration into the limited space in a substation architecture.

[0007] The problem is solved by a circuit arrangement of a plurality of RC elements comprising the features of claim 1.

[0008] The use of an RC filter circuit (a series connection of a resistor R and a capacitor C) can significantly reduce the impact of transient overvoltages. Such a solution has been used in medium-voltage systems for many years and is state-of-the-art. Consequently, RC filter circuit components are also available for the medium-voltage level.

[0009] The transfer of this technology to high-voltage applications also opens up reactor switching applications for high-voltage vacuum switching devices. The inventive arrangement of available, discrete medium-voltage free-air RC elements represents an efficient method for serving high-voltage applications as well. The efficient arrangement of these RC elements can be particularly suitable for integration into the corresponding substation architecture. In this case, available installation space is limited.

[0010] Existing medium-voltage RC solutions essentially cover voltage ranges up to 36 kV. To enable expansion to high voltage, several of these elements are interconnected according to the invention.

[0011] The R and C elements may be housed together in a metallic housing G. This housing has a fixed, outdoor bushing D. The electrical series connection of such discrete components makes use at higher voltage levels possible.

[0012] In an advantageous development of the invention, an RC element is secured by one or more post insulators SI. This serves both to provide mechanical strength and to maintain the distance to the voltage insulation.

[0013] Advantageous further developments of the invention are specified in the subclaims.

[0014] The invention is explained in more detail below as an exemplary embodiment to the extent necessary for understanding with reference to figures.

[0015] Showing:

[0016] Fig. 1 shows an arrangement according to the invention of three individual RC elements with bushings aligned to the same side,

[0017] Fig. 2 shows an arrangement according to the invention of three individual RC elements with bushings aligned to opposite sides,

[0018] Fig. 3 shows an arrangement according to the invention of three individual RC elements with bushings aligned in a row and

[0019] Fig. 4 shows an arrangement according to the invention of three individual RC elements in exactly two planes.

[0020] In the figures, like designations refer to like elements.

[0021] Fig. 1 shows an arrangement of the individual RC elements according to the invention. Three RC elements RC, each having a series circuit comprising a resistor and a capacitor, are arranged with their main surfaces parallel to one another. The RC elements are each designed for a medium voltage up to 36 kV. The RC elements each have two electrical connections, a housing connection GA and a feedthrough connection DA. One feedthrough connection DA is arranged at the end of the feedthrough D facing away from the housing G. The feedthrough D itself may be arranged on the housing G off the center of its fastening surface.

[0022] In the arrangement according to Fig. 1, the feed-through connections DA of several RC elements face one side. The feed-through connections DA of adjacent RC elements can be offset from one another, in particular aligned to the right or left, for improved interconnection of the RC elements. The RC elements can be stacked on top of one another or arranged horizontally next to one another. This allows adaptation to the respective space conditions in a transformer substation. The RC elements can be fastened by post insulators not shown in the figure. These serve on the one hand to provide mechanical strength and on the other hand to maintain the distance to the voltage insulation.

[0023] Figure 2 shows a second possible arrangement of the individual RC elements, in which the bushings D of the discrete RC elements are arranged alternately at the front and rear. To improve the interconnection of the various RC elements, the bushings are arranged alternately on the left and right. The RC elements can be stacked on top of one another or arranged horizontally next to one another. This allows adaptation to the respective space conditions in a transformer substation. The RC elements can be attached by post insulators (not shown in the figure). These serve both to provide mechanical strength and to maintain the distance to the voltage insulation.

[0024] Figure 3 shows an arrangement in which the RC elements are stacked vertically on top of each other, but also arranged in series with their bushings D. There are two possibilities here:

[0025] As shown in the figure on the left, the bushings D are arranged alternately to the left and right. On the other side of the RC element, a supporting insulator SI is arranged to absorb the forces of the stacked elements. The housing G of the lowest RC element is directly connected to a base surface carrying earth potential. This arrangement requires only two supporting insulators SI for three RC elements.

[0026] However, there is also the variant, shown on the right in Figure 3, in which all bushings D are arranged on one side and all post insulators SI are arranged on the other side. The bottommost RC element is connected directly to a base carrying earth potential via the bushing connection DA of its bushing D. This arrangement requires three post insulators SI for three RC elements.

[0027] Figure 4 shows a particularly compact arrangement of the RC elements. Here, the elements are positioned side by side in exactly two levels. They are arranged vertically, and the interconnection is from one element on the left to one on the right. Here, too, the feedthroughs could always be arranged on one side (as shown in the figure) or alternately (front / back). The housing G of the lowest RC element is directly connected to a base carrying earth potential.

[0028] The series connection of the RC elements can be further developed so that a high-ohm resistor with the same resistance value is connected in parallel to each RC element. This ensures that the high voltage HV is evenly distributed among the individual RC elements.

[0029] An RC element can be provided by a commercially available type MV APP from TDK Electronics AG.

[0030] High voltage, as defined by the invention, is understood to mean a voltage of 72.5 kV (kilovolts) and higher, including direct current, alternating current, and, if three-pole, three-phase current. The present invention has been explained in detail for illustrative purposes using specific embodiments. Elements of the individual embodiments can also be combined with one another. The invention is therefore not intended to be limited to individual embodiments, but is limited solely by the appended claims.

[0031] Reference symbol list

[0032] D - Feedthrough / Exit / Voltage Feedthrough

[0033] DA - Feedthrough connection EP - Earth potential, ground

[0034] G - Housing

[0035] HV - high voltage

[0036] SI - Post Insulator

Claims

Patent claims 1. Circuit arrangement for the use of electrical RC elements designed for medium voltage in high-voltage electrical energy transmission, in which the high voltage (HV) is greater than or equal to 72.5 kilovolts, characterized in that a series circuit comprising a plurality of RC elements is arranged between a conductor carrying the high voltage (HV) and earth potential (EP), and the sum of the dielectric strengths of the plurality of RC elements is greater than the high voltage (HV).

2. Circuit arrangement according to claim 1, characterized in that a respective RC element has a cuboid-shaped, in particular metallic, housing (G), an outdoor fixed voltage feedthrough (D) is arranged on one side of the housing, a first connection (GA) on the housing and a second feedthrough connection (DA) are provided by the voltage feedthrough (D), a series circuit comprising at least one electrical resistor and at least one capacitor is arranged in the housing, which is connected to the first connection (GA) and to the second feedthrough connection (DA) respectively.

3. Circuit arrangement according to claim 2, characterized in that the voltage feedthrough (D) is arranged off-center on an end face of the housing.

4. Circuit arrangement according to one of the preceding claims 2 to 3, characterized in that The RC elements are arranged with their main surfaces facing each other and their voltage feedthroughs (D) are arranged alternately offset from each other on one side of the housing. (FIG. 1) 5. Circuit arrangement according to one of the preceding claims 2 to 3, characterized in that the RC elements are arranged with their main surfaces facing each other and their voltage feedthroughs (D) are arranged alternately on opposite sides of the housing. (FIG2) 6. Circuit arrangement according to one of the preceding claims 2 to 3, characterized in that an RC element is connected to the voltage feedthrough (D) of an adjacent RC element. (FIG3) 7. Circuit arrangement according to one of the preceding claims 2 to 5, characterized in that the RC elements are arranged with their main surfaces in exactly two different planes and RC elements of different planes are electrically connected successively. (FIG4) 8. Circuit arrangement according to one of the preceding claims characterized in that an RC element is attached by a support insulator (SI).

9. Circuit arrangement according to one of the preceding claims characterized in that a high-ohm resistor with the same resistance value is connected in parallel to each RC element.

10. Circuit arrangement according to one of the preceding claims characterized in that it is connected to a high-voltage vacuum switching device which switches a choke.

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