Low power meter transformer (LPIT) in tapered connector

Abstract

A sensor device for a gas insulated switchgear is provided. The sensor device includes a connector having a housing defining a hollow interior, a current conductor passing through the interior of the housing, a low power meter transformer, a shielded field electrode, and a resin. A low power meter transformer includes an electrode having an annular shape and including a voltage sensor for measuring a voltage of a current conductor. The low power meter transformer also includes a current sensor positioned for measuring a current of the current conductor. The shielded field electrode is disposed between the current sensor and the current conductor. The resin cooperates with and surrounds the current conductor, the voltage sensor, the current sensor, and the shielded field electrode to fill the hollow interior.

Description

Technical Field

[0001] The present application relates to a low power instrument transformer device comprising a voltage sensor and a current sensor, wherein the voltage sensor has a measuring electrode for detecting a voltage. The low power instrument transformer device can be used to measure a current flowing through a current conductor. Background Art

[0002] Gas insulated switchgear (GIS) generally comprises an encapsulated container filled with pressurized insulating gas. The pressurized container surrounds a switch panel, which includes components arranged and enclosed within the pressurized container, such as circuit breakers, cable seals and (multiple) conductors. Current / voltage transformers detect current and / or voltage, respectively, within high-voltage cables connected to the gas insulated switchgear.

[0003] GIS is an important part of the power grid and is mainly located in areas with limited space. The connection to the grid is usually made through bushings or cables. Plug-in systems for wind tower systems have replaced medium voltage switchgear and are becoming more common due to less installation space and faster installation and commissioning.

[0004] Traditionally, GIS switchgear has current transformers that are arranged around the high-voltage cables for protection purposes, outside the encapsulating container before the cables to the switchgear plug-in connectors. The installation of these current transformers is time-consuming and must be done before the installation of the high-voltage cables. The high-voltage cables have a large diameter of about 80 mm and are difficult to bend or pass through the current transformer coils. Summary of the invention

[0005] The present invention relates to a sensor device for a gas insulated switchgear, comprising a connector having a shell defining a hollow interior, a current conductor passing through the interior of the shell, a low-power instrument transformer, a shielding field electrode and a resin. The low-power instrument transformer comprises an electrode having an annular shape and comprising a voltage sensor for measuring the voltage of the current conductor. The low-power instrument transformer also comprises a current sensor positioned to measure the current of the current conductor. The shielding field electrode is arranged between the current sensor and the current conductor. The resin cooperates with the current conductor, the voltage sensor, the current sensor and the shielding field electrode and surrounds the current conductor, the voltage sensor, the current sensor and the shielding field electrode to fill the hollow interior.

[0006] In another configuration, the present invention relates to a gas insulated switchgear, comprising a sensor device. The sensor device comprises a connector having a housing defining a hollow interior, a current conductor passing through the interior of the housing, a low-power instrument transformer, a shielding field electrode, and a resin. The low-power instrument transformer comprises an electrode having an annular shape and comprising a voltage sensor for measuring the voltage of the current conductor. The low-power instrument transformer also comprises a current sensor positioned to measure the current of the current conductor. The shielding field electrode is disposed between the current sensor and the current conductor. The resin cooperates with the current conductor, the voltage sensor, the current sensor, and the shielding field electrode and surrounds the current conductor, the voltage sensor, the current sensor, and the shielding field electrode to fill the hollow interior. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To easily identify the discussion of any particular element or action, one or more significant digits in a reference number refer to the figure number in which the element is first introduced.

[0008] Figure 1 A cross-section of a wind tower is shown.

[0009] Figure 2 A diagram showing a gas insulated switchgear and a conventional current transformer Figure 1 Partial cross-section of a wind tower.

[0010] Figure 3 A cross-sectional view of a connector with an integrated current transformer is shown.

[0011] Figure 4 Shows that there is Figure 3 A perspective view of a connector with an integrated current transformer. DETAILED DESCRIPTION

[0012] The present disclosure describes a plug-in connector with integrated measurement of current and voltage based on LPIT (low power instrument transformer) technology for high voltage applications such as above 45 kV. LPIT combines a low power voltage transformer and a low power current transformer.

[0013] Figure 1is a cross-sectional view of a wind tower 100, which includes a tower resting on a foundation. At the end of the tower opposite the foundation is a nacelle 102, which supports a rotor 106. The rotor 106 is connected to a generator 104, which converts the movement of the rotor 106 into variable frequency electrical energy. The generator 104 is connected to an inverter 108 and a transformer 110, so that the electrical energy from the generator 104 can be converted to a standard value, such as 60 Hz in the United States, via the inverter 108 and the transformer 110. The transformer 110 converts the generated energy into a voltage level suitable for transmission, such as 960VAC-6600VAC. The transformer 110 is connected to a pressurized gas insulated switchgear 112 via a first cable connection 118. At Figure 1 In the view shown, the gas-insulated switchgear 112 is located in the tower of the wind tower 100 towards the base. Although the gas-insulated switchgear 112 is depicted as a component of the wind tower 100 in this case, this is only for illustration purposes. The gas-insulated switchgear 112 can also be used in other applications, such as a transmission station on shore. The second cable connection 114 connects the gas-insulated switchgear 112 to the electrical energy transmission network (not shown). In the embodiment shown, the second cable connection 114 includes a node 116 that branches into two cables running parallel to each other.

[0014] Figure 2 yes Figure 1 A partial cross-sectional view of components of the wind tower 100 is shown. The gas insulated switchgear 112 is Figure 2 1. The gas insulated switchgear 112 includes a pressurized vessel 204. The pressurized vessel 204 may include a metal, such as aluminum, and may include a hollow cylindrical structure that is closed at each end in a fluid-tight manner. The interior of the pressurized vessel 204 is filled with a fluid that is pressurized to a pressure that is higher than the pressure of the medium surrounding the pressurized vessel 204, so that the components located within the interior are electrically insulated. The pressurized fluid may be sulfur hexafluoride gas.

[0015] The gas-insulated switchgear 112 further comprises a switchgear 206. The switchgear 206 may be designed in a multi-phase manner, wherein the switch paths of the respective phases may be designed similarly. For simplification purposes only, Figure 2 2 shows one phase of a switchgear 206. Each phase of the switchgear 206 comprises a contact forming a first side 208 and a contact forming a second side 210. A switch contact 212 is arranged between the first side 208 and the second side 210, which is movable relative to each other. The first side 208 and the second side 210 are connected by an electrically insulating spacer 214.

[0016] A drive device 216 arranged outside the gas-insulated switchgear 112 is used to move the contacts 212 relative to each other via a drive rod 218 guided in a fluid-tight manner through the housing of the pressurized vessel 204. A connecting conductor 228 connects the first side 208 to an output line 232 outside the pressurized vessel 204. An earthing switch arranged in the interior of the gas-insulated switchgear 112 can be used to earth the first side 208 of the switchgear 206.

[0017] A connector 220 including a housing may be used to incorporate the switchgear 206 into a current path. A current conductor 224 passes through the hollow interior of the housing. The current conductor 224 may be a three-phase conductor that conducts the three phases through the pressurized vessel 204 to the second side 210 of the switchgear 206 via a connecting conductor 230. The connector 220 is connected to a plug 226. The plug 226 provides a point for connecting the second cable connection 114 to the second side 210.

[0018] Figure 2 Also included is a conventional conical current transformer 202 disposed around and concentric with the second cable connection 114. Current transformers are often used to perform current measurements on phase conductors when DC measurements may be difficult to obtain. In order to install such a conventional current transformer 202, the second cable connection 114 must pass through the current transformer 202.

[0019] The inventors have appreciated that the current transformer may be included within the connector 220 connecting the current conductor 224 from the gas insulated switchgear 112 to the second cable connection 114 .

[0020] Figure 3 Shows Figure 2 2 is a cross-sectional view of a connector 220 including a current transformer, such as a low power instrument transformer 302 (LPIT), and Figure 4 A perspective view of the connector 220 is shown, wherein a low power instrument transformer 302 is mounted inside the connector 220. The LPIT operates according to the principle of an instrument transformer based on a specific adaptation of an internal shunt. This principle is extremely insensitive to external stray fields. The secondary current generates a voltage across an internal shunt resistor, which is proportional to the primary current. The connector 220 includes a housing 308 defining a hollow interior. The material of the housing 308 includes an electrically insulating material. As previously described, the current conductor 224 passes through the hollow interior of the connector 220. The housing 308 includes a first tapered portion 304 and a second tapered portion 306. The first tapered portion 304 is positioned within the interior of the gas insulated switchgear 112 and passes through a flange cover 222 of the pressurized vessel 204 (see Figure 2), wherein the conical shape improves the fluid tight seal for maintaining the pressurized fluid. The first conical portion 304 connects the phase conductor of the current conductor 224 to the connecting conductor 228. The second conical portion 306 is positioned on the outside of the gas insulated switchgear 112, and its conical shape is suitable for connecting to a standard cable plug 226. A disk-shaped partition 310 is provided between the first conical portion 304 and the second conical portion 306, which is flush with the outside of the flange cover 222.

[0021] The shielding mesh 314 is positioned within the hollow interior of the connector 220 and surrounds the current conductor 224. The shielding mesh 314 provides a dielectric shield to control the electric field and protect the current conductor 224. The shielding mesh 314 can be made of a metal mesh. In one embodiment, the metal mesh includes stainless steel. The low power instrument transformer 302 and the shielding mesh 314 are both circumferentially surrounded (see Figure 4 ) and concentric with the current conductor 224, which is disposed along the longitudinal axis 322. The shield mesh 314 may include ends that flare outwardly and away from the current conductor 224 to further protect the low power instrument transformer 302.

[0022] Wire 316 carries the measurement signals of current sensor 318 and / or voltage sensor 320 through disc-shaped separator 310 so that the current and / or voltage can be displayed to the user. Wire 316 terminates in a merging unit having a processor that collects the current and voltage signals and transmits the current and voltage information to the GIS protection relay. Resin 312 is incorporated into the hollow interior so that the low power instrument transformer 302 and the current conductor 224 are surrounded by resin 312. Resin 312 provides further insulation function for the internal components of connector 220 as well as holding the components in place. Low power instrument transformer 302 can be configured to fit within the first tapered portion 304 of connector 220 and disc-shaped separator 310.

[0023] Figure 4 Shows Figure 3 20 is a perspective view of a connector 220 having a low power instrument transformer 302 integrated therein. From this perspective view, a voltage sensor 320 circumferentially surrounding a current conductor 224 can be observed. A shielding mesh 314 is disposed between the voltage sensor 320 and the current conductor 224, and the shielding mesh 314 also circumferentially surrounds the current conductor 224. The shielding mesh 314 includes a first end and a second end, which are respectively flared away from the current conductor 224 to further protect the voltage sensor 320 and the current sensor 318. The current sensor 318 also circumferentially surrounds the current conductor 224 and is adjacent to the voltage sensor 320 along a longitudinal axis 322 of the current conductor 224. The shielding mesh 314 is located between the current sensor 318 and the current conductor 224.

[0024] In one embodiment, the current sensor 318 may be a Rogowski coil. A Rogowski coil is an instrument used to safely measure an alternating current traveling through a primary conductor, such as a cable. In one embodiment, two transformer coils are used. When two transformer coils are used, there is redundancy of the Rogowski coils so that if one fails, the other can be utilized.

[0025] In operation, the current sensor 318 inserted into the groove 602 of the ring electrode 502 can relay the current flowing through the corresponding phase conductor 508 via the wire 316, see Figure 5 and Figure 6 . The ring electrode 502 is attached to the flange ring 504 via a retainer 506. The voltage provided by the voltage sensor 320 can also be relayed via wires for display and further processing. Utilizing a low power instrument transformer 302 embedded within a conical connector provides a compact design that can be installed in the factory before the high voltage equipment is installed in the field. The current transformer can be used to measure the current flowing through the current conductor 224 or to detect overcurrent (i.e., current above a threshold) in order to protect the switchgear 206. In the event of an overcurrent, such as from lightning, the overcurrent detection can be used to automatically disconnect the switchgear 206.

Claims

1. A sensor device for a gas insulated switchgear, comprising: a connector having a housing defining a hollow interior; a current conductor extending through the hollow interior of the connector; Low power instrument transformers, including: an electrode having a ring shape and comprising a voltage sensor for measuring the voltage of the current conductor, and a current sensor positioned to measure a current of the current conductor; a shielding field electrode disposed between the current sensor and the current conductor; and A resin cooperates with and surrounds the current conductor, the voltage sensor, the current sensor, and the shield field electrode to fill the hollow interior.

2. The sensor device according to claim 1, wherein: The current sensor is a Rogowski coil which surrounds a current conductor of the low power instrument transformer.

3. The sensor device according to claim 2, wherein: The current sensor includes a first Rogowski coil and a second Rogowski coil, wherein the second coil operates in response to a failure of the first Rogowski coil.

4. The sensor device according to claim 1, wherein: The shielding field electrode comprises a shielding mesh.

5. The sensor device according to claim 4, wherein: The shielding mesh comprises a metal mesh.

6. The sensor device according to claim 1, wherein: The shielding field electrode comprises a first end and a second end, wherein the first end and the second end are respectively opened away from the current conductor.

7. A gas insulated switchgear, comprising: The sensor device according to claim 1.

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