Magnetic ring device for suppressing very fast transient overvoltage in gas-insulated switchgear

Abstract

The present invention provides a magnet ring device for inhibiting very fast transient overvoltage in a gas insulated switchgear. The magnet ring device comprises a magnet ring string, a copper foil adhesive tape and a fixed housing. The magnet ring string is formed by a plurality of open-loop anti-saturation magnet rings, and each two adjacent open-loop anti-saturation magnet rings are tightly connected through adhesives; each open-loop anti-saturation magnet ring is provided with an air gap; and the outer surface of the magnet ring string is coated with the copper foil adhesive tape, and the fixed housing is fixed at the outer portion of the magnet ring string. The magnet ring is provided with the air gap with the appropriate length to effectively improve the saturation characteristic of the device, cause more energy consumption for the traveling wave and reduce the VFTO (Very Fast Transient Overvoltage) value caused by operating a disconnecting switch in GIS (Gas Insulated Switchgear); the copper foil adhesive tape can effectively avoid leakage of a magnetic line, enhance the eddy current loss of the magnet ring device, reduce the influence of the VFTO on the device, improve the distribution of the electric field at the surface of the magnet ring string and avoid the partial discharge phenomenon caused by too high local field intensity. The fixed housing can improve the intensity and the rigidity of the whole magnet ring device.

Description

technical field [0001] The invention relates to the technical field of overvoltage suppression, in particular to a magnetic ring device for suppressing ultra-fast transient overvoltage in gas insulated switchgear. Background technique [0002] In the power grid system, due to the advantages of GIS (Gas Insulated Switchgear, gas insulated switchgear) with small footprint, high reliability, good safety, short installation period and convenient maintenance, GIS has become an important component of power grids at all levels. Some of them are widely used in power grids. From the perspective of composition structure, GIS is a high-voltage power distribution device composed of circuit breaker, busbar, disconnector, voltage transformer, current transformer, lightning arrester and bushing. When the isolating switch is operated, multiple arc restrikes or pre-breakdowns will occur between the fractures of the isolating switch. Transmission on both sides, after multiple refractions an...

AI Technical Summary

Problems solved by technology

[0004] However, if the current magnetic ring device is used on a large scale, or the current magnetic ring device is applied to the GIS of the ultra-high voltage and ultra-high voltage level, when the isolating switch is operated, under extreme conditions, the voltage value generated by the contact gap of the isolating switch It is about twice the amplitude of the power frequency voltage, so the peak value of the current flowing through the conductive rod inside the busbar near the disconnector can easily reach the kA level

Since the current magnetic ring device adopts a closed-loop structure, it can be seen from Ampere's loop law that when the current value I flowing through the conductive rod is very large, the magnetic field intensity H induced on the closed-loop magnetic ring is also very large, and combined with the hysteresis curve. , when the magnetic field strength H is very large, the magnetic ring is easy to enter a saturated state; finally, from the relationship between the magnetic flux density, magnetic field strength and magnetic permeability, it can be known that when the magnetic field strength H induced on the magnetic ring is very large, the magnetic ring's magnetic The conductivity is close to 0, at this time, the equivalent inductance and impedance are significantly reduced, resulting in a significant decline in the inhibition of the magnetic ring

Therefore, due to the closed-loop structure of the current magnetic ring device, the magnetic ring device is easy to saturate. When the magnetic ring is used on a large scale or the magnetic ring is applied to the GIS of the ultra-high voltage and ultra-high voltage level, the current magnetic ring device cannot be effective. to suppress VFTO

Images