Method and apparatus for mitigation of dynamic overvoltage
AssigneeABB Technology AG
InventorsUlf Andersson, Hans Bjorklund, John Daniel, David Dickmander
Life of this patent
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Abstract
A distribution and power transformer has its primary connected to the high voltage bus of the network and its secondary connected to a switching device. Upon the occurrence of a condition known to cause a dynamic overvoltage (DOV) and the occurrence of the DOV, a control system causes the switching device to change from a nonconductive mode to a conductive mode in less than the time for one cycle of the operating frequency of the AC network. This change in switching device conduction places a short circuit across the transformer secondary and thus mitigates the DOV.
Claims14
An apparatus for mitigating in less than the time for one cycle of a predetermined operating frequency of an AC network a short term dynamic overvoltage on said AC network, said apparatus comprising:
- a distribution and power transformer having a primary connected to a high voltage bus and a secondary directly connected to a switching device that can switch from a nonconductive mode to a conductive mode within a time that is less than the time for one cycle of said network predetermined operating frequency;
- and
- a system connected to said switching device, said system comprising:
- one or more detectors for detecting the occurrence of a condition known to cause a dynamic overvoltage on said AC network and the occurrence of a dynamic overvoltage on said AC network;
- and
- a control system connected to said switching device,
- said control system in response to said one or more detectors detecting at the same time both said occurrence of a condition known to cause a dynamic overvoltage on said AC network and the occurrence of a dynamic overvoltage on said AC network causing said switching device to change in less than said time for one cycle of said predetermined operating frequency from said nonconductive mode to said conductive mode to thereby short circuit said transformer secondary.
A method for mitigating in less than the time for one cycle of a predetermined operating frequency of an AC network a short term dynamic overvoltage on said AC network, said method comprising:
- detecting by one or more detectors the occurrence of a condition known to cause a dynamic overvoltage on said AC network and the occurrence of a dynamic overvoltage on said AC network;
- and
- providing from a control system in response to said one or more detectors detecting at the same time both said occurrence of a condition known to cause a dynamic overvoltage on said AC network and the occurrence of a dynamic overvoltage on said AC network a signal to a switching device connected to the secondary of a transformer whose primary is connected to said AC network to cause said switching device to change in less than the time for one cycle of said predetermined operating frequency from a nonconductive mode to a conductive mode to thereby short circuit said transformer secondary.
Dependencies are inferred from the claim text.