Method and device for adaptive modification of ground fault protection settings in a three-phase grid
A three-phase power grid, ground fault technology, applied in the direction of automatically disconnected emergency protection devices, fault locations, emergency protection circuit devices, etc., can solve the problem of increasing system complexity, lack of automatic adaptive modification of protection settings, and immediate change of direction characteristics And other issues
Active Publication Date: 2015-11-25
ABB (SCHWEIZ) AG
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Problems solved by technology
[0008] The problem with the above method is that if the neutral point grounding method of the system is changed, for example, when the arc suppression (Petersen) coil or the neutral point grounding resistor in the network is turned on or cut off, the directional characteristics must be changed immediately and the applicable setting
The disadvantage of the automation change is that it increases the complexity of the system by e.g. requiring auxiliary wiring, which involves additional costs
A possible disadvantage of the proposed solution is that it only provides a partial solution for automatic adaptation: when the neutral grounding process is changed, only the directional condition is adapted, but lacks other parameters that may need to be changed. Automatic adaptation of possible protection settings
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[0032] The application of the present invention is not limited to any particular system, but can be used in conjunction with various three-phase power systems to adapt ground fault protection settings.
[0033] An electric power system implemented in connection with the present invention may be eg a transmission grid or a distribution grid or parts thereof and may comprise several feeders or sections. Furthermore, the use of the present invention is not limited to systems employing 50 Hz or 60 Hz fundamental frequencies or to any particular voltage level.
[0034] figure 2 is a simplified diagram showing an example of an electrical grid with which the present invention may be used. For the sake of simplicity, the figure shows only the components necessary for understanding the invention. The network may be, for example, a medium voltage (eg 20 kV) distribution network. figure 2 A protection directional relay unit (R) 10 is shown located at the power line 20 . It should b...
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A method and an apparatus for adapting earth-fault protection settings in a three-phase electric network, the apparatus (10) comprising means for determining a value for a directional phasor quantity at a measuring point in the three-phase electric network after an earth fault has been detected in the three-phase electric network, means for comparing the determined value for the directional phasor quantity with predetermined boundaries on a complex plane, means for determining, on the basis of the comparison, a neutral earthing state of the electric network, and means for adapting one or more earth-fault protection settings on the basis of the determined neutral earthing state of the electric network.
Description
technical field [0001] The invention relates to the adaptive modification of ground fault protection settings in a three-phase grid. Background technique [0002] Generally, directional earth fault protection can be based on two conditions of simultaneous monitoring of directional quantities: [0003] ●direction [0004] ●Amplitude [0005] When the above two conditions are met at the same time, that is, the direction matches the set operating direction and the magnitude of the monitored quantity exceeds the set operating threshold, the operating condition of the directional ground fault protection is satisfied. There may be one or several monitored quantities whose magnitudes are monitored and must exceed the set threshold limit. [0006] A typical arrangement for directional earth fault protection in high resistance earthed networks is such that a general fault indication is obtained when the magnitude of the fundamental frequency component of the residual voltage excee...
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IPC IPC(8): H02H7/26
CPCH02H3/165G01R31/086H02H3/38H02H3/33H02H3/006
Inventor阿里·瓦尔罗斯扬内·阿尔托宁
OwnerABB (SCHWEIZ) AG