Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific current responsive fault sensor
Patent
1996-05-24
1998-03-10
Leja, Ronald W.
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific current responsive fault sensor
361 86, 361 87, H02H 300
Patent
active
057268479
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for generating a protection-triggering signal using a triggering device of a selective-protective arrangement for an electrical power network.
BACKGROUND INFORMATION
It is known to use selective-protective arrangements for detecting disruptions in electrical power networks in order to be able to selectively switch off the components or network parts of an electrical power network which are affected by the disruption. Such selective-protective arrangements generally do not initiate their activity until protection-triggering signals have been generated using triggering devices. For example, it can be understood from the book by L. Muller/E. Boog "Selektivschutz elektrischer Anlagen" (Selective protection of electrical systems), 2nd edition, 1990, pp. 122-124 as well as from the book by H. Ungrad, W. Winkler and A. Wiszniewski "Schutztechnik in Elektroenergiesystemen" (Protection technology in electrical power systems), 1991, pp. 114 and 116 that triggering devices responding to overcurrents have overcurrent relays in the phase conductors, which in the classic design actually also have relays as components but which represent purely electronic arrangements in modern technology. With the known overcurrent relays, it is checked whether the peak value of the current or the effective (rms) value lies above a specified allowable current value. If this is the case, then a protection-triggering signal is output.
SUMMARY OF THE INVENTION
The present invention provides a method for generating a protection-triggering signal using a triggering device of a selective-protective arrangement for an electrical power network to be monitored in which the protection-triggering signal is generated for values of the currents in the phase conductors of the power network lying above allowable values (overcurrents).
The present invention further provides a method wherein a protection-triggering signal can be generated with the method in a relatively short time upon occurrence of an overcurrent.
In accordance with the present invention, a triggering device is provided in which a neural network, having an input layer, an intermediate layer, and an output layer having an output neuron, is associated with each phase conductor of a power network to be monitored. Each neural network is trained by simulating the currents for different load states of the power network to be monitored.
Successively sampled normalized values of the current in the respective associated phase conductor of the power network are applied at the same time to the different neurons of the input layer of each neural network in order to form an output signal of the output neuron corresponding to the predictable curve of the current. A subsequently sampled normalized value of the current in the respective associated phase conductor is compared with the output signal of the output neuron and thus with the predictable curve of the current. The protection-triggering signal is generated if the normalized comparison value of the current in the respective associated phase conductor exceeds the output signal of the output neuron of the corresponding neural network.
The essential advantage of the method according to the present invention is that a protection-triggering signal is generated with the method a relatively short time after the occurrence of an overcurrent. This can be attributed to the fact that in the carrying out of the method according to the invention, the progression vs. time of the respective current does not have to be monitored until the current in the respective phase conductor has exceeded a value characterizing an overcurrent. Instead, due to the use of trained neural networks, the possibility exists, based on the curve of the sampled current values which is predictable with the neural network, an overcurrent can be detected if, for example, shortly after a zero crossing of the current, the current curve has a curve which is characteristic of an overcurrent. It is thus possible to dete
REFERENCES:
patent: 5159660 (1992-10-01), Lu et al.
patent: 5537327 (1996-07-01), Snow et al.
G. W. Swift, Detection of High Impedance Arching Faults Using a Multi-Layer Perceptron, IEEE, Oct. 7, 1992, pp.1871-1877.
Bohme et al., Optimierung von Distanzchutz-algorithmen mit Hilfe neuronaler Netze, Eledtrie, 1993, pp. 2-10, No Month.
Schoneburg et al., Neuronale Netzwerke, Einf uhrung, 1991, pp. 26-29, 75-76 and 108-109,No Month.
Ungard et al., Schutztechnik in Elektroenergiesystemen, Vorwort, 1991, pp. 116-117, No Month.
Muller et al., Selektivischutz elektrischer Anlagen, Aug. 2, 1990, pp. 122-124.
Leja Ronald W.
Siemens Aktiengesellschaft
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