Mixed isolated island detection method

Abstract

The invention discloses a mixed isolated island detection method. On the basis of mixing of artificial intelligence, voltage and frequency positive feedback of a decision tree (DT), the method based on artificial intelligence of the decision tree measures and stores characteristic quantity indexes of default events of selected target positions, information of a data collection is extracted and analyzed to train a DT classification device, and the operation state of DG (Distributed Generation) is judged to be whether network operation or isolated island operation through comparing the former data collection with a data collection in the case of pre-specified events. According to the method, on the basis of the DT method, the inverter control-based positive feedback method is further combined, complementarity and compatibility are strong; through introducing positive feedback disturbance, the characteristic quantity indexes can be obviously distinguished in the case of isolated island operation of the system and the network operation, judging the isolated island by the DT method is facilitated, and through increasing difference of the characteristic variable parameters in the case of isolated island operation or non-isolated island operation, the error rate of isolated island detection is thus reduced, and reliability of isolated island detection is improved.

Description

technical field [0001] The invention relates to the technical field of island detection, in particular to a hybrid island detection method. Background technique [0002] Distributed generation (Distributed Generation, DG) usually refers to a small modular, decentralized, efficient and reliable power generation unit arranged near the user with a power generation of several kilowatts to hundreds of megabytes. Mainly include: internal combustion engines fueled by liquid or gas, micro gas turbines, solar power generation (photovoltaic cells, photothermal power generation), wind power generation, biomass power generation, etc. [0003] Distributed power is usually connected to medium-voltage or low-voltage power distribution systems, and its operating status includes island operation and grid-connected operation [Document 1]. DG island operation means that the distributed power supply is disconnected from the main network and operates independently with local loads. Due to equi...

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Problems solved by technology

[0009]5) Cost of misclassification: The inherent cost associated with misclassifying the data under test

When there is a certain voltage deviation between the operating voltage of the external power grid and the standard value, for example, the system voltage is 0.9p.u, because it is relatively close to the threshold value, when the DG system load is disturbed or a certain amount of load is suddenly increased, this method may cause islanding false detection

On the other hand, this method needs to inject a certain amount of disturbance to the DG system all the time, which cannot completely eliminate the impact on power quality

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