Abnormal State Sensing Method of Active Distribution Transformer Based on Digital Twin

Active distribution transformer refers to a transformer in a distribution network located in many distributed power supplies. This article proposes a perception method of faulty state -based transformers based on digital twin. It can meet the requirements of transformer protection speed, and at the same time, it has the advantages of unwillingness to be influenced by external failure of transformers, high sensitivity in the region, and rapid judgment. This article establishes a digital space model based on the physical mechanism of the transformer and establishes the mapping relationship between the voltage and current of the transformer. First analyze the single -phase transformer, rely on the improved T -type equivalent circuits and differential equations to model, and then expand to a three -phase transformer. By the voltage and current on one side of the transformer, the voltage current on the other side of the transformer can be accurately calculated in real time. The calculated voltage current becomes “virtual voltage” and “virtual current”. As long as the internal state of the transformer is normal, the calculation value of the virtual voltage and virtual current is very close to the value of the actual voltage current. If there is a failure inside the transformer, the value of the virtual voltage current and the actual voltage current will be significantly different. Unlike the longitudinal protection, relying on this different to distinguish the abnormal state of the transformer, it can not be affected by the influence of excitation surge, which greatly reduces the impact of the imbalanced current. It also has very high sensitivity to the discrimination of minor faults. In the end, the calculation error of the virtual voltage and virtual current under normal operation of the transformer and the calculation error of the virtual current discussed the differences between the virtual current and the actual sampling current when the fault occurred. According to the difference, the internal fault and abnormal operation state of the transformer can be judged.