Research Of Electronic Power Transformer Online Monitoring System

Electronic power transformer (EPT) is a novel kind of power transformer developedcorresponding to the technical innovation of power systems and the rapid development ofpower electronics. For developing and debugging EPTs, and for securing the stableoperation of EPTs, it is necessary to effectively monitor the operating status and the controlparameters of EPTs. Therefore, according to the characteristics of EPTs, an onlinemonitoring system (OMS) for EPT is researched and developed in this paper.After analyzing the online monitoring technologies and the designs of OMS forconventional power devices, this paper proposed a hierarchical distributed design of theOMS for EPT, since the control system of EPT adopts a distributed arrangement of multipleDSPs. Plus, to ensure the effective communication between the host computer and theDSPs as well as the real-time data exchange between the DSPs in the EPT, acommunication architecture combining CAN bus communication and SCI serialcommunication is adopted.To realize the CAN bus communication, after analyzing the EPT’s requirement of theCAN bus’s function and communication, this paper demonstrated the protocol design onthe application layer and the module design on the physical layer in detail, as well as theusage of the modules.After summarizing the monitoring variables required by the OMS, the main functionmodules of the OMS are designed following the guidelines of developing host computers.Then the host computer procedure is programmed using Visual C++, and the whole OMS isfinished.The OMS is applied in the developing and debugging process an EPT. The resultshows that the OMS can effectively monitor the EPT’s operation and control the relatedparameters of the EPT, as well as record waveforms in real time and monitor thecommunication within the EPT. However, when the input voltage of the EPT rises,interferences are observed in the CAN bus communication. Hence, based on analyzing theregular anti-interference measures for CAN bus communication, the CAN bus communication of the proposed OMS is tested and evaluated from multiple aspects using aCAN recorder analyzer, and eventually the interference signals in superposition with theoriginal signals are determined. The interference problem is fixed by introducing isolationdevices to filter the interference signals. Therefore, in a CAN bus communication design,the single CAN nodes are suggested to be accessing the CAN bus directly, and thecommunication cable of the CAN bus should be away from strong electric circuits or usingoptical cables instead.