The Design Of Transformer Protection Device Based On Dual-DSP Technology

The power transformer is a very important equipment in power system, which has been widely used in every aspect of power system. Safe and stable operation of the power transformer has great influence to the entire power system stability, so, appropriate protection are needed to ensure security and stability of power system, choosing by the capacity, the importance and fault or abnormal operating conditions of the transformer.The article analyzes the possible fault and abnormal condition of the transformer, introduces the principle of relay protection for power transformer, especially researches on the causes and measures for the unbalanced current and magnetizing inrush current of differential protection. The improved Fourier algorithm is raised for problems in practice and it provides a theoretical basis for the design of the device software system.According to the basic theoretical research of transformer protection, the author designs the protection device for power transformer based on dual-DSP platform, which integrates protection, measurement, control, communication functions, and achieves these functions through the protecting DSP and the monitoring and control DSP. The protecting DSP samples independently and completes digital filtering, protection algorithms, logical judgment and export logic. The monitoring and control DSP completes start-up of the device, keyboard control, man-machine interface and background communication. The paper focuses on the framework structure of the hardware system, describes the design of the module circuits in detail such as the signal acquisition circuit, analog-digital conversion circuit, the switch input and output circuit, power circuit, the CAN communication circuit and the dual-DSP communication circuit. The modular design is used in software system and classified for the protecting DSP program and the monitoring and control DSP program. The article shows the flow chart of these procedures. To make the acquisition of signal as precise as possible and ensure the device act reliably and accurately, the paper provides the measures taken by the hardware and software system in terms of interference.