Research On The Detection Methodology Of Main Electrical Equipments In Substation

Transformer is the pivot equipment of power system, capacitive equipment accounts a great proportion in the equipments of transformer substation, therefore, the normal operating of transformer and capacitive equipment directly affects the security and reliability of transformer substation power supply. Years of operating experience and the accident data show that the key causes of electrical equipment fault is deterioration of its insulation, so the study on the detection of transformer and capacitive equipment insulation has a great significant for the security of power grid operation.For the transformer detection, especially the detection of transformer winding fault, for many years, the detection and calculation method based on the study of transformer windings mathematical model.In view of the shortcomings that the original single-phase transformer windings model has great error and does not accurately reflect the device structure, this paper presents a new transformer windings model which contains the interphase coupling capacitance, and make a rigorous derivation of the relevant calculations. By a simulation of lightning impulse test, proves that the new windings model is accurate, effective and more in line with the characteristics of the transformer mechanical structure. Finally, this paper proposed a new diagnostic method for the transformer windings fault based on the new windings model, and the results show that the method is simple and effective.For capacitive equipment, by the sensitivity analysis of several commonly used characteristic parameters of capacitive equipment insulation detection, this paper points out that these characteristic parameters have some problems in effective reflecting the insulation condition of capacitive equipment. Based on the equivalent circuit of capacitive equipment, this paper presents several new characteristic parameters to reflect the capacitive equipment insulation fault and make some simulation. The results of simulation show that these new characteristic parameters can reflect the condition of capacitive equipment insulation more accurately and effectively.The new insulation detection method for transformer and capacitive equipment proposed in this paper has strong maneuverability and practicability, and contribute to the development of the insulation detection technology of main electrical equipments in substation.