Research And Development Of Large Oltc Auto-transformer

The increasing demand of power system,with the rapid development of economic construction in our country has promoted the rapid development of our domestic power industry. The 220 kV power transformer has entered the city center and industrial park,becoming the hub of power supply.The auto-transformer has the advantage of small size,light weight,low loss,compared to the normal one,with the same capacity and voltage level.The 220 kV auto-transformer and above have been widely used in power system.The design and calculation of auto-transformer is different from that of normal one, because the primary side and secondary side of auto-transformer have not only magnetic relationship,but also electrical relationship.The special regulating method makes it hard to manufacture because of the complex inner lead structure. Only a few domestic manufacturers have the capabilities and experience to produce large auto-transformer with voltage level of 220 kV and above. My research subject is derived from one of my company ’s product procurement contract, the model of which is OSFZ11-100000/230 and that is the first 220 kV auto-transformer from my company.My paper mainly make analysis, calculation and comparison between different regulating methods and determine the suitable one. My paper also analyze the on-load tap-changer and determine that three single phase OLTC are used. What’s more, it conducts a discussion about the arrangement of tap-changer and transformer leads, making the auto-transformer easy to conduct voltage regulation.This subject gives a simulation about tank distortion under vacuum condition, conducting the finite element analysis on tank strength during structure design process, with the aid of analysis software ANSYS. Thus the flaws of designed tank can be found in the process of product design, and we can strengthen the parts that have maximum distortion according to the simulation result to meet the technical requirement. Also, this paper compares the distortion of improved design model with the result of real product to verify the accuracy of this analysis software. The result show that the analysis software has certain accuracy and some guiding significance on design of transformer tank.Finally, a design example is given. Experiments show that the designed autotransformer can meet the requirements of the technical agreement and national standard, what’s more, the loss, a key parameter which affects the cost is much better than the technical agreement, and the amount of copper, silicon steel sheet are reduced a lot compared to the ordinary power transformer with same capacity.