Analysis And Calculation Of No-Load Performance And Electromagnetic Parameter For Powerformer

Powerformer is a new type of high-voltage generator. It took ABB corporation eight years to develop the generator. Powerformer represents a totally new system concept in power plant technology. It is suitable for both hydro and thermal applications. The stator windings of Powerformer are XLPE cables. The windings have cylindrical cross-section. The circular conductor yields an even electric field distribution around its entire circumference. The rectangular conductor of the conventional generator yields an uneven electric field distribution around its periphery. The design philosophy of the conventional generator has prevented the output voltage from exceeding 36kV. But the circular conductor can overcome this disadvantage. The use of circular conductor has made it impossible to increase the output voltage of the generator to the grid voltage level. So Powerformer offers a direct connection to the power network without the need for a step-up transformer. It offers the power plant several advantages such as enhanced reliability, higher efficiency etc.The research of electromagnetic theory is the foundation of electromagnetic design. And it is also the basis of the design of cooling system and mechanical system on electric machine. As a new type of energy conversion device, Powerformer is different from the conventional generator in the structure of the stator in essence. The conventional design method cannot meet the design demand of Powerformer. So far, the research is not carried out deeply in analysis and calculation, theoretical design, and operation analysis of Powerformer in our country, as the Powerformer system is developed recently.In the paper, firstly, theory, structure, design characteristic and development survey of Powerformer are introduced. Secondly, the two mathematic models of 2D and 3D are established by the finite element software—ANSYS, the distribution of air gap magnetic field is solved, the 2D and 3D characteristic curve of Powerformer at no-load are obtained. The no-load characteristic can better approach to that of the test value. Finally, the theory of reactance parameters calculated by 2D finite element method is introduced in detail. These parameters include the static reactance, transient and sub-transient reactance of Powerformer. At the same time, the 3D static reactance is also calculated by the magnetic scalar potential method when the model is simplified.The result of the electromagnetic parameter for Powerformer has some practical value. And it can meet the demand of engineering application.