Electromagnetic Design And Characteristics Analysis Of ITER PPEN Transformer

International Thermonuclear Experimental Reactor (ITER) is the world's largest tokamak fusion experimental device under being built currently. Its transmission voltage and installed capacity is the level of 400 kV / 1.2 GVA / 27 GW. PPEN is a transformer substation, which transforms 400 kV power to 66 kV and 22 kV and distributes to 100 pulse power loads of MVA level magnet power and microwave heating system. ITER device runs randomly by pulse mode; pulse power is huge and the instantaneous active power is more than 600 MW; reactive power rises or falls sharply and the instantaneous reactive power is more than 900 Mvar. Such a complex condition is unprecedented ordeal for PPEN equipments, especially the most core equipment - the main transformer, its design is different from the conventional power transformer, which is also one of the biggest difficulties of PPEN project. In this paper,the design of PPEN main transformer is carried on the detailed analysis and research.Finally, PPEN transformer manufacture, test and delivery are guaranteed to be finished smoothly. Innovations and achievements are as follows:For ITER pulsed power load characteristics, this paper deeply analyzes the electromagnetic characteristics of PPEN transformer and completes the transformer engineering design. For PPEN transformer three winding loads balance demands, this paper puts forward that a reactor, whose inductance value is 2.72 mH, is built-in series in the low voltage winding side, and solves the problem of the three winding reactive power imbalance based on the power trend analysis. Transformer no-load loss, load loss and temperature rise are analyzed by the way of analytical calculation and simulation analysis. Finally, the three transformers are developed successfully. The correctness of electromagnetic design is verified by test datas.PPEN transformer short-circuit faults are analyzed from two aspects of dynamic stability and thermal stability in this paper. All short circuit current values are calculated in detail. The leakage magnetic field is analyzed and calculated under short-circuit fault by BB-XCX008A, which is transformer leakage magnetic field analysis software. Then, the axial electromotive force, radial electromotive force and short-circuit winding conductor temperature are calculated. Finally, it proves that PPEN transformer has enough anti-short circuit ability.The insulation levels of PPEN transformer were analyzed detailedly in this paper.PPEN transformer insulation structure is built a two-dimensional model using two-dimensional electric field finite element analysis software ELECTRO. The electric field cloud distributions and their insulation safety margins are acquired by simulation analysis. The insulation test items are carried out according to IEC60076.3:2013. The correctness and reliability of transformer insulation structure design are verified.Manufacture, test and delivery of three PPEN transformers are completed in turns in 2016-2017. The indicators of manufacture and test have reached IEC standards and 10 technical requirements.