Numeric magnetic field calculation and field current calculation for synchronous generators
Purpose - The paper aims to cover a numerical routine design calculation module for treating the magnetic circuit of hydrogenerators. Design/methodology/approach - A leading manufacturer of hydrogenerators proposed to overcome the standstill in the development of conventional design calculation tools by replacing his existing program module for treating the magnetic circuit of hydrogenerators by a new one based on numerical algorithms. The new module should use the existing interfaces and not change the scope of the existing design program providing hundreds of additional design results. Fulfilling these requirements the numerical calculation module using an enhanced finite integral method had to be self-organising with regard to everything, e.g. the grid system generation for discretising the calculation area, the handling of the input data including the currents driving the magnetic field, the handling of the boundary conditions and the iterative load case treatment providing the field current producing exactly the required terminal voltage and factor at the machine terminals. Efforts were made for employing grid generation techniques, numerical algorithms and various iteration strategies which were easy to handle and to minimize the calculation time. Findings - The effort necessary for automating the calculation approach so that interference of a numerical field calculation expert is unnecessary was found to be more challenging than handling the numerical algorithms. Practical implications - The program module is ready for implementation. Originality/value - The paper describes the transfer of numerical field calculation software into existing tools for routine design calculations.
magnetic fields design calculations numerical analysis finite difference methods field testing