考虑次同步分量的变压器时间并行有限元及铁心动态损耗分析

Finite Element Method for Transformers Using Parareal and Core Dynamic Loss Analysis Considering Subsynchronous Components

针对串补电容或电力电子装置导致系统次同步振荡以及各类次同步振荡抑制器接入系统,使变压器运行在含次同步分量条件下,并引起铁心非对称偏置磁化,从而导致损耗增加的问题,该文提出一种考虑铁心损耗的场路耦合有限元时间并行计算方法。首先,基于定点法建立关于矢量磁位和电流密度的三维时变磁场有限元方程,并嵌入损耗分离理论,建立场路耦合有限元模型;其次,为实现大时间尺度周期问题的加速并行计算,并处理损耗瞬时值无意义的问题,提出基于Parareal的时间并行计算方案对模型进行求解;再次,对计算模型中多频率分量的计算周期确定、铁心损耗计算、定点磁阻率的选择以及初值选择提出方案;最后,利用一台物理变压器模型,验证了该计算模型的有效性以及算法的计算效率,并对比分析了变压器在额定基波及含次同步分量激励下的动态损耗特性。

For series-capacitors or power electronic devices that may cause sub-synchronous oscillation,and various subsynchronous oscillation suppressors connected to the system,the transformers are often operated with subsynchronous components,which may cause asymmetrical bias magnetization,and lead to increased losses.This paper establishes a field-circuit coupling finite element model considering the core loss conductance for simulation.First,the 3D time-varying magnetic field finite element equation of magnetic vector potential and current density is established based on the fixed-point method,and the loss separation theory is embedded to establish the field-circuit coupling finite element model.Secondly,to realize the acceleration and parallel calculation for the large time-scale periodic problem,and to deal with the problem that the instantaneous value of loss is lack of physical meaning,the parallel-in-time(Parareal)algorithm is introduced to solve the models.Then,the calculation period with multi-frequency components,the core loss calculation scheme,the selection of fixed-point magnetoresistance,and the initial value scheme are analyzed.Finally,a physical transformer is used to verify the validity of the calculation model and the calculation efficiency of the algorithm,and the dynamic conductance characteristics of the transformer are analyzed under the excitation of the rated fundamental voltage only and with subsynchronous components.