A dynamic mathematical model for surface heaters is presented in the paper. 建立了表面式加热器的高精度的动态数学模型。
It is difficult to obtain the dynamic models of converters, overlong overhead HVDC lines and passive filters in audio frequency. 然而，由于运行工况及气候的影响，难以求取换流器及长距离高压架空线路在音频带内的动态数学模型。
