Анализ влияния высших гармоник на потери мощности в системах электроснабжения

Abstract

В статье представлены результаты исследований влияния высших гармоник тока на сопротивление сети, потери мощности, а также КПД системы электроснабжения. На основании уравнений Бесселя первого рода представлены зависимости активного сопротивления сети от частоты высшей гармоники при влиянии скин эффекта. Установлено, что кроме влияния скин эффекта, высшие гармоники обуславливают дополнительные потери, обусловленные увеличением среднеквадратического значения тока, представлена зависимость дополнительных потерь мощности в сети от коэффициента гармонических искажений тока. Установлено, что высшие гармоники тока сети, вызванные импульсной нагрузкой, вызывают большие потери в сети, нежели высшие гармоники от источника питания.

Increasing energy efficiency is a priority for the energy sector. To realize maximum energy efficiency, a clear understanding of the significance of the component losses and methods of their elimination is necessary. This is also necessary to determine the power losses caused by higher harmonics, as well as to determine the energy-saving effect of the power active filter. The article presents the results of studies of the influence of higher current harmonics on the network resistance, network losses, as well as the efficiency of the power supply system. On the basis of the solution of differential and algebraic equations, it is established that the existing approximating expressions that determine the dependence of the network resistance on frequency, caused by the skin effect, are not accurate. For a certain frequency range, the network resistance is below the nominal. In addition, they do not take into account the effect of the cross-sectional area. Based on the solution of the Bessel functions of the first kind, a method is developed for calculating the dependence of the active resistance of the network on the frequency, which takes into account the geometric parameters of the conductor. It is established that the skin effect makes the resistance of the network a frequency-dependent parameter. Thus, the electrical network can be represented as a filter. Additional losses of energy arise in the electric network from higher harmonics due to an increase in the rms current. The dependence of additional losses in the network on the higher harmonics as a function of the resulting coefficient of current harmonic distortion is established. It is established that the higher harmonics of the current caused by the power source and the load in different ways affect the efficiency of the network.