Nonlinear Electromagnetic Field and Its Harmonic Problems

Harmonics are mainly generated from both the component level i.e., nonlinear magnetic or dielectric components and the circuit level, including power electronic circuits. This chapter illustrates the examples of load current waveforms with harmonics. To understand harmonic distribution in the transformer the excitation voltage and magnetic flux waveforms and associated current waveforms should be investigated. The chapter discusses the impact of harmonics on renewable energy and microgrid systems. Power electronic devices, as used for renewable energy systems and microgrids, might be able to cause harmonics. Since harmonic loading, direct current (DC) injection, voltage ripple, and voltage range of operation are key areas that influence the operation of the transformer in renewable energy and microgrid systems, the harmonic balance finite element method (HBFEM) is an effective method to analyze the harmonic problem in the transformer connected with voltage or current sources.