Improved control method for voltage regulation and harmonic mitigation using electric spring

Abstract

An electric spring (ES) with series connection to non-critical loads (NCLs) is mainly known as a smart load (SL) technology that can compensate undervoltages and overvoltages. In this paper, an improved control method is presented for the electric spring to regulate the effective value of the critical load (CL) voltage to the nominal value and to compensate the harmonics of the critical load voltage caused by the grid side. The electric spring’s performance for simultaneous voltage magni-tude regulation and harmonic distortion compensation is investigated through simulation studies. The results are compared with those of a conventional control scheme. It has been demonstrated that the electric spring, using the improved control system, reduces the amplitude deviation and distortion of critical load voltage.