Contents I. Introduction
Shunt capacitors have been utilized for voltage support and power factor correction as a common practice in the electric power grids. Every power system has a natural frequency that is a function of the system reactance and the amount of power factor correction capacitors connected to the system [1]. Therefore, the installation of shunt capacitors can result in harmonic resonance and cause an increase in the system impedance at the corresponding frequency. In the case that a source of excitation; such as harmonic currents of nonlinear loads exists with a frequency near or equal to the system natural frequency, large harmonic voltage distortions can result due to the occurrence of resonant conditions. With the increasing spread of harmonic-producing loads such as motor drives, power electronic converters, electric arc furnaces, … the possibility of parallel resonance due to shunt capacitors has become a routine concern for capacitor applications [2] [5]. The problems associated with the parallel resonance are typical of harmonic related heating, including blown fuses, circuit breaker heating, and unexplained general equipment failures.
