This thesis addresses power quality at two different levels, transmission and utilization. Harmonics injected at these levels can severely degrade the performance and long term reliability of the power system; At the utilization level, a typical industrial power system configuration that requires power factor capacitors and tuned harmonic filters for reactive power compensation and harmonic-control is analyzed. The resonant conditions for a given power factor correction or harmonic frequency are determined directly from the roots of a quadratic expression. This formulation allows a quick evaluation of the power factor range with excessive harmonic levels and reveals the effect of tuned reactors on the resonant frequencies; At the transmission level, a method for analyzing series capacitor placement on long transmission lines to improve line loadability is described. The influence of the compensator on harmonic current propagation and circuit resonant frequencies is investigated. Computer simulations are performed on an actual 345 kV, 238 mile line