Control Strategies for Load Compensation Using Instantaneous Symmetrical Component Theory Under Different Supply Voltages

In this paper, the theory of instantaneous symmetrical components is applied to explore various control strategies of load compensation, under different supply voltages. When the supply voltages are balanced and sinusoidal, all of these strategies converge to the same compensation characteristics. However, when the supply voltages are not balanced sinusoids, these control strategies result in different degrees of compensation in harmonics, power factor, neutral current, and compensator ratings. These control strategies are discussed in detail and a comparative study of their performance in terms of the rms value, total harmonic distortion, power factor of source currents, and compensator ratings is presented. Based on this study, it is possible to select the best strategy to meet the required load compensation characteristics for available supply voltages. A three-phase four-wire distribution system supplying an unbalanced and nonlinear load is considered for simulation study. The detailed simulation results using MATLAB are presented to support the proposed compensation strategies.