Search

The use of certain electrical equipment connected to conventional power systems has raised concerns regarding the quality of the power system. Some equipment has been perceived to be unequipped to sustain the surges, faults, and distortions in traditional distribution systems. Common voltage issues exist, such as imbalance, harmonic distortion, sag, and swell. Such issues are usually contained using a dynamic voltage restorer (DVR). In this study, the determination of voltage references for DVR based on a robust and simple detection method of positive and negative sequence components is analyzed. This method detects the components in real time. With the proposed method, either the reference load voltages can be generated, or the reference DVR voltages can be generated, depending on which voltages are controlled. Moreover, contrary to other methods, the proposed technique avoids the use of phase-locked loop (PLL) and vector transformation. The voltage compensation technique controls the DVR in real time to prevent steady-state and disturbance conditions at the load side. The proposed system is evaluated by simulation and experimentation under several steady-state and transient cases. Finally, the proposed control is compared with common control methods. [ABSTRACT FROM AUTHOR]

Shunt active power filters (APFs) are used to address power quality issues such as harmonic distortion and power system imbalance. Many control systems for shunt APFs demand measurements of voltages and currents for the determination of instantaneous real and reactive power signals. From these signals, the reference currents of the shunt APF are calculated. A method of control for the APF shunt that only measures currents is proposed in this paper. The control method includes a modified technique to extract the positive and negative sequence components in the time domain. The reference currents in the shunt APF are calculated by the negative sequence components of the measured currents. Simulation and experimental results confirm the efficiency of this control scheme under ideal and non-ideal conditions. [ABSTRACT FROM AUTHOR]