Power Quality Enhancement of Stand-Alone Hydro Power Generation System Using UPQC

This article analyzes an application of a unified power quality conditioner (UPQC) for improving power quality (PQ) in a stand-alone hydro generating system that supplies electricity to nonlinear loads. In this scenario, a series power active filter (SEPAF) is employed to ensure a consistent and fundamental voltage magnitude across loads, irrespective of any voltage variations produced by the hydro generator [squirrel cage induction generator (SCIG)]. Moreover, a shunt power active filter (SHPAF) of the UPQC improves the PQ of source terminals by addressing several issues such as reactive power, current harmonics, currents unbalancing, and power factor. Furthermore, by running the SCIG at a voltage level that is 10-20% lower than its rated value, the need for excitation from a capacitor bank is minimized. This reduction in magnetizing current leads to a decrease in overall losses. To have a coordinated control between the SEPAF and the SHPAF, a control approach referred to as a damped ratio adaptive second-order generalized integrator is used for extracting fundamental components of load currents. The utilization of UPQC enhances voltage characteristics of critical loads and currents at the generation end, hence ensuring compliance with standards set by the IEEE . Hardware validations demonstrate the efficacy of the system.