Reduced Sensor-Based Control of Unified Power Quality Conditioner

Many critical loads require protection against various disturbances related with voltage, current or power. The unified power quality conditioner (UPQC) provides protection against such problems. A reduced sensor-based control approach is presented for a UPQC in this paper. Two back-to-back connected voltage source converters are employed with shared DC bus as a series active compensator (SEAC) and a shunt active compensator (SHAC). The control of SEAC of a UPQC is implemented using instantaneous symmetrical component theory. The SEAC injects voltage in series with the supply to effectively regulate the load bus voltage under voltage swell, sag and harmonics. The SHAC is implemented employing the power balance theory-based control to mitigate harmonics and unbalancing in load currents and reactive power demand. The SEAC is controlled for load voltage and its harmonics compensation. Similarly, the SHAC is controlled derived using reference source currents, respectively. A prototype of UPQC is developed to observe the performance of control approaches under balanced/unbalanced nonlinear loads for compensation of harmonics, voltage sag and swells conditions. © 2021, The Institution of Engineers (India).