Abstract: When consumers connect inductive loads to the power system, the power factor lags, creating high current demand, thus high active power losses are incurred in the system. In Nigeria, when the power factor goes below 0.8 (lagging), the electric supply company charge penalty to the consumers. This calls for a system control hence power factor correction. Earlier, the power factor correction was done by adjusting the capacitor bank manually. The automated power factor correction using a capacitive bank helps provide the power factor correction, thereby decreasing the time taken to correct the power factor, which also helps to increase the power efficiency. It has been demonstrated in this work that the phase difference between voltage and current can be determined using zero-crossing detectors, optocouplers, XOR gate, and some primary function of the microcontroller (ATmega 328). Voltage and current transformers have been used for transforming load voltage and current respectively to bring them in the desired working range for the zero-crossing detectors. The device reads the time difference between the line voltage and line current, which is now calculated as the phase angle, and the corresponding power factor is then calculated. If the calculated power factor is less than 0.8, the microcontroller calculates the compensation requirement and accordingly switches on the required capacitor with the aid of an electromagnetic relay. The display used was 162 liquid crystal display module. In conclusion, according to the test carried out during simulation for three different inductive loads, the power factor was corrected from 0.59 to 0.99, 0.60 to 0.99, and 0.55 to 0.87, respectively, and also, the power factor was adjusted from 0.73 to 0.98 during the hardware test. These results show that the designed and constructed automatic power factor correction device works properly.
Keywords: Power Factor, Power Factor Correction, Zero Crossing Detectors, ATmega 328, Capacitor Bank
| DOI: 10.17148/IJIREEICE.2019.7905