Design and Implementation of a PLC Based Monitoring and Control System for Reactive Power Compensation System.

In this study, a reactive power compensation system has been implemented using a programmable logic controller (PLC). The four induction motors, which are used as reactive power consumers, are run or stopped by PLC in the power system. Thus the power system containing more than one reactive power consumer has been prepared. The current and the voltage of the power system are measured and then processed in the PLC to calculate the power factor of the system. The power factor calculation procedure is a novel algorithm developed by the authors. The required reactive power is provided by switching the capacitor groups automatically using the developed software. In addition, the developed system can protect the induction motors against some possible problems, such as overcurrent, high/low voltage, and phase sequence error. Owing to the improved computer interface, starting and stopping of the motors and monitoring of the parameters of the power system could be easily achieved using the computer. Furthermore, it has been shown that the proposed system is very flexible and expandable for different applications. In the study the most important disadvantage is that the grid current waveform is destroyed after reactive power compensation since the motors used as load do not draw a complete sinusoidal current from the grid. [ABSTRACT FROM AUTHOR]