Development of a PC based multi-function recorder for the laboratory model power system on RTAI-Linux platform

This paper presents the development of a PC based multi-function recorder using an open-source real-time application interface (RTAI) in Linux environment. Here, various quantities such as three-phase real and reactive power (including the sign), power factor, RMS value of the voltage and currents and frequency are estimated employing the instantaneous samples of 3-phase voltages and currents. Such a setup not only permits easy handling of plots in an off-line environment, but also helps to visualize the operating conditions of machines which are generally learnt only by mathematical models and time-domain simulations. In the paper, this aspect has been demonstrated by acquiring the operating conditions of a lab synchronous machine when it is subjected to loss-of-synchronism and loss-of-excitation. Further, since the system provides values of quantities in realtime, it is found that such a set up can be upgraded to a protective relaying system, for example, reverse power detection relay, and even for controller implementation.