A novel power quality assessment using real time hardware-in-the-loop simulation

While off-line simulations and laboratory measurements have been the tool of choice to study power quality issues in the past, a novel method based on real-time (RT) hardware-in-the-loop (HIL) simulation is proposed in this paper. The RT-HIL environment employs a commercial real-time digital simulator allowing RT simulations of large power systems and its controls at a bandwidth between DC and 3 kHz. In the example described in this paper an industrial controller provides firing pulses to a simulated thyristor controlled rectifier. The latter is fed form a simulated distribution system. In such a truly closed loop environment the firing board is tested for its sensitivity to poor quality power. The results show that the board is insensitive to large voltage distortions exceeding values recommended in the standards. However, certain single-phase voltage sags which cause a phase shift of the faulted phase voltage lead to misfiring of the board. It is concluded that such detail can only be revealed by the proposed RT-HIL method and will lead to a substantial improvement in equipment performance in the future.