Estimation of voltage dips at the terminals of Double Fed Induction Generators

The existence of non-linear loads in the power system, as well as the increased use of power electronics and electronic/microprocessor based devices, contributes to unwanted distortions in voltage and current waveforms. This creates a need for more accurate, fast and robust methods for tracking all the relevant signal parameters. In this paper Newton Type Algorithm (NTA) is implemented to estimate the unknown harmonics amplitudes and their phase angles. Furthermore, the NTA algorithm possesses an additional feature: simultaneous estimation of the spectrum and the unknown frequency of the input signal, making it a robust means, applicable for monitoring, protection and measurements in the modern power systems. Once the signal parameters are determined, the other important parameters such as Root Mean Squares (RMS) and Total Harmonic Distortion (THD) are calculated. The algorithm is successfully applied for the assessment of voltage dips at a Double Fed Induction Generators wind farm. In this special case, the existence of signal distortions due to power electronics were the particular challenge to be solved.