Calculation of Harmonic and Inter-Harmonic Pollution of Wind Doubly-Fed Induction Generators by a Hybrid Method

In bad weather condition، doubly-fed induction generators (DFIG) are injecting harmonic and interharmonic components into the power networks. Since frequency range and resolution needed for harmonic and interharmonic measurements are very different، measurement of these parameters are usually done separately. Therefore in this paper a hybrid method for simultaneous identifying of these components is presented. For this purpose، first the voltage envelope and real fundamental frequency of waveform are obtained by an extended kalman filter and then interharmonic and harmonic components are respectively calculated by a linear kalman filter and adjusted window DFT. The main advantage of this method is simultaneous measurement of harmonic and inter harmonic components by a suitable accuracy and computational burden in compare to separated implementation of each of these methods. Finally، the performance of proposed method is evaluated by synthesized waveforms and the voltage waveforms of DFIG in a 34-bus Italy network. The results show that the proposed method is highly capable in analysis of harmonic and interharmonic pollution of power networks in presence of DFIGs.