Research On Harmonic Filter With Continuous Multi-Tuning

Tuned AC filter is a cost-effective device for harmonic mitigation. Recently, Active Power Filter(APF) which has a better filtering performance over Tuned AC filter has been quickly developed, but it is restricted by the size and voltage rating of power electronic devices. So Tuned AC filter also has predominance in the large size and high voltage power transmission system.The principle and the inherent demerits of Tuned AC filter are discussed. From the view of solving detuning problem, which is the main cause of deterioration of filtering performance, and covering the shortage that single LC branch only can mitigate single harmonics, the active reactor based on harmonic magnetic flux compensation was investigated. This reactor can independently and continuously adjust the equivalent inductance at different harmonic frequencies. The active reactor and a filter capacitor compose a multi-tuned filter with continuous auto-tuning, which can mitigate multiple harmonics in a single LC branch and can be automatically adjusted with the varying filtering parameter.The harmonic detection based on instantaneous reactive power theory and the incremental algorithm of window translation Fourier transformation for the single phase and arbitrary number harmonic were both investigated and compared .The whole testing system of filter was simulated by MATLAB. The harmonic detection and the control strategy based on harmonic phase are realized by DSP.The results of simulation and experiment verified the feasibility of harmonic filter with continuous multi-tuning, and it has the advantage of simple structure and better filtering performance.