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Power-electronic interfacing based devices such as wind generators (WGs) and electrical vehicles (EVs) cause harmonic distortions on the power grid. Higher penetration and uncoordinated operation of WGs and EVs can lead to voltage and current harmonic distortions, which may exceed IEEE limits. It is interesting to note that WGs and EVs have some common harmonic profiles. Therefore, when EVs are connected to the grid, the harmonic pollution EVs impart onto the grid can be reduced to some extent by the amount of wind power injecting into the grid and vice versa. In this context, this work studies the impact of EVs on harmonic distortions and careful utilization of wind power to minimize the distortions in distribution feeders. For this, a harmonic unbalanced distribution feeder model is developed in OpenDSS and interfaced with Genetic Algorithm (GA) based optimization algorithm in MATLAB to solve optimal harmonic power flow (OHPF) problems. The developed OHPF model is first used to study impact of EV penetration on current/voltage total harmonic distortions (THDs) in distribution grids. Next, dispatch of WGs are found at different locations on the distribution grid to demonstrate reduction in the current/voltage THDs when EVs are charging.

Condition monitoring of the insulation of the windings of a power transformer depends on the accuracy with which the neutral current is measured during impulse test both at full and at reduced voltage. The most common problem faced while measuring neutral current is that it contains noise that causes ambiguous fault signatures. This paper presents an effective means for filtering out the noise from the neutral current using framelet technique. A fast and yet simple algorithm has been used here to calculate the framelet coefficients. Results presented are for an electromagnetic transient program (EMTP) simulated model of a 3 MY A transformer mostly used up to 33 kV. Studies have been carried out with both high and low frequency synthetic noises. Comparison of the results with that obtained from wavelet technique based method has also been reported in the paper.

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