Dual-Tap Chopping Stabilizer With Subcyclic AC Soft Switching

Frequency Estimation of Distorted and Noisy Signals in Power Systems by FFT-Based Approach

“…Many methods focusing on this task are presented in scientific literature, including the Kalman filter [7], zero-crossing technique [8], least-squares methods [9], [10], recursive method [11], Taylor series [12], artificial neural networks [13], [14], and the well-known discrete Fourier transform (DFT) [2], [15]. Unfortunately, the determination of the model order for the parametric (time-domain) methods, e.g., Kalman filter, least-squares methods and recursive method, often require intensive computational algorithms.…”

An Improved Control Scheme for On-load Tap Changers with Reduced Harmonics Injection

“…The above drawbacks were greatly reduced with an electronically assisted OLTC regulator topology, as shown in Figure 1(b) [21], although there are various alterations and modifications in the OLTC schemes [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] in between to eliminate the problems already mentioned. The OLTC regulator has a number of tapings on the secondary or primary of the main transformer, which are connected to load terminals through fast-acting solid-state switches.…”

“…It has considerable limitations and drawbacks, including arcing, high maintenance costs, and slow response time [1]. To address these limitations and drawbacks, new configurations for tap changers have been recommended [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].They have been classified in to two groups: the electronically assisted OLTC regulator [2][3][4][5][6][7][8][9][10] and the fully electronic OLTC regulator [11][12][13][14][15][16][17][18][19][20][21]. Various other feasibility propositions for electronic tap-changing stabilizers have been reviewed for medium-voltage lines [4].…”

“…To minimize the number of switches or taps in an electronic tap changer, a new scheme was proposed with help of a discrete cycle modulation (DCM) technique [15]. Electronic tap changer designs for enhancing the power quality of distribution transformers through several soft-switching techniques were given in [16][17][18][19][20]. These techniques are similar to high-frequency AC/AC converters.…”

Harmonic analysis based on time domain mutual-multiplication window

“…The most commonly recognized algorithm is weighted interpolation FFT by using nonrectangular window [7][8][9][10] which could significantly suppress the spectral leakage and reduce the picket fence effect to increase the accuracy of the harmonic analysis. Selecting the appropriate window function can effectively suppress the influence of spectral leakage [7]. It is well known that the performance of windowed FFT is mainly determined by the window function [8].…”