Analysis, Design, and Implementation of a Fast On-Load Tap Changing Regulator

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].…”

“…These techniques are similar to high-frequency AC/AC converters. Further, an electronic tap changer with bidirectional solid-state switches along with a compensating transformer has been developed to enable correction of such disturbances as sag and swell [21].…”

“…The topology proposed in this article is nearest the second option in [21]. The proposed technique is a modified control scheme of an electronically controlled OLTC regulator and can replace the classical OLTC regulators.…”

“…The control is achieved with the help of two switched insulated-gate bipolar transistor (IGBT) diode modules for regulation of output voltage. The proposed methodology removes the requirement of mechanical switches or series inductors as used in [21], which can introduce several undesirable effects in the schemes as already mentioned. As IGBT switchings within a power cycle can introduce harmonics in the overall output voltage, measures are taken to generate the switching pulses in such a way that the maximum number of harmonics including the significant lower orders are reduced with fewer switchings.…”