High performance reactive control for unbalanced three-phase load

In this paper we consider the problem of balancing a three-phase load and how to optimize the TCR operation. For an unbalanced load change a VAT technique is developed by the authors to determine the three compensating susceptance values and then the unsymmetrical firing angles of TCR, which are necessary for a balanced load operation. An objective function (THD) is determined to measure the discontinuity of the TCR operation. For an unbalanced load change, the availability of TSC and the control of TCR produce different values of reactive volt-amperes, in which all produce the balanced operation but with different amounts of harmonics. The paper introduces and develops an iterative algorithm to obtain the optimum firing angle values of TCR, and this is based on minimum generation of harmonics. The results show that a modulated THD is achieved, and this approach guarantees the high performance reactive control for unbalanced three-phase load. Copyright (C) 2009 John Wiley & Sons, Ltd.