Factors in Choosing Transformer Paralleling Methods

This paper describes several important factors to be analyzed when deciding on the method of paralleling power transformers. Commonly used methods for controlling paralleled LTC transformer taps are described, as well as comparisons and evaluations of those methods for different system applications. This paper discusses the newest paralleling method that provides optimal operation for substation configurations that are becoming more prevalent in present-day power systems; these configurations have not been addressed by previous paralleling methods. The comparisons include the negative reactance method, the master/follower method, the power factor method, the circulating current method and the VAr balancing method. The effect of other control functions on proper parallel operations, such as LDC (line drop compensation) or reverse power operation settings, is also noted