Hi, Regarding transmission line booster transformer topologies I'm curious as to what would happen over all the possible permutations. I refer you to the following: http://top10electrical.blogspot.com.au/2015/03/booster-transformer.html I presume that in real life the booster transformers are all 1:1, but for this discussion imagine that all the primaries and secondaries have tap changes, so all buck-boost configurations are possible. For this thought exercise I'm defining the power flow of left to right (through the regulating transformer) as forward, as well as down to up (through the booster transformer) as forward. As well as defining the primary as being on the left of the regulating TX and the primary as being the top of the booster transformer. I haven't yet put in the values for if the polarity of the secondary of the booster transformer being swapped. But I am curious as to what would happen if you reversed this as well, so in good time I want to record the effects of swapping the dot on the secondary of the booster transformer as well. Please see the following table I have attached the .xlsx of: I have just used 1;2 as short-hand for a boost ratio, and 2;1 for bucking ratio. I have inputted a couple of the resulting power flow and voltage changes, as I expect they would occur. If someone could help me understand the operation and fill in the rest, that would be wonderful. Thank you!