diff --git a/docs/optimizer/preprocessing.md b/docs/optimizer/preprocessing.md index 77143ade..f51c711e 100644 --- a/docs/optimizer/preprocessing.md +++ b/docs/optimizer/preprocessing.md @@ -18,7 +18,7 @@ Note that for lines considered as non-impedant and connecting two different nomi ## Impedance of transformers -In the calculations of the ACOPF (see [AC optimal powerflow](acOptimalPowerflow.md)), the transformers with an impedance (specified in `ampl_network_branches.txt`) considered as null (see [Zero-impedance threshold](#zero-impedance-threshold)) **are treated as lines**. Then, the transformation ratios/phase shifts are ignored, as well as the impedance specified in the tap changer table `ampl_network_tct.txt`. +In the calculations of the ACOPF (see [AC optimal powerflow](acOptimalPowerflow.md)), the impedance specified in tap changer table `ampl_network_tct.txt` is ignored for transformers with an impedance (specified in `ampl_network_branches.txt`) considered as null (see [Zero-impedance threshold](#zero-impedance-threshold)). Note that the transformer ratios and phase shiftings are considered anyway. For phase shifters transformers considered as impedant, the reactance values from the tap changer table (in `ampl_network_tct.txt`) replace the reactance specified in `ampl_network_branches.txt`. The resistance is then calculated proportionally. For the ratio tap changers, the impedance stays as specified in `ampl_network_branches.txt`. **Please notice there is no specified handling for cases where resistance and/or reactance is negative or if there is both a ratio tap changer and a phase shift transformer on the same branch.**