WG A2.50 Effect of the distributed energy sources and consequent induced reverse power flow (step-up) on transmission and distribution transformers

Convenor: Jean-Christophe Riboud (

WG A2.50 Reverse power flow (pdf, 51kB)

The scope of this working group is to address the effect of step up operation on transformers that were not designed for this purpose. The effect on flux density, temperature rise, noise and other performances for both core and shell types designs shall be addressed. Possible tap changer control problems will also be taken into account. Differing transformer locations in final distribution, primary distribution and principal transmission will be examined, as well. The report will address the theoretical consequences for core flux and voltage regulation, risks and limitations to step up operation for each technology and the assessments necessary to allow this mode of network operation.