TSO/DSO collaboration to solve constraints regarding voltage in HV networks and HV/MV on-load tap changers

High voltage issues are a growing concern for the French power network operators (LV, MV and HV). Moreover, HV/MV on-load tap changers (OLTC) are more often at their lowest tap, resulting in degradation of MV and LV voltage management and therefore considered as a constraint. Therefore, a collaborative working group between the French transmission system operator (TSO) Rte and the main French distribution system operator (DSO) Enedis aims at identifying levers to solve these constraints. These solutions can be located on either the transmission or the distribution network. This cooperation between the TSO and the DSO allows a more comprehensive approach to constraints and potential levers. Indeed, some levers could be efficient for both the TSO and the DSO constraints, while some others would be efficient for only one operator. This paper focuses on high voltage constraints in HV networks, managed by the TSO, and HV/MV on-load tap changer (OLTC) constraints, managed by the DSO. A cost-benefit analysis method is proposed to compare the technical and economic performance of the different levers on real HV-MV network cases.