Analysis of Power Flow Reversion in Distribution Transformers Due to Medium-Voltage Fault and Distributed Generation in Secondary Networks.

Distributed generation (DG), when renewable, is part of the necessary decarbonization of the electric energy sector. Although DG can provide benefits, it is known as well for its operational challenges. This work addresses the problem caused by DGs in distribution systems with meshed secondary circuits. In these kinds of networks, there is more than one medium-voltage (MV) primary feeder supplying a meshed low-voltage (LV) grid, and the distribution transformers in between are connected to network protectors (NPs) through their LV side. These NPs are adjusted to activate the circuit breaker when reverse power flow is detected, usually meaning there is a fault in the upstream feeder. Alternatively, DG penetration can lead to NP false tripping since it produces energy that can flow from LV to the MV side. Considering faults on MV and DG penetration, a set of simulations is carried out with two distribution networks to verify any patterns in the power flow reversion. A Brazilian 81-bus test system and the IEEE 390-bus are employed using the OpenDSS software. The found results indicate the high complexity of the problem, which does not have a simple solution. As DG grows, further work needs to be done to provide advances in this rising protection issue. [ABSTRACT FROM AUTHOR]