Variable Switching Frequency Control of Distributed Resources for Improved System Efficiency

This contribution explores the possibility of improving the global efficiency of three-phase inverter-based distributed resources (DR) embedded in low-voltage distribution feeders, by the adaptation of their switching frequency (SF) to the operation point of both the converter and local loads. The core of this proposal lies on the fact that in a good number of applications, in both service and residential sectors, the owner of the DR is also in charge of the losses caused in the local electric power system. This fact leaves room for a global optimization of the power losses, i.e., converter losses will be considered together with those losses caused by the current harmonics injected into the local grid. A dynamic adaptive SF frame of the DR is considered in this proposal to allow its operation beyond its rated frequency at light loads, subjected to the thermal constraints of the device. Simulation results obtained using PLECS software as well as an experimental validation of the method are included.