Optimization of railway microgrid operation under conditions of minimizing energy outflow to the grid

The railway energy microgrid, in terms of both photovoltaic installation and energy storage, should be dimensioned so that there is no or minimal energy outflow. Only under this assumption - that there is no energy flow outside the microgrid - can the consumer freely define the microgrid without the risk of disagreement from the grid operator. The article presents an optimization analysis of microgrid operation to minimize the energy exported to the grid. The microgrid operation was analysed regarding the load generated by one of Poland's railway traction substations. The Particle Swarm Optimization method was used to optimize microgrid operation. Different photovoltaic panel orientations, values for the maximum energy export, and depth of discharge of energy storage were considered. The results show that it is possible to significantly reduce the value of energy export to the grid and use excess energy to charge the designed optimal battery energy storage. An analysis of the green energy used to power the traction substation was also carried out. The results indicate that it can represent a significant percentage of the energy used to power a traction substation.