The challenge of increasing power system support from microgrids
One of the upcoming challenges in the energy industry will be the seamless integration of numerous microgrids into the operation of the power system.
The Transmission System Operator (TSO) presently sees, on average, an estimated 80–85% of the total power flow. This percentage is shrinking due to increased local generation and balancing at the lower voltage levels. TSOs want to know what is going on with microgrids at lower voltage levels, as problems could suddenly arise—but also because of a possible resource of ancillary services for the transmission grid. Figure 1 displays a microgrid equipped with sensors and actuators controlled by its own Energy Management System (µEMS). The microgrid often has a single Point of Common Coupling (PCC) with the overlaying power grid, and there is communication between the Distribution Management System (DMS) and the µEMS.
In some cases, however, the power system and microgrid objectives may be in conflict, or possibly involve a cost for one party to meet the objective of another party. For a seamless integration into the power system operation, a microgrid must be able to support volt/var control, exhibit fault ride through capabilities, initiate emergency actions in case of system contingencies, etc. Additionally, information about the microgrid status, predictions for load and generation, the amount of aggregated dispatchable generation and load, and protection settings need to be communicated, and sufficient sensors and actuators must be available to provide the information and allow for adjustments. As the impact and importance of microgrids for the safe and reliable operation of the transmission grid is rapidly growing, it is important to rethink how the future power system should operate as a whole, rather than simply adding more automation and controls with the risk of introducing more (local) conflicts that will have to be solved ad hoc.