Impact of Distributed Energy Resource Integration on Real-time Energy Market Oscillation

With the growing penetration of small-scale distributed energy resources (DER), DERs are allowed to participate in the independent system operator (ISO) energy market in the form of aggregation. However, the current approximation model for aggregated DERs, in terms of distribution factors (DF), cannot reflect their actual contributions to power flows of transmission lines, thus leading to market clearing solutions that are suboptimal or even infeasible to the physical system. In this paper, we use real-time security-constrained economic dispatch (RT-SCED) problem as an example to show that DF based DER aggregation approach could lead to oscillations in consecutive time intervals, and analyze the reasons behind this. A novel network equivalence based DER aggregation approach is put forward to mitigate the oscillation and ensure the physical feasibility of RT-SCED solutions. Numerical simulations illustrate the oscillation of DF based approach, and validate effectiveness of the proposed approach.