Analyzing Real-Time Market Oscillation of Demand Response Resource Aggregation - A MISO Case

In observing the rapid growth of distributed energy resources (DERs), regional transmission organizations (RTOs) have been investigating the upcoming challenges and potential methods to support their deeper market integration. This article studies the Midcontinent Independent System Operator's (MISO) distribution factor-based commercial pricing node (Cpnode)-elemental pricing node (Epnode) network model, analyzing its suitability and potential issues in supporting the market integration of DERs across multiple locations as aggregated demand response resources (DRRs). Specifically, this article modifies the MISO's existing DRR models to aggregate component resources on different Epnodes via distribution factors as dispatchable DRRs at Cpnodes. These aggregated dispatchable DRRs will directly participate in the MISO's real-time (RT) energy market and follow the MISO's dispatch instructions at Cpnodes through the Epnode-level component resource redispatch. However, distribution factor inaccuracy could cause oscillations in locational marginal prices (LMPs) and dispatches of DRRs in the RT energy market. To this end, influential factors contributing to the occurrence of oscillations are discussed, and five distribution factor updating strategies are studied. Moreover, a correction term is proposed to resolve the timing misalignment issue in transmission constraints. Numerical simulations via the MISO's RT Security-Constrained Economic Dispatch (RT-SCED) tool and actual MISO production cases are conducted to evaluate these strategies and influential factors.