Real-Time Power Imbalance Time Series With Solar Power Penetration: Butterfly Curve

Variable renewable energy (VRE) is known to be highly influenced by weather events and may ramp up or down abruptly. Therefore, increasing penetration of solar power will cause fundamental and structural changes to power system operation regimes. In this letter, we conduct an analysis of a 1-minute temporal resolution dataset from 6 Regional Transmission Organizations (RTOs) in the US during 2018 and 2019. By examining day-ahead power exchange and real-time power imbalance time series characteristics, distinct patterns can be observed: the day-ahead power exchange time series curve looks like the canyon, while the real-time power imbalance time series curve looks like a butterfly shape, which becomes bigger as solar penetration level increases. This letter will provide some scientific evidence for the reform of the day-ahead power exchange and real-time power balance operation in response to high solar power penetration.