Coordinated Control Strategy within VPP for Operation Flexibility Improvement under Tertiary Frequency Regulation of Internal Power Deviations

A virtual power plant (VPP) plays a key role in integrating renewable energy and responding grid frequency fluctuations caused by the variable output of renewable sources. However, correcting frequency deviations doesn't represent maintain the power balance. VPPs must maintain stability through tertiary frequency regulation (TFR), often relying on power trading with the grid due to limited internal resources. To reduce this grid dependency, a coordinated control strategy is proposed to optimize the use of internal energy storage. It includes three methods: time-sharing to handle fluctuation timing uncertainty, demand analysis to address fluctuation power uncertainty, and resources selection to identify VPP resources for TFR participation. Simulations show that during the "longest duration of fluctuation", the strategy effectively stabilized the VPP and reduced power trading, decreasing the grid power from 32.5 MW to 3.8 MW through coordinated control of plan adjustments, overlimit power regulation. In the "highest power deviation of fluctuation" coordinated control of plan adjustments and over-limit power regulation reduce power trading from 43 MW to 9.7 MW and energy traded from 215 MWh to 48.5 MWh—a 77.44% reduction.