To incorporate the operating constraints of a virtual power plant (VPP) in transmission-level operation and market clearing

the concept of the VPP capability curve (VPP-CC) is proposed which explicitly characterizes the allowable range of active and reactive power outputs of a VPP. A two-step projection-based calculation framework is proposed to approximate the VPP-CC by the convex hull of critical points on its perimeter. The output of the proposed algorithm is concise and can be easily incorporated in the existing system operation and market clearing. Case studies based on the IEEE 33 and 123 test feeders show the computational efficiency of the proposed method outperforms existing methods by 4~7 times. Additionally

many fewer inequalities are needed to depict the VPP-CC while achieving the comparative approximation accuracy compared to sampling-based methods

which will relieve the communication and computation burden.