With the rapid growth of wind and photovoltaic power

the power system is facing issues of insufficient adequacy. To ensure an ample capacity supply

it is necessary to introduce the capacity market mechanism. Compared to the large-scale thermal power plants with long construction periods and high investment costs

virtual power plants（VPP）that aggregate distributed adjustable resources has a shorter construction period

lower investment

and quicker effectiveness. VPPs serve as effective resources for providing generation capacity to the system

they can be used to manage the peak demand. Therefore

a VPP unforced capacity（UCPA）formula and a comprehensive capacity market clearing model which is designed to consider capacity offers including VPP is proposed. The proposed VPP UCAP computation formulas consider power capacity

energy capacity and operational attributes. The proposed capacity market clearing model introduces the participation of VPPs with the consideration of wind power

photovoltaic power and conventional generation units. The presented capacity market clearing model considers system constraints such as peak demand

base demand

energy requirement

off-peak demand

and ramp power demand. Finally

the impact of UCPA of VPP

total capacity demand and renewable energy installed capacity on market cleared results is analyzed by conducting the study cases

it shows the validity of the proposed VPP UCPA formulas and the capacity market clearing model.