Abstract: Virtual power plant （VPP） is an effective means to solve the problem of regulation and operation of  abundant distributed generation （DG） access to power grid regulation and operation. DGs participation in the auxiliary service market of power system through VPPs， provides auxiliary services such as peak shaving and frequency regulation for power grid， and is benefited from them， to realize win-win between power grid and DG users. On the basis of fully distributed coordination control mode based on sparse communication and point-to-point information interaction， an economic primary frequency control method for VPP applying distributed control method based on sub-gradient projection is proposed. On the premise of minimizing its own operation cost of VPP， this method can improve its grid-connected friendliness and frequency support level for power grid. Compared with traditional droop control， this method not only achieves optimal power allocation， but also avoids competitive control， and can better deal with the power limit problem of DGs compared with the common distributed sub-gradient method. It also has better adaptability to communication delay. 

Key words:  distributed generation （DG）, virtual power plant （VPP）, distributed control, primary frequency control, sub-gradient projection