With the increase of installed capacity of distributed renewable energy in the power system, renewable power generation should undertake the corresponding secondary frequency regulation task, and a virtual power plant is an important way for distributed generation to participate in the power market. First, the operation mechanism of a virtual power plant which participates in energy and frequency regulation markets is proposed. The virtual power plant in this paper consists of generalized energy storage, such as distributed wind power, electric vehicles and air conditioning loads. Then, a price-driven demand response model of generalized energy storage is established. The frequency regulation performance index of the virtual power plant is introduced to predict the frequency regulation performance of the virtual power plant. A robust optimization strategy for day-ahead bidding is proposed considering demand response and the frequency regulation performance index of virtual power plant. Finally, the influence of the change of demand response model parameters on users and the virtual power plant income is discussed in an example study. The result shows that the proposed virtual power plant operation mechanism can effectively improve the comprehensive income of the virtual power plant, as well as prompt the virtual power plant to provide better frequency regulation service. This work is supported by the Youth Fund of National Natural Science Foundation of China (No. 52107113).