Solar Power Aggregation Framework for Virtual Power Plant's Energy Trading

Enhancing solar power integration to a modern power transmission network will require advanced energy management systems. Virtual power plant (VPP) provides a framework for solar power aggregation and optimization to participate in wholesale energy trading while also behaving more permissible concerning grid cooperation. This paper presents a solar power aggregation framework for VPP operation which consists of multiple solar power plants, each of which is rated 10 MW or above, also defined as a small power producer (SPP) by contracted capacity. The formulated optimization problem is to obtain the maximum profit of the VPP operation in energy trading of a day-ahead market (DAM), and to comply with the required hourly ramp-rate limit of the aggregated power. In this study, DAM price is assumed hourly varying, with reference to New York Independent System Operator (NYISO). The optimal solution of the hourly SPPs' generated power commitments is solved by linear programming (LP). Test results from the case studies with 6 SPPs combined, at most, show that profit per capacity can be improved by 1.22%, and profit coefficient of variation can be improved by 8.14%. Furthermore, the aggregated power characteristics can be more effectively smoothen using the constraints of ramp-rate limit and the bias term of ramp-rate cost.