Optimal Portfolio Strategy of DERs for Offering the Flexible Ramping Ancillary Services under High Penetration Distributed PV Scenario

The high penetration of distributed photovoltaic (PV) causes the rapid and dramatic fluctuation in the net load. As a result, flexible ramping ancillary services (FRAS) are needed to keep supply-demand balance and maintain frequency stability. For the FRAS provided by the distributed energy resources (DERs), utilizing only one type of resources has technical and economic limitations, so it is crucial to explore the DERs portfolio strategy. To this end, firstly, a technical and economic quantitative analysis method of FRAS provided by the portfolio of DERs including the incentive-based demand response (IBDR), right transfer demand response (RTDR), energy storage system (ESS) is proposed based on portfolio theory. Secondly, for different PV output scenarios that have corresponding FRAS demand, a risk-constrained and scenario-based portfolio model for aggregators is proposed using the conditional value at risk (CVaR). Extensive numerical results demonstrate that the proposed portfolio strategy enables DERs to provide FRAS and improves the aggregator's profit.