An Adaptive Importance Sampling Method for Spinning Reserve Risk Evaluation of Generating Systems Incorporating Virtual Power Plants

The concept of virtual power plant (VPP) has been proposed to manage distributed renewable energy sources as packaging to engage in the energy and reserve planning on contemporary generating portfolios. In this context, an efficient tool is needed to support analysis of generating flexibility of conventional units in combination with VPPs to cooperatively counterbalance the fluctuation of net demand. In this paper, an adaptive importance sampling method is proposed, intentionally for efficiently evaluating specific indices capturing the possibility and severity of rare inadequate spinning reserve events of a deployed unit comment schedule for a generating system incorporating VPPs, in terms of short-term stochastic unit failures and power fluctuation of VPPs. The proposed method is based on the standard cross-entropy (CE) method, which newly introduces a mathematical transformation aiming at diverting evaluations of customized risk indices to a generic rare-event probability estimation problem. A Markov chain Monte Carlo method is employed to train the proposal density, to efficiently gain on the best, owing to avoiding the iterative parameter-updating mechanism of the standard CE method. The efficacy of the proposed method is tested on a modified RTS-96 generating system emulating a portfolio of conventional and renewable generating sources modeled as VPPs.