Stochastic Short-Term Scheduling of a Wind-Solar-hydro Complementary System Considering Both the Day-Ahead Market Bidding and Bilateral Contracts Decomposition

Complementary operation of hydropower, wind and photovoltaic (PV) power is one of the most cost-efficient solutions for integration of intermittent wind and PV power. In a deregulated market, synergetic optimization of day-ahead (DA) market bids and the decomposition of daily physical bilateral contracts (BCs) can increase profits for a wind-solar-hydro complementary system (WSHCS) by coordinating the spot market and the forward market. However, this short-term scheduling problem is challenging because of complex market mechanisms and uncertainties of multiple energy resources and market prices. A stochastic scheduling model is established to address this issue. First, uncertainties of wind, PV power and DA market prices are characterized by stochastic scenarios simulation with the adoption of the simultaneous backward reduction algorithm. Then, a two-layer nested optimization framework is conducted to optimize both the DA market bidding strategy and the decomposition of daily BCs. A WSHCS in China’s Yalong River Basin is selected as a case study. Results show that: the proposed model can decompose the total energy of the daily BC reasonably by leaving flexible bidding spaces in the DA market according to price variation, thus larger volume of bidding energy can be sold when DA market prices are higher than the contract price. Besides, the optimal decomposition outperforms the average decomposition of daily BCs with larger benefits, less power curtailment, and higher water resources utilization efficiency. These findings verify the effectiveness and applicability of the proposed model for synergetic optimization of both the decomposition of daily BCs and DA market bids for a WSHCS.