The wind-hydro hybrid power system has been proven a viable solution in helping the integration of variable wind power to the grid. While few studies consider the joint operation of the wind-hydro
power system with the power grid, even fewer extend the research to improve the flexibility of the grid connected wind-hydro power system (WHGS) in real-time operation, aiming to reduce the load shedding in the face of increasing fluctuation and uncertainty from both wind power and demand. To handle this gap, a novel two-stage framework is proposed. In the first stage of the framework (F-first stage), a scenario-based two-stage connection node decision model is proposed to improve the topology relationship between the wind power plant, hydropower plant and demands. In the second stage of the framework (F-second stage), a two-stage bilevel flexibility shortage risk averse model is proposed to dynamically decrease the load shedding of the current time period and flexibility shortage risks for the following time period in real-time operation. Then, a bilevel resource saving model is nested to reschedule the WHGS to save resources. Finally, all models are reformulated as MILPs. The case study shows that (1) improving the topology relationship between power plants and demands can decrease the impact of insufficient transmission line capacity and improve the flexibility of WHGS; (2) the real-time flexibility improvement model can improve the flexibility of WHGS and eventually decrease the load shedding (by 39.82%) in real-time operation. It works even under low power transmission capacity (reducing load shedding by 2.58%), low generation capacity (reducing load shedding by 7.93%), and low confidence level (reducing load shedding by 15.82%); (3) the choice of confidence level depends on the scenario condition and operation preference of the system operator.
Citation
Lai, C., & Kazemtabrizi, B. (in press). A novel two-stage framework to improve the flexibility of grid connected wind-hydro power system in real-time operation. Applied Energy,
