Evaluating the flexibility supply and demand reliability of hydro–wind–PV–battery complementary systems under different consumption modes

Abstract

Evaluating the flexibility supply and demand reliability offers a new approach for configuring the capacity of hydro–wind–PV (HWP) or hydro–wind–PV–battery (HWPB) complementary systems. However, traditional flexibility evaluations ignore the operational characteristics of the complementary systems, and tend to underestimate the wind and PV flexibility demand in the case of cross-regional power delivery. To this end, we propose an approach for evaluating the flexibility supply and demand reliability in HWP/HWPB complementary systems under different consumption modes (i.e., external delivery consumption and local consumption). First, a novel flexibility demand optimization model is established by redefining the flexibility demand based on the day-ahead scheduling process of the system. The flexibility supply guaranteed rate of HWP/HWPB complementary systems is then calculated using a statistical model. Finally, the effectiveness of the proposed approach is verified under different wind and PV capacity configuration schemes, and the optimal capacity ratios of wind and PV are determined under different consumption modes. Results using a clean energy base in the upper Yellow River basin indicate that: (1) Stronger peak-shaving performance of the system produces higher wind and PV flexibility demand. On average, the flexibility demand under external delivery consumption is 33.7 % higher than that under local consumption. (2) Improving the system's flexibility can effectively enhance the flexibility supply guaranteed rate when the original guaranteed rate is less than 95 %. If the flexibility supply guaranteed rate is greater than 95 %, further increasing the flexibility of the system has little effect. (3) For the clean energy base in the upper Yellow River basin, appropriately increasing the proportion of wind power in the current system is beneficial for the operation of complementary systems. Generally, the proposed flexibility evaluation approach provides effective guidance for the planning and management of watershed-type HWP/HWPB complementary energy bases.