Clustering and dispatching hydro, wind, and photovoltaic power resources with multiobjective optimization of power generation fluctuations: a case study in southwestern China

Hydropower can be used to smooth out the output fluctuations from power systems including wind and solar sources. This paper proposes a double-layer model for coordinating the operations of cascaded hydropower and neighboring wind and photovoltaic (PV) facilities. In a local complementary model, hydropower with less regulating ability (local complementary hydropower, LCH) is dispatched to alleviate short-term fluctuations (i.e., hourly variations), whereas in the global one, hydropower with greater regulating capacity (global complementary hydropower, GCH) is operated to alleviate long-term fluctuations (i.e., intraday peak-valley differences). The results of a case study of a hydro-wind-PV cluster project in southwestern China show that most (90%) short-term fluctuations can be smoothed by LCH with a minimum impact on the capacity factor (-0.02). In contrast, alleviation of long-term fluctuations can be achieved with GCH, but this causes a large capacity factor reduction (-0.25). The discharge fluctuation of GCH is notably lower (70~75%) than that of LCH. In this system (which includes 5,200 MW wind and 1,400 MW PV), the output fluctuations can be eliminated if hydropower capacity reaches 2,200 MW. These findings demonstrate that clustering of hydropower cascades with wind and solar generation facilities is a promising avenue for the decarbonization of electricity systems.