Research on Short-term Multi-objective Nested Multi-energy Complementary Operation Mode of Large-scale Hydro-energy-enriched Power Grid

In the context of “double carbon”, it is urgent to study how to promote the synergy between different energy sources in the multienergy complementary system and promote the deep integration of energy sources. To address this issue, this paper proposes a multi-objective nested multi-energy complementary model that distinguishes between the inner and outer layers, progressively optimises and consumes as much clean energy as possible from wind and solar, and takes into account the degree of matching between sources and loads of the whole network, with both layers being solved by the Mixed-Integer Linear Programming（MILP） algorithm. The inner layer is based on the crosssection perspective, with the objective of maximising channel utilisation rate, and the water-wind-solar bundles are optimised to maximise their output and occupy the full channel as much as possible. The outer layer is based on the perspective of the whole network, taking the maximisation of source-load matching as the objective, and adopting the minimum fluctuation of the residual load after the joint regulation of water-wind-solar power sources in the whole network to express the objective of source-load matching, so as to make the residual load smooth. This paper takes a large-scale power grid in a hydro-energy-rich area in Southwest China as the research object, including 304 hydropower stations and 12 sections. We select four typical days for simulation: the maximum day of the peak-valley difference between wind and light, and the average power generation day of wind and light in the summer and autumn flooding period, and the average day of the winter and spring drying period. The average channel utilization rate of the power grid is about 80% during the abundant water period and 40%during the dry water period, and the residual load fluctuation rate of the whole network during the abundant and dry periods is less than 5%.The following conclusions are drawn: in summer and autumn flood season, the water-wind-scenery system can provide more power for the grid, and in winter and spring dry season, the water-wind-scenery system is more stable in the process of power output. In the period of smooth power output of wind and solar system, it can provide more power for the power grid, and at the same time, it makes the power grid operation more stable. The results of this study provide a reference for the optimal scheduling and operation of multi-energy complementary power grids in large-scale hydro-energy-rich areas.