Optimal dispatching scheme of multi-objective cascade reservoirs by parallel mechanism-optimization algorithms

Abstract

• Develop multi-objective optimal operation models for cascade reservoirs. • Hybrids Parallel Mechanism with optimization algorithms to optimize multi-objective. • Water supply contradiction and transformation rules among three objectives are obtained. • Optimal scheme ensures power generation efficiency, irrigation requirements and ecological safety. In recent years, the water conflict between competing users in the middle and lower reaches of the Heihe River has intensified, causing severe social, economic, and ecological problems. This research aims to alleviate water conflicts between multiple objectives that consider eight cascade reservoirs in the upper reaches of the Heihe River Basin to be the regulatory bodies using the optimal operation model and fuzzy optimization evaluation model. The innovative approach combining the parallel mechanism with optimization algorithms (i.e., Flower Pollination Algorithm and Non-dominated Neighbor Immune Algorithm) is proposed to solve the optimal operation models, analyze the time distribution laws of water supply dilemma and the transformation rules among three objectives (power generation, irrigation, and ecology). Based on the evaluation indicator system and subjective and objective comprehensive weighting methods (i.e., Analytic Hierarchy Process and Entropy Weight Method), a fuzzy optimization evaluation model is applied to search for the optimal dispatching scheme for the multi-objective joint operation of cascade reservoirs. Results indicate several findings. First, the Parallel - Flower Pollination Algorithm produces high precision and stability with outstanding calculation efficiency. Second, the period of the water supply dilemma is October and next April, and the annual water supply dilemma is affected by the frequency of incoming water. Third, the competitive relationship between irrigation and ecology is the strongest, followed by the relationship between ecology and power generation, the relationship between ecology and power generation is relatively weak. Fourth, the optimal dispatching scheme in each typical year is the scheme with the ratio values of the transformation coefficients among power generation, irrigation, and ecological objectives the closest to 1:1:1, respectively. It is conducive to scientifically guiding the dispatch of water resources in the Heihe River Basin, alleviating water conflicts, and ensuring socio-economic development and ecological safety.