The coordinated operation of a hydro-wind-photovoltaic system can mitigate the conflict between power generation and output fluctuations and overcome the bottleneck of new energy development. Because of the lack of available research on the coordination mechanism for analysing the relationship between power generation and output fluctuations, depicting the grid architecture and allocating power curtailment, this study establishes a multi-objective model for the coordinated operation of a hydro wind -photovoltaic power system. The model seeks to maximize power generation and minimize output fluctuations under the constraints of multilayer architecture of the power network and balanced allocation of power curtailment. In a case study of a prefectural-level power grid in southwest China, three schemes are compared: independent operation with a single objective, coordinated operation with a single objective, and coordinated operation with multiple objectives. The complementary role of hydropower for increasing power generation and mitigating output fluctuations is explored; the effects of coordinated operation on transmission utilization and the hydrological regime are analysed; and the Pareto frontier of power generation and output fluctuations is obtained and the interaction of these factors is discussed. This study refines the model of a hydro-wind-photovoltaic system and investigates the complementary mechanism underlying multi-energy systems. (C) 2017 Elsevier Ltd. All rights reserved.