Multi-Risk Interaction Analysis of Cascade Hydropower Stations Based on System Dynamics Simulation

The operation of cascade hydropower stations is accompanied by various target risks while exerting the comprehensive benefits of water resources. The systematic analysis of multi-risk interactions in system operation can improve the operational benefit of hydropower stations. However, the current hydropower operating model used for risk simulation cannot show the dynamic operation processes within the system, which may limit the popularization of the model. In addition, most existing studies define risk from the perspective of reliability and lack analyses of risk resilience and vulnerability. In this study, a system dynamics model for cascade hydropower stations and a unified multi-objective performance index system are constructed. The relationships among the multi-risk of the Xiluodu-Xiangjiaba (XLD-XJB) cascade hydropower stations are explored from the aspects of reliability, resilience and vulnerability. The results are as follows. (1) The system dynamics model can effectively simulate the dynamic process of system operation and can be used to study the performance risk changes in the operation process of hydropower stations. (2) The current operating rule leads to ecological risk and shipping risk in the system in the normal scenario. There are also power risks in wet and dry scenarios. (3) There is a contradiction between power risk and shipping risk. In addition, in the case of insufficient inflow, there is a contradiction between the reliability and vulnerability of power risk. (4) The regulation of ecological risk helps reduce shipping risk and power risk. Therefore, ecological outflow should be regarded as the minimum outflow requirement of cascade hydropower stations. Based on system dynamics, a simulation model is constructed to reflect the operation dynamic process of cascade hydropower stations. A multi-performance evaluation index system suitable for reliability, resilience and vulnerability risk evaluation is developed. Through the simulation of operating rules with different risk control priorities, the dynamic relationships among multi-risk are analyzed.