Stochastic simulation model of forecast errors in the process of reservoir runoff based on IGMM-Copula

In order to reveal the statistical characteristics and changing laws of forecast errors in the process of inflow runoff, so as to provide more accurate input conditions for the optimal operation of hydropower stations and reservoirs. The optimal Gaussian mixture number is selected based on the AIC and BIC criteria, and the K-means++ algorithm in data mining is introduced to determine the initial parameter values of the Gaussian mixture model. The GMM part of the GMM-Copula model is improved, based on which the stochastic simulation model of the forecast error in the reservoir runoff process is established. The model not only has more advantageous in the quantitative estimation of the runoff forecast error at a single foreseeable moment, but also can realize the stochastic simulation of the error sequence by establishing a multidimensional distribution function of the error. The results applied to the reservoir of Jinping I Hydropower Station show that the model in this paper fits the runoff forecast errors at 6h, 12h, 18h, 24h foreseeing moments, and the graphical effect and applicability test results of the fitted curve are better than those of GMM -Copula model, and the statistical parameters of the simulation error of the IGMM-Copula model are closer to the actual error, which verifies the rationality and feasibility of the model, and provides a more accurate and effective method for the estimation and simulation of the forecast error of the reservoir runoff process method. © 2021, China Water Power Press. All right reserved.