Risk Analysis Of Operation Level Scheme Of The Lower Reservoir Of Wuyue Pumped Storage Power Station In Flood Season

In recent years,China’s electricity demand has been increasing,and the power industry has developed rapidly.In order to improve the power supply quality of the power grid and adjust the peak electricity consumption,a large number of pumped storage power stations were constructed.The frequent exchange of water between the upper and lower reservoirs has changed the original real-time water intake process of the lower reservoir,which directly affects the operation and scheduling of the pumped storage power station,especially the flood control operation,and is affected by various uncertainties.,Leading to varying degrees of risk during operation of the reservoir under the power station.How to determine the water level of the pumped storage power station during the flood season and conduct risk assessment is the key issue of current research.It has certain theoretical value and important importance for the safe and efficient operation of the planned and built pumped storage power station(reservoir)Practical significance.The upper reservoir of Wuyue Pumped Storage Power Station is built by digging and filling dams,and the water collection area is very small.The lower reservoir uses the already built Wuyue Reservoir.Since the area of the upper and lower reservoirs is quite different,and there is no natural incoming water in the upper reservoirs,the risk of flood control of the lower reservoirs is mainly considered when conducting risk assessment.The water level of the reservoir during the flood season before the reconstruction is 88.384 m.After the completion of the power station,it is planned to adjust the water level of the reservoir during the flood season to 87.285 m.In this paper,based on the concept of risk analysis,on the basis of considering the characteristics of the operation and scheduling of pumped storage power stations,Monte Carlo simulation technology is used to conduct a risk assessment of the operating water level plan during the flood season before and after reconstruction.(1)Risk factors and distribution forms of water level control for the operation of the pumped storage power station during the flood season.Identify the risk factors generated during flood season operation water level control through the accident tree,and generalize the main risk factors into design flood uncertainty,dispatch delay uncertainty,forecast error uncertainty,and discharge capacity uncertainty 5 risk factors including the uncertainty of water level storage capacity.Among them,the distribution delay error adopts the triangular distribution,the error of the discharge capacity curve and the water level storage capacity curve adopts the normal distribution,and the flood forecast error adopts the lognormal distribution to simulate.(2)Copula function and Monte Carlo method are used to simulate the flooding process of the pumped storage power station under storage.The Gumbel Copula function is selected as the function to construct the joint distribution,and the twoparameter joint distribution of the flood peak and the daily flood volume is established,and the peak volume combination under different recurrence periods is derived;the multi-field design flood process is obtained by the variable magnification ratio method.According to the characteristics of the pumped storage power station,considering the risks encountered by the upper reservoir power generation discharge and the lower reservoir natural incoming water,the power generation water and natural incoming water are randomly stacked as the reservoir flood.(3)Use Monte Carlo simulation to evaluate the operation plan of Wuyue Pumped Storage Power Station.Through calculation,the risk distribution of various risk factors was obtained.Monte Carlo simulation method was used to combine various risk factors.Through the flood adjustment calculation of multiple floods,the simulated calculations showed that the lower reservoir of Wuyue Pumped Storage Power Station encountered 20 The risk rate of the discharge flow exceeding the limit during the annual flood and the risk rate of the water level before the dam exceeding the high water level of the flood control during the design flood and the verification flood.By comparison with the limit risk rate,the original dispatch method is no longer applicable to the rebuilt Wuyue For pumped storage power stations,the newly proposed scheme meets the safety requirements of reservoir flood control.(4)Based on the risk theory,it proposes a water level control scheme that is more suitable for the operation of the Wuyue Pumped Storage Power Station during the flood season.In this paper,the triangular fuzzy number analysis method is used to determine multiple confidence intervals.The Monte Carlo simulation method is used to calculate the flood control risk rates of different confidence intervals.The final results show that when the confidence degree α is 0.9,the reservoir encounters once every 20 years.The flood control risk rate during flood,design flood and check flood is below the limit risk rate,the result is [87.005 m,87.395m],the flood control risk rate of each water level scheme in this interval is less than the limit risk rate,so in order to obtain For greater benefits,it is recommended to adjust the operating water level in the flood season from 87.285 m to 87.395 m.