Study On Short-Term Method Of Hydropower Absorption In Hydropower Rich Region

Southwest China is the richest region of hydropower resources in China.It is also the green energy base and the pilot region of power market reform.With large scale commissioning of hydropower,increased proportion of new energy,and further development of power market,hydropower absorption faces new challenges.Flood resource utilization,the integration of large-scale wind and solar power into power grid,cross-regional HVDC delivery,electricity spot market,are taken as the main research on hydropower absorption.The main results are as follows:1.Flood resource utilization is an important part of hydropower absorption.Based on three-period flood characteristics,the calculation method of Power Generation Increase on Flood Dispatching(PGIOFD)is proposed.A flood process is partitioned into three periods:Water Level Rising Period,Flood Peak Period and Water Level Falling Period.Then,the dispatching rules adopted in the three periods are as follows:generating power with water level constant,generating power with expected output and generating power with water level even drawdown.Based on the rules,baseline power generation without optimization is calculated.At last,baseline power generation is compared to practical power generation to get the PGIOFD.The method was applied to the Dahuashui Reservoir.Results show that the method can be efficiently applied to analyze flood process and evaluate the effectiveness of flood dispatching.2.Hydropower needs to provide reserve to cope with the uncertainty of wind and solar power.A cascade hydropower dispatching method considering blocked output is proposed.Gaussian distribution is used to describe the uncertainty of wind and solar power prediction error.Then,the confidence interval of a certain confidence level is used to express the up and down reserve of the system.The multi-step progressive optimality algorithm(MSPOA)is used for the problem.Cascade hydro plants in the Wujiang River are selected as an example.The results illustrate that the method can achieve good performance for peak shaving and reserve.3.The huge peak shaving pressure of receiving-end power grids increases the difficulty of cross-regional hydropower absorption.An MILP model for inter-basin cascaded hydro plants is proposed,which takes into account the peak operation among multiple power grids and hydropower absorption.By adjusting the weight corresponding to the average value of the absolute value of the residual load for each power grid,the model considers peak operation among multiple power grids and hydropower absorption.By introducing the special order sets(SOS)constraint,an easy formulation of minimum duration constraint is introduced.18 hydro plants are selected as an example to verify the feasibility and effectiveness of the model.4.Complex hydraulic connection increases the difficulty for hydropower to participate in the electricity market.Based on the cascade hydropower family,the cross-regional clearing model of spot market is proposed.Firstly,the nonlinear constraints are linearized.Secondly,the cascade hydropower family is introduced and the complex hydraulic connection is transformed into the maximum and minimum power generation of cascade hydropower stations(PGCHS).Further,hydropower units participate in spot market clearing in the way of equivalent "thermal power units".The model is applied to the hydropower transmission from Yunnan Province to Guangdong Province.Results demonstrate that the clearing results meet the unit operation constraints and the locational marginal price(LMP)can reflect market price signals truthfully.