Abstract
The short-term scheduling schemes of cascaded hydropower plants are based on day-ahead hydrological forecasting information. Affected by the accuracy of prediction, real-term hydrological information can considerably vary from previously forecasted values, especially for the power load and local inflows. As a result, short-term scheduling schemes are difficult to apply directly in real-time scheduling. To solve this problem, a rolling optimal hourly operation model for interbasin cascaded hydropower plants is proposed to rapidly balance the load demand. The model is deemed an ultrashort-term model, and it has a short-cycle schedule between short-term and real-time schemes. The basic strategy of solving the model is as follows. First, the day-ahead power load and local inflow information are corrected using a statistical method based on the most recent real-time information. Second, the water delay time, defined as the time between when water is released from upstream reservoirs and arrives at downstream reservoirs, is updated based on the most recent real-time information. Third, a heuristic method is proposed to dynamically update the short-term scheduling scheme over the next few hours. The objective is to minimize the maximum relative deviation between the actual water level of a reservoir at the end of 24 hours and the day-ahead forecasted value. This approach can keep the reservoir water level at the end of 24 hours close to the forecasted value and improve the accuracy of estimating the initial water level the next day. The developed method is applied to solve an ultrashort-term scheduling problem involving the cascaded hydropower plants located in Yunnan Province, China. The results indicate that the proposed model can achieve seamless coupling between short-term scheduling and real-time scheduling. The proposed method can provide a scientific basis for the real-time dispatching of large-scale hydropower plants and improve the practicality of short-term dispatching schemes.
Highlights
In recent decades, with the unceasing expansion of the hydropower scale in fast-growing countries, such as China and Brazil, the problem of large-scale hydropower plant (HP) scheduling has become increasingly complicated
The objective is to minimize the maximum relative deviation between the water level of the reservoir at the end of 24 hours and the day-ahead forecasted value under various hydraulic and electrical constraints. The innovation of this model is that is uses the latest local inflow and power load information to dynamically update the short-term scheduling scheme to effectively overcome the drawbacks of traditional short-term scheduling, which is difficult to apply in real-time scheduling and planning
The UST model consists of three submodels: a runoff forecasting model, which is developed to predict the local inflow of cascaded HPs; an upstream reservoir release forecasting model, which is developed to predict the downstream reservoir inflows from the water released by upstream reservoirs; and a real-time optimization scheduling model, which is developed to update the power generation plan of each HP when the power supply is not equal to the power load in the UST scheduling horizon
Summary
Number of time periods before tnow Maximum limiting transmission power in control section s in period t in MW rs,m. Maximum ramping capacity of the mth HP in period t in MW Minimum storage volume of the mth reservoir in period t in m3 Maximum storage volume of the mth reservoir in period t in m3 Minimum turbine discharge of the mth plant in period t in m3/s. Forecasted value of the mth reservoir for the D+1th series Weight coefficient wt in period t for the sample data Correlation coefficient Power generation increment of the mth HP in period t Idle capacity of the mth HP in period t Maximum ramping capacity of the mth HP in period t αmt ,3 βmt βmt ,1 βmt ,3 βmt ,2 αmt ,2. Local inflow forecasting value of the mth reservoir for the rolling calculation (based on times) in period t
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
