Abstract:Optimal load distribution (OLD) among generator units of a hydropower plant is a vital task for hydropower generation scheduling and management. Traditional optimization methods for solving this problem focus on finding a single optimal solution. However, many practical constraints on hydropower plant operation are very difficult, if not impossible, to be modeled, and the optimal solution found by those models might be of limited practical uses. This motivates us to find multiple optimal solutions to the OLD p… Show more
“…[] state that the search for MNOS offers more flexibility than that of a single optimum; besides, the search for a single optimum ought to be replaced by that of a limited number of alternatives that can later be compared, possibly using criteria that were not accounted for in the objective function to be optimized [ Loucks and van Beek , ]. For instance, the presence of MNOS in a deterministic hydropower production problem enables the exploration of the solutions to find which are best for the reliability and safety of the production units [ Liu et al ., ]. In this work, a NOS is given by a sequence of Bender's cuts that covers a year, and that lies within a desired range of any other solution, e.g., one percent.…”
Stochastic dual dynamic programming (SDDP) is one of the few algorithmic solutions available to optimize large‐scale water resources systems while explicitly considering uncertainty. This paper explores the consequences of, and proposes a solution to, the existence of multiple near‐optimal solutions (MNOS) when using SDDP for mid or long‐term river basin management. These issues arise when the optimization problem cannot be properly parametrized due to poorly defined and/or unavailable data sets. This work shows that when MNOS exists, (1) SDDP explores more than one solution trajectory in the same run, suggesting different decisions in distinct simulation years even for the same point in the state‐space, and (2) SDDP is shown to be very sensitive to even minimal variations of the problem setting, e.g., initial conditions—we call this “algorithmic chaos.” Results that exhibit such sensitivity are difficult to interpret. This work proposes a reoptimization method, which simulates system decisions by periodically applying cuts from one given year from the SDDP run. Simulation results obtained through this reoptimization approach are steady state solutions, meaning that their probability distributions are stable from year to year.
“…[] state that the search for MNOS offers more flexibility than that of a single optimum; besides, the search for a single optimum ought to be replaced by that of a limited number of alternatives that can later be compared, possibly using criteria that were not accounted for in the objective function to be optimized [ Loucks and van Beek , ]. For instance, the presence of MNOS in a deterministic hydropower production problem enables the exploration of the solutions to find which are best for the reliability and safety of the production units [ Liu et al ., ]. In this work, a NOS is given by a sequence of Bender's cuts that covers a year, and that lies within a desired range of any other solution, e.g., one percent.…”
Stochastic dual dynamic programming (SDDP) is one of the few algorithmic solutions available to optimize large‐scale water resources systems while explicitly considering uncertainty. This paper explores the consequences of, and proposes a solution to, the existence of multiple near‐optimal solutions (MNOS) when using SDDP for mid or long‐term river basin management. These issues arise when the optimization problem cannot be properly parametrized due to poorly defined and/or unavailable data sets. This work shows that when MNOS exists, (1) SDDP explores more than one solution trajectory in the same run, suggesting different decisions in distinct simulation years even for the same point in the state‐space, and (2) SDDP is shown to be very sensitive to even minimal variations of the problem setting, e.g., initial conditions—we call this “algorithmic chaos.” Results that exhibit such sensitivity are difficult to interpret. This work proposes a reoptimization method, which simulates system decisions by periodically applying cuts from one given year from the SDDP run. Simulation results obtained through this reoptimization approach are steady state solutions, meaning that their probability distributions are stable from year to year.
“…It can be noted that efficiency is higher when the power generation flow is lower. The optimal solution can save over 200 m 3 /s water in some months whereas in some other literature, the optimized solution could save, at the most, 10 m 3 /s [6]. After fitting the curve, the equal micro-increment method was used to calculate the results of optimal power generation flow and dynamic programming was used to find the optimal power generation.…”
Section: Water Flow Optimizationmentioning
confidence: 99%
“…There are many algorithms for mathematical models to optimize operation with correctly conceptualized theories and formulas [3]. In designing a model, there are two methods used: optimization and simulation [4][5][6]. A simulation model is a descriptive model that tries to express the actual system of operation characteristics by using the complicated interrelations between components.…”
The short-term optimal operation model discussed in this paper uses the 2016 to 2018 daily and monthly data of Baluchaung II hydropower station to optimize power generation by minimizing water consumption effectively in order to get more revenue from optimal operation. In the first stage, run-off-river type Baluchaung II hydropower station data was applied in a mathematical model of equal micro-increment rate method for optimal hydropower generation flow distribution unit results. In the second stage, dynamic programming was used to get optimal hydropower generation unit distribution results. The resultant data indicated that optimized results can effectively guide the actual operation run of this power station. The purpose of the optimal load dispatching unit was to consider the optimal power of each unit for financial profit and numerical programming on the actual data of Baluchaung II hydropower plant to confirm that our methods are able to find good optimal solutions which satisfy the objective values of 17.75% in flow distribution units and 24.16% in load distribution units.
“…Along with the rapid development of global economy over the past several decades, the power demand has increased continuously, and a large amount of hydro and thermal plants have been successively built to supply sufficient energy [1][2][3]. However, thermal plants inevitably produce emissions of pollutants like sulfur oxide and nitrogen oxide, which gives rise to a series of serious environmental problems and high social economic costs [4][5][6].…”
Abstract:With the increasingly serious energy crisis and environmental pollution, the short-term economic environmental hydrothermal scheduling (SEEHTS) problem is becoming more and more important in modern electrical power systems. In order to handle the SEEHTS problem efficiently, the parallel multi-objective genetic algorithm (PMOGA) is proposed in the paper. Based on the Fork/Join parallel framework, PMOGA divides the whole population of individuals into several subpopulations which will evolve in different cores simultaneously. In this way, PMOGA can avoid the wastage of computational resources and increase the population diversity. Moreover, the constraint handling technique is used to handle the complex constraints in SEEHTS, and a selection strategy based on constraint violation is also employed to ensure the convergence speed and solution feasibility. The results from a hydrothermal system in different cases indicate that PMOGA can make the utmost of system resources to significantly improve the computing efficiency and solution quality. Moreover, PMOGA has competitive performance in SEEHTS when compared with several other methods reported in the previous literature, providing a new approach for the operation of hydrothermal systems.
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