Optimal Operation Of Hydropower Station Research Articles

Long-Term Optimal Dispatching of Hydropower Station Based on Controlling the Frequency of Reservoir Level Fluctuation

In this paper, a method for long-term optimal operation of hydropower station is proposed to control the frequency of reservoir level fluctuation. We introduce the integer variable which describes the rise and fall of the reservoir level, the number of changes, and the state transition equation for the change of the reservoir level fluctuation into the dynamic programming method. This method can obtain the global optimal solution under the control of different numbers of reservoir level rise and fall, thus improving the controllability and practicability of optimal operating results. We consider the maximum number of water level fluctuations as a constraint condition while the reservoir level, the state of fluctuation, and the number of state changes that have occurred as the three state variables to construct a dynamic programming model. Three state transition equations are the water balance, the state of the reservoir level rise and fall, and the number of fluctuations. Besides, the penalty function is used to handle minimum output and surplus water. We solve this model by using a dynamic programming reverse recursion equation. The application of this method in the Manwan Hydropower Station shows that it can effectively solve the frequent water level fluctuation problem that is generally inconsistent with the actual situation in the long-term optimal dispatch scheme of hydropower stations and improve the practicability of the optimal dispatch results.

Stochastic MPC For Optimal Operation of Hydropower Station Under Uncertainty

The operational condition at the Dalsfoss power station is complicated due to many requirements related to environmental regulations and safety constraints such as the seasonally varying water level requirement at the reservoir. However, the operation becomes more difficult due to uncertainties in the system. In this paper, at first a certainty equivalent MPC is applied to the uncertain hydro power system and it has been shown that its robustness property is poor. Secondly, to prevent the constraint violations due to the uncertainties in the system, two measures are taken. One measure is to introduce a safety margin for the constraints and further design a certainty equivalent MPC. The other measure is to implement a multi-stage MPC for robust constraint satisfaction. Two types of multi-stage MPC are considered in this paper. The first employs all of the possible 50 scenarios of the uncertainty of an input disturbance variable, and the latter generates and uses three synthetic scenarios to approximate all of the possible 50 scenarios. All of the simulation results are compared for their robust performances and computational time.

Ecological Optimal Operation of Hydropower Stations to Maximize Total Phosphorus Export

AbstractCascade reservoirs have interrupted the distribution and transportation of nutrients, which brings environmental and ecological problems. However, the current ecological operation methods f...

Analysis of the gyroscopic effect on the hydro-turbine generator unit

Abstract The existence of the gyroscopic effect has significant impact on the stability, dynamical behaviors and vibrational characteristics of the high-speed rotating systems. In this paper, the vibration characteristics of the hydro-turbine generator unit with the gyroscopic effect is analyzed. First, a novel nonlinear mathematical model of the hydro-turbine generator unit with consideration of the gyroscopic effect and multi-degree of freedom is established. Second, the vibration of the shaft system are investigated using time histories, phase trajectories and spectrograms based on an operation hydropower station. Some interesting phenomena are obtained by comparing the vibration laws of the hydraulic generator unit in the cases of both K = 0 (without gyroscopic effect) and K ≠ 0 (with gyroscopic effect). Those phenomena show that the effect of gyroscopic intensifies the vibration to some components of the hydraulic generator unit, and it has significant effect on the safe and stable operation of hydropower stations. Meanwhile, the proposed mathematical model can accurately reflect the influence of gyroscopic effect on the vibration characteristics of the hydro-turbine generator unit. The results of this study provides theoretical basis for the design and installation of hydraulic generator units and the optimal operation of hydropower stations.

Multi-objective optimized scheduling model for hydropower reservoir based on improved particle swarm optimization algorithm.

In order to make hydropower station's development and operation harmonious with ecological protection, the optimal operation of hydropower stations to meet the needs of ecological protection is studied. Firstly, the ecological protection function of river course is defined according to the minimum ecological runoff and suitable ecological runoff. Then, a multi-objective optimal running model of reservoir which can maximize the capacity of ecological protection and generation is proposed. Finally, an improved multi-objective particle swarm optimization algorithm (MOPSO), which can construct a neighborhood for each particle and choose the neighborhood optimal solution by adopting self-organizing mapping (SOM) method, is proposed to solve the model. The model is applied to the Shui-Kou Hydropower Station in Minjiang, China. The results show that the model can get the optimal schedule with balanced consideration of ecological benefits and power generation benefits, which has not a great impact on the economic benefits of reservoirs while achieving the goal of ecological environment. The research results can provide theoretical basis and concrete scheme reference for reservoir operation.

Research on a layered coupling optimal operation model of the Three Gorges and Gezhouba cascade hydropower stations

The uncertainty of electricity demands and reservoir inflows makes the optimal operation of hydropower stations extremely difficult. Therefore, it is very important to establish a multi-time-scale coupling model that not only reflects the current inflows of short-term strategies but also adapts to the mid-term and long-term optimal strategies. In this paper, using the Three Gorges and Gezhouba cascade hydropower stations as examples, the principles of the layered coupling on multiple time scales are proposed. The control strategies and mechanisms of information feedback for layered models are also presented. Based on these theories, this study establishes an optimal five-layered coupling operation model of the Three Gorges and Gezhouba cascade hydropower stations with the objective of maximizing the generated energy solved by Incremental Dynamic Programming (IDP). Data from 2009 is used as the case study for the optimization of the cascade system. The results show that the model can preferably take advantage of the forecasted inflows with different levels of precision and coordinate the “control and feedback” relationships between short-term and long-term strategies.

A New Particle Swarm Optimization Algorithm to Hierarchy Multi-objective Optimization Problems and Its Application in Optimal Operation of Hydropower Stations

Some engineering optimization problems, such as multi-objective daily generation scheduling for the hydropower stations, the objective functions has obvious hierarchy and priority, simultaneously, the constraints is very complex. It is difficult to solve the operation problems by adopting traditional optimal technique. In this paper, a new particle swarm optimization algorithm solving hierarchy multi-objective timization problems is proposed. The algorithm can handle the level multi-objective optimization problem effectively. By adopting the adaptive inertia weight algorithm (AWA) and mutative scale local search algorithm (MSLSA), the convergence performance of the algorithm is improved. Then, A multi-objective daily generation scheduling model for the hydropower stations is established, in which two objective functions including maximization of peak-energy capacity benefits and maximization of power generation are involved. Finally, Multi-objective daily generation scheduling problem of the Three Gorges cascade hydropower system during low-flow period is studied with proposed algorithm to obtain the maximum peak-energy capacity benefits, as well as power generation benefits of three gorges cascade stations.

Chaotic Optimal Operation of Hydropower Station with Ecology Consideration

Traditional optimal operation of hydropower station usually has two problems. One is that the optimal algorithm hasn’t high efficiency, and the other is that the optimal operation model pays little attention to ecology. And with the development of electric power market, the generated benefit is concerned instead of generated energy. Based on the analysis of time-varying electricity price policy, an optimal operation model of hydropower station reservoir with ecology consideration is established. The model takes the maximum annual power generation benefit, the maximum output of the minimal output stage in the year and the minimum shortage of eco-environment demand as the objectives, and reservoir water quantity balance, reservoir storage capacity, reservoir discharge flow and hydropower station output and nonnegative variable as the constraints. To solve the optimal model, a chaotic optimization genetic algorithm which combines the ergodicity of chaos and the inversion property of genetic algorithm is exploited. An example is given, which shows that the proposed model and algorithm are scientific and feasible to deal with the optimal operation of hydropower station.