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Cheng C.,Dalian University of Technology | Yang F.,Dalian University of Technology | Wu X.,Dalian University of Technology | Su H.,Guizhou Electrical Power Dispatching and Communication Bureau
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2010

Hydroelectric plant operation is based on an operation chart. Most of the existing literatures, however, paid much more attention to the single reservoir chart than cascade reservoirs. In this paper, an approach of working out the optimal operation chart for cascade reservoirs is proposed and applied to the well-developed Wujiang River hydropower system in China. Based on the initial traditional operation charts for single reservoir and cascade reservoirs, power results of each single plant and the cascade system are obtained. Then the load dispatching strategy of cascade reservoirs is adopted to regulate the power variance between the sum power of all the single plants and the power of cascade system. By repeating this procedure, the simulated runoff history is obtained. Finally a dynamic programming successive approximation (DPSA) is used to modify the basic parameters of the two charts at an objective of energy maximizing. In comparison with the traditional effort, this approach can give an integrated optimal operation charts for single reservoirs and cascade system. Simulation results indicate that the proposed approach is valuable and feasible and it significantly improves the power generation benefit under the power grid requirements. © Copyright.


Feng Z.-K.,Dalian University of Technology | Liao S.-L.,Dalian University of Technology | Cheng C.-T.,Dalian University of Technology | Su H.-Y.,Guizhou Electrical Power Dispatching and Communication Bureau
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2014

In order to overcome the curse of dimensionality of Progressive Optimality Algorithm (POA) in solving the long-term optimal scheduling of cascade reservoirs, Orthogonal Progressive Optimization Algorithm (OPOA) is proposed on the basis of the orthogonal experiment design method, reducing the dimensions of stages, the number of discretization of water level and cardinal number of set. Firstly, POA is employed to decompose multistage decision problem into several two stage sub-problems, and then solve each sub-problem by carrying out the orthogonal experimental design multiple times, taking the objective function as experimental index, reservoirs as experimental factors and discrete status as factor levels. All sub-problems are calculated respectively by building water levels in equilibrium distribution, until obtaining the optimal solution of each sub-problem successively. The computer simulation results of 4 reservoirs in the Wujiang River show that OPOA is distinctly superior to particle swarm optimization and takes only the 28.4 percent of the computing time compared to POA in obtaining the global optimal solution, which is an effective algorithm in long-term optimal operation for hydropower system.


Feng Z.,Dalian University of Technology | Liao S.,Dalian University of Technology | Niu W.,Dalian University of Technology | Cheng C.,Dalian University of Technology | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

With the rapid expansion of the huge cascade hydropower system in China, the computing scale of hydro scheduling optimization is undergoing an explosive growth and faces the increasingly severe curse of dimensionality. It is essential to find some novel and effective methods to enhance the computing efficiency. An orthogonal discrete differential dynamic programming (ODDDP) algorithm for mid-long term optimal operation of cascade hydroplants was proposed. On the basis of classical discrete discrete differential dynamic programming (DDDP), the proposed algorithm took advantage of orthogonal design to choose small but representive state combinations of different plants at each period, which led to a significant reduction in the computation time and memory requirement. The results of Wujiang River show that ODDDP is comparable to DDDP while making a significant reduction in computing time. The ODDDP is an effective algorithm for the mid-long term optimal operation of hydropower system. © 2015 Chin. Soc. for Elec. Eng.


Wang J.,Dalian University of Technology | Cheng C.,Dalian University of Technology | Liao S.,Dalian University of Technology | Wang M.,Guizhou Electrical Power Dispatching and Communication Bureau | Su H.,Guizhou Electrical Power Dispatching and Communication Bureau
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

The key problem of real-time scheduling of hydro cascaded system is how to fast and reliably adjust day-ahead scheduling according to deviation of load forecasting and runoff prediction. It encounters three primary difficulties: avoidance of unit's restricted zones, consideration of day-ahead scheduling and generation smoothness, and minimization of surplus water. This paper presented a real-time scheduling method and strategy for hydro cascaded system with complex constraints, including processes of computation order decision, plant commitment strategy, load deviation smoothing, load deviation dispatch and surplus water adjustment strategy. Load deviation smoothing process is adopted to shape load deviation to ensure generation smoothness constraint satisfied. In the process of load deviation dispatch among plants, plants' generation is modified dynamically based on day-ahead scheduling, and unit's restricted zones can be rapidly avoided. Simultaneously, an adjustment strategy for preventing surplus water is adopted to achieve pre-discharge by revising plants' generation along constraint boundary. The proposed method and strategy can implement the following effects: full coordination with day-ahead scheduling, prevent of frequent fluctuation of plants' generation, avoidance of unit's restricted zones, and surplus water prevention. Two case studies on Wujiang mainstream cascaded hydropower plants oriented to the coordination of power plants and power grid is used to test the proposed method and strategy, and shows that it is feasible and can meet actual operation demands. © 2015 Chin. Soc. for Elec. Eng.


Li S.,Dalian University of Technology | Li G.,Dalian University of Technology | Cheng C.,Dalian University of Technology | Fan X.,Dalian University of Technology | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

The sorted table of generating units and equal incremental principle are recommendatory methods for solving the load dispatch problem under energy conservation power generation. However, there are some issues for the practical applications. Hence, this paper presented an energy-saving load dispatch method for thermal unit, which took the durative constraints of generating units into account. The dynamic unit commitment algorithm, which can flexibly deal with the durative constraints and optimizes unit commitment, was designed using generating sorted table. In order to meet the climbing requirements and upper-lower limits of power generation units, the equal incremental principle was improved by using Kuhn-Tucker optimality conditions. The load modifying strategy was introduced to handle the difference of the load changing trend between unit generation and system load. This method was applied as a case study in Guizhou Power Grid, and the results show that the proposed methodology can implement better energy-saving, and better meet actual operation demands. © 2011 Chinese Society for Electrical Engineering.

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