Research On Short-term Optimal Operation And Economic Dispatching Of Trans-provincial Power Cascade Hydropower Stations

The short-term optimal operation and economic dispatching of trans-provincial power cascade hydropower stations has some characterastics, such as multi-dimensional, the huge differences among different grids, non-uniform scheduling subjects, and the different power regulation performances of hydropower stations and dynamic characteristics of units. This problem is also influenced by the hydrological and meteorological conditions, inflow process, peak saving demands, power structure and hydropower scheduling mode. As a result, the short-term optimal operation and economic dispatching of trans-provincial power cascade hydropower stations is a typical type of complex optimization problem with multi-dimensions and multi-constraints, at the same time, it is also the research hotspot in the field of hydropower energy optimal operation. Currently, the large scale development of southwest hydropower resources and uhv transmission technology provide the favorable conditions for peak saving operation and electric power inter-provincial coordination distribution among multiple power grids. At the same time, the grid-connected of new energy, the sharp fluctuations in grid loads and the hydropower absorbing among multiple regions also raise new requirements for the joint operation of cascade hydropower plants, which make the hydropower optimal operation and control of management more complex. Therefore, to realize the optimal operation of hydropower energy and its interconnected power system, it is necessary to explore the method of the short-term optimal operation and economic dispatching of trans-provincial power cascade hydropower stations. This dissertation focuses on the key scientific and technical problems of optimal operation for cascade hydropower stations under the background of joint grid all over the country. Supported by the science of hydroelectric energy, intelligent optimization method, and complex system science theory. The Xiluodu and Xiangjiaba cascade hydropower stations, as well as the large hydropower stations commanded by the central dispatching authority of Central China grid, are set as the main research object. Finally, we study the modeling and the solving method of the short-term optimal operation and economic dispatching of trans-provincial power cascade hydropower stations on theories and engineering practice. The research production have been applied in the production and scheduling system of "Dispatching control center of Jinsha River basin" and "Dispatch and communication center of central China grid" successfully. The main research contents and innovations include:(1) Based on the comprehensive analysis of the organizational structure and operational principle of Economic Dispatching Center (EDC) in a river basin, we have developed a new economic operation control method for cascade hydropower stations using an improved binary-real coded bee colony optimization (IB-RBCO) algorithm, while simultaneously meeting the hydraulic and electrical constraints. First of all, according to the different objectives and requirements at different stsges, an economic operation model for cascade hydropower stations, in which the minimized water consumption or maximized water storage during the whole scheduling period is taken as the objective, is established. Meanwhile, IB-RBCO is proposed to solve unit commitment (UC) problem of a giant hydropower station. Finally, via a nested iterative method, in which the model is decomposed into two parallel sub-problems of unit commitment (UC) and economic load dispatch (ELD), the rational and optimal results of economic load dispatch and unit commitment are derived. The reasearch provided technical support for the secure, stable and economic operation of power systems.(2) Taking into account the association and differences between hydraulic power dispatching and electric power dispatching in a cascaded dispatch center, an intergrated dispatching mode for daily generation scheduling and inner-plant economic operation is proposed. From the perspective of generation side and demand side, a daily generation scheduling model, in which the maximized short-term peak load regulation is taken as the objective, is established, and through peak load ratio based peak load regulation mode the output scheme of the hydropower plant is generated, and based on the optimal flow allocation table the proposed model can be solved high-efficiently. Combining with analysis on coupling property between daily generation scheduling and inner-plant economic operation, the integrated loop nesting dispatching mode for both is constructed, and the result of daily generation scheduling is taken as the input of the inner-plant model and at the same time the inner-plant simulation result is utilized to perform feedback correction of the output scheme, thus under the premise of satisfying the requirement of minimized released flow the optimal daily generation planning, the optimal unit commitment and the strategy of allocating load among units can be made. In this way, it is implemented that grid, water and power dispatch department can cooperate with each other.(3) Considering the complex application requirements of peak operation in power grids, a novel method of peak operation and electric power inter-provincial coordination distribution for huge cascade hydropower plants among multiple power grids was proposed, and Xiluodu-Xiangjiaba cascade hydropower plants were selected for the research. Specifically, with the perspective of coordination on plants and power grid, an optimal operation model was established with the objective of minimizing the grid residual mean square error. Moreover, considering the complementary features among grids, the stochastic search algorithm is applied to optimize the power output distribution plan of the hydropower stations, while considering the peaking capacity of hydropower station and power limits of uhv transmission lines. The simulation results show that the generation plan obtained by proposed method can balanced response to the demands of grids, and the proposed method presents a strong practicability.(4) The short-term economic/environmental hydro-thermal-wind complementary scheduling (HTWCS) system is established while considering wind power uncertainty, as well as the complement of hydro-thermal-wind. Meanwhile, instead of the standard bee colony optimization algorithm (BCO), an enhanced multi-objective bee colony optimization algorithm (EMOBCO) is developed to solve the multi-objective problem. Some improvements like Elite archive set, adaptive mutation and selection mechanism based on crowding distance and feasibility method, local search strategy and novel constraints repairing strategy are proposed in EMOBCO to ensure accuracy and improve searching efficiency. The simulation results indicate that the proposed EMOBCO can provide a set of widely distributed and uniform non-dominated solutions (equilibrium solutions) in HTWCS problem, which will provide guidance for both energy optimization and efficient and economic operation of power systems.