The Study And Application Of Coordinated Operation Of Large And Small Hydropower Reservoirs In Hydropower Rich Region

Hydropower is the second largest power resource with the largest capacity among all the clean energies in China. Hydropower resources mainly concentrate in southwest China. Recently, with the progress of west-east power transmission project in China, as a hydropower base, hydropower in southwest China has achieved great-leap-forward development, the installed capacity of hydropower has grown rapidly. Meanwhile, small hydropower (SHP) has been greatly developed on the basis of increasing economic demands and national policy orientation. SHP is oriented to provide support for local economic development and plays an important role in promoting power industry development. However, the fast growth of the hydropower system makes the dimension of optimal operation problem of hydropower expand rapidly, traditional methods have difficulties to meet the needs of large-scale hydropower optimal operation. Moreover, as the lack of integrated planning and management rules for SHP, there has appeared disorder exploitation and grid-connection, and appeared seasonal electric power surplus with the growth of SHP installed capacity. Under current load demand, small hydropower, large hydropower and other kinds of energy sources crowded the limited power generation space to generate electricity and crowded to export electricity under limited power transmission capacity. These metioned problems result in large scale hydropower curtailment and bring significant influence on power system security and stability.This dissertation takes southwest hydropower-rich regions as the study background and take the coordinate optimal operation of large and small hydropower reservoris as the main line, deeply analyzes the characteristic of large-scale hydropower optimal operation, large hydropower and SHP’power output characteristics and the electricity connections between them. Long-term optimal operation of large scale hydropower stations, the coordinate optimal operation of large hydropower and SHP in different scheduling periods, and coordinate optimal operation with wind power have been studied. The main achievements of this research are as follows:(1) A multi-core parallel tabu genetic algorithm is proposed for long-term optimal operation of hydropower system to overcome high complexity and low computational efficiency of computation when a large number of hydropower stations are considered. Based on decimal strings genetic algorithm, the algorithm divides population into several sub populations, and then multi-population migration strategy is adopted to prevent premature. The tabu search ideologically is adopted to avoid computing fitness value repeatedly and genetic algorithm is successfully mapped into multi-nodes structure which developed rapidly in recent years. The result of cascaded hydropower stations on Lanchang river and Hongshuihe river shows that the proposed method can effectively prevent premature and reduce computational time, which is a valid method for optimal operation of large-scale hydropower system.(2) A long-term coordinate optimal scheduling method based on decision tree is presented for large hydropower and SHP, which aims to solve the problem of limited transmission access being completely occupied in hydropower-rich regions. Firstly, the decision tree data mining algorithm is established. Secondly, a long-term large hydropower and SHP optimal operation model for absorbed energy maximization is built. Thirdly, the ideal yearly optimal scheduling process in history is obtained by deterministic optimization method. Finally, scheduling rules is derived by decision tree. In the model application period, rainfall prediction information by CFS is used to forecast the runoff of large hydropower reservoirs and the generation ability of SHP, which are also used as decision tree’s condition attributes. The method has been tested in SHP rich areas of Dehong. The result shows that the proposed method can make full use of large hydropower regulation capacity and spare transmission access for SHP, which effectively reduce the curtailment of SHP.(3) During flood seasons, the large and small hydropower crowded to export electric power with limited transmission capacity, resulting in large scale hydropower curtailment. Based on the grid connection characteristics of SHP stations, the small hydropower stations in the same region are considered as a whole. Firstly, regional SHP’s power output deviation between plan and reality is calculated and fuzzy clustering analysis method and silhouette coefficient are introduced to establish the SHP output scenario. Secondly, heuristic search method and successive associated search method are combined to solve the problem. By utilizing large hydropower’s regulation capacity, curtailment of SHP is prevented and realized large and small hydropower optimal operation. The application in the small hydropower rich areas of Dehong, Banna and Pu’er shows that this model can effectively use the regulation capacity of large hydropower stations to optimize coordinate operation and reduce the curtailment of SHP. It is a practical optimal model for large and small hydropower coordinate operation.(4) To reduce increasing electricity exportation pressure in flood season caused by wind power’s growth in hydropower-rich regions, large hydropower, SHP and wind power coordinated optimal operation model for consumption energy maximization is built. Firstly, SHP and wind power are treated as random variables and nonparametric kernel method is introduced for error distribution of SHP and wind power predicted power output. Secondly, improved particle swarm optimization algorithm (IPSO) is proposed from the initial particle generation, dynamic updating inertia factor and add crossover and mutation operation between particles. Thirdly, the PSO and Monte Carlo simulation are combined to solve the mentioned problem. The result from northwest Yunan province shows that the IPSO is much better than PSO and GA, the proposed model can take SHP and wind power’s uncertainty into consideration reasonablely. Meanwhile, coordinate operation of large hydropower, SHP and wind power can balance the operational risk and expected energy consumption, which illustrates the method’s effectiveness.Finally, the content of the whole dissertation is summarized and some valuable research directions are also discussed.