Long-term Optimal Operation Model Of Hydrothermal System Considering Grid Demands Of Typical Day

Power demand in China is increasing with the fast development of economic, urbanization and industrialization. Hydropower, as one of clean energies, plays a more important role in power system. Moreover, energy structure adjustment, energy conservation and emission reduction can benefit from a healthy development of hydropower. However, in power system operation, hydropower undertakes not only the task of generating, but also take the task of peak-shaving and frequency adjustment because it is convenient to start up and shut down and run at a low cost. Thermal power is the foundation of power supply in China, but it has severe problems of pollution, so some high energy consumption thermal units need to be obsoleted in order to achieve the purpose of energy conservation and emission reduction. Moreover, there is lot of energy losses in power system in the process of generation, transmission and distribution. That mainly caused by the transmission loss of trans formers,transmission lines, motors and other electrical equipment. Thus, it is of great value to study the long-term generation schedule in hydrothermal system considering the energy-saving and the effective operation of the system. This paper mainly focuses on the following three aspects:long-term operation of cascade hydropower, long-term optimal operation of hydrothermal system and multi-objective operation of hydrothermal system.Firstly, in order to tackle the low efficiency of GA in calculating long-term operation of cascade hydropower, this paper proposes a coarse granularity parallel GA algorithm based on multi-core environment. This algorithm is based on a Fork/Join frame, and it accelerates the calculating speed by taking the advantage of thread pool and multi-core CPU resources. The numerical results from five cascades hydropower on LanCang river (upstream of Mekong River) show that the proposed algorithm can reduce computation time, raise the efficiency of CPU utilization and achieve the load balance.Secondly, this paper proposes two long-term optimal operation models in hydrothermal system with the objective of minimization of coal consumption and maximization of minimum generation respectively. The proposed model is solved by POA and successively load shaving is introduced to allocate the typical day load. The comparison results between the two models indicate that the model with the objective of minimization of coal consumption results in a more energy-saving system, while the model with the objective of maximization of minimum generation results in a system with sufficient peak-shaving generation for hydropower in dry season and with more stable generation schedule for thermal power.Focus on the problem of long-term generation scheduling of hydrothermal system, this paper combines OPF and long-term optimal scheduling hydrothermal system, that proposes the multi-objective model of generation maximization of hydropower, spillage minimization of hydropower, consumption minimization of coal-fired thermal power and line loss minimization. The model takes into account the hydraulic constraints, water balance constraints, security constraints in the power grid, power balance constraints and power supply. The multi-objective is transformed into a single objective by using the linear weighted sum method. On the basis of the typical daily load curve, hydrothermal power output distribution and the power flow and network loss are calculated with hydropower successive cutting load and thermal power equal incremental rate. Finally, the genetic algorithm is used to solve this problem. IEEE-30 bus system is used to verify the effectiveness of the proposed method. The numerical results show that the generation scheduling obtained from the proposed method can reduce the total loss of the power grid, it's a feasible long-term optimal dispatching method.Finally, a conclusion of this paper and a prospect of further and future work are given.