| In our country, energy conservation, which refers to efforts made to reduce energy consumption, is a long-term policy for the development of economy and society. Furthermore, the electric power conservation is the most important part of the national tactic of energy conservation. However, with the rapid development of various industries such as the steel-smelting, the nonferrous metallic and the petrochemistry, it is urgent for these industries to reduce the cost of electric power. In addition, it also introduces stress on the national policy of continuous development because there exists numerous high energy consumption industries in China. These enterprises are not only of high cost of energy but also with low efficiency. Therefore, it is of special significance to start the research on the electric power conservation for enterprises, by which can raise the usage factor of the electric power and can improve the quality of the power grid as well as the reliability of the power supply.This thesis is supported by the national high technology research and development of china 863 program and the scientific research plan of hunan provincial science. For modern industries such as the steel-smelting, the nonferrous metallic and the electric railway, they all have technical requirements for reactive compensation and suppression of dynamic harmonics and unbalanced negative-sequence currents. Thus, the technics for solving these problems as well as the technic for electric power management are deeply investigated in this thesis. As a result, the key technologies of electric power conservation and corresponding equipment technology are studied for the requirement of enterprises. Finally, the centralized management and optimal compensation for reactive power, harmonics and negative-sequence currents in the enterprise grid are realized while the purpose to reduce the power cost is also achieved.Three enterprises corresponding to the industries of smelting, manufacture and chemistry are selected for investigation, respectively. Firstly, the demand of the electric power conservation of enterprises is derived by analyzing three main problems such as the suppression of harmonics and reactive power, the energy conservation by using frequency variation and the electric power management and optimization. Finally, some useful solutions for realizing the synthesized electric power conservation of the enterprise grid are introduced. A novel shunt hybrid active power filter (NSHAPF) for compensating the harmonics and reactive power is proposed, which is for solving the problem of electric power loss caused by the harmonics in the high grade grid. The corresponding topology structure is analyzed, and the filtering principle is introduced theoretically. The suppression of high order harmonics by using NSHAPF is investigated by simulation. In addition, the stability of NSHAPF is analyzed by simulating the faults in the grid such as the single phase earthing, the short circuit between phases, the short circuit of three phases, the voltage leap, the voltage swell and sags. The control scheme for the DC-link voltage of NSHAPF and the control strategy for harmonic currents by using the double close-loop are proposed then. The experimental analysis is introduced at last, which shows that the proposed NSHAPF can satisfy the requirement of the suppression of harmonics in the high grade grid.Due to the voltage fluctuation, low power factor and negative phase sequence (NPS) current caused by loads of distribution network, at where the static var compensator (SVC) is used to solve those power quality problems. A multiple objects unified controller is proposed. The proposed control method is composed of two control parts:one control branch is closed-loop control of power factor and NPS current compensation feedforward control, another control branch is closed-loop control of bus voltage at the point of common coupling (PCC) and NPS current compensation feedforward control. The two branches could be automatically switched following the variation of electric power qualities corresponding to different load conditions. In addition, a fuzzy-PI controller is designed for closed-loop control of power factor, which can coarsely adjust or finely adjust the power factor by hysteresis loop width. A nonlinear PI controller is proposed for the closed-loop control of PCC voltage, whose PI constants are adjusted by an improved accelerate simplex method. The correctness and effectiveness of proposed methods are verified by industrial applications and simulations.At present, there is no report about the key technologies and the complete set of equipment for electric power conservation of enterprises while most of the existing researches and applications only focus on the single aspect of this technology and show limited effectiveness in energy conservation. Thus, a synthesized management system based on genetic algorithm based multi-agent system (GA-MAS) for the electric power conservation of grid is proposed in this thesis. The GA-MAS is based on the combination of genetic algorithm and multi-agent system technology, which can be used to calculate the optimal adjustment of energy-saving equipment. With GA-MAS, the benefit of energy-saving equipment can be maximized while the cost of equipment adjustment is minimized, and the synthesized energy conservation of grid can be achieved. At first, the structure models of systems such as the synthesized management system, the agent structure models of all the energy-saving equipment and the structure model of the multi-agent system are introduced. The two subsystems of the management layer, viz. synthesized automatic system and power management system, are introduced then. The synthesized automatic system, which is mainly based on the real-time control technology of the micro-controller, can coordinate the functions such as protection, monitoring, control and motion control. Furthermore, it can establish a synthesized micro-controller based protection/monitoring system. The power management system mainly focuses on two aspects for energy conservation, viz. management and equipment optimization. For enterprises, it can be effective in reducing the costs of electric power and manufacturing and raising the production efficiency and the level of electric power management simultaneously.Finally, these t proposed echnologies for energy conservation in this thesis are employed in enterprises and the whole structure of related engineering applications is introduced. The design and related application of the proposed NSHAPF and SVC in engineering are also presented. The hardware platform of the synthesized automatic system is established and the analysis on the efficiency of energy conservation is introduced, which shows good performance in power conservation.
|
PDF Full Text Request