The Emergency Control Of Hybrid Electric Power System Based On Petri Nets

Recently, the electric power system has been developing dramatically. As more and more new methods and advanced technologies have been introduced into the design and research of electric power system, the network structure and the operation mode of electric power system have also become more and more complicated. Moreover, with the development of the electricity market, and due to a hot pursuit for some higher economic efficiency, the operating point of electric power system is being urged to its running stability limit. All of these factors required the electric power system emergency control not only to play a more effective role in its stability control but also to gain a satisfactory control result. Thus, some significant problems, such as how to ensure the electric power system stability under the optimal economic requirement, how to restore the normal operating of power system quickly after a heavy perturbance with the minimal loss, and how to reenergize the black-out network with minimal economic loss and maximal velocity when a condition of partial or total deenergization of the network is accepted, are challenging to the scientists and engineers in the fields of both electric power system and automatic controls. Apart from the high dimensionality, strong non-linearity and multi-time-scale, one of the most important properties for electric power system is its hybrid nature which shows in the continuity of generating process of electric power, the algebraic logic constraints of transmission and distribution systems and the requirement of multi-objective optimization for the dispatch and control program driven by discrete events. The electric power system emergency control also consists of both the continuous variable and the discrete event controls. It is a typical hybrid control system and it would be proper to introduce the theory of hybrid control system to solve this kind of problems. According to the properties discussed above, the conception and character of hybrid power system emergency control are introduced firstly in this thesis. And then, the fundamental theory of general hybrid control system is illustrated in chapter 2. In chapter 3, the necessary knowledge for Petri nets is reviewed and a new kind of powerful modelling for hybrid control systems, differential Petri nets is addressed. Moreover, the hybrid power system emergency control model based on differential Petri nets is given in chapter 4. Furthermore, the optimal strategy and the corresponding algorithm for emergency control are designed in chapter 5. Finally, the simulation results of emergency control of electric power system and a conclusion remarks for this thesis are given in chapter 6 and chapter 7 respectively.