Study On Self-healing Control Of The Urban Power Grid Based On Hierarchical Control Theory

City is the center of electric power load. It is important that the urban power grid can provide continuous power supply and operate in security and reliability state, which is closely linked with social production and life. The operation of power system needs energy to be in instantaneous equilibrium. The urban power grid and its operating environment is increasingly complex with enlarged uncertainty, which increase the difficulty of the urban power grid control. According to the principle of maintaining the self-healing power of organisms, and considering the characteristics of the urban power grid, the self-healing control method adapting requirements of the urban power grid control is studied in this paper. The self-healing control architecture and control model is established based on hierarchical control theory and multi-agent system theory. The implementation method of self-healing control is designed, and a proper control scheme is implemented on the basis of vulnerability assessment for the operation of the urban power grid.The specific work is as follows:(1) Hierarchical control architecture of self-healing urban power grid is put forward by combing with hierarchical control theory and the basic framework of power system control. Under the architecture, the self-healing power of the urban power grid is raised by giving full play to the beneficial supplement and emergency supporting function of distributed generation.(2) Hierarchical self-healing control structure of the urban power grid based on multi-agent system is put forward by combined with hierarchical control theory and multi-agent system theory. The mathematical model of self-healing control and three-dimensional coordination mode of its control strategy are established for the urban power grid. The self-healing control model based on hierarchical control theory is established with unified interface model.(3) Dynamic random variable is defined, and its probability model is established. And then dynamic probability power flow is calculated by using semi-invariant of random variables and the Gram-Charlier progression. The harms to the urban power grid caused by various disturbances are analyzed in this paper. Evaluation index and method for the vulnerability assessment to the urban power grid are provided based on risk theory. It can provide the basis for making self-healing control scheme by evaluating the operating status of the urban power grid.(4) Based on hierarchical control architecture and control model of self-healing urban power grid provided in this paper, system framework of self-healing control for the urban power grid is designed, and then agent structure and its coordination strategy at all levels are provided.Self-healing control system of the urban power grid is established through the aforesaid self-healing control architecture, control model, analysis methods and system framework. The system is installed in Jiangning urban power grid and Luhe urban power grid in Nanjin. The practical application shows that the self-healing control sysemt could realize the adaptive closed-loop control in the urban power grid. So the urban power grid can keep the self-healing power of transferring to a more healthy state, and ensure continuous power supply for customers.