| With the implementation of the development strategy of "west-east electricity transmission, south-north electricity exchange and interconnection of nationwide power grid", a nationwide integrated power system has begun to take shape. As the construction of UHV, smart grid roll out, the development of our power industry has began to enter a new stage which is characterized by UHV, high intelligence, interconnection of nationwide power grid and optimum distribution of energy in more areas. The interconnected network will bring unprecedented challenge for relaying protection system, although it has the advantage of optimizing the allocation of energy, enhancing power system reliability effectively and so on. The wide area protection system is one of the important methods to enhance the security and stability of the large interconnected network, which relies on communication networks to get power network information in wide area and isolates faults quickly and precisely in an as small as possible outage region through compound decisions.The power grid catastrophe caused by extreme nature disasters happens occasionally at present, and the disasters have brought various influences upon protection system, which have the research on wide area relaying protection faced many new challenges. Therefore a new-type power grid protection system that is able to cope with various kinds of disasters independently should be researched. Considering the limited wide area intelligent protection system coping with catastrophe, the following aspects are studied:the demarcation of protected zones, the wide area protection algorithm which is characteristic of fault-tolerance, the intelligent technology based on multi-agent system, the construction of a unified information communication platform, communication scheme and a method of transmitting information, communication channel reconstruction technology, etc.Firstly, the necessity of demarcating protected zones is analyzed, and the basic principles of the demarcation based on remote backup protection are determined. A new method on the demarcation is proposed, which can distinguish the significant change of amperage by means of t statistic test method. Based on incidence matrix operation, a fault detection algorithm of wide area directional comparison protection is given, which makes use of the fault direction information gathered from the protected zones. The concept of fault confirmation loop is introduced, which can be used to form the treatment measures of fault tolerance with the operation information of distance protection. And the trip flow of wide area protection is given as well.Secondly, the system faults can be isolated in a minimal region as quickly as possible, when all kinds of the fault information is coordinated and processed comprehensively by wide area protection that is a complex dynamic system. It is very effective to construct a wide area protection system by multi-agent technology. According to the wide area protection algorithm proposed in this paper, a multi-agent system of wide area protection is designed. And the design process are analyzed in detail, such as follow the system architecture, the task decomposition of protection agent, the constitution of a single agent and the typical sub-function agents. For the wide area protection algorithm, a dynamic cooperation mechanism of the wide area protection multi-agent system is proposed and the transition process of all kinds of working condition is elaborated.Thirdly, the wide area protection system is built upon how to get and use effectively information in a wide area. So it is essential to construct a unified information exchange platform that is able to meet a variety of functional requirements. Based on IEC 61850, an information transmission platform of wide area protection is proposed in this thesis. On the basis of analyzing the general modeling step of Intelligent Electronic Device (IED) based on IEC 61850 and the function decomposition of wide area protection system, the information model of the IED used for wide area protection is built up. According to the standard code, the logical node classes of wide area directional protection and wide area error correction protection are set up. The exchanged-message among the functional logic nodes of wide area protection is analyzed, which belongs to the fast message transmission services. Then the idea of transmitting failure message needed by wide area protection function through the service model of Generic Substation Event (GSE) is provided, and the publish/subscribe mechanism of information transmission is discussed.Fourthly, communication networks are the foundation to realize wide area protection, and the rapid development of communication technology makes them possible to gather the information of power grid in wide area. A wide area protection system can realize two main functions:relaying protection and security & stability automatic control. Considering the construction cost and expandability of a communication system, a communication scheme is proposed in the paper, that the wide area protection information is transmitted through the electric power system dispatching data network. Analyzing the performance requirement of communication networks that is needed by wide area protection, a networking scheme for wide area communication based on IP over SDH with MPLS VPN and an information transmission method are proposed. The communication system adopts a hybrid model composed of distributed model and centralized model. The information for the wide area relaying protection IED is exchanged with the distributed, peer-to-peer model, while the other information is transmitted to power dispatching centers with the centralized model. The service quality of the information transmission for wide area protection can be guaranteed by Traffic Engineering and Differentiated Service Model in MPLS technology. An actual communication system of wide area protection is designed, and its model is built with OPNET Modeler for testing the real-time and reliability of the protection information transmission in all circumstances.Fifthly, under conditions of extreme climate or damaged communication channels, not only pilot main protection system could be out of service, but also the theory of wide area protection based on unbroken power grids could be no more appropriate. Therefore, research for communication channel reconstruction technology is conducted. There are two relevant methods given in the paper, and one is to transmit protection information through undamaged links in roundabout ways. A circuitous routing algorithm based on shortest path is proposed. Furthermore, considering the congestion of undamaged links under simultaneous failure of multiple links, a shortest path circuitous routing algorithm based on the link load constraints is suggested. Combined with the monitoring of power facilities, the other one is to construct emergency communication channels by introducing wireless sensor networks. Taking the power facilities monitoring system under frost climate as an example, an emergency communication channel system for relaying protection is designed, which is based on the wireless sensor networks. Firstly the styles of required sensor nodes are chosen, and then the layout of the nodes is completed, finally the topological structure of the network is given. Since the sensor nodes adopt batteries to supply power and the lifetime of a network is limited by the capacity of the batteries, research for the discharge characteristics of the batteries is carried out and the simulation result shows that batteries have obvious restoration effect. According to the feature that the sensor nodes are around the transmission lines, a prioritization scheme of power supply for the nodes is suggested, that the power comes from little CT as well as batteries. Meanwhile the suggestion that the nodes should operate in the mode of pulse discharge is given. Then, a cluster-header node election method based on battery status is proposed, so is the routing algorithm based on directed diffusion with rumor routing.The wide area protection system coping with catastrophe has been deeply investigated in this paper. The research lays the theoretic foundation for the research transformation of wide area protection, from conceptual exploration to application basic study. At last, the research result could not only make the wide area protection system capable of coping with power grid catastrophe, but also strengthen the first line of defense of power system security and stability.
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