Reliability Analysis And Optimal Design Of Wide Area Communication Network In Power System

Power Systems are increasingly interacting with the communication networks, merging the information highways with the power transmission and distribution networks, depending more and more on communication based information exchange. Power System Communication becomes the key technology to enable a smart grid. Wide Area Network(WAN) communication system in power grid has the different communication requirements with different services from the aspects of real-time, reliability and security, which the Wide Area Protection System(WAPS) and Wide Area Control System(WACS) need to satisfy the most stringent requirements.WAN communication system acquires and exchanges information within substations and beyond. Therefore, it requires reliable and secure communication for critical information delivery within the specific time period. The communication system of substation automation and that of wide area measurement are both the important parts of Wide area communication network in power grids. The former communicates over the intra-substation LANs, while the latter communicates over the inter-substation WAN. With respect to the specific requirements on the wide are communication network, comprehensive analyses should be carried out on different aspects:including reliability analysis and evaluation of the softeware and the hardware, the related communicaton architecture meeting the requirement of real application, together with the suitable model solving algorithms, should be studied. A suite of performance indices should be proposed to quantitatively evaluate the reliability and real-time of the systems. Above work is able to provide guidelines for engineering and implementation. Based on the graph theory and by means of the reliability and real-time performance, the topology of communication architectures of WAN together with path selection of the WAN are studies in this thesis.Firstly, the communication media and the related technologies, together with the performance requirement of reliability and security of the rea-time wide area communication network are investigated in this thesis. The access mode, load mode and selecting ways of the WAN based communication system are analyzed.Secondly, connectivity and tenacity indices are utilized to quantitatively assess the invulnerability and survivability of communication architectures, and they are demonstrated using typical network topologies commonly used in Substation Automation Systems (SAS). In this thesis, the Parallel Redundancy Protocol (PRP), High availability Seamless Ring (HSR) and Rapid Spanning Tree Protocol (RSTP) protocols are tested respectively, and Dynamic Fault Tree Analysis (DFTA) method is employed to assess their reliaility over various network topologies.Thirdly, the reliability and real-time of information transmission is the core of the WAMS. Optimal design of communication network is crutial for information transmission, and it affects the performance of the whole network. This thesis not only takes the traffic flow on the network, reliability and speed when selecting an architecture into account, but employs the Improved Cut Saturation Algorithm (ICSA) based on the graph theory to design the optimal architecture.Fourthly, the transmission-path-selection model based on MPLS traffic engineering is put forward in this thesis, which can meet the QoS requirements of the wide area protection system. The Heuristic Genetic Algorithm (HGA) is used to solve the model, in which the natural number coding method is used to realize the path selection of traffic balancing in accordance with the constraints of delay. In this way, the coding efficiency is improved and the real-time requirement of power systems can be satisfied.