Study On Communications Of Smart Distribution Grid Based On Cognitive Radio Technology

Smart distribution grid(SDG)，as an important component of national smart gridstrategy, is very critical for improving operation security, stability, and power quality ofthe power grid. As well known, SDG relies on real-time and integrated communicationsystem which usually possesses high-speed and bidirectional communication. Actually,information collection and command transmission also require high-speed and reliablecommunication network (i.e., communication system). Thus, the first step for therealization of SDG is to build up a secure and reliable communication system. Generally,the communication system of SDG has two major categories. The one is the backbonenetwork, and the other is the access network. The weak link of communication systemisthe access network, and there is no existent single network can satisfy the requirementsof the quality of service (QoS) for the communication services. As the development ofintelligent distribution network, its applications has expanded to more fields which inreturns gives a large amount of data in an exponential growth. It is difficult for currentcommunication mode to deal with an enormous amount of data collection, transmission,and storage in the process of communication. Meanwhile, it is a great challenge fortraditional distribution communication network to satisfy the requirements of channelbandwidth, delay, capacity, and security for different types of data.Cognitive radio(CR), as a promising intelligent wireless communication system,can be employed for the development of next generation of communication technologydue to its dynamic spectrum access ability. The communication mode of CR realizesspectrum sharing for both the authorized users and the cognitive users, which to a greatextent improves the utilization of the allocated spectrum, and the flexibility, validity andreliability of information transmission. Clearly, CR is very suitable for the accessnetwork of intelligent distribution communication. In this study, a novel radio-cognitivecommunication scheme is proposed for intelligent distribution network. With dueconsideration of quality requirements of the intelligent distribution communicationservices, further researches about spectrum allocation of services terminal and terminalaccess technology are conducted in a bid to provide a new perspective for theconstruction of more reliable and stable intelligent distribution communication network.In this study, in terms of CR technology, classification of intelligent distributioncommunication services, and requirement analysis, an radio-cognition communication scheme based on intelligent distribution network is presented. In view of theradio-cognition and reconfiguration ability of the presented scheme, communicationterminal is compatible with various wireless communication technologies and candynamically allocate spectrum resources, which undoubtedly provide more reliable datatransmission for different intelligent distribution communication services.In the proposed scheme, the extent spectrum allocation problems in servicesterminal are discussed. After deep analysis of current spectrum allocation mode, theauthor have conducted spectral allocation algorithm on the basis of game theory.Admittedly, different service terminals have different QoS requirements such as delay,delay jitter and bandwidth and so on. With above QoS requirements, service terminalscan be graded by use of fuzzy comprehensive assessment. Then, profit functiondesigned by the author makes the service terminals with different grades acquirespectrum resources of different bandwidth in the process of gambling. Specifically, inan authorized network, all service terminals transmit their own data by the acquiredspectrum resources, and these spectrum resources are allocated by utilizing static gameand dynamic game algorithms. Finally, an average and explicit results are obtained byuse of some numerical methods.For a power company with a reasonable amount of spectrum resources, utilizationof spectrum resources can be improved by defining Real-time service terminal(RT) asan authorized user and non-real-time service terminal (NRT) as RT spectrum resourcesshared by cognitive users. In this study, access control algorithm based on Markovdecision process is employed to deal with NRT access problems. The proposedalgorithm is generalized for the following aspects as: decision cycle, state space,strategy space, the state transition probabilities and revenue functions, policy iterationalgorithm used to obtain the system’s maximum revenue and its correspondingstrategies. The algorithm is simulated under the circumstances of NRT throughput andeconomic profit of the system, respectively. By comparing random access strategy andprobability access strategy with NRT terminal’s blocking rate, call drop rate, systemthroughput and payment, the result demonstrates that the proposed strategy has obviousadvantages.