| Due to the characteristics of centralized control and network programmable,SDN has advantages in the transformation of power communication networks in the development of smart grids.Network performance is significantly affected by the location and number of SDN controllers.In this paper,the deployment of SDN controllers in power communication networks is studied.The method of node importance evaluation in the power communication network is introduced because the power communication node usually overlaps with the power grid site,and the difference exists in the importance degree of each communication node in the network.And the importance of the corresponding power communication node by this method is calculated.On this basis,the degree of network impact in the case of single link failure is used as the evaluation criterion for the reliability of SDN controller deployment.The mathematical model of the SDN controller deployment conforming to the characteristics of power communication is constructed based on the transmission delay between the switch and the controller and the synchronization delay between the controllers.Considering that delay is the most important factor in the power grid.The transmission delay between the controller and the switch is used as a single optimization target and some common algorithms such as random algorithm,k-means algorithm,greedy algorithm and k-center algorithm are simulated.In this paper,k-center algorithm is proved effective to be used in delay optimization.Harmony search algorithm is used to solve the deployment of multiple controllers while considering transmission delay,reliability,and synchronization delay between controllers,and a group of Pareto solution set is achieved.Then the optimal solution is chosen through the method of fuzzy decision.It is verified that the application of harmony search algorithm is effective in multi-target controller deployment with the IEEE30 power communication topology as an example. |
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