Research On Security Strategy Based On Optimal Power Flow In Smart Grid

Power flow calculation is used to solve the power planning problem,which provides a guarantee for the secure and reliable operation of the smart grid.However,with the continuous expansion of smart grid scale and its in-depth integration with the information network,power flow calculation has become more and more complicated.In addition,the security requirements when processing electricity data also bring great challenges to power flow calculation.In order to solve the issues above,we first propose the optimal power flow based on the Alternating Direction Method of Multipliers.This method can solve the non-convexity of power flow calculation considering the maximum current limit and voltage stability constraints on the line.We further use data noise and encryption aggregation to protect data security while ensuring the accuracy in power flow calculation.The main contributions of this thesis can be summarized as follows:(1)To optimize the power flow calculation,we propose an optimal power flow algorithm based on distributed ADMM.Specifically,the algorithm uses Semi-definite Programming to address the non-convexity of power flow calculation.Then,using the decomposable characteristics of ADMM,the power flow can be decomposed into multiple sub-problems.Finally,thanks to the communication between adjacent buses during the calculation process,the bandwidth requirements are reduced.Experimental results prove that the algorithm proposed can make the power flow calculation reach the optimal under the condition of satisfying the operating constraints.(2)A data protection algorithm based on ADMM with noise is proposed to solve the security problem in the collection process of local electricity data.Specifically,the algorithm measures the privacy protection level of electricity data in the smart grid by introducing the differential privacy.Then,by adding randomly attenuated noise to the user data,the data cannot be directly restored by malicious attackers.Through extensive experiments,we demonstrate that the proposed algorithm protects the security of user data.(3)A data protection algorithm based on One-time Pad is proposed to enhance the data transmission security problem between various nodes over the smart grid.Specifically,the algorithm encrypts the aggregated data through a homomorphic encryption method.Then,the number of data packets can be processed.The experimental results verify the validity of our proposal that the algorithm can effectively protect the security of data during transmission.