Vulnerability and augmentation of power grids: a complex network approach
Creators: name: Wang, Jinjian
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400805
subject: Electrical energy transmission, networks and systems

description: Vulnerability assessment of power system networks is becoming an essential requirement for minimizing the risk of disastrous power outage events especially while power networks are constantly growing in size and complexity due to the increasing power demands and low-carbon mission agreement all over the world. This thesis is dedicated to study the vulnerability and augmentation of power grids with complex network approach. The work in this thesis can be broadly categorised into three parts: vulnerability analysis, network augmentation and vulnerability analysis of growing power networks. First of all, two different vulnerability indices are introduced. Firstly, a novel maximum flow based centrality index is proposed which treats the power system as two complex networks: real power flow network and reactive power flow network. Both real and reactive powers are important in maintaining the robustness of the network. Two vulnerability indices (real power flow centrality index and reactive power flow centrality index) are proposed which represent the vulnerability level in two different networks. They are combined using fuzzy logic to generate the system composite centrality index. The analysis is carried out on the IEEE 14 bus system. Second, complex network based hybrid approach is proposed which take time varying net-ability ratio as a centrality index to assess vulnerable components in a modern power network while considering the intermittent and unpredictable characteristic of renewable generation. To demonstrate the applicability of the proposed method, three case studies are performed on IEEE 14 and IEEE 30 buses power structures utilising both simulation data and real data. The simulation results verify the effectiveness of the method to identify the critical transmission lines in a modern power grid. Secondly, while modern networks constantly change in size, few studies have sought methods for the difficult task of optimising this growth. Here works of this thesis study theoretical requirements for augmenting networks by adding source or sink nodes, without requiring additional driver-nodes to accommodate the change i.e., conserving structural controllability. We determine the minimum number of nodes augmentable to arbitrary networks in parallel. Our "effective augmentation" algorithm takes advantage of clusters intrinsic to the network topology, and permits rapidly and efficient augmentation of a large number of nodes in one time-step. "Effective augmentation" is shown to work successfully on a wide range of model and real networks. The method has numerous applications (e.g. study of biological, social, power and technological networks) and potentially of significant practical and economic value. Finally, IEEE 118 bus and South-East Australia power networks are applied to investigate the feasibility of the proposed vulnerability analysis and network augmentation methods. First the power system complex network model is proposed. Then, with proposed vulnerability analysis method, vulnerable lines are identified. The simulation result shows that adding additional lines accordingly could potentially enhance the system robustness. Finally, effective augmentation method is feasible of maintaining the structural controllability of the network without requiring additional driver-nodes to accommodate the change.