Study of cascade failures of power grids

• Main Author: Ng, Jason Wei Long.
• Other Authors: Chong Han Joo Peter
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering; DRNTU::Engineering::Electrical and electronic engineering::Electric power::Production, transmission and distribution
• Online Access: http://hdl.handle.net/10356/53272
• Institution: Nanyang Technological University

The vulnerability of power grid is a key issue with large blackouts, causing power supply to be halted for millions. The complexity of power grid together with the excessive number of components made it difficult to be modeled. Complex networks have been the recent model that researchers adopted so as to study the power grid in greater detail. Making use of the ring network topology, the power grid is then modeled into a complex network. The substations and the transmission lines are denoted as the nodes and edges of the complex network respectively. The effects of three different attacks on the network are analyzed. Subsequent to this, three protection techniques were proposed to improve the robustness of the network. Simulations results have shown that the effects of the attack have a close relation to the tunable load variable α, which is also the load demand of the nodes/substations. In the event during the attack of the lowest nodes when all the nodes has α  0.6, the cascading failure would have greater cascading effect than attacking the highest load. The effects of the high and low load attacks are identical at α = 0.8 and only when α  1 then high load attack will cause a greater cascading failure. Among the three attacks, the attack on two nodes with an adjacent connecting node had caused the greatest cascading effect on the network. In order to create a realistic simulation, the network was simulated to have random load demands in contrast to previous simulation. The high and low load attacks were done on this network and the highest load attack was found to create a greater effect on this network. Three protections schemes were then introduced to each of these attacks to determine the influence and appropriateness they have imposed their effectiveness in protecting the network. The simulations had shown that Cascaded Load Cut-off(CLC) and Cascaded Load Overflow(CLO) are more effective in improving the robustness of the network than Adaptive-Cascaded Load Overflow(A-CLO) protection scheme. Even so, however, the CLC protection scheme is effective only at the expense of a certain percentage of the network without their power supply. Thus CLO protection scheme dominates all the rest of the protection scheme as the robustness of the network was improved with the right amount of load cut-off determined.