| Smart Grid (SG) significantly improves the computing and communication capabilities of power systems. As a result, smart power generation, distribution, and protection are realized using more intelligent devices. These improvements provide many opportunities to better address issues in existing systems, such as cascading failures in traditional grids. Through the investigation of several large blackouts, malfunctional distance relays have been recognized as one of the critical causes of cascading failures. To deal with the false trips of relays and cascading failures, many monitoring and protecting methods have been proposed on traditional grids. However, many areas are still needed to be further investigated. In this dissertation, we focus on three issues related to SG protection. We first proposed an effective resource management scheme for agent-based remote relay protection. Second, we investigated cyber attacks on relay protection systems, analyzed their impacts, and explored how to mitigate these attacks. Third, we proposed a synchronized routing framework for real-time delivery of measurement and control data. We briefly introduce these three research areas in the following.;To protect remote relays from hidden failures, several agent-based protection schemes have been investigated. However, they do not consider the details in network resource management and different failure cases. We propose a set of resource allocation schemes to address the practical deployment issue of these protection schemes. Our results show that the basic agent-based protection consumes significant amounts of network resources and cannot effectively support many new SG applications, and is unable to deal with communication link failures. We further improve the proposed basic scheme, and develop backup schemes to handle network failures. Furthermore, when utilizing power system knowledge, we can make the resource allocation more efficient. Our evaluation shows that our proposed schemes can use less network resources while achieving the required system reliability. Moreover, we also investigate Peer-to-Peer (P2P) agent protection schemes. We propose an effective resource management scheme and a backup scheme in the P2P mode. The results show that P2P v protection can fulfill the reliability requirement using less resources.;It is well known that the reliability of power systems is a difficult challenge. To address this problem, basic agent-based protection and agent-reputation-based protection are developed for future smart grid to enhance the reliability of relay protection. While effective in many situations, these schemes may be exploited by malicious attackers to disrupt the power system, or even trigger cascading failures in the system. Unlike occasional faulty behaviors, cyber attacks deliberately target various components in power systems, which cannot be resolved from the perspective of device reliability. Currently there is limited work on how such attacks are carried out, and to what degree damage can be achieved. The goal of our research is to better understand the problem, by examining the potential methods to attack the relay protection system, and evaluating their effectiveness. We also explore how to mitigate potential cascading failure damage due to cyber attacks.;As the accurate measurement and sampling of system states are the foundation of SG monitoring and protection applications, we develop a synchronized framework to achieve predictable delivery for large-scale real-time applications. With the synchronized time as a global reference, we design the synchronized routing framework and evaluate its effectiveness with different packet scheduling schemes. The results show that we can adjust service order of packets according to their urgency. Compared with existing packet scheduling schemes, by using both upstream and downstream delay information, the proposed method has a larger adjustable range, and achieves much better efficiency and predictability.;In summary, we have explored remote relate protection, relay cyber security, and realtime communication related problems in SG, and proposed several solutions, including network resource management, analysis and defense of attacks on smart relays, and synchronized real-time packet delivery. Our future work will focus on more detailed issues within each problem, such as advanced agent-protection structure, refined attack and defense strategies, and improved measurement accuracy of network delays. |
