Smart grid is the nexus of advanced Information and Communication Technologies (ICT) and legacy power systems. With increasing awareness on vulnerabilities of smart grids to cyber-attacks, cybersecurity is becoming a prime concern. Earlier, it was assumed that power system communication protocols are very specialized and different, so the security by obscurity approach would be sufficient. However, with the standardization of communication protocols for power utilities and emergence of power market, this approach is no longer valid. IEC 62351 standard has been published to provide security recommendations for different power system communication protocols including IEC 61850. Therefore, in this paper, a detail analysis of security threats, possible attacks and security requirements for IEC 61850 communication is presented. Building on this, the security considerations presented in IEC 62351 for securing different IEC 61850 messages such as GOOSE, SV, Routable-GOOSE (R-GOOSE), Routable-SV (R-SV) and Manufacturing MMS messages have been presented in detail.

This paper studies the system identification and robust control of a multi-input multi-output (MIMO) active magnetic bearing (AMB) system. The AMB system under study is open-loop unstable, and the presence of right-half plane zeros and the rotor flexible modes bring additional degrees of difficulty to the control design of such a system. First, a closed-loop system identification is performed using frequency-domain-response data of the system. Genetic-algorithm-based weighted least squares method is employed to obtain the best frequency-weighted model of the system. As the cross-coupling channels have negligible gains in the low-frequency region, it is assumed that the system can be diagonalized. This allows the analysis of the system as a family of low-order single-input single-output (SISO) subsystems. On the other hand, the effects caused by the coupling channels become more significant at higher frequencies. Therefore, a similar method is used to obtain a high-order MIMO model of the system by including the cross-coupling effects. Next, SISO H _∞ controllers and lead-lag-type compensators are designed on the basis of the SISO models of the systems. To strive for a better performance, MIMO H ₂ and HH _∞ optimal controllers are synthesized on the basis of the MIMO model of the system. Extensive experimental studies are conducted on the performance of the designed SISO and MIMO controllers in real time by taking into consideration both constant disturbances while the rotor is stationary and sinusoidal disturbances caused by the centrifugal forces and the rotor mass imbalance while the rotor is in rotation. Unlike the recently published works, it is shown that the accurate modeling of the system being controlled is the key to the successful design of high-performance stable controllers that not only guarantee the internal stability of the system-controller interconnection but also that no further modifications are required before the real-time implementation of the designed controllers.

IEC 61850 is one of the most prominent communication standards adopted by the smart grid community due to its high scalability, multi-vendor interoperability, and support for several input/output devices. Generic Object-Oriented Substation Events (GOOSE), which is a widely used communication protocol defined in IEC 61850, provides reliable and fast transmission of events for the electrical substation system. This paper investigates the security vulnerabilities of this protocol and analyzes the potential impact on the smart grid by rigorously analyzing the security of the GOOSE protocol using an automated process and identifying vulnerabilities in the context of smart grid communication. The vulnerabilities are tested using a real-time simulation and industry standard hardware-in-the-loop emulation. An in-depth experimental analysis is performed to demonstrate and verify the security weakness of the GOOSE publish-subscribe protocol towards the substation protection within the smart grid setup. It is observed that an adversary who might have familiarity with the substation network architecture can create falsified attack scenarios that can affect the physical operation of the power system. Extensive experiments using the real-time testbed validate the theoretical analysis, and the obtained experimental results prove that the GOOSE-based IEC 61850 compliant substation system is vulnerable to attacks from malicious intruders.