489 research outputs found
Resilient distributed control strategies in microgrids against cyber attacks
No full textMicrogrids rely on cyber networks in their monitoring and control systems. This poses significant challenges in terms of cybersecurity in microgrids. This chapter addresses this problem by the design of a resilient cooperative distributed control system for DC microgrids that are resilient to stealthy false data injection (FDI) cyberattacks, which adversely impact the data integrity of the control systems and the communication networks, while simultaneously remaining undetected by anomaly detection algorithms. The chapter also reviews some of the recent scientific contributions in the resilient control systems for DC microgrids and discusses some of the research challenges in this area
Stealth cyber attacks in microgrids: detectability and observability
No full textThis chapter discusses a cooperative mechanism for detecting potentially deceptive cyber attacks that attempt to disregard average voltage regulation and current sharing in cyber-physical microgrids. Considering a set of conventional cyber attacks, the detection becomes fairly easy for distributed observer-based techniques. However, a well-planned set of balanced attacks, termed as the stealth attack, can bypass the conventional observer-based detection theory as the control objectives are met without any physical errors involved. In this chapter, we discuss the formulation and associated scope of instability from stealth attacks to deceive distributed observers realizing the necessary and sufficient conditions to model such attacks. To address this issue, two disagreement indices (DIs) for each agent are introduced to detect potential threats to voltage and current, which accurately identify the attacked agent(s) under various scenarios. To facilitate detection under worst cases, the DIs from the secondary voltage control sublayer are strategically cross-coupled to the current sublayer, which ultimately disorient the control objectives in the presence of stealth attacks and provide a clear norm for triggering defense mechanisms. Finally, its performance is simulated under many potential threats on sensors and communication links
Synchronization Stability of Inverter Based Resources during Faults on Low Voltage Grids
No full textCyber security in power electronic systems
No full textGrid-connected power electronic converters are crucial technologies that allow the electrical grid to interface renewable energy sources, energy storage systems, electrical vehicles, microgrids, and high-voltage DC transmission lines. As the number of power electronic converters in modern grids continues to grow, their monitoring and coordinated grid-supportive services have become subjects of increased practical interest. Recent standards have also specified mandatory set of control parameters for grid-tied converters, which should be monitored by a remote entity that sends commands through a communication network. Although remote control capability enables numerous new control functions for grid-tied converters, it also makes them vulnerable to cyber attacks. Hence, this chapter aims to shed light on portions of the power electronic converter control systems, which are vulnerable to cyber attacks. Next, some of the prominent cyber attacks are overviewed by considering numerous grid-tied converter applications. Further, some of the common cyber attack detection and mitigation principles have been discussed in brief. Finally, this chapter is concluded with a summary and guidelines for further research in cyber security in power electronic systems.</p
Cyber Security for Microgrids
No full textMicrogrids use ICT to intelligently deliver energy and integrate clean generation. They can operate independently from a larger grid and can help to strengthen grid resilience. Applications include remote as well as urban areas, hospitals, and manufacturing complexes. Cybersecurity challenges arise, exposing the microgrids to cyber-attacks, possibly resulting in harm to infrastructure and to people. Research has classified attacks based on confidentiality, integrity, and availability, and most countermeasures focus on specific attacks or on protecting specific components. A global approach is needed combining solutions that can secure the entire system and respond in milliseconds. This reference work for researchers, in academia, industry and at grid operators as well as for students, provides an up-to-date framework for cybersecurity technologies and perspectives on operation, control, testbed and protection of microgrids from a system level perspective. Coverage includes the role of modern power electronics in active distribution networks, cyber-induced steady-state and dynamic issues, situational awareness of cyber-attacks, AI aided detection of data manipulation, cyber security threats in multi-agent microgrids, communication assisted protection, design and modeling of cyber-attacks for grid tied PV systems, stealth cyber-attacks, resilient distributed control, cyber-physical testbeds for smart grids and EV charging, and event-driven resiliency of microgrids against cyber-attacks. The book offers advanced cyber-attack detection strategies for microgrids to address breaches, counter attacks, deploy appropriate countermeasures, and stabilize microgrids under cyber-attacks
On the role of the helicity in the energy transfer in three-dimensional turbulence
No full textBehavior of the turbulent flows could be changed by changing the nature of the external force or the confining geometry which essentially results in breaking some of the symmetries of the ideal homogeneous and isotropic flows. In a numerical simulation, however, it is possible to selectively break symmetries of the Navier-Stokes equations with other constraints like helicity. In a recent [1] simulation of a decimated version of the incompressible three dimensional Navier-Stokes equations, where helicity was maintained sign-definite using a helical projection, a reversal of energy cascade similar to two-dimensional Navier-Stokes equations was observed. The sign- definite helicity breaks the parity symmetry of the flow. It is one of the important symmetries of the flow that contributes to the forward energy cascade in three dimensional Navier-Stokes equations. In our study we measure the degree to which the parity symmetry controls the direction of the cascade. We introduce a mechanism in which the parity is broken stochastically but in a time frozen manner with helical constraints. We keep triadic interactions in Fourier space involving modes with definite sign of helicity and decimate the triads of other modes with opposite sign of helicity with a fixed probability. We studied the cascade of energy in three dimensional turbulence by changing the relative weight between positive and negative helicity modes. We present the results from our recent simulations
Real-space Manifestations of Bottlenecks in Turbulence Spectra
No full textAn energy-spectrum bottleneck, a bump in the turbulence spectrum between the inertial and dissipation ranges, is shown to occur in the non-turbulent, one-dimensional, hyperviscous Burgers equation and found to be the Fourier-space signature of oscillations in the real-space velocity, which are explained by boundary-layer-expansion techniques. Pseudospectral simulations are used to show that such oscillations occur in velocity correlation functions in one- and three-dimensional hyperviscous hydrodynamical equations that display genuine turbulence
Spike Talk: Genesis and Neural Coding Scheme Translations
No full textAlthough digitalization of future power grids offer several coordination
incentives, the reliability and security of information and communication
technologies (ICT) hinders its overall performance. In this paper, we introduce
a novel architecture Spike Talk via a unified representation of power and
information as a means of data normalization using spikes for coordinated
control of microgrids. This grid-edge technology allows each distributed energy
resource (DER) to execute decentralized secondary control philosophy
independently by interacting among each other using power flow along the
tie-lines. Inspired from the field of computational neuroscience, Spike Talk
basically builds on a fine-grained parallelism on the information transfer
theory in our brains, particularly when neurons (modeled as DERs) transmit
information (inferred from power streams measurable at each DER) through
synapses (modeled as tie-lines). Not only does Spike Talk simplify and address
the current bottlenecks of the cyber-physical architectural operation by
dismissing the ICT layer, it provides intrinsic operational and cost-effective
opportunities in terms of infrastructure development, computations and
modeling. Hence, this paper provides a pedagogic illustration of the key
concepts and design theories. Since we focus on coordinated control of
microgrids in this paper, the signaling accuracy and system performance is
studied for several neural coding schemes responsible for converting the
real-valued local measurements into spikes
- …
