Application of Advanced Early Warning Systems with Adaptive Protection

This project developed and field-tested two methods of Adaptive Protection systems utilizing synchrophasor data. One method detects conditions of system stress that can lead to unintended relay operation, and initiates a supervisory signal to modify relay response in real time to avoid false trips. The second method detects the possibility of false trips of impedance relays as stable system swings “encroach” on the relays’ impedance zones, and produces an early warning so that relay engineers can re-evaluate relay settings. In addition, real-time synchrophasor data produced by this project was used to develop advanced visualization techniques for display of synchrophasor data to utility operators and engineers

An Assessment of PIER Electric Grid Research 2003-2014 White Paper

This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of California’s California Institute for Energy and the Environment, from 2003-2014

Adaptive Protection and Control in Power System for Wide-Area Blackout Prevention

This paper presents a new approach in adaptive outof-step (OOS) protection settings in power system in real-time. The proposed method uses extended equal area criterion (EEAC) to determine the critical clearing time (CCT) and critical clearing angle (CCA) of the system, which are vital information for OOS protection setting calculation. The dynamic model parameters and the coherency groups of the system for EEAC analysis are determined in real time to ensure that the newly calculated settings suit with the prevalent system operating condition. The effectiveness of the method is demonstrated in a simulated data from 16-machine 68-bus system model

Electric System Vulnerabilities: a State of the Art of Defense Technologies

Vulnerability of the European electrical infrastructure appears to be growing due to several factors: - demand is always growing, and, although this growth may be forecast, it cannot be anytime easily faced; - transactions increase, following electrical system liberalisation, and this involves operating the whole infrastructure closer to the system capacity and security limits; - an increased control systems complexity, required for secure system operation, may in turn raise system vulnerability, due both to accidental faults and malicious attacks; - critical infrastructures, and the electrical system primarily, are well known to be a privileged target in warfare, as well as terrorist attacks. In recent years, both Europe and America have experienced a significant number of huge blackouts, whose frequency and impact looks progressively growing. These events had common roots in the fact that current risk assessment methodologies and current system controls appear to be no longer adequate. Beyond the growing complexity of the electrical system as a whole, two main reasons can be listed: - system analysis procedures based on these methodologies did not identify security threats emerging from failures of critical physical components; - on-line controls were not able to avoid system collapse. This report provides a state-of-the-art of the technology on both regards: - as far as risk assessment methodologies are concerned, an overview of the conceptual power system reliability framework is provided, and the current N-1 principle for risk assessment in power systems is introduced, together with off-the-shelf enforcement methodologies, like optimal power flow. Emerging methodologies for dynamic security assessment are also discussed. The power system reliability approach is compared with the global approach to dependability introduced by computer scientists, and the conceptual clashes pointed out. Ways ahead to conciliate both views are outlined. - concerning power system controls, the report overviews the existing defense plans, making specific reference to the current Italian situation. The two major recent blackout events in the American North East and Italy are analysed, and the drawbacks of the existing arrangements and the installed control systems are discussed. Emerging technologies, such as phasor measurement units and wide area protection are introduced. Their likely impact on the existing control room is discussed. Finally, potential cyber vulnerabilities of the new control systems are introduced, the role of communication standards in that context is discussed, and an overview of the current state of the art is presented.JRC.G.6-Sensors, radar technologies and cybersecurit

A New Solution for Improving Transmission Line Distance Protection Security During System-Wide Cascading Failures

Protection misoperation is responsible for a large portion of all cascading failures. These cascading failures can lead to blackouts that have tremendous social impacts. This dissertation proposes a new method that uses local distance relay instantaneous three-phase currents to enhance the security of distance protection of transmission lines during wide-area cascading events. The method incorporates advanced signal processing techniques and pattern recognition approaches to prevent zone 3 distance protection misoperation. Prevention of misoperation is done through three major stages. The first stage is fault detection. In this first stage, the proposed method merely recognizes that a fault exists somewhere in the transmission system. The second stage determines whether this fault is within the distance relay’s protective reach. The last stage detects whether this fault has been cleared. If the second stage determines that the fault is outside the zone 3 reach of the relay, a blocking signal will be sent to the relay to prevent operation even if the impedance falls within the operating characteristics of the relay. Alternatively, if the second stage determines that the fault is indeed within zone 3 protection reach of the relay, a permissive trip signal will be sent to the relay only if the third stage determines that the fault has not been cleared yet. The first and second stages use three different k-nearest neighbor classifiers that are trained using level 3 detail coefficients of discrete wavelet transform of the aerial mode currents. The third stage uses the current fundamental to detect fault clearing. Several wide area cascading scenarios were simulated, and various performance metrics were analyzed to study the effectiveness of the proposed methodology

Management of Islanded Operation of Microgirds

Distributed generations with continuously growing penetration levels offer potential solutions to energy security and reliability with minimum environmental impacts. Distributed Generations when connected to the area electric power systems provide numerous advantages. However, grid integration of distributed generations presents several technical challenges which has forced the systems planners and operators to account for the repercussions on the distribution feeders which are no longer passive in the presence of distributed generations. Grid integration of distributed generations requires accurate and reliable islanding detection methodology for secure system operation. Two distributed generation islanding detection methodologies are proposed in this dissertation. First, a passive islanding detection technique for grid-connected distributed generations based on parallel decision trees is proposed. The proposed approach relies on capturing the underlying signature of a wide variety of system events on a set of critical system parameters and utilizes multiple optimal decision tress in a parallel network for classification of system events. Second, a hybrid islanding detection method for grid-connected inverter based distributed generations combining decision trees and Sandia frequency shift method is also proposed. The proposed method combines passive and active islanding detection techniques to aggregate their individual advantages and reduce or eliminate their drawbacks. In smart grid paradigm, microgrids are the enabling engine for systematic integration of distributed generations with the utility grid. A systematic approach for controlled islanding of grid-connected microgrids is also proposed in this dissertation. The objective of the proposed approach is to develop an adaptive controlled islanding methodology to be implemented as a preventive control component in emergency control strategy for microgrid operations. An emergency power management strategy for microgrid autonomous operation subsequent to inadvertent islanding events is also proposed in this dissertation. The proposed approach integrates microgrid resources such as energy storage systems, demand response resources, and controllable micro-sources to layout a comprehensive power management strategy for ensuring secure and stable microgrid operation following an unplanned islanding event. In this dissertation, various case studies are presented to validate the proposed methods. The simulation results demonstrate the effectiveness of the proposed methodologies

Modeling and Experimental Verification of Adaptive 100% Stator Ground Fault Protection Schemes for Synchronous Generators

Salient pole synchronous generators as the main component of an electricity generation station should be carefully maintained and their operation has to be monitored such that any damage on them is avoided. Otherwise, the generating station might experience frequent shut downs which results in electricity generation interruptions and high costs associated with repairing and compensation of lack of energy. In this sense, many protective schemes focusing on a variety of synchronous generator faults have already been proposed and are still modified and developed to further enhance the quality of protection. In this thesis, synchronous generator stator windings to ground fault is studied as one of the most common and crucial faults in these machines. Numerous methods of stator winding to ground fault protection schemes are also reported in the literature. Third harmonic differential voltage and sub-harmonic schemes are studied in this research. A novel adaptive scheme for both methods is modelled and implemented in a comprehensive lab scale set-up where a real generation unit is scaled down including all different components and apparatus. The simulation model is also established based on simultaneous finite element analysis (FEA) and coupled magnetic circuit to assist with system configuration design and parameter selections. The adaptive scheme is proved to be capable of detecting stator windings to ground faults based on actual experimental data. Finally, the proposed adaptive scheme is compared against other available non-adaptive protection schemes currently used in industrial relays. Several important performance evaluation criteria in protection schemes such as sensitivity and security of operation referred to as reliability are considered. It is shown that the adaptive scheme offers higher reliability than other schemes which emphasizes its credibility and applicability

A survey on online monitoring approaches of computer-based systems

This report surveys forms of online data collection that are in current use (as well as being the subject of research to adapt them to changing technology and demands), and can be used as inputs to assessment of dependability and resilience, although they are not primarily meant for this use