Matching Items (5)
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- All Subjects: Smart power grids
- Creators: Heydt, Gerald T
Description
The safety issue in an electrical power distribution system is of critical importance. In some circumstances, even the continuity of service has to be compromised for a situation that can cause a hazard to the public. A downed conductor that creates an electrical path between a current carrying conductor and ground pose a potential lethal hazard to anyone in the near proximity. Electric utilities have yet to find a fully accepted and reliable method for detecting downed conductors even with decades of research.
With the entry of more automation and a smarter grid in the different layers of distribution power system supply, new doors are being opened and new feasible solutions are waiting to be explored. The 'big data' and the infrastructures that are readily accessible through the smart metering system is the base of the work and analysis performed in this thesis. In effect, the new technologies and new solutions are an artifact of the Smart Grid effort which has now reached worldwide dimensions. A solution to problems of overhead distribution conductor failures / faults that use simple methods and that are easy to implement using existing and future distribution management systems is presented.
A European type distribution system using three phase supply is utilized as the test bed for the concepts presented. Fault analysis is performed on the primary and the secondary distribution system using the free downloadable software OpenDSS. The outcome is a set of rules that can be implemented either locally or central using a voltage based method. Utilized in the distribution management systems the operators will be given a powerful tool to make the correct action when a situation occurs. The test bed itself is taken from an actual system in Norway.
With the entry of more automation and a smarter grid in the different layers of distribution power system supply, new doors are being opened and new feasible solutions are waiting to be explored. The 'big data' and the infrastructures that are readily accessible through the smart metering system is the base of the work and analysis performed in this thesis. In effect, the new technologies and new solutions are an artifact of the Smart Grid effort which has now reached worldwide dimensions. A solution to problems of overhead distribution conductor failures / faults that use simple methods and that are easy to implement using existing and future distribution management systems is presented.
A European type distribution system using three phase supply is utilized as the test bed for the concepts presented. Fault analysis is performed on the primary and the secondary distribution system using the free downloadable software OpenDSS. The outcome is a set of rules that can be implemented either locally or central using a voltage based method. Utilized in the distribution management systems the operators will be given a powerful tool to make the correct action when a situation occurs. The test bed itself is taken from an actual system in Norway.
ContributorsAbusdal, Geir Magne (Author) / Heydt, Gerald T (Thesis advisor) / Ayyanar, Raja (Committee member) / Heydt, George (Committee member) / Arizona State University (Publisher)
Created2014
Description
The objective of this thesis is to detect certain cyber attacks in a power distribution ener-gy management system in a Smart Grid infrastructure. In the Smart Grid, signals are sent be-tween the distribution operator and the customer on a real-time basis. Signals are used for auto-mated energy management, protection and energy metering. This thesis aims at making use of various signals in the system to detect cyber attacks. The focus of the thesis is on a cyber attack that changes the parameters of the energy management system. The attacks considered change the set points, thresholds for energy management decisions, signal multipliers, and other digitally stored parameters that ultimately determine the transfer functions of the components. Since the distribution energy management system is assumed to be in a Smart Grid infrastructure, customer demand is elastic to the price of energy. The energy pricing is represented by a distribution loca-tional marginal price. A closed loop control system is utilized as representative of the energy management system. Each element of the system is represented by a linear transfer function. Studies are done via simulations and these simulations are performed in Matlab SimuLink. The analytical calculations are done using Matlab.
Signals from the system are used to obtain the frequency response of the component transfer functions. The magnitude and phase angle of the transfer functions are obtained using the fast Fourier transform. The transfer function phase angles of base cases (no attack) are stored and are compared with the phase angles calculated at regular time intervals. If the difference in the phase characteristics is greater than a set threshold, an alarm is issued indicating the detection of a cyber attack.
The developed algorithm is designed for use in the envisioned Future Renewable Electric Energy Delivery and Management (FREEDM) system. Examples are shown for the noise free and noisy cases.
Signals from the system are used to obtain the frequency response of the component transfer functions. The magnitude and phase angle of the transfer functions are obtained using the fast Fourier transform. The transfer function phase angles of base cases (no attack) are stored and are compared with the phase angles calculated at regular time intervals. If the difference in the phase characteristics is greater than a set threshold, an alarm is issued indicating the detection of a cyber attack.
The developed algorithm is designed for use in the envisioned Future Renewable Electric Energy Delivery and Management (FREEDM) system. Examples are shown for the noise free and noisy cases.
ContributorsRavi, Vaithinathan (Author) / Heydt, Gerald T (Thesis advisor) / Karady, George G. (Committee member) / Sankar, Lalitha (Committee member) / Arizona State University (Publisher)
Created2014
Description
In the deregulated power system, locational marginal prices are used in transmission engineering predominantly as near real-time pricing signals. This work extends this concept to distribution engineering so that a distribution class locational marginal price might be used for real-time pricing and control of advanced control systems in distribution circuits. A formulation for the distribution locational marginal price signal is presented that is based on power flow sensitivities in a distribution system. A Jacobian-based sensitivity analysis has been developed for application in the distribution pricing method. Increasing deployment of distributed energy sources is being seen at the distribution level and this trend is expected to continue. To facilitate an optimal use of the distributed infrastructure, the control of the energy demand on a feeder node in the distribution system has been formulated as a multiobjective optimization problem and a solution algorithm has been developed. In multiobjective problems the Pareto optimality criterion is generally applied, and commonly used solution algorithms are decision-based and heuristic. In contrast, a mathematically-robust technique called normal boundary intersection has been modeled for use in this work, and the control variable is solved via separable programming. The Roy Billinton Test System (RBTS) has predominantly been used to demonstrate the application of the formulation in distribution system control. A parallel processing environment has been used to replicate the distributed nature of controls at many points in the distribution system. Interactions between the real-time prices in a distribution feeder and the nodal prices at the aggregated load bus have been investigated. The application of the formulations in an islanded operating condition has also been demonstrated. The DLMP formulation has been validated using the test bed systems and a practical framework for its application in distribution engineering has been presented. The multiobjective optimization yields excellent results and is found to be robust for finer time resolutions. The work shown in this report is applicable to, and has been researched under the aegis of the Future Renewable Electric Energy Delivery and Management (FREEDM) center, which is a generation III National Science Foundation engineering research center headquartered at North Carolina State University.
ContributorsRanganathan Sathyanarayana, Bharadwaj (Author) / Heydt, Gerald T (Thesis advisor) / Vittal, Vijay (Committee member) / Ayyanar, Raja (Committee member) / Zhang, Junshan (Committee member) / Arizona State University (Publisher)
Created2012
Description
The Smart Grid initiative describes the collaborative effort to modernize the U.S. electric power infrastructure. Modernization efforts incorporate digital data and information technology to effectuate control, enhance reliability, encourage small customer sited distributed generation (DG), and better utilize assets. The Smart Grid environment is envisioned to include distributed generation, flexible and controllable loads, bidirectional communications using smart meters and other technologies. Sensory technology may be utilized as a tool that enhances operation including operation of the distribution system. Addressing this point, a distribution system state estimation algorithm is developed in this thesis. The state estimation algorithm developed here utilizes distribution system modeling techniques to calculate a vector of state variables for a given set of measurements. Measurements include active and reactive power flows, voltage and current magnitudes, phasor voltages with magnitude and angle information. The state estimator is envisioned as a tool embedded in distribution substation computers as part of distribution management systems (DMS); the estimator acts as a supervisory layer for a number of applications including automation (DA), energy management, control and switching. The distribution system state estimator is developed in full three-phase detail, and the effect of mutual coupling and single-phase laterals and loads on the solution is calculated. The network model comprises a full three-phase admittance matrix and a subset of equations that relates measurements to system states. Network equations and variables are represented in rectangular form. Thus a linear calculation procedure may be employed. When initialized to the vector of measured quantities and approximated non-metered load values, the calculation procedure is non-iterative. This dissertation presents background information used to develop the state estimation algorithm, considerations for distribution system modeling, and the formulation of the state estimator. Estimator performance for various power system test beds is investigated. Sample applications of the estimator to Smart Grid systems are presented. Applications include monitoring, enabling demand response (DR), voltage unbalance mitigation, and enhancing voltage control. Illustrations of these applications are shown. Also, examples of enhanced reliability and restoration using a sensory based automation infrastructure are shown.
ContributorsHaughton, Daniel Andrew (Author) / Heydt, Gerald T (Thesis advisor) / Vittal, Vijay (Committee member) / Ayyanar, Raja (Committee member) / Hedman, Kory W (Committee member) / Arizona State University (Publisher)
Created2012
Description
Optical Instrument Transformers (OIT) have been developed as an alternative to traditional instrument transformers (IT). The question "Can optical instrument transformers substitute for the traditional transformers?" is the main motivation of this study. Finding the answer for this question and developing complete models are the contributions of this work. Dedicated test facilities are developed so that the steady state and transient performances of analog outputs of a magnetic current transformer (CT) and a magnetic voltage transformer (VT) are compared with that of an optical current transformer (OCT) and an optical voltage transformer (OVT) respectively. Frequency response characteristics of OIT outputs are obtained. Comparison results show that OITs have a specified accuracy of 0.3% in all cases. They are linear, and DC offset does not saturate the systems. The OIT output signal has a 40~60 μs time delay, but this is typically less than the equivalent phase difference permitted by the IEEE and IEC standards for protection applications. Analog outputs have significantly higher bandwidths (adjustable to 20 to 40 kHz) than the IT. The digital output signal bandwidth (2.4 kHz) of an OCT is significantly lower than the analog signal bandwidth (20 kHz) due to the sampling rates involved. The OIT analog outputs may have significant white noise of 6%, but the white noise does not affect accuracy or protection performance. Temperatures up to 50oC do not adversely affect the performance of the OITs. Three types of models are developed for analog outputs: analog, digital, and complete models. Well-known mathematical methods, such as network synthesis and Jones calculus methods are applied. The developed models are compared with experiment results and are verified with simulation programs. Results show less than 1.5% for OCT and 2% for OVT difference and that the developed models can be used for power system simulations and the method used for the development can be used to develop models for all other brands of optical systems. The communication and data transfer between the all-digital protection systems is investigated by developing a test facility for all digital protection systems. Test results show that different manufacturers' relays and transformers based on the IEC standard can serve the power system successfully.
ContributorsKucuksari, Sadik (Author) / Karady, George G. (Thesis advisor) / Heydt, Gerald T (Committee member) / Holbert, Keith E. (Committee member) / Ayyanar, Raja (Committee member) / Farmer, Richard (Committee member) / Arizona State University (Publisher)
Created2010