# Sohrab Asgarpoor

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Professor, Associate Chair and Undergraduate Advisor

- Ph.D., Texas A&M University, 1986
- M.S.E.E., Texas A&M University, 1981
- B.S.E.E., Texas A&M University, 1978

Areas of Research and Professional Interest

- Advanced computer applications in planning, design, and operation of electric power systems including distributed generation
- Mathematical modeling and simulation of power systems under uncertainty
- Impact of maintenance and equipment aging on system reliability
- Survivability and vulnerability assessment of energy infrastructure
- Monitoring, diagnostics, and control of electric power systems

- ELEC 121 - Introduction to Electrical Engineering
- ELEC 211 - Elements of Electrical Engineering I
- ELEC 215 - Electronics and Circuits I
- ELEC 216 - Electronics and Circuits II
- ELEC 305 - Probability Theory and Introduction to Random Processes
- ELEC 406/806 - Power Systems Analysis
- ELEC 407/807 - Power Systems Planning
- ELEC 410/810 - Multivariate Random Processes
- ELEC 438/838 - Introduction to Electric Power Engineering
- ELEC 454/854 - Power Systems Operation and Control
- ELEC 498/898 - Special Topics in Electrical Engineering IV
- ELEC 957 - Advanced Computer Methods in Power Systems Analysis
- ELEC 996 - Topics in Electrical Engineering

### About Sohrab Asgarpoor

Dr. Asgarpoor is the Associate Chair and Professor of Electrical Engineering. From 1985 to 1986, he worked as a lecturer in the Department of Electrical Engineering at Texas A&M University. In 1986, he joined ABB Network Management Technology Inc., Houston, Texas (formerly Ferranti International Controls Corp.) as a Senior Engineer, where he designed and developed advanced power system applications software for energy management systems. Since September of 1989, he has been with the University of Nebraska-Lincoln. His research involves mathematical modeling, simulation, optimization, and reliability evaluation of electric power and energy systems including Distributed Generation (DG) toward the goal of improved decision making under uncertainty.

### Experience

**Projects:**

- Optimum Maintenance Strategies for Maximizing the Availability of Wind Farms
- Modeling and Simulation of the Effects of Distributed Generation Dynamics on Distribution Systems
- Modeling and Simulation of Distributed Generation with Dynamic Load Conditions
- Reliability Modeling and Maintenance Optimization of Aging Substations
- Power System Studies Using Advanced Computer Software
- Expected Cost Penalty Due to Deviation from the Economic Dispatch for Interconnected Power Systems

### Selected Publications

- Power System Reliability and Optimization
- Wind Farm Availability and Optimal Maintenance
- Advanced Computer Modeling and Simulation
- Production Costing
- Risk Assessment

- Haifeng Ge, S. Asgarpoor, and J. Hou, “Aging equipment Maintainability Assessment for Management of Critical Utility Assets,” 2011 IEEE PES General Meeting, Detroit MI, July, 2011, 7 pages.
- Haifeng Ge and S. Asgarpoor, “Parallel Monte-Carlo Simulation for Reliability and Cost Evaluation of Equipment and Systems,” Electric Power Systems Research, Vol. 81, No. 2, February 2011, pp. 347-356.
- Salman Kahrobaee and S. Asgarpoor, “Short and Long-Term Reliability Assessment of Wind Farms,” Proceedings of 2010 North American Power Symposium, Arlington, TX, September 2010, 6 pages.
- H. Ge and S. Asgarpoor, “Reliability Evaluation of Equipment and Substations with Fuzzy Markov Processes,” IEEE Transactions on Power Systems, Vol. 25, No. 3, August 2010, pp. 1319-1328.
- Curtis L. Tomasevicz and S. Asgarpoor, “Optimum Maintenance Policy Using Semi-Markov Decision Processes,” Electric Power Systems Research, Vol. 79, No. 9, 2009, pp. 1286-1291.
- S. Asgarpoor and A. Azadmanesh, “Toward Reliable, Secure, and Survivable Cyber-Physical Energy Systems,” National Workshop on New Research Directions for Future Cyber-Physical Energy Systems, Baltimore, MD, June 2009.
- Baohua Dong, Sohrab Asgarpoor, and Wei Qiao, “Voltage Analysis of Distribution Systems with DFIG Wind Turbines,” Proceedings of IEEE Power Electronics and Machines in Wind Applications, Lincoln, NE, June 2009, 5 pages.
- Haifeng Ge and S. Asgarpoor, “Markov Processes with Fuzzy Parameters – A Case Study,” Proceedings of International Conference on Probabilistic Methods Applied to Power Systems, Rincon, Puerto Rico, May 2008, 6 pages.
- Haifeng Ge, Liqin Ni, and S. Asgarpoor, “Reliability-Based Stand-Alone Photovoltaic System Sizing Design – A Case Study” Proceedings of International Conference on Probabilistic Methods Applied to Power Systems, Rincon, Puerto Rico, May 2008, 8 pages.
- Haifeng Ge and S. Asgarpoor, “An Analytical Method for Optimum Maintenance of Substations,” Proceedings of the 2008 IEEE/PES Transmission and Distribution Conference and Exposition, Chicago, IL April 2008, pp. 1-6.
- Haifeng Ge, Curtis L. Tomasevicz, and S. Asgarpoor, “Optimum Maintenance Policy with Inspection by Semi-Markov Decision Processes,” Proceedings of the 2007 North American Power Symposium, Las Cruces, NM, September 2007, pp. 21-26.
- Curtis L. Tomasevicz and S. Asgarpoor, “Optimum Maintenance Policy Using Semi-Markov Decision Processes,” Proceedings of the 2006 North American Power Symposium, Carbondale, IL, September 2006, pp. 21-26.
- Curtis L. Tomasevicz and S. Asgarpoor, “Preventive Maintenance Using Continuous-Time Semi-Markov Processes,” Proceedings of the 2006 North American Power Symposium, Carbondale, IL, September 2006, pp. 3-8.
- G. K. Chan and S. Asgarpoor, “Optimum Maintenance Policy by Markov Processes,” Electric Power Systems Research, vol. 76, No. 6-7, April 2006, pp. 452-456.
- A. Jayakumar, S. Asgarpoor, “Maintenance Optimization of Equipment by Linear Programming,” Probability in the Engineering and Information Science, Vol. 20, No. 1, January 2006, pp. 183-193.
- X. Bai and S. Asgarpoor, “A Fuzzy-Based Approach to Substation Reliability Evaluation,” Electric Power Systems Research, Vol. 69, No. 2-3, May 2004, pp. 197-204.
- A. Jayakumar and S. Asgarpoor, “Maintenance Optimization of Equipment by Linear Programming”, Proceedings of International Conference on Probabilistic Methods Applied to Power Systems, Ames, IA, September 2004, pp. 145-149.
- J. McCalley, S. Asgarpoor, et. al. (IEEE/PES Task Force on Probabilistic Aspects of Reliability Criteria, J. McCalley, Chair), “Probabilistic Security Assessment for Power System”, Proceedings of 2004 IEEE PES General Meeting, Denver, CO, June 2004, pp. 212-220.
- A. Jayakumar and S. Asgarpoor, “A Markov Method for Optimum Preventive Maintenance of a Component”, The Third International Association of Science and Technology for Development (IASTED) Conference on Power and Energy Systems, Marbella, Spain, September 2003, Page 745-750.
- G. K. Chan and S. Asgarpoor, “Preventive Maintenance with Markov Processes,” Proceedings of the 2001 North American Power Symposium, College Station, TX, October 2001, pp. 510-515.
- X. Bai and S. Asgarpoor, “A Fuzzy-Analytical Technique for Substation Reliability Evaluation,” Proceedings of the 2001 North American Power Symposium, College Station, TX, October 2001, pp. 93-98.
- J. Endrenyi, S. Asgarpoor, et. al. (IEEE/PES Task Force on Impact of Maintenance Strategy on Reliability, J. Endrenyi, Chair), “The Present Status of Maintenance Strategies and the Impact of Maintenance on Reliability”, IEEE Transactions on Power Systems, Vol. 16, No. 4, pp. 638-646, November 2001.
- S. J. Benson and S. Asgarpoor, “A Fuzzy Expert System for Evaluation of Demand-Side Management Alternatives,” Electric Machines and Power Systems, Vol. 28, No. 8, pp. 749-760, August 2000.
- S. Narasimhan and S. Asgarpoor, “A Fuzzy-Based Approach for Generation System Reliability Evaluation,” Electric Power Systems Research, Vol. 53, No. 2, pp. 133-138, February 2000.
- S. Asgarpoor and M. Doghman,"A Maintenance Optimization Program for Utilities' Transmission and Distribution Systems, " Proceedings of the 1999 North American Power Symposium, San Luis Obispo, CA, October 1999, pp. 454-459.
- S. Asgarpoor and 5 others (Bibliography Task Force on Engineering Issues Associated with Transmission Access, J. D. McCalley, Chair, S. Asgarpoor, T. Gedra, M. Halpin, NK. Saini, and M. H. Schrameyer), “Second Bibliography on Transmission Access Issues,” IEEE Transactions on Power Systems, Vol. 12, No. 4, pp. 1654-1659, November 1997.
- S. Narasimhan and S. Asgarpoor, ``A Fuzzy-Based Approach for Generation System Reliability Evaluation,'' Proceedings of the 1997 North American Power Symposium, Laramie, WY, October 1997, pp. 301-306.
- S. J. Benson and S. Asgarpoor, ``Evaluating Demand-Side Management Alternatives Through the Use of a Fuzzy Expert System,'' Proceedings of the 59th American Power Conference, Chicago, IL, April 1997, pp. 1103-1108.
- S. Asgarpoor and M. J. Mathine, “Reliability Evaluation of Distribution Systems with Non-Exponential Down Times,” IEEE Transactions on Power Systems, Vol. 12, No. 2, pp.579-584, May 1997.
- S. Asgarpoor, S. J. Benson, and M. J. Mathine, “Transmission Constrained Production Costing Strategy for Optimal SO2 Compliance,” Electric Power Systems Research, Vol. 38, No. 3, pp. 239-244, September 1996.
- S. Asgarpoor and S. J. Benson, “A Production Costing Strategy for Optimal SO2 Compliance Using Monte Carlo Simulation,” Electric Power Systems Research, Vol. 37, No. 3, pp. 159-164, June 1996.
- S. Asgarpoor, ``Distribution System Reliability Evaluation with Fuzzy Data,'' Proceedings of the 58th American Power Conference, Chicago, IL, April 1996, pp. 1378-1382.
- S. Asgarpoor and 18 others (IEEE PES Task Force on Generator Data Pooling, A. M. Breipohl, Chair), “Pooling Generating Unit Data for Improved Estimates of Performance Indices,” IEEE Transactions on Power Systems, Vol. 10, No. 4, pp. 1912-1918, November 1995.
- S. Asgarpoor and M. J. Mathine, ``An Analytical Approach for Reliability Evaluation of Distribution Systems with Non-Exponential Down Times,'' Proceedings of the 1995 North American Power Symposium, Bozeman, MT, September 1995, pp. 561-566.
- S. Asgarpoor, ``Generation System Reliability Evaluation with Fuzzy Data,'' Proceedings of the 57th American Power Conference, Chicago, IL, April 1995, pp. 631-635.
- S. Asgarpoor and M. J. Mathine, “Distribution System Reliability Evaluation with Aging Equipment,” Electric Power Systems Research, Vol. 33, No. 2, pp. 133-137, May 1995.
- S. Asgarpoor and S. K. Panarelli, “Expected Cost Penalty Due to Deviation From Economic Dispatch for Interconnected Power Systems,” IEEE Transactions on Power Systems, Vol. 10, No. 1, pp. 441-447, February 1995.
- S. Asgarpoor and C. Singh, ``Methods for Detection of Equipment Aging and Incorporating it in the Reliability Analysis,'' NSF Symposium on Electric Power Systems Infrastructure, Pullman, WA, October 1994.
- S. Asgarpoor, ``Comparison of Linear, Non-Linear, and Network Flow Programming Techniques in Fuel Scheduling,'' Electric Power Systems Research, Vol. 30, No. 3, pp. 169-174, September 1994.
- S. Asgarpoor and M. J. Mathine, ``Reliability Evaluation of Distribution Systems Using Interval Mathematics Approach,'' Proceedings of the 1994 North American Power Symposium, Manhattan, KS, September 1994, pp. 270-277.
- S. Asgarpoor and M. J. Mathine1, ``Simulation of Substation Breaker Failure Using EMTP,'' EMTP Technical Notes, Issue # 94-3, Electrotek Concepts Inc., July 1994.
- S. Asgarpoor and D. T. Walter, ``Reliability Evaluation of Transmission Systems Using the Efficient Bounding Method,'' Proceedings of the 56th American Power Conference, Chicago, IL, April 1994.
- S. Asgarpoor and S. K. Panarelli, ``Generation System Cost Penalty by Monte-Carlo Simulation,'' Proceedings of the 24th North American Power Symposium, Reno, NV, October 1992, pp. 50-58.
- S. Asgarpoor and N. Gul, “Long Term Fuel Scheduling by Linear Programming,'' Proceedings of the 54th American Power Conference, Chicago, IL, April 1992, pp. 1090-1094.
- S. Asgarpoor and C. Singh, “A New Index for Generation Capacity Reliability Studies -- Expected Cost Penalty,” Electric Power Systems Research, Vol. 23, No. 1, pp. 23-29, January 1992.
- S. Asgarpoor, ``Calculation of Expected Cost Penalty for Multi--Area Power Systems,'' Proceedings of the 23rd North American Power Symposium, Carbondale, IL, October 1991, pp. 174-183.
- S. Asgarpoor and C. Singh, “An Analytical Technique for Bulk Power System Reliability Evaluation,”' Electric Power Systems Research, Vol. 20, No. 1, pp. 63-71, December 1990.
- S. Asgarpoor and C. Singh, ``A Tie--Set Approach for Multi--Area Reliability Evaluation,'' Proceedings of the 17th International Reliability, Availability, and Maintainability Conference for the Electric Power Industry, Hershey, PA, June 1990, pp. 125-130.
- C. Singh and S. Asgarpoor, “Reliability Evaluation of Flow Networks Using Delta-Star Transformations,”' IEEE Transactions on Reliability, Vol. R-35, pp. 472-477, 1986.
- C. Singh, S. Asgarpoor and A. D. Patton, “A Markov Method for Generating Capacity Reliability Evaluation Including Operating Considerations,”' International Journal of Electric Power and Energy Systems, Vol. 6, No. 3, pp. 161-168, July 1984.
- C. Singh and S. Asgarpoor, “Comparison of Mean Time to First Failure and Mean Up Time,” Microelectronics and Reliability, Vol. 23, No. 1, pp. 79-90, 1983.
- C. Singh and S. Asgarpoor, ``Comparative Study of Reliability Indices for a 2-Unit Standby System with Repair,'' Proceedings of the International Conference on Systems Theory and Applications, India, December 1981.

###### Research Publications:

- Optimum Maintenance Strategies for Maximizing the Availability of Wind Farms

The main goal of this project is to develop an analytical technique for repairable equipment such as wind turbines, and quantify the equipment maintenance rate by maximizing the availability of equipment. Also, reliability indices for wind power plants are calculated, and the impact of maintenance are determined. Moreover, risks associated with safety hazards at wind farms are quantified. Development of a knowledge-based maintenance management system will assist in proper and more cost-effective maintenance of various parts of a wind farm depending on a range of parameters such as operating temperature, lubricant viscosity, and turbine size. - Modeling and Simulation of the Effects of Distributed Generation Dynamics on Distribution Systems

The proposed research involved acquiring software (PSCAD/EMTDC) and DIgSILENT, and for developing suitable dynamic models and control parameters for proper operation of various DG types and determining the impact of existing DGs (different penetration levels), interaction with other types of DGs, and on the power distribution network. The proposed research has a strong engineering and mathematical components. It involves a mix of theoretical, computational, modeling & simulation, and software development to address practical future energy systems and education/training of graduate and undergraduate students. - Modeling and Simulation of Distributed Generation with Dynamic Load Conditions

In the first phase of the project, an algorithm for phase detection and frequency detection was developed and simulated using the Matlab® Simulink® program using a per unit system. In the second phase of project the synchronization algorithm was used with the bus considered as a continuous sinusoid (no engine or generator model). The third phase involved designing a circuit layout for each component and drawing, testing and validating circuit layout for each component in a PCB design software. The final phase of the project involved combining all the necessary parameters as input into a dedicated program which will evaluate the needs of the system. It will thereby determine which generator will be the best solution for each particular system. The program was designed and developed in Matlab/Simulink environment. - Reliability Modeling and Maintenance Optimization of Aging Substations

The main goals of this project are: 1) to create a theoretically defensible yet practical framework for repairable equipment such as breakers and transformer which are deteriorating with time in service in order to quantify and maximize their availability, 2) to develop and demonstrate algorithms which incorporate penalties/rewards associated with different levels of maintenance activities so that optimum maintenance policies and their associated costs can be determined. The proposed research will significantly contribute to the quantification of effectiveness of maintenance strategies on equipment availability and calculation of the cost/benefits associated with different strategies while considering the deterioration process and failure risk of the equipment. - Power System Studies Using Advanced Computer Software

The major objective of this project is to perform studies requested by a local utility which involve different operation and design scenarios. It is also a goal to provide power system engineers at electric utility with a better understanding of the capabilities of the software to be used: EMTP is a computer software for simulating and analyzing high-speed transients in electric power systems, Insulation Coordination Workstation is a computer software for performing the insulation coordination of a substation, HarmFlo+ is a computer software for performing harmonic studies. All of the aforementioned are EPRI software, and run on PC. - Expected Cost Penalty Due to Deviation from the Economic Dispatch for Interconnected Power Systems

The main goal of this project was to provide power system planners with a new index called “Expected Cost Penalty due to Deviation from the Economic Dispatch” for determining the adequacy of interconnected power systems in the event of equipment failures. The significance of this index is that it represents common events such as operating problems that can be observed over short periods (i.e., one or two years) rather than the rare events such as load curtailment which is currently used for reliability evaluation of power systems. The change in the average cost penalty can be observed while load levels, generation capacities, generation costs, tie line flow, and tie line/generating unit failure rates are varied. An analytical technique and a Monte Carlo simulation algorithm were developed to calculate this new index and to verify the results.