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UTSA PV Systems Integration Laboratory

Welcome to the homepage of PV Systems Integration Laboratory. Our research focuses on systems integration challenges associated with high penetration of solar into the power grid.

 

 

 

Research

Research Thrusts

Power Converters for utility-scale solar PV
Multi-level Power Converters
Control of multi-level and multi-port power converters
Real-time simulation of power electronics
Power Hardware in the Loop (PHIL) Simulations
Intra hour solar forecasting
Quasi-static time series analysis of distribution systems with PV

Research Projects
No. Year Funding Agency Amount Role
G-1 2016-17 U.S. Department of Defense (DoD) – Office of Naval Research (ONR) $280,410 PI
G-2 2013-16 U.S. Department of Energy (DOE) – EERE SunShot Initiative $750,000 PI
G-3 2013-14 City Public Service (CPS) Energy of San Antonio – Grid of the Future Initiative $172,262 Co-PI
G-4 2012-13 City Public Service (CPS) Energy of San Antonio – Utility-scale Solar Initiative $79,000 PI
G-5 2011-12 University of Texas at San Antonio – Seed Grant $100,000 PI
G-6 2013-16 Sun Edison $150,000 Co-PI
G-7 2010-11 City Public Service (CPS) Energy of San Antonio – Smart Grid Initiative $250,000 Co-PI
G-8 2010-12 Texas State Energy Conservation Office (SECO) $1,079,000 Co-PI
G-9 2010-13 University of Minnesota – DOE Education Consortium $25,000 PI
  Grand Total $2,605,262

Details of Research Projects

(G-1) Department of Defense – Office of Naval Research, “Acquisition of Real-Time Simulator for Intelligent Power Networks in Operational Energy Applications,” $280,410; Aug 2016 – Aug 2017

Abstract: This project proposes to acquire a real-time Power Hardware-in-the-Loop (PHIL) Simulator system that will enable research in intelligent, adaptive and reconfigurable power networks for mobile and fixed power installations to enhance DoD mission effectiveness.

(G-2) Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE) SunShot Initiative, “Diversity in Solar Talent Through Innovative Curriculum and Training: An Integrated Research and Education Approach Towards Creating Diversity and Advancing Utility-Scale Solar Technology,” $750,000; Sep. 2013 – Sep. 2016

Key contributions: The project developed an innovative electrical power conversion architecture using an N-port converter system that replaces the output 60Hz transformer with an integrated high-frequency low-weight solid-state transformer reducing power electronics and BOS costs to meet DOE SunShot goals. An integral part of this effort is to increase the diversity of students pursuing solar research, to enhance and expand the solar classroom experience and to provide extensive opportunities for solar research and internships with an expansive network of strategic partners present locally, regionally and nationally.

(G-3) City Public Service (CPS) Energy, San Antonio and the Texas Sustainable Energy Research Institute, UTSA, “Solar Forecasting,” $172,262, Feb 2013 to Feb 2014.

Key contributions: A novel, intelligent tool for predicting solar irradiance accurately in a short time frame (from second-ahead to up to 20 minutes-ahead) to help utilities integrate renewable energy resources into the grid more reliably, from meteorological and solar irradiance data. This project resulted in two patents on short-term solar forecasting. In addition, the project developed a sky-imager, named as Macroscope for accurate mapping of clouds on an utility-scale solar plant.

(G-4) City Public Service (CPS) Energy, San Antonio and the Texas Sustainable Energy Research Institute, UTSA, “Large Scale PV Penetration,” $79,000, Jan 2012 – Aug 2012

Key contribution: Developed several quasi-static time-series simulation models using openDSS, an open source Distribution System Simulator, to assess the impact of solar variability on the voltage profile of the distribution circuit.

(G-5) University of Texas at San Antonio Seed Grant, “Modeling Photo-voltaic systems with spatial and temporal variability for building and distribution grid integration studies,” $100,000, Sep. 2011 – Aug. 2012

Key contribution: Developed methods for integrating statistical analysis results and solar irradiance data in power system simulation software to model the effects on the distribution grid voltage. This seed funding and the resultant work on forecasting formed the basis towards funding from DOE (G-1) and CPS Energy (G-2).

(G-6) SunEdison, “UTSA-SunEdison R&D Collaboration on Cyber Security and Grid Integration,” $150,000, Jan. 2013 – Dec. 2016

Key contribution: Identified grid integration and cybersecurity research opportunities for large-scale PV power plants. Currently, the project is investigating the cyber vulnerabilities associated with smart inverters in utility-scale PV power plants.

(G-7) City Public Service (CPS) Energy, San Antonio and the Texas Sustainable Energy Research Institute, UTSA, “Distributed and Secure Smart Grid Network,” $250,000, Jan 2010 – May 2012

Key contribution: Developed a laboratory-scale distributed generation test bed that provides a basis for test, evaluation and modeling of distributed energy system components including performance of PV systems, inverter hardware and smart grid functionalities.

(G-8) State Energy Conservation Office (SECO), Texas, “Installation of Distributed Solar Energy Resources at UTSA campus with Sensor Network Monitoring and Control,” $1,080,000, Mar. 2010 – Dec. 2011

Key contribution: Designed and developed an innovative functional 170kW PV system specifically in the areas of power inverter, electrical configuration and sensors deployment that is saving energy costs and most importantly, is providing a research test-bed for solar research community at UTSA. In addition, developed the configuration of the high-resolution sensor network that allows the right data to be captured for effective monitoring and future solar resource assessment.

(G-9) University of Minnesota, Department of Energy (DOE) education Consortium, “A Nationwide Consortium of universities to revitalize electric power engineering education by state-of-the-art laboratories,” $25,000, Jul. 2010 – Jul. 2013

Key contribution: Dr. Krishnaswami, as an active member of the nationwide consortium has contributed to the development of new experiments on power electronics teaching laboratories in an effort to reform electric power engineering education nationwide.

Publications

Published in peer reviewed journals

  1. Duman, T.; Marti, S.; Moonem, M.A.; Abdul Kader, A.A.R.; Krishnaswami, H. A Modular Multilevel Converter with Power Mismatch Control for Grid-Connected Photovoltaic Systems. Energies 2017, 10, 698.
  2. Richardson, W.; Krishnaswami, H.; Vega, R.; Cervantes, M. A Low Cost, Edge Computing, All-Sky Imager for Cloud Tracking and Intra-Hour Irradiance Forecasting. Sustainability 2017, 9, 482.
  3. Moonem, M.A.; Pechacek, C.L.; Hernandez, R.; Krishnaswami, H. Analysis of a Multilevel Dual Active Bridge (ML-DAB) DC-DC Converter Using Symmetric Modulation. Electronics 2015, 4, 239-260.
  4. H. Krishnaswami, N. Mohan; “Three-Port Series-Resonant DC–DC Converter to Interface Renewable Energy Sources With Bidirectional Load and Energy Storage Ports,” Power Electronics, IEEE Transactions on, vol.24, no.10, pp. 2289-2297, Oct. 2009.
  5. H. Krishnaswami and V. Ramanarayanan; “Control of high frequency ac link electronic transformer,” IEE Proceedings in Electric Power Applications, vol. 152, no. 3, pp. 509-516, May 2005.

Refereed conference proceedings

  1. J. A. Ahamioje and H. Krishnaswami, “Interconnection study of distributed PV systems byinterfacing Matlab with OpenDSS and GIS,” Accepted for Publication in 2017 IEEE Photovoltaics Specialists Conference (PVSC).
  2. S. Marti and H. Krishnaswami, “Novel MPPT algorithm for active power control of multi-level dual-active bridge PV converter implemented in NI myRIO,” Accepted for Publication in 2017 IEEE Photovoltaics Specialists Conference (PVSC).
  3. W. Richardson, H. Krishnaswami, L. Shephard and R. Vega, “Machine Learning versus Ray- Tracing to Forecast Irradiance for an Edge-Computing SkyImager,” Accepted for Publication in 2017 Intelligent Systems Application to Power Systems (ISAP), USA.
  4. T. Duman, M.A. Moonem and H. Krishnaswami, “Capacitor Voltage balancing in a Neutral-point Clamped Multilevel dc-dc Dual Active Bridge Converter,” To be published in Proceedings of 2017 EEE 8th International Symposium on Power Electronics for Distributed Generation Systems (PEDG 2017).
  5. S. Marti and H. Krishnaswami, “Control algorithm for port power imbalance in two-stage, N-port modular multilevel cascaded photovoltaic inverters,” 2017 IEEE Texas Power and Energy Conference (TPEC), College Station, TX, 2017, pp. 1-6.
  6. S. Marti and H. Krishnaswami, “Sensorless real-time active power control of PV systems,” GEARED Workshop, Distributech 2017.
  7. T. Janssen and H. Krishnaswami, “Fault-tolerant control for a modular cascaded NPC Inverter Configuration,” Proceedings of 2016 IEEE 17th Workshop on Control and Modeling for Power Electronics, COMPEL Trondheim 2016.
  8. T. Janssen and H. Krishnaswami, “Voltage and current control of a multi-port NPC inverter configuration for a grid-connected photovoltaic system,” Proceedings of 2016 IEEE 17th Workshop on Control and Modeling for Power Electronics, COMPEL, Trondheim 2016.
  9. M. Cervantes, R. Vega, W. Richardson and H. Krishnaswami; “Utilization of Low Cost, Sky-Imaging Technology for Irradiance Forecasting of Distributed Solar Generation,” 2016 IEEE Green Technologies Conference (GreenTech), Kansas City, MO, 2016, pp. 142-146.
  10. Meghasai; Monger, S.; Vega, R.; Krishnaswami, H., “Simulation of smart functionalities of photovoltaic inverters by interfacing OpenDSS and Matlab,” in Control and Modeling for Power Electronics (COMPEL), 2015 IEEE 16th Workshop on, pp.1-6, 12-15 July 2015.
  11. S. Marti, R. Hernandez, H. Krishnaswami; “Implementation of Maximum Power Point Tracking Control Using NI myRIO-1900 for Multi-Level Dual-Active Bridge DC-DC Converter,” GEARED Workshop, North American Power Symposium, 4-6 October 2015.
  12. M.A. Moonem, T. Duman, H. Krishnaswami; “Capacitor Voltage balancing in a Neutral-point Clamped Multilevel dc-dc Dual Active Bridge Converter,” GEARED Workshop, North American Power Symposium, 4-6 October 2015.
  13. M.A. Moonem, T. Duman, H. Krishnaswami; “Power Converter Configuration with Integrated High-Frequency Transformer for High-Voltage Grid-Connected Large-Scale Photovoltaic System” Photovoltaic Specialists Conference (PVSC), 2014 IEEE, June 2014, Denver, CO, USA.
  14. M.A. Moonem, H. Krishnaswami; “Control and Configuration of Three-Level Dual-Active Bridge DC-DC Converter as a Front-End Interface for Photovoltaic System,” Applied Power Electronics Conference and Exposition (APEC), 2014 IEEE, pp.3017-3020, 16-20 March 2014,Dallas, TX, USA.
  15. J. Nummikoski, Y.S. Manjili, R. Vega and H. Krishnaswami; “Adaptive Rule Generation for Solar Forecasting: Interfacing with a Knowledge-Base Library,” Photovoltaic Specialists Conference (PVSC), 2013 IEEE, 16-21 June 2013, Tampa, FL, USA.
  16. M.A. Moonem, H. Krishnaswami; “Analysis and Control of Multi-level Dual Active Bridge DC-DC Converter,” Energy Conversion Congress and Exposition (ECCE), 2012 IEEE, pp.1556-1561, 16-20 Sept. 2012, Raleigh, NC, USA.
  17. M.A. Moonem, H. Krishnaswami; ” Analysis of Dual Active Bridge based Power Electronic Transformer as a Three-Phase Inverter,” Industrial Electronics Society Annual Conference (IECON), 2012 IEEE, pp. 237-242, 25-28 Oct. 2012, Montreal, Canada.
  18. E. Mohyedinbonab, E. Morales, H. Krishnaswami, M. Jamshidi; “Bi-directional Multi-Mode Grid-Tied Converter for Solar Energy Conversion Systems,” Proceedings of World Automation Conference, 2012, 24-28 June 2012, Puerto Vallarta, Mexico.
  19. Touseef F. Mohammed, H. Krishnaswami; “Voltage Profile Simulation using OpenDSS in High Penetration PV Scenario,” IEEE T&D Conference, Orlando, 2-10 May 2012, Orlando, FL, USA.
  20. H. Krishnaswami; “Photovoltaic microinverter using single-stage isolated high-frequency link series resonant topology,” Energy Conversion Congress and Exposition (ECCE), 2011 IEEE, pp.495-500, 17-22 Sept. 2011, Phoenix, AZ, USA.
  21. S.N. Vaishnav, H. Krishnaswami; “Single-stage isolated bi-directional converter topology using high frequency AC link for charging and V2G applications of PHEV,” Vehicle Power and Propulsion Conference (VPPC), 2011 IEEE, pp.1-4, 6-9 Sept.2011, Chicago, IL, USA.
  22. H. Krishnaswami, N. Mohan, “Constant switching frequency series resonant three-port bidirectional dc-dc converter,” in Proc. IEEE Power Electronics Specialists Conference (PESC’08), 2008, pp. 1640–1645, 15-19 June 2008, Rhodes, Greece
  23. H. Krishnaswami, N. Mohan, “Simulation model of a three-port bi-directional series resonant dcdc converter to determine component specifications,” in Proc. SCS Grand Challenges in Modeling and Simulation (GCMS’08), pp. 180-184, 16-19 June 2008, Edinburgh, Scotland
  24. H. Krishnaswami, N. Mohan, “A current-fed three-port bi-directional dc-dc converter,” in Proc. IEEE International Telecommunications Energy Conference (INTELEC’07), 2007, pp. 523–526, Sept. 20 – Oct 4, 2007, Rome, Italy.
  25. R. K. Gupta, H. Krishnaswami, N. Mohan, “A unified analysis of ccm boost pfc for various current control strategies,” in Proc. IEEE Power Electronics, Drives and Energy Systems (PEDES’06), 2006, pp. 1–5, New Delhi, India.

Patents

  1. J. Nummikoski, R. Vega and H. Krishnaswami, “A Novel Tool for Intra-hour Solar Forecasting,” Patent application filed by UTSA Office of Technology Commercialization on April 2015, Serial Number 61/977,834.
  2. M. Cervantes, R. Vega, W. Richardson and H. Krishnaswami, “Low-cost superimager to map, forecast and publish distributed solar energy predictions,” Patent application filed by UTSA Office of Technology Commercialization on June 2016, Serial Number 62/168,403.
  3. H. Krishnaswami and G. Shanmugavel, “Proximity detector and radiography system,” US Patent Number 6985556B2, January 2006

Invited/Non-refereed Presentations

H. Krishnaswami, “Advances in the Electric Power Engineering Curriculum at UTSA,” GridED Tech Transfer Workshop, Dallas, TX, April 2017.

H. Krishnaswami, UVIG workshop on variable generation forecasting applications to utility planning and operations, “Distributed Power Forecasting”, UVIG, Denver, CO. (February18, 2015).

H. Krishnaswami, “N-port converter architecture for large-scale PV plants,” US Department of Energy SunShot Summit and Peer Review, May 2014

H. Krishnaswami, “Reforming power related curriculum – power electronics,” ONR/NSF Sponsored Workshop on Electric Energy Systems Curriculum for Sustainability 2-5 Feb 2012, Napa, CA, USA.

G. Trevino, C. Fronda, B. Kelley, M. Jamshidi, H. Krishnaswami and L. Shephard, “Hi-Fi PV: Advanced Data Acquisition to Enable Solar Production Forecasting,” NI Week, August, 2012.

H. Krishnaswami, “Power Electronics Teaching Lab Implementation: Barriers and Solutions,” DOE Consortium Workshop, University of Minnesota, 8-9 Aug 2011, Minneapolis, MN, USA.