Walmir Freitas
Professor

UNICAMP/FEEC/DSEE
Av. Albert Einstein, no. 400
13083-852 - Campinas, SP, Brazil
Phone: +55 19 3521-3740
Fax: +55 19 3521-3866

walmir (you know what) unicamp . br

Short-Bio:

Dr. Freitas obtained the B.Sc. and M.Sc. degrees in Electrical Engineering from the Universidade Estadual Paulista (UNESP), in 1994 and 1996, respectively, and the Ph.D. degree in Electrical Engineering from the University of Campinas (UNICAMP), in 2001, Brazil. He worked as a Researcher Associate and a Visiting Professor at the University of Alberta, Canada, from 2002 to 2003, 2005 to 2006, 2011 to 2012 and, 2013 to 2014, and as a Visiting Professor at Ryerson University, Canada, from 2016 to 2017. Currently, he is a Professor at UNICAMP. In the last 15 years, Dr. Freitas has participated as principal investigator in more than 50 R&D projects for Brazilian, Canadian and Indian utilities and government agencies, published more than 50 journal papers and supervised more than 50 Ph.D and M.Sc. students. He is an Editor of the IEEE Transactions on Power Delivery and IEEE Power Engineering Letters. He is also the Chair of the IEEE Working Group on Power Quality Data Analytics. His main research interests are distribution systems, distributed generation, power quality and smart grids.

Researcher ID
Google Scholar
Scopus
Lattes (in Portuguese)

Books:

  1. Sato, Fujio; Freitas, Walmir; Análise de Curto-circuito e Princípios de Proteção em Sistemas de Energia Elétrica – Fundamentos e Prática (in Portuguese), Elsevier/Campus, 2015.

Journal papers:

  1. Torquato, R., Salles, D., Pereira, C. O., Meira, P. C. M., Freitas, W., "A Comprehensive Assessment of PV Hosting Capacity on Low Voltage Distribution Systems," IEEE Transactions on Power Delivery, v. 33, p. 1002-1012, 2018.

  2. Masteri, K., Venkatesh, B., Freitas, W.,  "A Fuzzy Optimization Model for Distribution System Asset Planning with Energy Storage," IEEE Transactions on Power Systems, v. 33, p. 5114-5123, 2018.

  3. Trindade, F., Ferreira, T. S. D., Lopes, M. G., Freitas, W., "Mitigation of Fast Voltage Variations During Cloud Transients in Distribution Systems with PV Solar Farms," IEEE Transactions on Power Delivery, v. 32, p. 921-932, 2017.

  4. Trindade, F., Freitas, W., "Low Voltage Zones to Support Fault Location in Distribution Systems with Smart Meters," IEEE Transactions on Smart Grid, v. 8, p. 2765-2774, 2017.

  5. Salles, D., Pinto, A. Freitas, W., "Integrated Volt/Var Control in Modern Distribution Power Systems based on Support Vector Machines," International Transactions on Electrical Energy Systems, v. 26, p. 2216-2229, 2016.

  6. Trindade, F., Vieira, J. C., Freitas, W., "Potential Solutions for Minimizing Voltage Sags Caused by DG Anti-Islanding Protection," IEEE Transactions on Power Delivery, v. 30, p. 2242-2251, 2015.

  7. Salles, D., Freitas, W., Vieira, J. C., Venkatesh, B., "A Practical Method for Nondetection Zone Estimation of Passive Anti-Islanding Schemes Applied to Synchronous Distributed Generators," IEEE Transactions on Power Delivery, v. 30, p. 2066-2076, 2015.

  8. Grilo, A.P., Salles, M.B.C., Trindade, F.C.L., Freitas, W., "An analytical insight into large-disturbance stability of doubly fed induction generators," Electric Power Systems Research, v. 122, p. 29-32, 2015.

  9. Borges, R. T., Shi, Q., Xu, W., Freitas, W., "Monte Carlo Simulation Platform for Studying Low Voltage Residential Networks," IEEE Transactions on Smart Grid, v. 5, no. 6, p. 2766-2776, 2014.

  10. Ayres, H. M., Salles, D., Freitas, W., “A Practical Second-Order Based Method for Power Losses Estimation in Distribution Systems With Distributed Generation," IEEE Transactions on Power Systems,v. 29, no. 2, p. 666-674, 2014.

  11. Trindade, F. C. L., Freitas, W., Vieira, J. C. M, “Fault Location in Distribution Systems Based on Smart Feeder Meters," IEEE Transactions on Power Delivery, v. 29, no. 1, p. 251-260, 2014.

  12. Lin, S., Correa, D. S., Freitas, W., Xu, W., "An Intelligent Control Strategy for Power Factor Compensation on Distorted Low Voltage Power Systems", IEEE Transactions on Smart Grid, v. 3, no. 3, p. 1562-1570, 2012.

  13. Hui, J., Freitas, W., Vieira, J. C. M, Yang, H., Liu, Y., "Utility Harmonic Impedance Measurement based on Data Selection", IEEE Transactions on Power Delivery, v. 27, no. 4, p. 2193-2202, 2012.

  14. Correa, D. S., Jiang, C., Xu, W., Freitas, W., Mazin, H. E., "Assessing the Collective Harmonic Impact of Modern Residential Loads Part I: Methodology", IEEE Transactions on Power Delivery, v. 27, no. 4, p. 1937-1946, 2012.

  15. Jiang, C., Correa, D. S., Xu, W., Freitas, W., "Assessing the Collective Harmonic Impact of Modern Residential Loads Part II: Applications", IEEE Transactions on Power Delivery, v. 27, no. 4, p. 1947-1955, 2012.

  16. Liang, X., Xu, W., Chung, C. Y., Freitas, W., Xiong, K., "Dynamic Load Models for Industrial Facilities", IEEE Transactions on Power Systems, v. 27, p. 69-80, 2012.

  17. Grilo, A.P., Meira, P.C.M., Vieira, J.C.M., Freitas, W., Bansal, R.C, "Analytical tools to assess the voltage stability of induction-based distributed generators", International Journal of Electrical Power & Energy Systems, v. 36, p. 31-39, 2012.

  18. Dong, M., Meira, P. C. M., Xu, W., Freitas, W., "An Event Window Based Load Monitoring Technique for Smart Meters", IEEE Transactions on Smart Grid, v. 3, p. 787-796, 2012.

  19. Salles, D., Freitas, W., Vieira, J. C. M., Xu, W., "Nondetection Index of Anti-Islanding Passive Protection of Synchronous Distributed Generators", IEEE Transactions on Power Delivery, v. 27, p. 1509-1518, 2012.

  20. Bagheri, P., Xu, W., Freitas, W., "A Resonant Tertiary Winding-Based Novel Air-Core Transformer Concept", IEEE Transactions on Power Delivery, v. 27, p. 1519-1528, 2012.

  21. Wang, X., Freitas, W., Xu, W., “Dynamic Non-Detection Zones of Positive Feedback Anti-Islanding Methods for Inverter-Based Distributed Generators”, IEEE Transactions on Power Delivery, v.26, p.1145 - 1155, 2011.

  22. Vieira, J. C.M., Salles, D., Freitas, W., “Power imbalance application region method for distributed synchronous generator anti-islanding protection design and evaluation”, Electric Power Systems Research, v.81, p.1952 - 1960, 2011.

  23. Wang, X., Yong, J., Xu, W., Freitas, W., “Practical Power Quality Charts for Motor Starting Assessment”, IEEE Transactions on Power Delivery, v.26, p.799 - 808, 2011.

  24. Ayres, H.M., Freitas, W., Almeida, M.C., Silva, L.C.P., "Method for determining the maximum allowable penetration level of distributed generation without steady-state voltage violations", IET Generation, Transmission & Distribution, v. 4, p. 495-508, 2010.

  25. Tazil, M., Kumar, V., Bansal, R.C., Kong, S., Dong, Z.Y., Freitas, W., "Three-phase doubly fed induction generators: an overview", IET Electric Power Applications, v. 4, p. 75-80, 2010.

  26. Wang, X., Freitas, W., Dinavahi, V., "Investigation of Positive Feedback Anti-Islanding Control for Multiple Inverter-Based Distributed Generators", IEEE Transactions on Power Systems, v. 24, p. 785-795, 2009.

  27. Wang, X., Freitas, W., "Influence of Voltage Positive Feedback Anti-Islanding Scheme on Inverter-Based Distributed Generator Stability", IEEE Transactions on Power Delivery, v. 24, p. 972-973, 2009.

  28. Nassif, A., Xu, W., Freitas, W., “An Investigation on the Selection of Filter Topologies for Passive Filter Applications", IEEE Transactions on Power Delivery, v. 24, p. 1710-1718, 2009.

  29. Grilo, A. P., Shargi, A., Freitas, W., "An Analytical Approach to Determine the Optimal Resistance for the Three-Series Resistor Method for Induction Generator Connection", IEEE Transactions on Energy Conversion, v. 23, p. 1111-1113, 2008.

  30. Vieira, J. C. M, Freitas, W., Xu, W., França, A. L. M., “An Investigation on the Non-Detection Zones of Synchronous Distributed Generation Anti-Islanding Protection”, IEEE Transactions on Power Delivery, v. 23, p. 593-600, 2008.

  31. Wang, X., Freitas, W., "Impact of Positive-Feedback Anti-Islanding Methods on Small-Signal Stability of Inverter-Based Distributed Generation", IEEE Transactions on Energy Conversion, v.23, p.923 - 931, 2008.

  32. Vieira, J. C. M, Correa, D. S., Freitas, W., França, A. L. M., "Um Método Prático para a Definição dos Ajustes de Relés Baseados em Medidas de Freqüência Usados para Detecção de Ilhamento de Geração Distribuída", Revista Controle & Automação - SBA. Sociedade Brasileira de Automática, v. 19, p. 199-213, 2008.

  33. Grilo, A. P., Mota, A. A., Mota, L. T. M., Freitas, W., “An Analytical Method for Analysis of Large-Disturbance Stability of Induction Generators”, IEEE Transactions on Power Systems, v. 22, p. 1861-1869, 2007.

  34. Vieira, J. C. M, Correa, D. S., Freitas, W., “Characteristics of Voltage Relays for Embedded Synchronous Generators Protection”, IET Generation, Transmission and Distribution, v.1, p.484 - 491, 2007.

  35. Wang, X., Freitas, W., Xu, W., Dinavahi, V., “Impact of DG Interface Controls on the Sandia Frequency Shift Antiislanding Method”, IEEE Transactions on Energy Conversion, v.22, p.792 - 794, 2007.

  36. Freitas, W., Xu, W., Huang, Z., Vieira, J. C. M, “Characteristics of Vector Surge Relays for Distributed Synchronous Generator Protection”, Electric Power Systems Research, v.77, p.170 - 180, 2007.

  37. Freitas, W., Zobaa, A. F, Vieira, J. C. M, “Control and Protection of Distribution Systems with Distributed Generators”, International Journal of Energy Technology and Policy, vol. 5, p. 533-549, 2007.

  38. Asada, E. N., Zobaa, A. F, Lázaro, R. A. R., Freitas, W., “Electric Power Systems Real-time Monitoring and Control”, International Journal of Energy Technology and Policy, v. 5, p. 651-657, 2007.

  39. Lázaro, R. A. R., Zobaa, A. F, Asada, E. N., Freitas, W., “Mathematical optimisation techniques applied to power system operation and planning”, International Journal of Energy Technology and Policy, v.5, p.393 - 403, 2007.

  40. Freitas, W., Asada, E. N., Zobaa, A. F, Hammons, T., Macconnach, J., “Policy and Economic Issues of Electrical Power and Energy Systems”, International Journal of Global Energy Issues, v.27, p.253 - 261, 2007.

  41. Freitas, W., Vieira, J. C. M, França, A. L. M., Silva, L. C. P., Costa, V., Lemos, F. A. B., “Comparative Analysis between Synchronous and Induction Machines for Distributed Generation Applications”, IEEE Transactions on Power Systems, v.21, p.301 - 311, 2006.

  42. Vieira, J. C. M, Freitas, W., Xu, W., França, A. L. M., “Efficient Coordination of ROCOF and Frequency Relays for Distributed Generation Protection by Using the Application Region”, IEEE Transactions on Power Delivery, v.21, p.1878 - 1884, 2006.

  43. Vieira, J. C. M, Freitas, W., Huang, Z., Xu, W., França, A. L. M., “Formulas for Predicting the Dynamic Performance of ROCOF Relays for Embedded Generation Applications”, IEE Proceedings - Generation, Transmission & Distribution, v.153, p.399 - 406, 2006.

  44. Vieira, J. C. M, Freitas, W., Xu, W., França, A. L. M., “Performance of Frequency Relays for Distributed Generation Protection”, IEEE Transactions on Power Delivery, v.21, p.1120 - 1127, 2006.

  45. Freitas, W., Huang, Z., Xu, W., “A Practical Method for Assessing the Effectiveness of Vector Surge Relays to Distributed Generation Applications”, IEEE Transactions on Power Delivery, v.20, p.57 - 63, 2005.

  46. Freitas, W., Vieira, J. C. M, França, A. L. M., Silva, L. C. P., Costa, V., “Análise Comparativa entre Geradores Síncronos e Geradores de Indução com Rotor tipo Gaiola de Esquilo para Aplicação em Geração Distribuída”, Revista Controle & Automação - SBA. Sociedade Brasileira de Automática, v.16, p.332 - 344, 2006.

  47. Freitas, W., Xu, W., Affonso, C. M., Huang, Z., “Comparative Analysis between ROCOF and Vector Surge Relays for Distributed Generation Applications”, IEEE Transactions on Power Delivery, v.20, p.1493 - 1501, 2005.

  48. Freitas, W., França, A. L. M., Sato, F., Xu, W., “Impacts of AC Generators and DSTATCOM Devices on the Dynamic Performance of Distribution Systems”, IEEE Transactions on Power Delivery, v.20, p.1493 - 1501, 2005.

  49. Freitas, W., Salles, M. B. C., Vieira, J. C. M, França, A. L. M., Silva, Luiz Carlos Pereira da, Costa, Vivaldo Fernando da, “Impacts of Dynamic Reactive Power Compensation Devices on the Performance of Wind Power Generators”, International Journal of Energy Technology and Policy, v.3, p.223 - 236, 2005.

  50. Freitas, W., Vieira, J. C. M, França, A. L. M., Xu, W., “Influence of Excitation Control Modes on the Allowable Penetration Level of Distributed Synchronous Generators”, IEEE Transactions on Energy Conversion, v.20, p.474 - 480, 2005.

  51. Freitas, W., Zobaa, A. F, Vieira, J. C. M, Macconnach, J., “Issues Related to the Operation of Wind Energy Conversion Systems”, International Journal of Energy Technology and Policy, v.3, p.313 - 323, 2005.

  52. Vieira, J. C. M, Freitas, W., França, A. L. M., “Análise Comparativa Sobre a Eficácia de Relés Baseados em Medidas de Freqüência para Detecção de Ilhamento de Geradores Distribuídos”, Revista Controle & Automação - SBA. Sociedade Brasileira de Automática, v.16, p.251 - 261, 2005.

  53. Freitas, W., França, A. L. M., “Modelagem e Análise Dinâmica de Dispositivos DSTATCOM Usando o SimPowerSystems para Matlab/Simulink”, Revista Controle & Automação - SBA. Sociedade Brasileira de Automática, v.16, p.187 - 199, 2005.

  54. Vieira, J. C. M, Correa, D. S., Freitas, W., Xu, W., “Performance Curves of Voltage Relays for Islanding Detection of Distributed Generators”, IEEE Transactions on Power Systems, v.20, p.1660 - 1662, 2005.

  55. Affonso, C. M., Freitas, W., Xu, W., Silva, L. C. P., “Performance of ROCOF Relays for Embedded Generation Applications”, IEE Proceedings - Generation, Transmission & Distribution, v.152, p.109 - 114, 2005.

  56. Freitas, W., Silva, L. C. P., França, A. L. M., “Small-Disturbance Voltage Stability of Distribution Systems with Induction Generators”, IEEE Transactions on Power Systems, v.20, p.1653 - 1654, 2005.

  57. Freitas, W., Xu, W., “False Operation of Vector Surge Relays”, IEEE Transactions on Power Delivery, v.19, p.436 - 438, 2004.

  58. Freitas, W., França, A. L. M., Xu, W., “Improvement of Induction Generator Stability Using Braking Resistors”, IEEE Transactions on Power Systems, v.19, p.1247 - 1249, 2004.

  59. Vieira, J. C. M, França, A. L. M., Freitas, W., “Phase-decoupled method for three-phase power flow analysis of unbalanced distribution systems”, IEE Proceedings. Generation, Transmission & Distribution, v.151, p.568 - 574, 2004.

  60. Freitas, W., França, A. L. M., “Improvement of Power System Transient Stability Based on Synchronous Generator Vector Control”, IEEE Power Engineering Review, v.20, p.64 - 66, 2000.

  61. Minussi, C. R., Freitas, W., “Sensitivity Analysis for Transient Stability Studies”, IEE Proceedings - Generation, Transmission & Distribution, v.145, p.669 - 674, 1998.

  62. Minussi, C. R., Freitas, W., “Uma Metodologia para o Controle de Segurança Dinâmica de Sistemas de Energia Elétrica”, Revista Controle & Automação - SBA. Sociedade Brasileira de Automática, v.9, p.65 - 76, 1998.

Conference papers:

(90+ papers - full list available here)


Current students/fellows:

PDFs:

  1. Tiago Rodarte Ricciardi
  2. Ricardo Torquato Borges

Ph.D. students:

  1. Andres de Jesus Arguello Guillen
  2. Vinicius Carnelossi da Cunha
  3. Caio Oriente Pereira
  4. Tiago de Moraes Barbosa
  5. José Carlos Garcia Andrade
  6. Thiago Correia Vieira

M.Sc. students:

  1. Tales Valias de Paiva
  2. Rafael Viviani Galdino
  3. Pedro Pereira Almeida
  4. Júlia Beatriz Ramos da Conceição
  5. Rafael Moya Rodrigues Pereira

Undergrad students:

  1. No current students

Past students/fellows:

PDFs:

  1. Diogo Salles Correa
  2. Paulo César Magalhães Meira
  3. Ahda Piokonski Grilo
  4. Fernanda Caseño Lima Trindade

Ph.D. students:

  1. Lívia Maria de Rezende Raggi
  2. Ricardo Torquato Borges
  3. Rafael Cuerda Monzani
  4. Tiago Rodarte Ricciardi
  5. Paulo César Magalhães Meira
  6. Newton José do Salles
  7. Fernanda Caseño Lima Trindade
  8. Diogo Salles Corrêa
  9. Hugo Murici Ayres
  10. Maurício Barbosa de Camargo Salles
  11. Ahda Pionkoski Grilo
  12. José Carlos de Melo Vieira Júnior

M.Sc. students:

  1. Andres de Jesus Arguello Guillen
  2. Caio Oriente Pereira
  3. Vinicius Carnelossi da Cunha
  4. Vitor Torquato Arioli
  5. Fábio Alexandre Martins Monteiro
  6. José Carlos Garcia Andrade
  7. Thiago Sonnewend Diniz Ferreira
  8. Adriano Costa Pinto
  9. Ricardo Torquato Borges
  10. Tiago de Moraes Barbosa
  11. Rafael Schincariol da Silva
  12. Esloany Daisy Carniatto Delvecchi
  13. Cecília de Freitas Morais
  14. Paulo César Magalhães Meira
  15. Tiago Rodarte Ricciardi
  16. Fernanda Caseño Lima Trindade
  17. Diogo Salles Correa
  18. Alexandre Haruiti Anzai
  19. Newton José de Salles
  20. Lísias Vieira Lima de Abreu
  21. Jesus Armando Moran Gallardo
  22. Maurício Barbosa de Camargo Salles

Undergrad students:

  1. Juliana Carvalho Silva de Sá
  2. Thiago Sonnewend Diniz Ferreira
  3. Anderson Cleyton Bravalheri
  4. Alexandre Ricardo Schwaida
  5. Mateus Gomes da Silva Tolentino Gonçalves
  6. David Carvalho
  7. Jonathan da Cruz Leão
  8. Diogo Salles Correa

Last update: Feb-19