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ACDC Transient is an independent consulting company specialized in HVDC and grid integration of renewable energy systems.

Our mission is to facilitate the clean energy transition. Leveraging our expertise, we provide cutting edge solutions across all project phases, including engineering, design, and operation. We offer support for system studies, grid code compliance, and tailored training for your team.

At ACDC, we are dedicated to maintaining confidentiality with unwavering integrity.

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Senior Expert to support you


Hani Saad 

  • B.Sc. and Ph.D. degrees in electrical power engineering from the Polytechnique of Montréal, Canada 

    • 2008: Award of Excellence “Profil de Vinci” from Polytechnic of Montreal

    • 2014: Winner of the French IEEE PES for Ph.D. students

    • 2015: Best Ph.D. thesis of Polytechnic of Montreal

  • 11 years at RTE (French TSO)

  • 5 years at RTE-International

  • Involved in the world’s largest HVDC-VSC systems, EMT studies and grid code compliance for the integration of renewable resources

  • 2022: French representative for CIGRE National Committee B4 - DC systems and Power Electronics

  • Involved in international expert groups such as IEEE task forces, ENTSOE EG and CIGRE

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Modern power transmission systems, incorporating HVDC links and renewable energy sources like wind farms, battery energy storage systems (BESS), and photovoltaics, rely on advanced AC/DC power electronics for grid integration. These technologies have revolutionized energy transition, replacing conventional synchronous generators with renewable sources, and enhancing grid reliability and flexibility. However, optimizing and ensuring the safe operation of such cutting-edge systems demands technical expertise.

ACDC Transient is well connected across the key industries and universities through its founder network. In case time or knowledge is limiting Hani acting as technical expert, ACDC Transient can potentially associate with other parties. 



This service covers EMT (or dynamic) simulations that we can perform or support you for :  

  • Grid code compliance of renewable power installation such as: wind farm, battery energy storage system (BESS) and photovoltaic.

  • Network interaction studies such as control interactions between several power electronic installations or sub-synchronous torsional interactions (SSTI) with conventional generators.

  • Dynamic behavior related to HVDC link and renewable resources: Dynamic performance, overvoltage, black start, Grid Forming, harmonic, transient stress, TRV, transformer magnetisation, ferroresonnance, reactive power and voltage support, frequency response, fault ride through (FRT) performance, transformer and AC cable energization, short current stress, multiterminal DC grid, etc.

  • R&D activities in the field of multi-terminal DC grid, new converter topologies and new ancillary services.


This service covers the technical support at each project phases  of HVDC and renewable energy systems:  

  • Provide technical support for specifications during planning and tender stages

  • System design and system testing review : Grid code compliance, insulation coordination, dynamic performance, EMT and RMS model validation, harmonic studies, control and protection, transient stability, TOV, frequency response, valve type test, FAT, commissioning, etc.

  • Technical support to analysis onsite events : such as equipment damage, HVDC link or renewable resources trip due to different electrotechnical phenomena such as fault events, resonances, inadvertent ac breaker opening, overcurrent, etc.



​This service covers model development in EMT tools for offline and real-time simulations :

  • Develop a realistic generic HVDC and renewable resources models for system studies such as: AC fault performances, grid forming studies, etc.

  • Develop Transmission network in EMT tools that includes loads, lines, cables, transformers, etc.

  • Develop multi-terminal DC grid systems in EMT tools that includes, MMC stations, offshore wind farms, DC cable/overhead lines, etc.

  • Models transcription from one software to another (EMTP, PSCAD, Matlab-Simulink, Hypersim, RT-Lab) of manufacturer's black-boxed or white-boxed models.

  • Provide costumer support for EMT model development and model validation with field test.


Based on its deep theoretical knowledge and vast experience in real projects, ACDC Transient offers private training tailored for your technical teams & engineers in the field of HVDC-VSC systems, renewable resource systems and EMTP software.

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Corporate Social Responsibility (CSR)

As a corporate citizen, not only our mission focuses on supporting the renewable energy transition, but we are also committed to societal goals to support the well-being of our community. For each service provided, ACDC Transient will donate a portion of our income to fund associations we believe in. 
Our goal is not to be the best in the world, but to be better for the world by continuously improving it. This road is endless!


Electriciens sans frontières, French international NGO and registered charity, has been fighting since 1986 against inequalities of access to electricity and water throughout the world. With the support of our 1200 volunteers and through partnerships with local actors and using renewable energies, we make access to electricity a lever for human and economic development.



À Bras Ouverts or ABO is a French association founded in 1986 by Tugdual Derville. It organizes the reception by volunteer guides of children, adolescents and young adults with a disability, for weekends or holiday stays.

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Hani is involved in more than 50 journal and conference papers as first author or co-author. Her below you can find a list of selected publications

Book :

  • H. Saad, S. Dennetière, J. Mahseredjian, et al “Simulation of Transients for VSC-HVDC Transmission Systems Based on Modular Multilevel Converters”, in Transient Analysis of Power Systems: Solution Techniques, Tools and Applications. Wiley-IEEE Press, Jan 2015

Cigré brochure :

  • B4.70, TB 832 “Guide for Electromagnetic Transient Studies involving VSC converters”, 2021

  • B4-67, TB 754 “AC side harmonics and appropriate harmonic limits for VSC HVDC”, 2019

  • B4 TF-77 "AC Fault response options for VSC HVDC Converters" 2019

  • B4-57, TB 604 “Guide for the Development of Models for HVDC Converters in a HVDC Grid”, 2014

Technical report :

Journal papers :

H. Saad, P. Rault, M. Goertz, and S. Wenig. "Parameter sensitivity analysis on DC transients between MMC station and cable" Electric Power Systems Research (EPSR), 2021, Vol: 196: 107277. H. Saad, Y. Fillion, S. Deschanvres, Y. Vernay and S. Dennetière, "On Resonances and Harmonics in HVDC-MMC Station Connected to AC Grid," in IEEE Transactions on Power Delivery, vol. 32, no. 3, pp. 1565-1573, June 2017 H. Saad, P. Rault, S. Dennetiere, “Study on transient overvoltages in converter station of MMC‐HVDC links” Electric Power Systems Research (EPSR), 2018, Vol: 160, Page: 397‐403. U. Karaagac, J. Mahseredjian, R. Gagnon, H. Gras, H. Saad et al., "A Generic EMT-Type Model for Wind Parks With Permanent Magnet Synchronous Generator Full Size Converter Wind Turbines," in IEEE Power and Energy Technology Systems Journal, vol. 6, no. 3, pp. 131-141, Sept. 2019. D. Jovcic, W. Lin, S. Nguefeu and H. Saad, "Low-Energy Protection System for DC Grids Based on Full-Bridge MMC Converters," in IEEE Transactions on Power Delivery, vol. 33, no. 4, pp. 1934-1943, Aug. 2018. F. Mohammadi, K. Rouzbehi, M. Hajian, K. Niayesh, H. Saad et al “HVDC circuit breakers: a comprehensive review” IEEE Transactions on Power Electronics. 2021 Apr 19. P. Rault, S. Dennetière, H. Saad, M. Yazdani, C. Wikström, N. Johannesson, “Real-time simulation with an industrial DCCB controller in a HVDC grid” Electric Power Systems Research. (EPSR) 189. 106593. 10.1016 U. Karaagac, J. Mahseredjian, L. Cai and H. Saad, "Offshore Wind Farm Modeling Accuracy and Efficiency in MMC-Based Multiterminal HVDC Connection," in IEEE Transactions on Power Delivery, vol. 32, no. 2, pp. 617-627, April 2017, doi: 10.1109/TPWRD.2016.2522562. J. Freytes, G. Bergna, J. Suul S. D’Arco, H. Saad et al., "Improving Small-Signal Stability of an MMC With CCSC by Control of the Internally Stored Energy," in IEEE Transactions on Power Delivery, vol. 33, no. 1, pp. 429-439, Feb. 2018 T. Ould-Bachir, H. Saad, S. Dennetièreand J. Mahseredjian, "CPU/FPGA-Based Real-Time Simulation of a Two-Terminal MMC-HVDC System," inIEEE Transactions on Power Delivery, vol. 32, no. 2, pp. 647-655, April 2017 Lin, Weixing & Jovcic, D. & Nguefeu, Samuel & Saad, Hani. (2016). Modelling of high-power hybrid DC circuit breaker for grid-level studies. IET Power Electronics. 9. 10.1049/iet-pel.2015.0518. H. Saad, J. Mahseredjian, S. Dennetière, S. Nguefeu "Interactions studies of HVDC–MMC link embedded in an AC grid" Electric Power Systems Research (EPSR). 2016 Sep 1;138:202-9. H. Saad, X. Guillaud, J. Mahseredjian, S. Dennetière and S. Nguefeu, "MMC Capacitor Voltage Decoupling and Balancing Controls," in IEEE Transactions on Power Delivery, vol. 30, no. 2, pp. 704-712, April 2015 H. Saad, S. Dennetière, Mahseredjian, et al, "Modular Multilevel Converter Models for Electromagnetic Transients," IEEE Transactions on Power Delivery, vol. 29, no. 3, pp. 1481-1489, June 2014. H. Saad, J. Peralta, S. Dennetière, J. Mahseredjian, J. Jatskevich, J. A. Martinez et al., "Dynamic Averaged and Simplified Models for MMC-Based HVDC Transmission Systems," in IEEE Transactions on Power Delivery, vol. 28, no. 3, pp. 1723-1730, July 2013 H. Saad, T. Ould-Bachir, J. Mahseredjian, C. Dufour, S Dennetière, S. Nguefeu “Real-time simulation of MMCs using CPU and FPGA.” IEEE Transactions on Power Electronics, 2013, vol. 30, no 1, p. 259-267 J. Peralta, H. Saad, S. Dennetière, J. Mahseredjian, S. Nguefeu, “Detailed and averaged models for a 401-level MMC-HVDC system,” IEEE Trans. on Power Delivery, vol. 27, no. 3, pp. 1501-1508, July 2012

Conference papers :

H. Saad, V. Rudan, F. Pezet, L Gagneur, Y. Vernay, S. Subrin, J. Dargot, H. Tourmihine, M. Duchaux, M. Aguado, P. Nguyen, G. Postiglione “Experience of Black Start Test using BESS in Grid Forming Operation to Energize Islanded System including a Wind Farm,” Cigre International Symposium Kyoto, Japan, 3-8 April 2022 H. Saad, M. Vor Dem Berge, B. Marshall, O. D. Adeuyi, and R. Pabat-Stroe. "Dynamic studies on HVDC-OWF systems - Impact of WTG on HVDC performances." 17th International Conference on AC and DC Power Transmission (ACDC 2021), 2021 p. 102 – 107 G. Torresan, H. Saad, V. Gomes. and P. Gartmann “2021, September. Study on the impact of fault current injection in a wind power plant using EMT-type tool” In 20th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power Plants (WIW 2021) (Vol. 2021, pp. 449-456). IET. H. Saad, P. Rault and S. Dennetière, "Investigation on parallel operation of two MMC-HVDC links in grid forming connected to an existing network," 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe), 2020, pp. P.1-P.10 S. Dennetiere, P. Rault, H. Saad, K. Sharifabadi, J. H. Johansson N. Krajisnik, ”Technical solutions to predict and mitigate inadvertent interaction of two parallel connected VSC-HVDC schemes feeding an islanded offshore Oil and Gas grid” CIGRÉ Session Papers & Proceedings, 2020, Paris, France. A. Petit, J. Michel, H Saad, G.Torresan, C.Faure-Llorens, Y.Vernay “System Studies on the French Network Including HVDC stations and using the Real time Simulation” CIGRE Conference, Paris, France, Aug. 2020 H. Saad, S. Dennetiere, P. Rault, " AC Fault dynamic studies of islanded grid including HVDC links operating in UF-control " 14th IET International Conference on AC and DC Power Transmission (ACDC 2019), 2019 H. Saad and S. Dennetière, "Study on TOV after Fault Recovery in VSC based HVDC systems," 2019 IEEE Milan PowerTech, 2019, pp. 1-6 M. Saltzer, M. Goertz, S. Wenig, W. Leterme, V. Joubert, H. Saad et. al. “Overvoltages in Symmetric Monopolar HVDC Cable Systems - a Parameter Study Approach,” CIGRE Symposium Aalborg, paper no. 134, Aalborg, Denmark, June 2019. S. Aparicio, A. Pizzini, H. Saad, S. Deschanvres " Switching overvoltages studies for Live Working on the Uruguayan 500 kV transmission network" IPST 2019 Conference, Perpignan, France. 2019 S. Beckler, H. Saad , P. Rault, S. Dennetiere “On Dynamic Performance Analysis for MMC-HVDC Systems during AC faults,” CIGRE Symposium Aalborg, Aalborg, Denmark, June 2019 S. Dennetière, H. Saad, “Validation of MMC station real-time models with field tests” CIGRÉ B4 Colloquium, Winnipeg, Canada, September 30 –October 6, 2017 D. Jovcic, W. Lin, S. Nguefeu and H. Saad, "Full bridge MMC converter controller for HVDC operation in normal and DC fault conditions," 2017 International Symposium on Power Electronics, 2017, pp. 1-6, doi: 10.1109/PEE.2017.8171662. J. Freytes, G. Bergna, J. Are Suul, S. D'Arco, H. Saad and X. Guillaud, "State-space modelling with steady-state time invariant representation of energy based controllers for modular multilevel converters," 2017 IEEE Manchester PowerTech, 2017, pp. 1-7. W. Lin, D. Jovcic, S. Nguefeu and H. Saad, "Protection of full bridge MMC DC grid employing mechanical DC circuit breakers," 2017 IEEE Power & Energy Society General Meeting, 2017, pp. 1-5, doi: 10.1109/PESGM.2017.8274130. H. Saad, A. Schwob and Y. Vernay, "Study of Resonance Issues Between HVDC Link and Power System Components Using EMT Simulations," 2018 Power Systems Computation Conference (PSCC), Dublin, 2018, pp. 1-8 H. Saad, Y. Vernay, S. Dennetière, P. Rault, B. Clerc “System Dynamic Studies of Power Electronics Devices with Real-Time Simulation -A TSO operational experience” CIGRE Conference, Paris, France, Aug. 2018 M. Saltzer, M. Nguyen-Tuan, A. Crippa, S. Wenig, M. Goertz and H. Saad “Surge and extended overvoltage testing of HVDC cable systems”, Int. Conf. Insulated Power Cables, Dunkerque, France, Nov. 2017, JICABLE-HVDC 17, S3.3. H. Saad, S. Dennetière and B. Clerc, "Interaction investigations between power electronics devices embedded in HVAC network," 13th IET International Conference on AC and DC Power Transmission (ACDC 2017), Manchester, 2017, pp. 1-7 Stepanov, H. Saad, J. Mahseredjian, and A. Watare, "Overview of Generic HVDC-MMC Control under Unbalanced Grid Conditions," International Conference on Power Systems Transients (IPST 2017), Seoul, South Korea, 2017 Stepanov, Anton, Hani Saad, Jean Mahseredjian, and Aurélien Wataré. "Overview of generic HVDC-MMC control under unbalanced grid conditions." IPST 2017 Conference, Seoul, Korea. 2017 Saad H, Dennetiere S, Lallemand C, Clerc B, Vernay Y. "Commissioning of the France Spain HVDC VSC control system replicas.". CIGRE-IEC Colloquium 2016 May 9, Montreal, Canada pp. 1-8 Y. Vernay, C. Martin, D. Petesch, S. Dennetière, “Hardware in the loop simulations to test SVC performances on the French Grid,” in IPST 2015, International Conf. on Power Systems Transients, Cavtat, Croatia, June 15-18, 2015 S. Dennetière, H. Saad, A. Naud, P. Hondaa, “Transients on DC cables connected to VSC converters” Jicable'15 - Versailles 21-25 June, 2015 M. M. Belhaouane, H. Saad, G. Guillaud, J. Mahseredjian, “ Control and Performance of Modular Multilevel Converters using Resonant Controller,” IECON 2014 - 40th Annual Conference on IEEE Industrial Electronics Society, Dallas, USA, Oct. 29 – Nov. 1, 2014 C. Dufour, H. Saad, J. Mahseredjian, J. Bélanger “ Custom-Coded Models in the State Space Nodal Solver of ARTEMiS,” IPST 2013, International Conf. on Power Systems Transients, Vancouver, Canada, July 18-20, 2013 E. Farantatos, U. Karaagac, H. Saad, J. Mahseredjian "Short-circuit current contribution of converter interfaced wind turbines and the impact on system protection," Bulk Power System Dynamics and Control - IX Optimization, Security and Control of the Emerging Power Grid (IREP), 2013 IREP Symposium , pp.1,9, 25-30 Aug. 2013 H. Saad, C. Dufour, J. Mahseredjian, S. Dennetière, S., Nguefeu, “Real time simulation of MMCs using the state-space nodal approach,” IPST 2013, International Conf. on Power Systems Transients, Vancouver, Canada, July 18-20, 2013 S. Dennetière, S. Nguefeu, H; Saad, J. Mahseredjian “Modeling of Modular Multilevel Converters for the France-Spain link,” IPST 2013, International Conf. on Power Systems Transients, Vancouver, Canada, July 18-20, 2013 U. Karaagac, J. Mahseredjian, H. Saad, S. Jensen, L. Cai “Examination of fault-ride-through methods for off-shore wind farms connected to the grid through VSC-based multi-terminal HVDC transmission,” IPST 2013, International Conf. on Power Systems Transients, Vancouver, BC, Canada, 18-20 July 2013 T. Vrana, Y. Yang, S. Dennetière, J; Jardini, H. Saad, D. Jovcic “The CIGRE B4 DC Grid Test System’’, ELECTRA issue 270, October 2013, pp 10-19

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