Abstract & Dissemination

Abstract
“Will the distance protection of EHV AC line connecting VSC based HVDC network perform well?” With this question in consideration, this thesis identifies a critical challenge of dynamic behavior impact of VSC and its associated fast control actions, grid codes for HVDC connections, during fault upon the performance of distance protection of AC line connected to VSC-HVDC system. This thesis also aims to present the solution to counter the problem faced by the distance protection in the presence of VSC-HVDC.
In this thesis, there is an investigation on the distance protection of AC lines in a power system consisting of point-to-point VSC-HVDC in PSCAD/EMTDC is carried out considering the grid codes and current limitation strategies. This chapter describes that the positive and zero sequence currents, fault impedance and fault current from the grid side are responsible for the difference in apparent impedance.
Additionally, this thesis elaborates the problem of distance relay malfunction by performing the closed-loop test using RTDS. A commercial distance relay is utilized to verify the analytical and simulation work performed. The analog signals are sent to the relay and digital trip signals from the relay are analyzed.
Moreover, a novel solution to upgrade the distance protection of transmission line in the form of Adaptive Relaying Scheme principle is also been proposed. This scheme computes the apparent impedance seen by the relay in real time and updates the the protection device with the new reach settings.

Dissemination
[ 1 ] M. M. Alam, H. Leite, and A. S. Carvalho. “Investigating Distance Relay Behaviour on an EHV AC Lines Connected with Voltage Source Converter Based HVDC.” In: Proc. CIGRE Symp., Across Borders - HVDC Systems And Market Integration.

[ 2 ] Mohammad Meraj Alam, Helder Leite, Nuno Silva, Adriano da Silva Carvalho, "Performance evaluation of distance protection of transmission lines connected with VSC-HVDC system using closed-loop test in RTDS", Electric Power Systems Research", Volume 152, November 2017, Pages 168-183, ISSN 0378-7796, https://doi.org/10.1016/j.epsr.2017.06.025.

[ 3] Mohammad Meraj Alam, Helder Leite, Jun Liang, Adriano da Silva Carvalho, "Effects of VSC based HVDC system on distance protection of transmission lines", International Journal of Electrical Power & Energy Systems, Volume 92, November 2017, Pages 245-260, ISSN 0142-0615, https://doi.org/10.1016/j.ijepes.2017.04.012.

Abstract & Dissemination

 
Abstract
The main objective of this PhD work was to propose and study improved HVdc circuit breaker topologies. The main challenges associated with the solid-state and hybrid dc circuit breakers include the need for a large number semiconductor switches in their main breaker branch and large surge arresters to limit the transient recovery voltage and absorb the system energy. This thesis proposed novel approaches for improving the performance if HVdc circuit breakers in order to tackle the mentioned problems. Furthermore, this thesis proposed a new type of dc circuit breaker with additional functionality as a current flow controller.

Dissemination

Journal Publications

[1]. Mokhberdoran, A.; Gomis-Bellmunt O.; Silva, N., Carvalho, A., “Current Flow Controlling Hybrid DC Circuit Breaker”, IEEE Transaction on Power Electronics Journal, vol.PP, no.99, pp.1-1, April 2017, doi: 10.1109/TPEL.2017.2688412
[2]. Mokhberdoran, A.; Carvalho, A.; Silva, ; N. Leite, H., Carrapatoso, A., “Application Study of Superconducting Fault Current Limiters in Meshed HVDC Grids Protected by Fast Protection Relays,” Electric Power Systems Research Journal, Volume 143, February 2017, Pages 292-302, doi:dx.doi.org/10.1016/j.epsr.2016.09.008
[3]. Mokhberdoran, A.; Silva, ; N. Leite, H.; Carvalho, A., “Unidirectional Protection Strategy for Multi-terminal HVDC Grids,” Transactions on Environment and Electrical Engineering Journal, Volume 1, Issue 4, November 2016, Pages 58-65, doi: http://dx.doi.org/10.1016/j.epsr.2016.09.008
[4]. Ajabi Farshbaf A.; Azizian, M.; Shazdeh, S.; Mokhberdoran, A., “Modeling of a New Configurationfor DFIGs Using T-type Converters and a Predictive Control Strategy in Wind Energy ConversionSystems,” Journal of Renewable Energy Research (IJRER), Volume 6, Issue 3, June 2016, [Online] http://www.ijrer.org/ijrer/index.php/ijrer/article/view/4013
[5]. Mokhberdoran, A.; Van Hertem, D.; Silva, N. ; Leite, H., Carvalho, A., “Multi-port Hybrid TypeHVDC Circuit Breaker” In the Second Round of Review at IEEE Transaction on Industrial ElectronicsJournal, Submitted in December 2016
[6]. Mokhberdoran, A.; Carvalho, A.; Leite, H.; Silva, N., Carrapatoso, A., “Design and implementation of a Surge-less DC Circuit Breaker” In the Second Round of Review at Electric Power System ResearchJournal, Elsevier, Submitted in September 2016
[7]. Mokhberdoran, A.; Sau-Bassols J.; Prieto-Araujo E.; Gomis-Bellmunt O.; Silva, N., Carvalho, A., “FaultMode Operation Strategies for Current Flow Controller in Meshed HVDC Grid” In the First Round of Review at Electric Power System Research Journal, Elsevier, Submitted in January 2017

Patents
[9]. A. Mokhberdoran, N. Silva, A. Carrapatoso, A. Carvalho, H. Leite, “Fault current managing branch for surge-less current interruption in dc system,” Patent No. WO2017025927 A1, International Application No. PCT/IB2016/054850, Filing date Aug 11, 2016, Publication date Feb 16, 2017.

International Conference Publications

[10]. Mokhberdoran, A.; Pirooz Azad, S.; Van Hertem, D.; Silva, N., Carvalho, A., “Unidirectional Protection of HVDC Grids Using Fast DC Circuit Breakers and Local Protection Algorithm,” The 13th IET274 advanced hvdc circuit breakers international conference on AC and DC Power Transmission, Manchester, UK, February 2017
[11]. Mokhberdoran, A.; Silva, N., Leite, H.; A.; Carvalho, “A Directional Protection Strategy for Multi-terminal VSC-HVDC Grids,” The 16th IEEE International Conference on Environment and Electrical Engineering (EEEIC), Florence, Italy, July 2016, dio: 2016 10.1109/EEEIC.2016.7555819
[12]. Mokhberdoran, A.; Silva, N., Leite, H.; A.; Carvalho, “Surge-less Fast dc Solid-state Circuit Breaker,”Poster at ENERGYCON 2016 IEEE international energy conference, Leuven, Belgium, April 2016
[13]. Mokhberdoran, A.; Carvalho, A.; Leite, H.; Silva, N., Carrapatoso, A., “A New Topology of Fast Solid-state HVDC Circuit Breaker for Offshore Wind Integration Applications,” The 17thEuropean Power Electronics Conference (EPE), 9-10 September. 2015, doi: 10.1109/EPE.2015.7309270
[14]. Mokhberdoran, A.; Carvalho, A.; Leite, H.; Silva, N., “A review on HVDC circuit breakers,” The 3rd Renewable Power Generation Conference (RPG2014), 24-25 September. 2014, doi: 10.1049/cp.2014.0859

Abstract & Dissemination

Abstract
This Ph.D. Thesis will investigate the effects of the integration of Distributed Energy Storage on Distribution networks. Issues related to the planning and operation of Distributed Energy Storage will be assessed, with focus ongrid operational constraints and the existence of Renewable Energy Sources.
The project will develop a Distributed Energy Storage planning tool that cantechnically and economic assess the optimal size, the appropriate technology and the most suitable location to these systems in order to optimize the network operational efficiency and defer distribution network investment cost while accommodating further levels of Renewable Energy Sources.
This Ph.D. Thesis will also examine Distributed Energy Storage control scheduling strategies that could ensure the most efficient, reliable and economic operation of Distribution networks. The development of a Smart Energy Storage Controller based on the Distributed Energy Storage operation control tool with SCADA (Supervisory Control And Data Acquisition) systems interface is also an objective of this work.

Dissemination
Journal papers:

[1]. Miranda, I., Leite. H, and Silva, N., "Coordination of multifunctional distributed energy storage systems in distribution networks," IET Generation, Transmission & Distribution, vol. 10, no. 3, pp. 726-735, February, 2016.
[2]. Miranda,  I.,  Silva,  N.,  Leite,  H.,  “A  holistic  approach  to  the  integration  of  battery energy storage systems in Island electric grids with high wind penetration”, Sustainable Energy, IEEE Transactions on, Vol.7, No.2, pp.775-785, 2015.
 
Conference papers:

[3]. Miranda, I., Silva, N., Leite, H., "Distribution storage system optimal sizing and techno-economic  robustness",  Energy  Conference  and  Exhibition  (ENERGYCON),  2012  IEEE International. IEEE, 2012.
[4]. Miranda, I., Silva, N., Leite, H., "Technical and economic assessment for optimal sizing of distributed storage", Innovative Smart Grid Technologies (ISGT Europe), 2012 3rd IEEE PES International Conference and Exhibition on. IEEE, 2012.
[5]. Miranda,  I.,  Silva,  N.,  Bernardo,  A.M.,  Leite,  H.,  “Multifunctional  battery  energy storage systems in isolated networks with wind generation”, International Conference and Exhibition on Electricity Distribution (CIRED – Workshop), Rome, 2014.
[6]. Miranda, I., Silva, N., Leite, H., “Integration of distributed energy storage systems as shared resources in distribution networks”, International Conference and Exhibition on Electricity Distribution (CIRED – Workshop), Rome, 2014.
[7]. Miranda, I., Silva, N., Bernardo, A.M., “Assessment of the potential of Battery Energy Storage Systems in current European markets designs”, European Energy Market (EEM), 2015 12th International Conference on the. IEEE, Lisbon, 2015.
[8]. Miranda,  I.,  Silva,  N.,  Leite,  H.,  Carrapatoso,  A.,  “Distributed  Energy  Storage potentiating  the  participation  of  PV  sources  in  electricity  markets”,  International Conference and Exhibition on Electricity Distribution (CIRED), Lyon, 2015.
[9]. Miranda, I., Silva, N., Leite, H., “Assessment of a Virtual Power and Storage Plant for provision  of  market-driven  and  regulated  activities”,  International  Conference  and Exhibition on Electricity Distribution (CIRED), Lyon, 2015.
 
 

Abstract & Dissemination

Abstract
Wind Energy (WE) has largely contributed to the de-carbonisation of the energy sector and consequently to the definition of the European Commission (EC) targets  on renewable-based electricity generation. During the last decade, massive investment has culminated in the substantial installation of Wind Farms (WF). Moreover, the ambitious plans for increasing these targets on renewable-based electricity generation demand the deployment of more WF. To tackle this challenge, a large amount of offshore WF is envisioned to be built during the next decade. From the technical perspective, the adoption of HVDC becomes crucial to allow the installation far from coast and large power WF. Most recent plans point for the adoption of DC-grids as the mean of interconnecting offshore WF and also inter-AC area, allowing further renewable integration and the development of a common European electricity market.
This thesis presents control strategies based on a communication-free framework that were developed in order to allow DC grid-connected offshore WF and interconnected AC areas on providing advanced system services such as: a) primary frequency regulation, b) inertial behaviour emulation, c) Fault Ride-through (FRT) capability. The association of the control strategies for primary frequency regulation and FRT has culminated in the design of the coordinated approach for increasing the DC grid reliability by allowing its operation following the disconnection of one onshore HVDC converter. The presented control strategies rely on local controllers tobe housed in offshore and onshore High Voltage Direct Current - Voltage Source Converter (HVDC-VSC) as well as on WT. The local controllers operate autonomously providing the adequate regulation based on quantity variations.
 
The main outcomes of this thesis consist on the development of communication free control strategies for MTDC grid with offshore WF participating in the mainland systems frequency regulation, the capability of remaining connected to the mainland grids during voltage sags, thus mitigating the problems resulting from the disconnection of a large amount of wind power. Finally, a control scheme to guarantee the operation of the DC grid following the disconnection of one evacuation node (onshore HVDC-VSC) is presented.

Dissemination
Journals

[1].  Silva, B. ; Moreira, C.L. ; Seca, L. ; Phulpin, Y. ; Peças Lopes, J.A., ”Provision of Inertial and Primary Frequency Control Services Using Offshore Multiterminal HVDC Networks,” Sustainable Energy, IEEE Transactions on , vol.3, no.4, pp.800, Oct. 2012 doi: 10.1109/TSTE.2012.2199774
[2].  Bessa R.J. ; Moreira, C.L. ; Silva, B. ; Matos, M., ”Handling Renewable Energy Variability and Uncertainty in Power Systems Operation”, Wiley Interdisciplinary Reviews: Energy and Environment, 2013.
[3]. Silva, B.; Moreira, C.L.; Leite, H.; Lopes, J.A.P., "Control Strategies for AC Fault Ride Through in Multiterminal HVDC Grids," in Power Delivery, IEEE Transactions on , vol.29, no.1, pp.395-405, Feb. 2014 doi: 10.1109/TPWRD.2013.2281331
 
Conferences
[4]. Moreira, C.L. ; Silva, B. ; Soares, F.J. ; Seca, L. ; Peças Lopes, J.A., ”Inertial Control in Offshore Wind Farms Connected to AC Networks through Multiterminal HVDC grids with VSC,” CIGRE SYMPOSIUM - Cigre International Symposium , Bologna, Italy, September, 2011.
[5]. Ciapessoni, E.; Cirio, D.; Gatti, A.; Pitto, A.; Denis, A.M.; Despouys, O.; He, L.; Moreira, C.L.; Silva, B., ”Dynamics and control of multi-terminal high voltage direct current networks for integration of large offshore wind parks into AC grids,” 44th CIGRE - CIGRE Session 2012 (44th ed.), Paris, France, August, 2012.
[6]. Silva, B.; Moreira, C.L. ; Leite,H.; Peças Lopes, J.A., ”Barriers and solutions for AC low voltage fault ride-through on Multi-terminal HVDC grids,”11th WIW - 11th Wind Integration Workshop, Lisbon, Portugal, November, 2012.
[7]. Silva, B. ; Moreira, C.L. ; Leite, H., ”Operation and control of multiterminal HVDC grids following the loss of an onshore converter,” Innovative Smart Grid Technologies Latin America (ISGT LA), 2013 IEEE PES Conference On , vol., no., pp.1,8, 15-17 April 2013 doi: 10.1109/ISGT-LA.2013.6554464

Abstract & Dissemination

Abstract
In the last decades, High Voltage Direct Current (HVDC) systems have had extensive growth due to the great development that has occurred in AC-DC-AC conversion technology based on power electronics, and also for being strongly promoted as a great solution for the connection of renewable energy sources through long distances, both offshore and onshore. However, there are still problems in the operation and maintenance of HVDC systems that can be reviewed and updated. Such is the case of automated methods of fault location. All currently available commercial methods are based on travelling wave technologies. These methods can have good accuracy, but they also have some disadvantages, such as the need for expensive measuring equipment dedicated exclusively to this purpose, and problems for detecting high impedance faults or faults close to the line terminals.
This thesis develops a method for fault location on HVDC lines based on line impedance estimation, as a proposal to complement the current methods in cases where commercial methods are not capable to give a satisfactory result. The reason to develop this method based on a different technology than traveling wave, is because it’s intended to prevent the problems that affect these type of technologies.
The proposed method uses a mathematical model of the transmission line as a basis for estimating the line’s impedance. This model was specifically attained to use in this project, and it was deducted from the transmission line differential equations in the time-domain. For this deduction is not required any approximation, so it was obtained a model that brings high accuracy to the fault location method.
 
The method’s behavior is evaluated from the technical point of view, using both actual fault records and simulated fault records. The results are compared with results obtained by traditional methods in order to verify the performance of the different methods. The proposed method aims to assist in the operation process of HVDC systems, providing a robust fault locator, with high accuracy, and low cost. This method is intended to replace the current traveling wave-based methods, or at least complement them in cases where traditional methods have not performed well.
 

Dissemination

Journals
[1]. L. de Andrade, H. Leite and M.T. Ponce de Leão. Time-Domain Distributed Parameters Transmission Line Model for Transient Analysis. Progress In Electromagnetics Research B Journal, Vol. 53, pp. 25-46, 2013.
[2]. L. de Andrade and M.T. Ponce de Leão. Fault Location for Transmission Lines Using  Wavelet . IEEE Latin America Trasactions, Vol. 12, No. 6, p. 6, 2014.

Conferences
[1]. L. de Andrade and E. Sorrentino, Inclusion of the Zero-Sequence Mutual Impedance in a Distributed Parameter Model of Transmission Lines, In Proceedings of IEEE 9th International Conference on Environment and Electrical Engineering, Prague, Czech Republic, pp. 242-245, May 2010,
[2]. L. de Andrade, P. De Oliveira and M. Ponce de Leão, Current Strategic Environmental Assessment in the Electrical Industry, In Proceedings of IEEE 11th International Conference on Electrical Power Quality and Utilisation, Lisbon, Portugal, p. 6, October 2011
[3]. L. de Andrade and M. Ponce de Le˜ao, Faults Location Methods Reviews for Transmission Lines, In Proceedings of CIGRE III Congreso Venezolano de Redes y Energia Elétrica, Caracas, Venezuela, p. 8, March 2012
[4]. L. de Andrade and M. Ponce de Leão, Travelling Wave Based Fault Location Analysis for Transmission Lines, In Proceedings of 2nd European Energy Conference, Maastricht, Netherlands, p. 9, April 2012
[5]. L. de Andrade and M. Ponce de Leão, Impedance-Based Fault Location Analysis for Transmission Lines, In Proceedings of IEEE PES Transmission and Distribution Conference, Orlando, USA, p. 6, May 2012
[6]. L. de Andrade and M. Ponce de Leão, A Brief History of Direct Current in Electrical Power Systems, In Proceedings of IEEE History of Electro-technology Conference, Pavia, Italy, p. 6, September 2012
[7]. L. de Andrade and M. Ponce de Leão, Current Interoperability of Electrical Systems, In Proceedings of IEEE IV International Congress on Ultra Modern Telecommunications and Control Systems, St. Petersburg, Russia, pp. 423-427, October 2012, [8]. L. de Andrade and M. Ponce de Le˜ao, Direct Current Power Systems, In Proceedings of CIGRE Smarts Grids: Next Generation Grids for New Energy Trends International Symposium, Lisbon, Portugal, p. 8, April 2013
[9]. L. de Andrade, Y. Blanco and M. Ponce de Leão, Using Power Systems Simulation Software for Fault Analysis, In Proceedings of Encontro Regional Ibero-americano do CIGRE, Foz do Iguaçu, Brasil, p. 8, May 2013

Abstract & Dissemination

Abstract
The research carried out focuses on the way generators connect to distribution networks. Permission to connect a generator to the distribution system is generally obtained on the basis that the generator’s effect is limited and that the network voltages and currents remain acceptable at all times. This firm access connection policy limits the capacity of generation that can be connected.
Generators may be allowed to connect to distribution networks above the limit defined by the firm access connection policy. When there is inadequate capacity in the system, the non-firm generators are generally constrained off on a “last-in, first-off” basis. Only the order of connection of the generators is taken into account. Different costs of operation and ability to be dispatched are not considered. Thus, the firm access connection policy does not maximise the economic value of the generators.
The coordination of independent distributed generators is formulated in this research to maximise the income received by the generators. The coordination schedules generators connected to the same circuit according to their different costs of operation and ability to be dispatched, without exceeding the power limit of the circuit. Additional income is obtained by the generators for the additional electricity sold and by the substitution of expensive generators by cheaper ones. An income-sharing mechanism based on cooperative game theory to share the additional income is outlined. The objective is to provide the generators an economic incentive to be operated in a coordinated manner.
Demand side flexibility can be used to maximise the production of the generators. The coordination of generators and controllable load is devised in this research to maximise the income of the generators. Controllable load is asked to shift its consumption to allow the generators to maximise their production. The additional income resultant of the coordination is allocated to the generators and the controllable load. A bargaining approach of Game Theory is used to determine this allocation. The controllable load receives part of the additional income to cover the increase of its electricity bill and to incentivise its coordination with the generators.
A reduced version of a Portuguese distribution network is used to validate the coordination of independent distributed generators and the coordination of generators and controllable load. Four independent distributed generators and a load equivalent are connected to the network. A number of cases of wind power, price of electrical energy and load consumption are considered. Different costs of operation of the generators are analysed. Different levels of load flexibility and load capacity are evaluated.

Dissemination
[1] J. A. Barros, H. Leite and N. Jenkins, “Coordinating Independent Distributed Generators”, in 3rd IEEE PES Innovative Smart Grid Technologies Conference, 2012 ISGT Europe, Berlin, 14 – 17 October 2012.
[2] J. Barros and H. Leite, “Feed-In Tariffs for Wind Energy in Portugal: Current Status and Prospective Future”, in 11th International Conference on Electrical Power Quality and Utilization, IEEE EPQU 2011, Lisbon, 17 – 19 October 2011.
[3] J. Carvalhosa, J. Barros, H. Leite, A. Barbosa, P. Pereira and P. Alves, “Technical and Economic Impacts of the 2010's Grid Code Requirements for Wind Energy in Portugal”, in 11th International Conference on Electrical Power Quality and Utilization, IEEE EPQU 2011, Lisbon, 17 – 19 October 2011.
[4] H. Leite, J. Barros, V. Miranda and R. Fiteiro, “Application of a Methodology based on the Evolutionary Particle Swarm Optimization to Protection Coordination”, in 21st International Conference and Exhibition on Electricity Distribution, CIRED 2011, Frankfurt, 6 – 9 June 2011.
[5] H. Leite, J. Barros, and V. Miranda, "The Evolutionary Algorithm EPSO to Coordinate Directional Overcurrent Relays," in 10th International Conference on Developments in Power System Protection, IET DPSP 2010, Manchester, 29 March – 1 April 2010.
[6] H. Leite, J. Barros, and V. Miranda, "Evolutionary Algorithm EPSO Helping Doubly Fed Induction Generator with Ride-Through-Fault," in International Conference on Power Systems, IEEE PowerTech 2009, Bucharest, 28 June – 2 July 2009.