2019 - SuperGrid Institute

Phd Ragavendran RAMACHANDRAN “Control and Power Management of an Offshore Wind Power Plant with a Diode Rectifier based HVDC Transmission”

Communications2019-12-18T16:53:03+01:00December 16th, 2019|Phd, Supergrid Architecture & Systems|

Energy Transition for a more sustainable world is now the priority in societies. Towards this objective, especially in Europe, the offshore wind energy development has been relatively rapid. For Offshore Wind Power Plants (OWPP) farther from the shore (50 km and beyond) Voltage Source Converter (VSC) based High Voltage DC (HVDC) Transmission has become the prominent solution. Replacement of the offshore VSC station by multiple Diode Rectifier Units (DRUs) led to a cheaper, more compact and robust solution. This thesis focusses on various technological and scientific problems involved in the control system of the Offshore Wind power Plant with Diode Rectifier (DR) based HVDC transmission. These challenges are first reviewed in detail along with the state of the art. Then, based on the system dynamics, a grid forming control scheme is proposed by using the P-V and Q-f droop relationships, with a solution for the synchronization of the wind generators. Moreover, some of the selected control solutions in the literature for this topology are reviewed, compared and assessed by using time domain simulations of a study case. Following this, the different solutions for black start of the offshore AC system are analyzed from the available literature and they are compared using the relevant qualitative criteria. The various faults in the offshore system are then analyzed and the above designed grid forming control scheme is extended with Fault Ride through (FRT) capability, for offshore AC grid faults. Finally, a brief analysis is done on the challenges for the integration of this OWPP topology into a Multi Terminal DC (MTDC) network.

Phd Juan PAEZ “HVDC Converters for the interconnection of HVDC grids”
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Phd Juan PAEZ “HVDC Converters for the interconnection of HVDC grids”

Phd, Power Electronics & Converters

Phd Juan PAEZ “HVDC Converters for the interconnection of HVDC grids”

Communications2019-12-13T15:15:25+01:00December 13th, 2019|Phd, Power Electronics & Converters|

In order to include large-scale renewable sources into the electrical system and to transport high amounts of energy through long distances, the actual AC grid must be upgraded. HVDC transmission grids appear as a promising solution to upgrade the system and answer correctly the future needs and requirements. The development of such grids can be done following two different approaches. For one side, a DC system designed totally from zero following a standardization of HVDC technology, and for the other side, an incremental evolution using the existing HVDC lines. The second approach seems more reasonable due to the reutilization of infrastructure, the inconvenient is that the technology used on each existing line is different. Thus, their interconnection will require DC¬DC converters as interface elements. These structures allow the interconnection of different HVDC schemes and offer more functionalities than only DC voltage adaptation like power flow control and protection.

SuperGrid Institute’s “Technical days”: an event dedicated to our industrial shareholders
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SuperGrid Institute’s “Technical days”: an event dedicated to our industrial shareholders

Event

SuperGrid Institute’s “Technical days”: an event dedicated to our industrial shareholders

Communications2019-11-22T09:48:26+01:00November 22nd, 2019|Event|

SuperGrid Institute has held its first ever ‘Technical days’ event! Dedicated to our industrial shareholders, this event was organised to facilitate exchange and to allow us to better adapt our roadmap to the industry’s tangible needs. These two exciting days of workshops, discussions and networking have bolstered our belief in the importance of our mission to shape tomorrow’s HV & MV power transmission grids.

A DC voltage source for long term GIS testing designed by SuperGrid Institute
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A DC voltage source for long term GIS testing designed by SuperGrid Institute

High Voltage Substation Equipment

A DC voltage source for long term GIS testing designed by SuperGrid Institute

Communications2019-11-07T17:32:54+01:00October 29th, 2019|High Voltage Substation Equipment|

As part of its research, SuperGrid Institute studies the phenomena of partial discharge under DC voltage. Environmental issues emphasised in the European project PROMOTioN encourage the exploration for possible replacement of SF6 gas and remains a strong component of the study at SuperGrid Institute.

NPC assessment in insulated DC/DC converter topologies using SiC MOSFETs for Power Electronic Traction Transformer

Communications2019-10-22T11:34:14+02:00October 24th, 2019|Power Electronics & Converters, Publications|

Power electronic traction transformers (PETT) are multilevel AC/DC on-board converters, studied for railway applications to replace traditional solution with low frequency transformers. This paper focuses on the insulated DC/DC converter in a PETT. Three variants of resonant single active bridges (R-SAB) with 3-level NPC primaries are optimised to maximise the efficiency, under mass and dimension constraints. They are sized and compared for a 2 MW PETT on a 15 kV/16.7 Hz railway infrastructure, using 3.3 kV SiC MOSFETs and nanocrystalline C-core transformers with cast resin insulation and forced air cooling. The highest efficiency at nominal power, 99.17 %, is reached for a configuration with a 3-level full bridge NPC primary, a 2-level full bridge secondary, and a 32.1 L/49.1 kg transformer operating at 6 kHz.

The renewables integration via HVDC grids
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The renewables integration via HVDC grids

Supergrid Architecture & Systems

The renewables integration via HVDC grids

Communications2019-10-28T08:59:10+01:00October 22nd, 2019|Supergrid Architecture & Systems|

The large-scale integration of renewable electricity generation poses both structural, economic and management challenges. Among the major challenges, one can note the grid integration and the routing of this energy from the production units to the consumption poles. Major issues have to be faced like insufficient transmission capability, inertia reduction, stability margins mitigation. The HVDC is not a new idea but it can provide some interesting answers to these challenges. The keynote will list the locks and how they can be addressed by the HVDC grid. Finally, the underlying scientific issues will be discussed.

Electric field computation for HVDC GIS/GIL spacer under superimposed impulse conditions

Communications2023-01-31T13:34:25+01:00October 21st, 2019|High Voltage Substation Equipment, Publications|

This paper evidences the influence of different parameters on the electric field on DC spacers in GIS/GIL and thus their dielectric withstand under S/IMP tests. A notable difference in term of electric field can be observed in function of impulse polarity, load condition (with/without heating current) and insulating material’s properties. For example, an overstress of 0.3pu was obtained on spacer’s surface in case of superimposed impulse test with opposite impulse polarity, high load condition and high leakage current in gas. Contrary to AC system where the simple LI tests were enough, S/IMP tests with both impulse polarity, ZL and HL conditions are mandatory to verify the insulating performance of HVDC GIS/GIL spacer. This paper gives a better understanding of the electric field distribution in HVDC GIS/GIL and helps for the design and tests

Phd Guilherme DANTAS DE FREITAS “Development of a methodology for DC grid protection strategies comparison”
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Phd Guilherme DANTAS DE FREITAS “Development of a methodology for DC grid protection strategies comparison”

Phd, Supergrid Architecture & Systems

Phd Guilherme DANTAS DE FREITAS “Development of a methodology for DC grid protection strategies comparison”

Communications2019-10-22T18:15:05+02:00October 18th, 2019|Phd, Supergrid Architecture & Systems|

High Voltage Direct Current (HVDC) grids are considered a promising solution for problems faced by nowadays power system such as: lines congestion, integration of large amounts of renewable power and enhancement of AC system stability. Among the challenges in the deployment of a HVDC meshed grid, the protection of these grids is regarded as one of the most critical. The protection of HVDC grid is challenging not only because the swift transients and fault currents without zero-crossing, but also due to the impact a DC faults can have on the AC system. Several propositions for HVDC grids protection strategies can be found in literature...

3-phase medium frequency transformer for a 100kW 1.2kV 20kHz Dual Active Bridge converter

Communications2019-10-15T15:13:19+02:00October 15th, 2019|Power Electronics & Converters, Publications|

The article presents a three-phase Medium Frequency Transformer being a part of a 100kW 1.2kV 20kHz Dual Active Bridge DC-DC converter. The transformer design is detailed focusing on winding and core power loss calculation. The high power three-phase MFT prototype is presented. The experimental results include the transformer impedance characteristics, no load test and three-phase DAB full load test waveforms.

Cost-performance framework for the assessment of Modular Multilevel Converter in HVDC transmission applications

Communications2019-10-15T15:10:51+02:00October 15th, 2019|Power Electronics & Converters, Publications|

This article proposes a methodology of Cost-Performance Assessment (CPA) enabling the efficient cost evaluation required for the Cost-Benefit Analysis (CBA). The proposed method is applied for the Modular Multilevel Converter (MMC) in offshore wind high voltage direct current (HVDC) transmission. Thanks to the developed model, an analysis of submodule voltage rating is performed demonstrating the interest of this methodology in the evaluation of new technologies for HVDC transmission. The analysis shows that increasing the submodule (SM) voltage could lead to savings in the MMC cost and weight.