Periodic Reporting for period 2 - SSTAR (Innovative HV Solid-State TrAnsformer for maximizing Renewable energy penetration in energy distribution and transmission systems)
Reporting period: 2023-11-01 to 2024-10-31
The on-going energy transition towards a decarbonized economy is changing profoundly the infrastructure of the power grids worldwide. Conventional high-power transformers are not fully prepared to overcome these challenges, as they do not have intrinsic capabilities regarding active system support. Instead, Solid-state Transformers (SSTs) have emerged in the last years as a disruptive technology able to extend the typical functionalities of a regular transformer, optimizing the power flows and introducing a high degree of digitalization and intelligence in the network. However, SSTs are not still a mature technology and only prototypes of up to 15 kV and 15 modules have been developed in the range of high frequency (40 kHz) so far. Therefore, their use is currently restricted to low-voltage applications.
In this context, SSTAR aims to increase the operation voltage level of SSTs to enlarge their applications within the energy power sector while improving its performance in a reliable, cost-optimized and sustainable way. To do so, three main R&I Lines will be developed: 1) Sustainable biobased dielectric fluid able to increase the SST modules insulation voltage while achieving up to 50% of CO2 saving comparing to traditional oils 2) New SST module based on SiC with a bidirectional Inductive Power Transfer (IPT) system able to increase the individual voltage and switching frequency of SST modules up to 1.5 kV and 50kHz respectively with a total efficiency of 98.5% and 3) Decentralized control cascade H-bridge (CHB) converter to scale-up the number of modules in a single SST device to achieve the voltage levels of transmission grids. The combined effect of these innovations will be validated at TRL 4 in two certified test-beds in Spain and Portugal. Hence, SSTAR seeks to pave the way for the development of new disruptive HV SST devices more attractive for commercial purposes than the prototypes made so far, and able to be used in distribution and transmissions grids.
In this context, SSTAR aims to increase the operation voltage level of SSTs to enlarge their applications within the energy power sector while improving its performance in a reliable, cost-optimized and sustainable way. To do so, three main R&I Lines will be developed: 1) Sustainable biobased dielectric fluid able to increase the SST modules insulation voltage while achieving up to 50% of CO2 saving comparing to traditional oils 2) New SST module based on SiC with a bidirectional Inductive Power Transfer (IPT) system able to increase the individual voltage and switching frequency of SST modules up to 1.5 kV and 50kHz respectively with a total efficiency of 98.5% and 3) Decentralized control cascade H-bridge (CHB) converter to scale-up the number of modules in a single SST device to achieve the voltage levels of transmission grids. The combined effect of these innovations will be validated at TRL 4 in two certified test-beds in Spain and Portugal. Hence, SSTAR seeks to pave the way for the development of new disruptive HV SST devices more attractive for commercial purposes than the prototypes made so far, and able to be used in distribution and transmissions grids.
During the first 30 months,the following technical activities have been performed:
- A new ester base has been identified and two new additive packages, for ester-based fluid and vegetable-based fluid have been developed.
- Formulation completed to be compliant to the standards IEC 61099 (for ester-based fluids) and IEC 62770 (for vegetable-based fluids).
- First assessment of risks of the biobased dielectric fluids inside SST modules, through a preliminary HAZID evaluation, to guarantee their safe performance.
- Numerical analysis to study the corona breakdown of the SST.
- Self-consistent plasma modelling to investigate the onset of partial discharges at the most critical parts of the SST module subjected to high potential differences.
- Two distinct sets of computations regarding the applied voltage waveform.
- Requirements and topology of the HV SST module.
- IPT design process with MATLAB and FEMM, iterating over various geometries and number of turns.
- Cooling system design.
- Several parametric analysis conducted to investigate the design aspects of the cooling system developed.
- A three level H bridge topology identifed.
- The control strategy scheme was studied and a constant voltage scheme in secondary was selected.
- The definition of a control architecture that could manage a highly scalable HV interface.
- Definition of some sustainability indicators and targets that SSTAR system can achieve in terms of circularity/avoidance of environmental risk (for dielectric fluid mostly) and facilitation of grid management particularly looking at intermittent RES integration.
-Production of 200 liters of selected biobased dielectric fluid.
-Safety measures developed to secure operational safety.
-Scenarios defined for corona breakdown.
-SST Design and IPT component selection.
-IPT simulations and thermal analysis.
-CHB control converter real-time operation in simulation.
-Prototypes list of material and procurement.
-LCA and S-LCA data gathering.
-Communication, stakeholder engagement and networking.
- A new ester base has been identified and two new additive packages, for ester-based fluid and vegetable-based fluid have been developed.
- Formulation completed to be compliant to the standards IEC 61099 (for ester-based fluids) and IEC 62770 (for vegetable-based fluids).
- First assessment of risks of the biobased dielectric fluids inside SST modules, through a preliminary HAZID evaluation, to guarantee their safe performance.
- Numerical analysis to study the corona breakdown of the SST.
- Self-consistent plasma modelling to investigate the onset of partial discharges at the most critical parts of the SST module subjected to high potential differences.
- Two distinct sets of computations regarding the applied voltage waveform.
- Requirements and topology of the HV SST module.
- IPT design process with MATLAB and FEMM, iterating over various geometries and number of turns.
- Cooling system design.
- Several parametric analysis conducted to investigate the design aspects of the cooling system developed.
- A three level H bridge topology identifed.
- The control strategy scheme was studied and a constant voltage scheme in secondary was selected.
- The definition of a control architecture that could manage a highly scalable HV interface.
- Definition of some sustainability indicators and targets that SSTAR system can achieve in terms of circularity/avoidance of environmental risk (for dielectric fluid mostly) and facilitation of grid management particularly looking at intermittent RES integration.
-Production of 200 liters of selected biobased dielectric fluid.
-Safety measures developed to secure operational safety.
-Scenarios defined for corona breakdown.
-SST Design and IPT component selection.
-IPT simulations and thermal analysis.
-CHB control converter real-time operation in simulation.
-Prototypes list of material and procurement.
-LCA and S-LCA data gathering.
-Communication, stakeholder engagement and networking.
Within WP2, the developed dielectric fluids, their HAZID&HAZOD applications and their suitability in SSTs, will enable to increase the current insulation of SST´s modules.
An innovative SST modulde including a bidirectional Inductive Power Transfer (IPT) for high voltage applications has being identifed through several simulations.
Effective and efficient dissemination of the project's main outcomes towards the targeted stakeholders to jointly achieve a climate neutral EU.
An innovative SST modulde including a bidirectional Inductive Power Transfer (IPT) for high voltage applications has being identifed through several simulations.
Effective and efficient dissemination of the project's main outcomes towards the targeted stakeholders to jointly achieve a climate neutral EU.