The Vienna Hydro Conference took place in Vienna from 13 to 15 November 2024. The IEAN was represented by Robert Schuerhuber, Darko Brankovic, Dominik Grall and Wendelin Angermann, who presented various electrotechnical considerations on the subject of hydropower plants to an expert audience:

• Darko Brankovic: Evaluation of state-of-the-art grid code requirements and future adaptations for hydropower plants.
• Dominik Grall: Detection and Stabilization of Regional Electric Islands Post Unintentional Islanding.
• Wendelin Angermann: Analytical optimization and practical verification of reactive power supply for power plants.

Many thanks to the Vienna University of Technology for the successful event!

In the current issue of IET Renewable Power Generation (August 2024), a study by Dr. Ziqian Zhang has been published, focusing on the dynamic modeling of clustered converter systems and the analysis of their "equilibrium manifold." The article, titled "Dynamic Modelling and Equilibrium Manifold of Multi-Converter Systems: A Study on Grid-Forming and Grid-Following Converters in Renewable Energy Power Plants," examines the interaction between grid-forming (GFM) and grid-following (GFL) converters.

The study proposes an innovative high-dimensional space modeling approach that facilitates the qualitative analysis of the transient stability of clustered converter systems. By developing a dynamic model for these systems, the equilibrium manifolds are derived and their stability analyzed. The research findings indicate that an appropriate capacity distribution between grid-following and grid-forming converters is critical for maintaining system stability. This study provides a theoretical foundation for the design and control of clustered converter systems and contributes to enhancing the operational stability of renewable energy power plants.

For more details, please refer to the full article in the current issue of IET Renewable Power Generation: Link

This year, the Institute of Electrical Power Systems was once again represented at the IEEE Power & Energy Society PESS 2024 conference. The following contributions were presented to the community and subsequently discussed:

Darko Brankovic
Comparison of different grid modeling structures for fault ride through analysis

Wendelin Angermann
Efficient method for calculating the reactive power supply by applying analytical load flow calculations

Gregor Schöpf
Evaluating Grid-forming Converter Performance: Insights from Power Hardware-in-the-Loop Testing

The published papers will be available on IEEE Xplore soon.

Foto by: TU Dresden

SF6 circuit breakers are the state-of-the-art in high-voltage systems to ensure safe grid operation. However, since SF6 is a greenhouse gas, alternative switching technologies, such as vacuum circuit breakers, must be used in the future. In the high-voltage field, there is still little operational experience with these alternatives. APG has decided, together with various partners, to conduct short-circuit tests and operational switching, during which high-frequency processes were measured using additionally installed CR dividers. The IEAN has been given responsibility for the scientific elaboration of this project.

In 2024, IEAN was once again represented by a delegation of 10 people at the OVE Energy Technology Conference in Salzburg. The top topics currently occupying the industry were: storage technologies for the integration of renewable energies, digitalisation in the energy system with the help of artificial intelligence, among other things, but also legal framework conditions for a successful energy transition and possible DC technologies in the distribution grids of the future.

In addition, selected key research areas from our institute were presented to an interested audience of experts during the moderated poster session. Once again this year, the IEAN was able to defend the Best Poster Award with the contribution ‘Future challenges in the grid connection of non-synchronous power generation plants’, congratulations to our colleagues Darko Brankovic and Philipp Hackl.

As in the previous year, IEAN graduates also received OVE Energy Technology Awards. We congratulate:

• Dipl.-Ing. Dr.techn. Philipp Schachinger in the category dissertation
• Dipl.-Ing. Wendelin Angermann in the category theses at universities and universities of applied sciences

Many thanks at this point to the entire OVE team for the great organisation of the event as always, we are already looking forward to the next OVE Energy Technology Conference (15-16.10.2025) in Kufstein.

Photos: OVE/C. Fürthner, and private

Have you ever heard of grid-forming converters? In the beginning of October the Wind & Solar Integration Workshop took place in Helsinki which is one of the world's best forums on how to safely integrate renewable energy sources. An IEAN research team has been working on the subject for years and contributed to this year's conference with two presentations. The audience was characterised by a high number of industry representatives, which led to good discussions on the actual situation with grid operators, wind farm developers, converter manufacturers, testing institutes and international universities.

Graz University of Technology (TU Graz) is receiving extensive laboratory equipment worth over 400,000 euros from DEWETRON, a leading manufacturer of high-precision measurement systems from Styria. This generous sponsorship will support and promote various institutes of TU Graz. Further information: Link

We would like to express our sincere thanks for the support and look forward to using the measuring devices!

From 17-18 September 2024, the VDE ETG symposium on ‘Grid control and system management’ took place in Munich. The IEAN was represented by Robert Schürhuber, Darko Brankovic and Dominik Grall, who presented a paper on experiences with grid reconstruction and island grid tests.

In addition to many interesting contributions on the system management of the electrical energy grid of the future with increasing penetration of inverter-coupled systems, we were able to share our experiences of real grid reconstruction tests with a high-calibre audience and congratulate the VDE on the successful event!

The Institute for Electrical Power Systems at Graz University of Technology would like to thank Omicron for providing a CMS 156 amplifier. This device will be used in future investigations and it allows testing protection devices in real-time using simulated power systems.

In electrical energy systems, protective devices have the task of reliably and safely distinguishing between normal operation and faults. They can ultimately isolate faulty system components and equipment by opening circuit breakers, thereby clearing up faults such as a short circuit.

The effects of state-of-the-art equipment such as inverters with innovative control strategies (grid-forming) or FACTS on conventional protection relays are not collectively known due to the large number of different influencing parameters, which is why it is necessary to extensively test the compatibility of the equipment with the protective devices. Real-time simulations can be a suitable way of examining this compatibility. The sequence of such a test environment is shown below.

In this example, a short circuit influenced by an SSSC is simulated in real time together with a supplying grid and the faulty line. The corresponding voltage and current measurements of the faulty line are exported to the Omicron CMS 156, which sends the signals to the Device-under-Test (DuT), a real protection relay. The DuT ultimately decides whether a fault is present and can, for example, send a trip signal to the circuit breaker within the simulation environment.

The expansion of photovoltaics (PV) plays a key role in achieving climate targets. In addition to small-scale projects, large-scale projects in the megawatt range are becoming increasingly important. These large-scale systems are increasingly being realised as ground-mounted systems. A significant difference when considering the ohmic influence of such PV systems compared to substations is the larger size. We are currently conducting research on topics relating to such PV systems. One of these topics is atmospheric discharges (lightning) - direct strikes - in such systems.

To give you a small foretaste of the results, the following graphic shows a direct lightning strike with 100 kA in a module table row of a PV system. It will be interesting!

International cooperation is an essential aspect of research activities at universities. The IEAN maintains excellent relationships in this regard, collaborating with institutions in China through not only joint courses but also regular student exchanges. This summer, two IEAN employees visited academic partners at Tongji University and Dianji University in Shanghai, as well as Hefei University of Technology. Their visit included technical exchanges through discussion sessions and tours of various state-of-the-art laboratories. They had the opportunity to visit facilities such as the maglev test track, earthquake and wind tunnel test benches, and a high-voltage laboratory.

The recent publication of a study by Dr Zhang Ziqian in the prestigious IEEE Transactions on Energy Conversion marks an advance in the characterisation of stability energy systems that are significantly powered by renewable energy sources. The article entitled "Reactive Current Response of Grid-Forming Converters during Low-Voltage Ride-Through: Analysis of Test Method Impact" examines the functionality of grid-forming converters during voltage dips at the converter terminals, as they occur in the event of a fault. This behaviour has a decisive influence on grid stability in the event of faults in a converter-dominated grid.

In this study, Dr Zhang emphasises the need for accurate test equipment to evaluate the performance of these converters, which play an essential role in supporting the grid during faults caused by voltage dips. The results of the research indicate that many existing test methods do not adequately replicate real grid conditions and could lead to misleading assessments of grid forming capabilities. His study argues for the introduction of more sophisticated testing approaches, such as hardware-in-the-loop, to ensure that grid-forming converters actually function properly under real-world conditions.

Figure: Differences in GFM reactive current during faults for different testing devices, Upper part: VCC‘s reactive current, lower part: VI‘s reactive current

For further details on Dr. Zhang's research, the full study is available in the latest issue of the IEEE Transactions on Energy Conversion:  Link

On 18 July 2024, some colleagues from our institute had the unique opportunity to visit the construction site of the Semmering Base Tunnel. After an extremely interesting introductory lecture on the monumental overall project, we took a shaft lift 400 metres down into the so-called emergency stop underground. This is an impressive cavern in the mountain, which was used during the construction phase for the assembly of two tunnelling machines (TBMs) and material handling. During operation of the tunnel, it can be used in the event of an emergency (e.g. fire) in one of the two tunnel tubes to evacuate a train and transfer to a train in the other tube.

The 27.3 km long Semmering Base Tunnel is expected to relieve the Ghegast line over the Semmering in 2029/2030 after a construction period of around 15 years and will reduce the journey time on the Graz-Vienna line by around 30 minutes at speeds of up to 230 km/h.

Many thanks once again to Manfred Praxl from IGT Geotechnik und Tunnelbau ZT GmbH and his colleagues from Implenia for the very competent and entertaining guided tour.

News for students of the lecture ‘Fundamentals of Electrical Power Systems’!  The Institute of Electrical Power Systems (IEAN) is now operating a Discord channel (see [1]) to support learning.

In the Discord channel, students have the opportunity to ask questions about the subject matter of the written and oral examinations. In addition, employees of the institute actively discuss with the students to enable an interactive exchange.

The aim is to offer a low-threshold discussion platform to promote dialogue among students and get them excited about electrical power engineering.

We look forward to exciting discussions and to getting students curious about electrical power engineering!

[1] Link to the Discord-Channel

Once again this year, IEAN traditionally celebrated the end of the semester at Lucky's Heuriger.

As part of the IRI4SGC (Interoperable Research Infrastructure for Managing Sustainable Grid Cells) project funded by the EU-LAC interest group, we organised a project workshop with participants from Bielefeld University of Applied Sciences (HSBI) and our institute from 25-27 June 2024. At the same time, Felix Annen from HSBI also put the interconnected test setup consisting of a protection tester, a protection relay, two Raspberry Pis and a MV circuit breaker into operation during his 14-day research stay at our institute.

We would like to take this opportunity to thank our colleagues at HSBI for the cooperation in the course of our joint project and look forward to many more interesting projects.

On June 26, Dr. Ziqian Zhang participated in a workshop titled "Green Energy and Battery Storage Applications" held at the Faculty of Engineering at the University of Rijeka in Croatia. He delivered a lecture on "Advanced Grid Forming Feature Application in Utility BESS Scenario/Analysis of the importance of Grid forming function". The attendees included faculty and students from the University of Rijeka, Croatian grid experts, and owners of renewable energy installations in Croatia.

The replacement of powerful thermal power plants has already led to grid conditions in which converter-based power generation plants dominate the electricity grid in certain grid areas. In this case, these must take over the stabilising features of the well-known synchronous machines. One possibility for this is the use of more grid-friendly control concepts known as grid-forming (GFM) converters.

A research group at the IEAN offered a workshop on "grid-forming converters" on 20 June 2024. The content of the workshop can be roughly summarised as follows

• Present status and the future challenges of the electricity grid
• Introduction and comparison of present and future grid codes
• Comparison between grid-following and grid-forming inverters
• Identification and test methods for grid-forming inverters
• Laboratory demonstrations in the Power Hardware-in-the-Loop Laboratory (PHILlab)

An unforgettable highlight for GEE students:

On June 19, 2024, the students of the course "Fundamentals of Electrical Energy Systems" had the opportunity to experience an impressive and technically highly interesting field trip to the Fragant power plant group. This field trip offered an in-depth insight into Kelag's power plant operations.

Stations visited:

• Außerfragant power plant: Visiting the power plant including a presentation on the history and key facts of Kelag.
• Innerfragant power plant: Live demonstration of a pump start on site, followed by a guided tour of the transformer station located there.
• Feldsee power plant: Visiting the two vertical machine sets.
• Wurtenboden storage facility: Visiting of the storage reservoir.

The field trip enabled our students to supplement their theoretical knowledge with practical experience and to experience the importance of renewable energies in practice. Many thanks to Mr. Sebastian Culetto and Mr. Christian Tengg from Kelag, who made this unforgettable day possible for our students.

Research at the Institute of Electrical Systems and Grids at Graz University of Technology is focussing on improving the reliability and performance of grid-forming inverters. The latest results have now been published in the journal IET Generation, Transmission & Distribution. The effects of current threshold variations on the dynamic response of grid-forming inverters are being investigated.

Grid-forming inverters are crucial for maintaining a stable power supply. They help to keep the voltage and frequency stable even during major disturbances such as sudden load changes or faults in the grid. This study presents a novel analysis method that equates current limiting and voltage regulation algorithms in a simplified circuit, which facilitates the modelling of grid-forming inverters and the power grid. This approach enables a deeper understanding of their behaviour during grid disturbances and helps to optimise their performance to better withstand disturbances.

The research led by Dr. Ziqian Zhang and Prof. Robert Schürhuber and their team shows that increasing the current threshold allows grid-forming inverters with certain control strategies to cope with larger phase jumps without losing synchronisation with the grid. This could lead to a more robust grid that is better able to cope with unpredictable conditions and integrate renewable energy sources.

Link to Paper

We are delighted that we as an institute were awarded the ‘Energy Globe Styria Award 2024’ on 5 June 2024 for two projects.

Of the 63 projects submitted, we were able to impress in the ‘RESEARCH’ category with the ‘PHIL-Lab’ project. However, we were also involved in the ‘Styrian Energy Transition Education Network’ project, which received the coveted award in the ‘Youth’ category.

The current solar cycle 25 is causing spectacular events: Four gigantic coronal mass ejections (CMEs) from the sun hit the earth and led to increased geomagnetically induced currents (GICs) in the Austrian transmission grid. For the first time, direct currents of over 22.5 A were measured across the transformer star point in the south of Austria. In addition, the sky offered a breathtaking spectacle in the night from May 10 to 11, when auroras were visible over large parts of Europe.

Our institute was represented at the Long Night of Research (LNF) 2024. Under the motto ‘Voltage in the bathroom’, Martin Fürnschuß and Daniel Herbst explained what can happen when a running hairdryer falls into the bathtub. How can the electric current spread through the human body? Why can this be harmful? What remedial measures are available (protective measures against electric shock, residual current circuit breakers, etc.)?

During seven presentations from 17:00 to 22:30, numerous visitors were entertained and at the same time sensitised to the dangers of electric shock.

Tidy laboratories, busy activity, flashing displays and slightly nervous researchers – this is probably the best way to describe the atmosphere at the institute this afternoon. The reason was a visit from a film crew. The variety of research topics covered by the institute, from energy generation and transmission to its utilisation, was staged. Stay tuned to see what the film material will be used for!

As part of an excursion organized by the institute on 13.02.2024, interested employees had the opportunity to gain experience and impressions from the practice of electrical power engineering at the Kaprun power plant group. On the one hand, the Kaprun Oberstufe power plant, which is currently being overhauled, and the Limberg II cavern power plant (593 MW in total) were visited; the former is currently being converted to full converter operation. We also had the opportunity to visit the impressive construction site of the Limberg III cavern power plant, which is currently under construction and will add a further 480 MW to the power plant group in the future.

Many thanks at this point to Stefan Polster from Verbund (former assistant at our institute), who guided us through the facilities and certainly made our day unforgettable!

Daniel Herbst

Blessed with fantastic weather, IEAN's snow-loving employees embarked on an alpine adventure on the Salzstiegel. Between perfect turns on the slopes and competitive races on the toboggan run, a well-deserved reward was a meal in a mountain hut.

On 17 November 2023, Prof. Schürhuber was invited by the Confucius Institute as a cross-university platform for promoting exchange between China and Europe to give a presentation on current research at the Institute of Electric Power Systems and on the academic exchange between the institute and Chinese universitites. The importance of current research topics for the future electricity grid was clearly emphasised, as well as the importance of international cooperation.

On National Day, Alexander Fröhlich und Peter Wohlfart presented our contribution to the research cooperation SWAP (Space Weather: An Austrian Platform) at the two-day performance show of the Austrian Armed Forces. They presented to numerous students and interested visitors the Europe-wide unique area-wide neutral point current measurement. The geomagnetically induced neutral point currents are measured and recorded at nine transformers in the Austrian transmission grid. The data obtained from these measurements serve as the basis for deriving valuable recommendations for action, which are available to APG to ensure and optimize the safety of the power grid.

Both days were extremely exciting and filled with joyful anticipation of future project work.

Further information on the project are available directly at SWAP: https://swap.zamg.ac.at/index.php/at/

As part of the TU Graz holiday programme "T³UG - – Teens treffen Technik” (Teens meet Technology), 25 young people, mostly female, visited us at the Institute of Electrical Power Systems.
Lothar Fickert organised guided tours of the electrical power laboratories, a trial lecture with Robert Schuerhuber on electrical power systems and a meet-and-greet with our two electrical engineers Katrin Friedl and Carina Lehmal. Dear students, thank you for your interest in becoming an enabler of the energy transition, and we would be very happy to welcome one or the other of you back as an electrical engineering student!
You also want to do an internship at TU Graz? Find out more here: https://super-science-team.tugraz.at/kurse/tttug/

This year too, IEAN's end-of-semester party was traditionally celebrated at Lucky's Heuriger!

This year, one of the most important conferences in electrical power engineering, Powertec, took place in Belgrade. IEAN was represented there and Darko Brankovic showed a highly topical subject on the verification of grid connection conditions of hydro generators. We also got to meet the master himself at the Nikola Tesla Museum!

In the course of the lecture Fundamentals of Electrical Energy Systems 25 students had the opportunity to gain experience and impressions of electrical power engineering from the practical side. The visit at KELAG/KNG on 2023/06/21 included:

• the KNG's "switchgear line" (training area for the training of switchgear operators with different technologies and voltage levels, circuit breakers, disconnectors, load breakers, etc.)
• he first large-scale photovoltaic plant of KELAG (Kirchengasse, Klagenfurt, ~ 4.5 MWp)
• the pumped storage hydro power plant Koralpe (55 MVA in generator mode and 35 MW in pump mode)
• the basin storage Soboth, with a tour of the inside of the dam

Special thanks to our colleagues from KELAG/KNG Christian Tengg, Hans-Jürgen Wernegger, Roland Kroll, Dietmar Holzer, Amel Skenderi, Markus Schoaß and Leo Friesacher for making this an unforgettable day.

With 11 persons, the Institute is extremely strongly and very actively represented with various contributions at this year's largest International Conference & Exhibition on Electricity (CIRED). The event with more than 1400 participants takes place every 2 years, this time in Rome.

Prof. Robert Schürhuber, Dr. Zhang Ziqian, and Mr. Maximilian Heinz Brestan participated in the 23rd International Scientific Conference on Electric Power Engineering (EPE) held in Brno, Czech Republic from May 24 to 26.
Prof. Schürhuber delivered an invited keynote speech titled "Grid Protection Issues of Converter Dominated Generation Systems." His insightful presentation delved into the challenges and innovative solutions surrounding grid protection in converter-dominated generation systems. Engaging in thought-provoking discussions, Prof. Schürhuber's expertise enhanced the intellectual exchange at the conference.
Dr. Zhang Ziqian's presentation, "Interactive Dynamic Characteristics of Angle Stability of Multi-Converters System," shed light on the complex dynamics and stability aspects of multi-converter systems. His contributions sparked fruitful discussions among researchers and industry professionals, exploring avenues for advancements in the field.
Mr. Maximilian Heinz Brestan presented on "Aspects of grid-connected converters and their inherent influence on the power grid." His comprehensive analysis provided valuable insights into the inherent impact of grid-connected converters on the power grid, encouraging further research and collaborative efforts.
Furthermore, Prof. Schürhuber assumed the role of chairperson for the conference session on Power System Components Co-simulation and Testing. His leadership ensured a productive and collaborative environment, facilitating fruitful discussions and knowledge sharing among the participants.
The 23rd International Scientific Conference on Electric Power Engineering served as an important platform for renowned experts like Prof. Robert Schürhuber, Dr. Zhang Ziqian, and Mr. Maximilian Heinz Brestan to exchange knowledge, share innovative ideas, and promote progress in power engineering. Their active participation in the discussions and sessions reinforced their commitment to driving advancements in the field.

As part of the course “Elektrische Energiesysteme 2”, an interactive course unit was held in the physics lecture room P1 on 2023/05/17. Students from several courses of our Institute were able to participate in exciting experiments in the field of thermodynamics. For example, the boiling and subsequent cooling (temperature curve comparable to the voltage at a capacitor) of water was analysed, the functioning of a Stirling engine was explained and the ignition of methane foam was demonstrated.
We would like to express our special thanks to the Institute for Experimental Physics, especially to Dr. Roland Lammegger and Prof. Martin Schultze for carrying out and supervising the experiments.

In the course of a scientific study, the electric field of a 220 kV overhead line was analysed using the finite element method (FEM). The aim of the study was to compare the field characteristics between two different tower configurations that differ in terms of geometry, conductor cables, phase arrangements, insulators and armatures. With the towers modelled in detail in CAD in three dimensions, an electrostatic model was created in the FEM programme Ansys Maxwell 3D. Of particular interest was the field curve (maximum value in the time domain) in the area of the insulators, i.e. between the conductor cables and the arms. It is noteworthy that the choice of phase arrangement and the position on the tower had hardly any effect on the magnitudes of the field curves in this area.

The largest solar storm in recent years hit Austria on April 23-24. Even polar lights were visible in Austria. Additionally, the highest ever recorded GICs were measured in the transmission grid of Austrian Power Grid AG. Peaks of up to 20 A DC were detected with our neutral point measurement system. The picture shows the magnetic field measurements at Conrad Observatory by GeoSphere Austria and one of the 9 neutral point measurements during the first phase of the storm.

Also this year, a delegation of TU Graz from the institutes IEAN, IHS and IEE travelled to Glasgow for a 3-day workshop to strengthen the cooperation with the University of Strathclyde. The topics covered included integrating powerful offshore wind power plants, energy distribution via MVDC cables, and local use via energy communities. A technical highlight was the visit to the National HVDC Centre, which has multi-terminal replicas of the control and protection systems of HVDC projects in Scotland. Thank you again for the hospitality and we are looking forward to the next workshop in Graz.

Shortly before the Easter vacations, Prof. Schürhuber visited the AHS HIB Liebenau in Graz. He presented a lecture on the topic of "Power grids and energy supply". In view of the climate crisis, the current state of energy supply was presented and approaches for future developments were discussed. Subsequently, educational paths from the HIB via the TU into the professional world of technology were shown and questions about studies and careers were discussed in plenary.

Maybe you have heard it in the media, or if you were in northern Germany and further north even seen it: In the night of March 24, a solarstorm hit the Earth. In addition to northern lights, solar storms also cause direct currents in power grids, which can lead to significant disruptions. The Institute of Electrical Power Systems measures these currents in the transmission grid of APG, analyzes the data and calculates possible effects. The picture shows one of the nine installed current measurements as well as the geomagnetic field measurements of GeoSphere Austria. The impact of the storm on the earth can be clearly seen in the measurements, but the induced currents remained at a harmless level for the grid. More info about solar storms and their effects can be found at
www.iean.tugraz.at
 

On September 10, 2022, real island tests took place in Upper Austria with the participation of Netz Oberösterreich and EnergieAG, in which the start-up process of a combined cycle power plant with a capacity of 400 MW was successfully tested with the help of hydropower plants with a total capacity of 100 MW.

Two hydropower plants, each with two generators and two pumping units of a pumped storage power plant, were used in the entire start-up process, which were interconnected by a 100 km long 110 kV single circuit system. Subsequently, the Institute of Electrical Power Systems created a simulation model and modeled and parameterized the electrical components based on the measurement results.

The simulation results, such as the validation of the simulation model or even the minimum required number of rotating masses for a successful start-up process, were prepared and submitted in a paper for CIRED 2023 in Rome.

From 12-13.1.2023 we welcomed Mr. Adam Dyśko, Senior Lecturer at University of Strathclyde in Glasgow, Scotland. The researcher, who comes from Poland, works mainly in the field of protection of electric power systems. During the laboratory tour at the Institute of Electrical Power Systems and the guest lecture, many interesting overlapping topics with our research groups emerged. In particular, the increased use of converters and the massive growth in distributed generation raise questions about the effectiveness of current protection methods. Many thanks for the detailed guest lecture and the subsequent discussion.

On 26 October 2022, the Dr. Karl-Heinz Weck Prize was awarded for the first time by the FGH (Research Association for Electrical Systems and Power Economics) to Wendelin Angermann in the historic transformer house in Mannheim. He was able to convince the jury with his Bachelor's thesis "Reactive Power Supply of Electric Power Plants" and the associated practical tests. In addition to the extensive calculations, the jury particularly emphasised the verification of the results by carrying out experiments in an operating power plant.

An exciting research colloquium where highly topical issues are discussed and an informal, inspiring and productive exchange of knowledge, experience and ideas takes place.

Many thanks to all participants with their contributed topics:

• Georg Erdmann (Berlin) - Energy prices and state intervention
• Albert Moser (Aachen) – Integrated operational simulation of electricity and gas transport infrastructures
• Christian Rehtanz (Dortmund) – Flexibility in holonic structures
• Robert Schürhuber (Graz) – Aspects of Stability of Converter-Coupled Plants on the Grid
• Lothar Fickert (Graz) – How can fault protection work with inverters?
• Peter Schegner (Dresden) – Digitalisation in the distribution grids
• Harald Weber (Rostock) – Ways to a secure and stable fully regenerative electric energy supply
• Lutz Hofmann (Hannover) – Aggregation of decentralised active and reactive power flexibilities for a flexibility market-based DSO-TSO cooperation
• Christian Becker (Hamburg) – Dynamic Modelling and Optimal Operation of Smart Integrated Energy Systems

As the Institute for Electrical Power Systems, we were also able to make a contribution to the Project Week Energy Communities in the form of presentations on the topics of future electrical grids, power quality and short-circuit calculation. In the course of the project week, students of the HTL-BULME Graz-Gösting and students of the FH Joanneum Kapfenberg had the opportunity to work on practical projects, e.g. on the integration of photovoltaic systems in different regions, based on interdisciplinary issues. A big thank you to all the organisers, especially Willi Weigend from the BULME.
Daniel Herbst

This year the IEEE Power & Energy Student Summit and Power Electronics Student Summit 2022 (PESS & PELLS 2022) was again held in Kassel, Germany. Our institute was strongly represented at this great conference with 4 participants, Darko Brankovic, Philipp Schachinger, Alexander Fröhlich and Manuel Galler.

Congratulations to our university assistant Manuel Galler for receiving the Best Presentation Award, sponsored by CIGRE NGN Germany.

Special thanks to Fraunhofer IEE, Universität Kassel and Hochschule Bonn-Rhein-Sieg for this great conference!

On October 19 and 20, the OVE Energy Technology Conference took place at the Seifenfabrik in Graz. In addition to interesting discussions about the future of the energy transition and e-mobility, the OVE Energy Technology Award was again presented. We are very pleased that our former master student and current PhD student Carina Lehmal was able to dust off the first place in the category master theses at TUs and FHs.
With her research on converter stability during grid connection, she was able to convince the expert jury.

The OVE Energy Technology Conference is the industry meeting of the year and was held this year as a home game for us directly in Graz, whereupon we participated in this event of the OVE Austrian Association for Electrical Engineering.

The focus of this year's conference was on energy storage technologies, infrastructure for e-mobility and innovative electricity-based processes for industry and commerce.
Due to the thematic coverage of our institute's focal points, it was a matter of course that the institute's director, Prof. Robert Schürhuber, provided an instructive contribution to the conference, including a small live experiment supported by his IEAN assistants.

Follow us on: https://www.linkedin.com/feed/update/urn:li:activity:6990642279308779520

To discuss the future orientation of the Institute as well as internal processes and procedures, the entire staff went on a retreat on 5 October 2022. In keeping with our profession, electrical power engineering, our workshop took place at the foot of the Kölnbreinsperre in the Berghotel Malta/Carinthia. In autumnal sunshine, a wide variety of questions and opinions were discussed.

The second day brought a marathon of 4 guided tours and visits to the Malta-Reißeck power plant group of Verbund: First thing in the morning we started with a tour over and through the dam wall of the Kölnbreinsperre, which is the highest dam in Austria with a height of 200 metres. Afterwards, the recently modernised Malta Oberstufe power station at 1655 m above sea level was visited with its two reversible vertical Francis pump turbines (5 - 80 MW each) together with the associated converters. Back in the valley, the tour continued past the impressive penstocks to the Malta main stage power station with a total congestion power of 730 MW distributed over four machine sets. From there we continued to the impressive Reißeck II power station, which with a capacity of 430 MW is the second largest pumped storage power station in the Malta-Reißeck power station group and was built completely underground in the mountain due to its cavern design. Many thanks at this point to our colleagues from Verbund for the great insights and the highly interesting guided tours.

At the end of the three-day team-building excursion, the last energies of the participants were activated to undertake a hike to the Umbal Falls in the Virgen Valley in East Tyrol.

Daniel Herbst

With his stage performance "Netzfehler - wir müssen draußen bleiben" energy technology researcher Manuel Galller from Graz University of Technology won the Science Slam 2022 at the Orpheum in Graz.

Dear Manuell, our institute is proud to have you as a staff member with us.

You can find a summary of the Science Slam: here

The Kaprun Oberstufe hydropower plant is part of the Kaprun power plant group. This group consists of several storage and pumped storage power plants and is located in the Glockner Group in Austria. In the Kaprun Oberstufe power plant, two full converter machine sets with 85 MVA each are currently being commissioned in the course of a power plant revitalisation. Thanks to the speed variability, active power points can now be flexibly approached at optimal efficiency levels in generator and pump operation. Thanks to the high active power flexibility, Kaprun Oberstufe makes an important contribution to achieving the energy transition and contributes to the stability of the Austrian transmission grid. The Institute of Electrical Power Systems TU Graz supported the operator of the power plant, Verbund Hydro Power GmbH, in carrying out a measurement to investigate the operating behaviour and the grid feedback effects. In the process, 34 measured variables were recorded and evaluated in a time-synchronised manner. Thanks to our colleagues at the University of Applied Sciences Upper Austria for their support with measuring equipment.

You can find further information at: ww.iean.tugraz.at.
Report: https://www.linkedin.com/feed/update/urn:li:activity:6939968207814348800

At the invitation of Austrian Standards International (ASI), the Austrian Electrotechnical Association (OVE), the European Commission, the Federal Ministry for Digitalisation and Economic Affairs (BMDW) as well as the Austrian Federal Economic Chamber (WKO), an information event on the new EU standardisation strategy (ENS) was held at ASI in Vienna on 9 June 2022. Numerous experts from the branch illustrated the importance of standardisation and the relationship with new challenges. Under the motto "green, digital, future-oriented", various aspects of different stakeholders were highlighted and discussed. Representatives of the EU Commission, the Austrian economy, education and training institutions, standardisation organisations and the BMDW presented their respective views on the topics to provide a basis for interesting discussions. Daniel Herbst participated on behalf of IEAN with a presentation on "Young Professionals and the Future of Standardisation".

Further information and pictures can be found at: austrian-standards.at/.../EU-Standardisierungs-Strategie

Copyright picture: Credit: Austrian Standards, Fotograf Lukas Ackermann
Text: Daniel Herbst

From 21.06. to 22.06.2022, a total of around 470 experts in protection and control technology from almost 10 nations met at the VDE ETG/FNN Tutorial in Berlin/Germany. In total, the audience was provided with technical contributions from practice-oriented research and industry in the form of almost 40 oral presentations and 32 posters. The topics discussed included

• the digital substation (IEC 61850),
• security aspects related to communication (cyber security),
• the context of the "Energiewende" (including protection concepts and secure grid operation)
• but also new ideas for new challenges.

Parallel to the presentations and workshops, the event was rounded off by an exhibition with 29 industry-specific manufacturers. IEAN was represented with an oral speech (Prof. Schürhuber), two posters (DI Galler, DI Herbst) and a total of 4 people on site.

DI Galler received first place in the Best Academic Poster Award for his contribution entitled " Distanzschutzverhalten auf den Fehlerstrombeitrag einer Erzeugungsanlage mit Vollumrichter “. Congratulations from the entire IEAN team!

Daniel Herbst

On 7 June 2022, the BIG Bundesimmobiliengesellschaft m.b.H. invited participants to an information event on BIG and UNIVERSITIES 2022. Wolfgang Marth (BIG Graz) organised 10 high-level speakers from science and industry who gave keynote speeches on the four key topics of

• Photovoltaics,
• OVE E 8101,
• EMC and
• electric vehicle charging stations

which laid the foundation for further discussions and technical exchanges. With the three pillars of the event "Sustainability - Electrical Engineering - Safety", the organiser has already summarised the burning issues of the industry in the subtitle. After a break of several years, a total of around 100 participants (all of them planners, partners from industry and research or employees of the Styrian universities or BIG) exchanged their views on the above-mentioned issues during the one-day event. Rector Harald Kainz also highlighted the importance of such an interaction between all stakeholders in the course of his opening speech. The IEAN was able to support the information event with presentations by K. Friedl, D. Brankovic, M. Fürnschuß, E. Schmautzer and D. Herbst.

Daniel Herbst

Students and institute members of IEAN had the opportunity to visit different mast construction sites of the Salzburg line in consultation with APG. APG took the time for one day to answer questions of all excursion participants and to present masts in different phases of completion.
Many thanks for this!
Finally, the absolute highlight of the day was the observation of the rope pull between two pylons. It was an absolute experience to witness line construction live and to be able to perceive the dimensions as well as the challenges of this demanding expansion project in Austria.

OMICRON serves the electrical power industry with innovative products and services for testing, diagnostics and monitoring of assets worldwide. We help to make the generation, transmission and distribution of electricity safe and reliable.

complete program:

In high voltage grids with a high percentage of cables, voltage limits can be exceeded due to the increased reactive power demand. A mitigation method can be shunt reactors, which are located on the tertiary side of coupling transformers or directly on the high voltage substations. For proper operation, not only the static compliance but also the transient voltages must be below the maximum limits of the equipment. With the investigation of switching operations for different compensation variants in EMTP, IEAN supported the grid operators in the planning of a substation with gas insulated switchgears. The variants were analyzed for grid restoration scenarios, grid resonances and the use of optimized RC snubbers in the medium voltage.

The head of the institute, Prof. Schürhuber, was especially interested in having another Christmas party in presence in 2021. The COVID regulations allowed this, so, no sooner said than done, we met on 2021.12.21 at the Ristorante/Focacceria San Pietro.
In a fine little round we were able to discover the full culinary range of this restaurant. Some of us were even tempted to try the house specialty, focaccia. At the beginning quite skeptically, however, finally all those colleagues who dared to do so were delighted by the specialty. Following an old tradition, our external lecturers were of course also invited to the IEAN Christmas party and, like all attendees, they visibly enjoyed the party.

From 6 to 7 October, the OVE Energy Technology Conference 2021 took place this year as a hybrid event with about 200 participants at the voestalpine Stahlwelt in Linz. Prof. Schürhuber talked about the technical challenges of integration of renewable energy sources in his presentation on "Grids and Power Electronics". Furthermore, the evening event was used to award prizes for graduation theses, and the IEAN would like to take this opportunity to congratulate Philipp Hackl as one of the winners of the Prof. Werner Rieder-Preis.

...the Christmas party is a fixed point on the calendar of the Institute of Electrical Power Systems (IEAN). Following this year's motto that "special times require special measures", we decided to hold our pre-Christmas get-together in 2020 virtually. Prof. Schürhuber summarised the smaller and larger highlights of the institute's year in his speech, the entire IEAN choir sang their way into the Advent season together, a virtual room escape game challenged the brain cells and one or two recited poems rounded off the event. Nonetheless, we are all already looking forward to when the social distance finally can be reduced to a good level and we can sit together again in the usual way.

The IEAN wishes all its friends and their loved ones a Merry Christmas and a Happy New Year 2021!

In close cooperation with the IHS of Graz University of Technology, the IEAN carried out the final earthing measurement of the new Murkraftwerk Graz Puntigam. The aim of the measurement was to check the earthing, equipotential bonding and lightning protection system of the power plant, which is already in full operation.

IEAN and IHS accompanied the project Murkraftwerk Graz Puntigam from the very beginning with regard to the earthing, equipotential bonding and lightning protection system. In cooperation with the planners, a special earthing and lightning protection concept was developed for this power plant, which ensures the protection of persons, animals and property.

In close cooperation with IHS, IEAN carried out the final measurement of the earthing system of the new substation Villach Süd. The 220/110 kV Villach South substation is designed as an outdoor switchgear, serves as a grid support and is intended to contribute to the continued reliable supply of electricity in the Villach area. IEAN and IHS were involved in the project from the very beginning and contributed important aspects regarding the earthing and equipotential bonding and lightning protection system to the conceptual design of the substation. The aim of this measurement was to check the effectiveness of the earthing, equipotential bonding and lightning protection system to ensure the protection of persons, animals and property. Furthermore, the measurement results serve to verify the calculations of the earthing, equipotential bonding and lightning protection system of the Villach Süd substation carried out at IEAN.

The increasing number of scientific journals, technical literature and theses in the inventory of the Institute of Electrical Power Systems required a new structuring of the institute library. The outdated archiving system was replaced by the centrally administered library system of Graz University of Technology. Thus, in addition to books, all diploma and master theses, dissertations and habilitations have been added to the inventory system of the library of Graz University of Technology. During the following reorganization of the institute library, some treasures were rediscovered.

The grid restoration strategy after large-scale blackouts in Austria focuses on hydro power plants in Salzburg and Carinthia. The management of the grid restoration is not only trained on the simulator, but also regularly tested on the real grid through black start and island grid tests. On September 18, 2020, such tests were carried out by KELAG and Kärnten Netz with the Fragant power plant group. The Institute for Electrical Power Systems (IEAN) accompanied these tests as a scientific partner, carried out part of the measurements and took over the evaluation of the measurement data.

Changes in the Earth's magnetic field can cause unwanted low-frequency currents in our electrical transmission grid. These currents flow through grounded transformer star points. In a joint research project with the Austrian transmission grid operator APG and Siemens, IEAN measures these low-frequency currents, also known as geomagnetically induced currents (GIC).

In order to be able to measure these currents also in case of future geomagnetic disturbances (GMD), the hardware of some measuring devices was updated on September 23rd and 24th, 2020. IEAN would like to thank the APG staff who supported us with the maintenance.

In the past few days, despite the currently difficult circumstances, five students have successfully completed their Bachelor's or Master's thesis at IEAN.

Congratulations to Benjamin Jauk, Abedin Bytqi, Matthias Rüschitz and Konstantin Tschabuschnig for successfully defending their master thesis. Congratulations also to Peter Wohlfart on the successful completed his Bachelor thesis.

The IEAN wishes you success in your future professional life or in your further studies. You are cordially invited to visit the IEAN again in the future - we always look forward to see you again!

Despite the current circumstances, it is possible to start your Bachelor's or Master's thesis at the IEAN. You can find our currently advertised work on the website. If there is nothing suitable, please contact us by phone or e-mail.

In the course of filming a documentary on the topic of geomagnetically induced currents in Austria, the IEAN was invited to the Conrad Observatory. Prof. Renner presented our simulation tool in the tunnel and explained the activities of IEAN in this area and the importance of the entire research area.

In January 2020, IEAN installed another measuring device for recording low-frequency neutral point currents in the Austrian transmission grid. In a joint research project with APG and Siemens, the influence of low-frequency neutral point currents on power transformers and the transmission grid is being investigated. These currents are influenced, for example, by changing solar activity and are therefore also called geomagnetically induced currents (GIC). Thanks to APG and Siemens for their support!

In the pre-Christmas season 2019, the Institute of Electrical Power Systems measured the behavior of the earthing system at a 380 kV substation, located directly next to an electrified railway. The reason for this is the extension of the railway and the construction of a pedestrian crossing. The measurement results serve as a basis for the calculations, on which results the earthing systems of the future installations will be dimensioned in such a way that, after integration into the existing earthing system, the protection of persons and property can be guaranteed both in normal operation and in the event of a fault.

On 13th / 14th November, the second technical colloquium of energy technology took place at the Institute for Electrical Power Systems at the TU Graz.

Prof. Bernd Oswald from Hannover, Prof. Peter Schegner from Dresden, em. Prof. Lothar Fickert from Graz and Prof. Lutz Hofmann from Hannnover, discussed with Prof. Robert Schürhuber and Prof. Herwig Renner from the IEAN current developments in the field of energy technology and exchanged views on research results. Furthermore, the Grazer culture and gastronomy could impress the guests.

At the beginning of the week, on 30.09.2019, IEAN visited the Siemens transformer plant in Linz. In addition to a project meeting, the students and employees of the IEAN had the opportunity to visit the plant in Linz. At the Linz location, each transformer is developed and produced individually for the special applications of the customers. From core layering to acceptance testing, all process steps are carried out at the site in Linz.

The IEAN met on the 23.09.2019 in the Wachau in order to set the course for a successful future of the institute. Under the excellent leadership of Bernhard Ibertsberger, a lively discussion about the challenges and goals of the institute developed in the morning, which was dealt with in detail after lunch in small groups.

Through the open and eye-level discussion, the different interests of the institute members could be cast into a common vision for the development of the institute. The labor-intensive day ended with the one and other wine at a cozy sitting together in a local Heurigen.

The second day was completely devoted to energy engineering with the visits of the nuclear power plant Zwentendorf and the substation Dürnrohr. The Zwentendorf NPP is worldwide unique, because it has never been in service. Therefore, areas of the reactor can be inspected which are normally not accessible due to radiation exposure even after shutdown. Thus, a direct view into the pressure vessel of the boiling water reactor and the committing of the containment is possible.

The second day was completely devoted to energy engineering with the visits of the nuclear power plant Zwentendorf and the substation Dürnrohr. The Zwentendorf NPP is worldwide unique, because it has never been in service. Therefore, areas of the reactor can be inspected which are normally not accessible due to radiation exposure even after shutdown. Thus, a direct view into the pressure vessel of the boiling water reactor and the committing of the containment is possible.

After extensive restoration work, a model of a Francis turbine can now be seen in front of the rooms of the Institute of Electrical Power Systems.

Many thanks to ANDRITZ HYDRO GmbH for providing the turbine model and many thanks to the IHS mechanical workshop (Anton Schriebl and Christoph Probst) for built-up the metal substructure.

Prof. Schürhuber, DI D.Herbst, DI M.Fürnschuß

In the period from 20 August to 30 September 2019, the Institute of Electrical Power Systems was represented by four academics at Tongji University in Shanghai. During the first week, Prof. Dr. Schürhuber, the institute's head, held a special lecture on " From Energy Turnaround to Challenges for High Penetration of Renewable Energy ". Further lectures were given by Em. Prof. Dr. L. Fickert and Dr. Ziqian. Furthermore, Mr. Alexander Atzmueller supported the Institute for Rail Transit in the sense of deepening the scientific cooperation by evaluating technical literature regarding the reliability of the power supply in the metro area.

Zigian Zhang

On 21.06.2019 we received a delegation of the Chinese Ministry of Science and Technology at our institute. The high-ranking delegation of representatives of the government and the automotive industry visited the laboratory facilities of our Institute of Electrical Power Systems, the laboratory of the Electrical Drives and Machines Institute as well as the Nikola Tesla Laboratory of the Institute of High Voltage Engineering and System Performance. The trip of our Chinese partners focused on the latest scientific findings in the field of electric drives, alternative fuels and e-mobility. Our institute presented in the course of its projects around electrical safety as well as protection against electric shock at DC charging stations for electric vehicles.

Ziqian Zhang and Daniel Herbst

With the signing of the cooperation agreement on 24.06.2019 a new era of cooperation between the Faculty of Electrical Engineering of Shanghai Dianji University and the Institute of Electrical Power Systems of Graz University of Technology has started. The two institutions, represented by Vice Rectors H.Bischof and D. Chen, our dean W.Bösch and professors R. Schürhuber and G. Chen, jointly unveiled a plaque in front of our institute expressing the university exchange. In addition to interesting discussions between the delegation participants and the representatives of Graz University of Technology, various laboratory facilities were also visited. We are already looking forward to a long-term partnership with our Chinese colleagues, for example in projects in the institute's own Power Hardware-in-the-Loop laboratory in the field of renewable energies.

Ziqian Zhang and Daniel Herbst

On 27.05.2019 we had again the opportunity to carry out an excursion to the thermal power plant Mellach of the Austrian Thermal Power Association as part of the lecture Electrical Energy Systems 2.

During this excursion, we were able to visit the coal-fired power station, the gas and steam power plant, the control room and the switchgear and receive detailed explanations on function and operation. We also got an interesting insight into the current driving style of thermal systems, which are strongly influenced by redispatch.

In sum, this excursion was an ideal complement to the lecture, in which the theory of thermal power plants was discussed in advance.

Under the title "Future Challenges for Electrical Power Systems", Prof. Schuerhuber's inaugural lecture was able to strike a balance between previous research work, the challenges in energy technology and the future research contributions of the Institute of Electrical Power Systems.

As a driving force for the changes in the energy sector, Prof. Robert Schuerhuber cites our rising consumption and mainly carbon-based production of energy. Due to the previous handling of raw materials, humans action influences the earth ecosystem more and more negatively. In order to counteract this negative trend, the electrical energy supply plays a key role. Due to the versatile usability, for example, in the area of mobility, air conditioning and heat engineering, resources can be used more effectively. The Institute of Electrical Power Systems do research for example in the field of sector coupling and in the planning and operation of large networks.

After the inaugural lecture, numerous guests from industry, families and universities discussed in a pleasant atmosphere in the foyer of the Energy Center Graz.

The Institute

In October 2017, Prof. Robert Schuerhuber took over the Institute of Electrical Systems from Prof. Lothar Fickert. In order to highlight the current and future research activities in the field of energy networks, the institute bears the name "Institute of Electrical Power Systems". The three core competences of the institute lie in the areas of

• calculation and planning of energy systems and of the grid connection for generating plants,
• analysis of quality of supply and supply reliablility,
• Assessment of earthing systems and questions regarding personal safety.

Under the motto Team Building, the winter sports enthusiasts of the IEAN spent a day of skiing in Schladming. With the view of a lot of sunshine and 20 cm of fresh snow on the slope, on March 12th, they started in the best of moods towards Planai and Hochwurzen.

On the last downhill, the employees competed in a downhill race.

Around 4 pm, the all-round successful skiing day ended with the last swing - the “Einkehrschwung” - at the valley station in Schladming. With a good day of skiing in the thighs and uninjured, all employees started their way back home to Graz at 5:30 pm.

The last stop of the field trip was to the district heating plant of Stadtwerke Klagenfurt, the central hub of the Klagenfurt district heating network and the location of the energy control center of Stadtwerke Klagenfurt. Until the turn of the millennium, a coal-fired combined heat and power plant (CHP) was operated at the site. After decommission of the CHP plant, modern gas boilers were put into operation to ensure the supply of the city with district heating. During the dismantling of the old steam power plant, the 70-year-old brick-built boiler and a partially dismantled turbine-generator were obtained.