Tutorials
Half-day tutorials will take place on Monday, June 22nd from 09:00 to 12:30 and from 13:30 to 17:00 at E.ON ERC, Mathieustr. 10, 52074 Aachen . Following topics will be offered:
- Topic 1: Harmonic Modeling and Stability in Power Electronics Based Power Systems (E.ON ERC, room 00.24, 13:30 - 17:00)
- Topic 2: Advanced Topics in PV Applications (E.ON ERC, room 00.23, 09:00 - 12:30)
- Topic 4: High-Voltage SiC Devices and High-Power Converters for Efficient and Flexible Future Distribution Grids (E.ON ERC, room 00.24, 09:00 - 12:30)
"Technical Tour 1" is for persons that attend only the morning tutorials.
"Technical Tour 2" is for persons that attend the afternoon tutorial (incl. those who attend a morning and the afternoon tutorial).
All tutorial attendees are invited for lunch and the according coffee breaks.
Topic 1: Harmonic Modeling and Stability in Power Electronic Based Power Systems
Power electronics technology, featured with full controllability and high-efficiency, is changing the way of electricity generation, transmission, distribution, and consumption. Power electronic based power systems are thus evolving with numerous applications of power electronic converters in renewable energy sources, energy storage systems, and energy-efficient loads. The nonlinear switching operation and fast control of converters tend to bring in a series of new power quality and stability challenges. High-frequency (2-150 kHz) switching harmonics may be aggravated by converters, which may even trigger resonance frequencies in the power system. Steady-state harmonic coupling and dynamic interactions among converters may also become more apparent, which may also further interact with the reactive elements of systems, leading to instability phenomena over a wide frequency range.
The main objective of this tutorial is to introduce the harmonic modeling and stability analysis methods for power electronic based power systems. It begins with a review of harmonic modeling methods for grid-connected converters, ranging from the small-signal modeling based on the state-space averaging theory to the harmonic state-space modeling based on linear time-periodic system. System stability analysis tools are then discussed and implemented with a number of examples emulating renewable power plants and micro-grids. The instability phenomena caused by the different levels of controllers, e.g. current control, grid synchronization, and power control, are illustrated. Active harmonic disturbance rejection and stabilization techniques, such as the virtual impedance control, passivity-based control, passive and active dampers, are subsequently discussed. Perspectives on the challenges and future trends of modeling, stability analysis and control of power electronic based power systems are also given.
Topic 2: Advanced Topics in PV Applications
Tamas Kerekes, Mario Cacciato, Laszlo Mathe, Francesco Gennaro, Sergiu Spataru
The objective of this tutorial is to present the most recent progress in several hot topics within photovoltaic (PV) system, from panel to plant level. The first part of the tutorial will give an update on the new features of PV panels, including functions like: firefighter protection, theft protection and diagnostic functions. However, from the control point of view several tasks like maximum power point tracking (MPPT), voltage and current control can be distributed which makes the control very complex. By installing a communication network between the panels a more simple centralized control can be realized. Furthermore, advanced diagnostic methods will be presented, that can be used to identify failures and degradation in PV panels, such as: optical losses, solar cell cracks and fractures, increased series resistance type degradation, shunting and potential-induced degradation. The methods presented are based on analyzing the light and dark I-V characteristic of the PV panels, as well electroluminescence imaging techniques.
The second part of the tutorial will deal with the converter focusing on certification, static efficiency, MPPT dynamic efficiency and EMC. The commercial competition is often played in terms of claims for weighted (European) efficiency but, this is measured in static conditions, while evaluating the inverter performance in term of energy produced on the basis of that available from PV field would be a more accurate method. The method for accurate estimation of inverters energy capability will be explained, considering the measurements of static and dynamic MPPT efficiency as well as a survey on new grid-connection code and EMC requirements. Finally auxiliary functions, like frequency support such as Frequency Sensitive Mode (FSM) and Inertial Response (IR) are presented, with the main goal of demonstrating their necessity in a power system with increased level of PV penetration. Using such functions large scale PV plants will become active players on the electrical power system market.
Topic 4: High-Voltage SiC Devices and High-Power Converters for Efficient and Flexible Future Distribution Grids
Subhashish Bhattacharya, Rik W. De Doncker
Over the last years, electricity generation especially in Europe has changed significantly. From a centralized top-down system, power generation has evolved to a more decentralized system. Moreover, vast amounts of renewable but volatile energy sources like wind and photovoltaic have been installed in the medium-voltage and low-voltage distribution grid. In the future, more flexible grid structures that increasingly rely on power-electronic converters will be needed to cope with this new situation of distributed and volatile power generation.
Moreover, the advent of wide bandgap devices made from SiC or GaN has revolutionized low-voltage power-electronics applications like for example roof-top photovoltaic systems or very-low voltage dc-dc converters for power supply of processor cores. Correspondingly, these new materials also might revolutionize medium-voltage and high-voltage applications. Thereby, these devices would become a key enabler for flexible electricity grids of the future.
In a first part of the tutorial, the design of high-power converters will be covered. Exemplarily, the tutorial describes in detail the design approach for the three-phase dual-active bridge dc-dc converter. This demonstrates the influence of the power semiconductors on the passive components and the efficiency.
In a second part, the tutorial will develop an understanding of the high frequency switching characteristics especially of medium-voltage SiC devices. It will focus on devices like 10 kV to 15 kV SiC MOSFETs and Schottky diodes as well as 15 kV SiC IGBTs. To judge their potential in future electric grids, these SiC devices are evaluated in applications like FACTs, dc-dc converters, high-speed generators and ac-dc interfacing converters. In a comparison with silicon IGBTs and IGCTs, the advantages of wide-bandgap devices are illustrated.