Tutorial 1:Flexible Distribution Grids based on DC Technologies
The liberalization of the energy market led to more decentralized power generation, such as small-scale CHP units and volatile, renewables power sources (wind und PV). Already in Germany, the installed capacities of power generator that feed in the grid are dived almost evenly at each voltage level, i.e. the high-voltage transmission grid, the medium- and low-voltage distribution network. In this tutorial, we focus on the DC technologies that support the so-called underlay grid, i.e. interconnecting substations and prosumers in the distribution grid. To realize such a multi-terminal, interconnected grid structure DC grids are clearly the best option. The advantages of DC grids in collector fields of wind and PV farms, as well as the medium- and low-voltage distribution grids will be presented in detail. Concepts for DC technologies in energy efficient home and buildings, as well as interoperability to electric vehicles are presented. DC components, DC conversion systems (DC-to-DC converters and DC protection gear) and their controls will be analyzed in detail.
Status of standardization activities are presented. Furthermore, the automation and the dynamic behavior of multi-terminal DC substations are briefly discussed. The tutorial concludes with an overview of the automation topics: on the one hand the new architectures required to support hybrid AC/DC solutions and on the other hand the benefits that the future digitalization via the Internet can offer, such as virtual aggregation of power plants, storage devices, sector coupling and prosumers.
Tutorial 2: Power Architectures, Application and Control of DC Distribution System and Microgrids
DC distribution systems have higher efficiency, better current carrying capacity and faster response when compared to conventional AC systems. They also provide more natural interface with many types of RES and ESSs and better compliance with consumer electronics. Furthermore, when components are coupled around a DC bus, there are no issues with reactive power flow, power quality and frequency regulation, resulting in a notably less complex control system when compared to the AC coupled systems. All these facts lead to more and more applications of DC systems in modern power systems, including data/telecom centers, maritime industry, high voltage transmission systems, electric vehicle charging infrastructure, and DC microgrids. Still, design and operation of general DC systems imposes a number of specific challenges.
The aim of this tutorial is to identify these challenges and transmit to the audience the instructor’s industrial and academic experiences in the field. Tutorial will provide a framework in hardware and control design of DC distribution systems and microgrids, as well as overview of recent research activities in this area. Practical requirements and implementation details of several types of DC distribution systems used in real world industrial applications will be presented. Also, a number of study cases power architectures will be discussed in the first part of the tutorial. On the other hand, second part will address the features of several types of coordinated control design concepts that can assure intelligent real-time control of MGs. Moreover, the concepts of constant power load (CPL) and negative impedance instability will be explained in detail. In line with this, principles of linear stability analysis techniques will be reviewed and a broad class of stabilization techniques for MGs loaded with CPLs will be presented and examined. Tutorial will also present the view of the instructor on the promising research directions and future industrial applications in this area.
Tutorial 3: Power Electronics and System Design for LVDC Microgrids
DC based low-voltage power supply networks offer many advantages over the historically grown AC infrastructure. The presentation shows the potentials for cost reduction, efficiency enhancement and equipment miniaturization.
Modern DC grids are increasingly less connected hard with battery storages, resulting in networks that are fully formed by power electronic converters. This entirely changes the grid characteristic compared to the conventional AC grid. Questions arising from this, concern grid stability and grid regulation, as well as fault and protection topics. Power electronics, on the other hand, also allows to realize completely new functionalities, new control and safety concepts. Selected aspects are discussed in the presentation.