Technological innovations and concepts, which can be characterized as Power Electronics, can nowadays be found in almost any electrical device or utility. A power electronic converter is a device, which converts electrical power from one form to another e.g., by changing the voltage level in a DC system or frequency in an AC system. The size of power electronic converters ranges from devices with size of a rice grain used in mobile applications up to large converter stations spanning over several hundreds of square meters, such as converter stations in power transmission networks. In principle, all of the electricity produced or consumed is at some point processed by a power electronic converter. Every electronic device we use includes a small power-electronics-based power system inside.
Power electronic converters transform electricity between different forms, such as from alternating current to direct current, allowing us to power our laptops from a wall outlet. Electrical storage and its associated power converters are becoming increasingly important to balance uncertain power production from renewable energy sources, such as wind and photovoltaics. The world’s energy systems are under a paradigm shift from traditional power systems to power-electronics-based power systems. In a power-electronics-based power system, the consumer may also act as a producer and may be a part of a microgrid, which is disconnected from rest of the national power grid. This in turn eliminates power outages but allows electricity trading between the grid and the customer when required. The paradigm shift to power-electronics-based power systems arouses profound challenges.
Power Electronics -research group at the Laboratory of Electrical Energy Engineering focuses on improving modern power converters in terms of power quality, overall control performance and stability. The long-term goal of the group is to enable stable and reliable power systems with 100% penetration of renewable energy by solving the most critical problems from the power electronics point-of-view. The main focus areas can be separated as follows:
* Novel control concepts to enable 100% share of renewable energy in future power systems
* Modeling and control of electrical drives
* Integration of power converters to smart and micro –grids
* Dynamic modeling of power converters to enable deterministic control design and passive component sizing
* Improvement of power quality in modern power systems
Figure 1 illustrates the conceptual design of our Power Hardware-in-the-Loop laboratory. The electric power flows between the renewable energy source simulator (or battery) and the three-phase voltage amplifier. The power electronic converter is used for three-phase DC-AC conversion. The setup allows studying the dynamic behavior, stability and power quality of grid-connected renewable sources, such as photovoltaic and wind generators, and grid-connected battery storages. Real environmental data from the 13.7 kW rooftop plant can be used to reproduce varying climatic conditions, dSPACE control platform for implementing inverter control system and RTDS for simulating the power system.
Figure 2 illustrates a measurement setup which allows studying the power quality and stability of a grid-connected photovoltaic inverter. Furthermore, the setup allows characterizing inverter AC-side impedance (up to power level of 15 kW) which is an important design parameter for stability in interconnected power electronics based power systems.
Contact: Tuomas Messo, email@example.com