The power system laboratory includes models of power plant generators, transformers, distribution networks and a transmission network with relay equipment, including an Omicron CMC356 relay tester for testing digital relays, used both in student projects and research activities. Also models of wind turbines and PV systems can be realized in the laboratory.
For measurements both universal and special instruments are being used. Many of the instruments have IEEE-488 interface or other interfaces which are used to transfer data to a computer for signal processing and documentation.
The section has licenses to many different software packages for simulating stationary and transient conditions in the network grid, for instance DigSilent from Power factory, PS-CAD/EMTDC, and Simulink and Matlab. Besides using measurements from the laboratory for verifying the simulation models, also data measured directly at different sites in the network grid are used for verification.
Phasor Measurement Unit (PMU) is a device which measures the electrical waves on a power grid, using a common GPS time source for synchronization. PMU is the significant component of Wide Area Measurement System (WAMS) for future power systems. Time synchronization allows synchronized real-time measurements of multiple remote measurement points on the grid. In power engineering, these are also commonly referred to as synchrophasors and are considered one of the most important measuring devices in the future of power systems.
The laboratory facilities also include:
- Smart Distribution Network Platform
- DC Network Test System
- Modular Multilevel Converters in Power Systems
- DFIG-based Wind Turbine system
Smart Distribution Network Platform
The smart distribution network platform includes two sets of dSPACE 1006 control units, and 4 Danfoss inverters, as well as transformer, active and reactive loads. The Danfoss inverters work as distributed generations and active loads, which are connected to the transformer by a bypass switch. The dSPACE control unit realizes relevant control algorithm.
The prototype can be used to test, analyze, and optimize various control algorithms in the smart distribution systems, such as power control, harmonics control, unbalance control and stability analysis.
DC Network Test System
The DC network test system includes two dc-dc converter prototypes: Parallel-Connected Single Active Bridge (PCSAB) dc-dc converter and Double Uneven Power (DUP) dc-dc converter. These converter prototypes have been built to verify the feasibility and operational principle of the converter topologies especially for high power applications. The laboratory also includes grid-connected inverters which operate as a source or a load in the dc network systems. The overall test system is controlled by dSPACE system and an auxiliary circuit to transform control signals to optic signals has been developed in the laboratory.
Modular Multilevel Converters in Power Systems
The modular multilevel converter (MMC) may be used as power electronics devices in power systems, such as HVDC, FACTS and renewable energy integration. The laboratory includes a down-scale prototype of 3-phase modular multilevel converter (MMC), designed for the application of multilevel converters for renewable energy system (e.g. HVDC, STATCOM, and generator control, etc.). The 3-phase MMC consists of 6 arms and each arm is composed of 4 submodules (SMs). Each SM consists of a half-bridge converter. The switch in each SM can take 48A/600V. The dSPACE is applied for the sampling of the voltage and current signals and used for the control of the 3-phase MMC.
The prototype can be used to test, analyze, and optimize the control algorithm (e.g. voltage-balancing, harmonic elimination, etc.) for the 3-phase MMC for developing new control strategy for the application of MMC in renewable energy system.
DFIG-based Wind Turbine system
Doubly fed induction generator (DFIG) based wind turbine system is one of the most popular renewable energy integration system. The DFIG-based wind turbine system includes a 7.5kW DFIG, 11kW asynchronous induction squirrel cage motor (AISCM). The DFIG is controlled by a 5.5kW back-to-back converter and the AISCM is controlled by an 11kW inverters. The system is control by a Dspace 1006.
The setup can be used to test, analyzed and optical control algorithm for the DFIG for the balanced and unbalanced gird voltage, as well as the low voltage ride through (LVRT).