The task has been carried out as a combination of numeric simulations and laboratory demonstrations.

Summary of achievements

New control strategies

• Defined a control strategy based on the concept of Virtual Synchronous Machine (VSM) for control of converters integrated in power systems with weak frequency regulation as:
  • Control of converters operating connected to grids benefiting from frequency support
  •  Control of converters operating in islanded grids with presence of synchronous generators
  • Control of converters operating in islanded grids dominated by power electronics with low or even zero physical inertia.
• Validation of the VSM concept and of its implementation by numerical simulations and on an experimental setup
  • Simulations performed in the Matlab Simulink environment
  • Experimental tests executed on a 20 kW converter unit while control running on a OPAL-RT platform.

Implementation of converter control algorithms on a FPGA-based processor board

• FPGA-based processor board
  • Xilinx Virtex5 FX 30 T
  • Embedded PowerPC440 core
  • 40 MHz ,  8 channel, 12 bit AD converter
  • 128 MB flash, 256 MB DRAM, 64k Eeprom
  • Interface for LEM current transducers
• Designed for converter control in drives and grid connected configurations
  • Local user interface with display
  • CAN-communication for receiving operating modes and references
• Operated as general purpose white-box converter controller in the lab

60 kVA laboratory converter modules

• Developed in-house by support from OPE and other projects
• Based on Semikron SEMIKUBE modules
• 400 V, 100 A RMS ratings
• LCL filter 500 µH, 50 F, 200 µH
• Cabinet contains contactor, pre-charging circuit and discharge resistor
• Internal rectifier to be used for motor drive demonstration
• Prepared for operation in back-to-back or DC grid configurations

Converter control overview