The objective has been to provide the required advanced control strategies for grid connected and islanding power electronics converters.

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