Requirement
Customer : ITER Organization
ITER is a very large-scale international scientific experiment for demonstrating the scientific and technological feasibility of electricity production using energy from nuclear fusion and leading to its industrial and commercial production.
With this goal, a magnetic plasma confinement system called a tokamak has been constructed using superconducting coils. These coils are supplied on a 66 kV and 22 kV distribution grid via AC/DC thyristor converters (12 pulses). This grid is supplied by three 3-winding transformers, 400kV/66kV/22kV, allowing it to be connected directly to the RTD grid on a dedicated 400 kV line.
The ITER Tokamak
The power consumption of the coils fluctuates greatly during a plasma shot and, in particular, during its initiation and extinction. The impact of these power fluctuations on the grid needed to be estimated in order to validate adherence to the connection constraints of the ITER grid to the supplier distribution grid including limits for active power, reactive power and voltage levels of the various buses.
Hence, the requirement expressed by ITER was to obtain a tool which could simulate the voltage plan of the grid and the power flows throughout the duration of a plasma shot scenario.
Realization
CAPSIM produced a simulation tool of the ITER grid, programmed in MATLAB language. This tool is able to take the currents and DC voltages of the coils, together with the grid parameters, and calculate the transient power flows and the voltage levels that occur. This calculation is made possible by integrating the models of the consumed power for each inverter as a function of the different topologies envisaged and by putting in place a load flow calculation (power flow in the distribution grid). A graphic interface makes it possible to use the tool and to configure these simulations in a clear and efficient manner.
The graphic interface produced allows the many parameters to be varied, such as the distribution of loads on the grid, the topology of the various inverters and the characteristics of the reactive compensation systems.
This tool was developed in such a way as to integrate the calculations of the flicker fusion rate as well as the harmonic calculations.
Results
This tool has been used to check the behaviour in terms of the supplier connection constraints for the ITER grid, in spite of its specific characteristics. These results entered into the discussions held with the energy supply compagny in which CAPSIM participated as part of its assistance project for ITER Organization.
Power and voltage results for the 66 kV and 22 kV bus
