Requirement
In order to connect a cogeneration plant to public grid, our customer needed to demonstrate to RTE that his facility was according to requirements. Especially, he needed to simulate the following cases :
- U/Q diagram
- Dynamic behaviour of voltage control and stability in small movements
- Stability in case of modifications of export lines configuration
- Stability in case of short-circuit
- Behaviour under voltage drop
- Behaviour under frequency variations
Example of U/Q diagram
Realization
CAPSIM has modelled with PSIM software the cogeneration plant network composed of motor/generator units and their speed and voltage control. Load flow calculation had been made in order to draw the U/Q diagram of the plant. Transient simulations allowed to analyse stability of the plant during disturbance events. And a frequency analysis had be made to calculate stability margins of controlled system.
Results
The study was used in order to demonstrate to RTE that plant could respect requirements and to deal deviations when criterions could not be respected.
Example of Nyquist diagram allowing stability margin calculation
