Nyhet | 2015-06-26 | 13:45

Frequency control – optimal distribution of FCR-N in real time

Master's thesis by Linda Ekmarker, Technical physics (300 hp), Uppsala universitet.

Supervisors at Vattenfall: Erica Lidström and Daniel Wall.

Abstract

Frequency control systems are used to keep the grid frequency at the nominal value of 50.00 Hz. Vattenfall employ hydropower plants for this purpose as they can easily adapt their production to counteract frequency deviations.

This master thesis focuses on trying to improve Vattenfall’s mechanism to provide FCR-N (Frequency Containment Reserve in Normal operation) for primary frequency control, i.e. the turbine governor. The efforts are made to operate the plants more efficiently, decreasing distribution losses and thus increasing the profits.

The current control system was modelled in MATLAB’s simulation tool Simulink to understand its complexity and to be used as base for comparison. Then a new model was developed based on the idea to introduce a global governor for the frequency control in each plant which controls the input signal to the individual turbine governors of each unit. OPT-data (tabulated data indicating how to operate a plant at the highest possible efficiency) was used to determine how to optimally distribute the FCR-N among the active units in a plant in real time.

The conclusions which can be drawn from this master thesis are that it is possible to make a more optimal distribution of FCR-N in real time. However, it has not been possible to make a good comparison between the two models and the results regarding the profits which can be made by introducing this new type of governor are therefore very inconclusive.

Improving the parameter values for the proportional and integral gains of the individual controllers and the precision of the OPT-table lookups may further improve the new model and also make it possible to perform a valid comparison between the two models.