Real time implementation for Grid-forming control of type-4 wind turbines to mitigate voltage and frequency instabilities in high renewable penetration
S. Sethi (TU Delft - Electrical Engineering, Mathematics and Computer Science)
José L. Rueda – Mentor (TU Delft - Intelligent Electrical Power Grids)
M.A.M.M. van der Meijden – Graduation committee member (TU Delft - Intelligent Electrical Power Grids)
Irina Oleinikova – Graduation committee member (Norwegian University of Science and Technology (NTNU))
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Abstract
The increasing penetration of PE converter interfaced generation units in electrical power systems have given rise to many challenges in the power system operation. Two of the most important challenges are the voltage control and frequency control in the absence of conventional generation units. Furthermore, the PE converters can interact with the power system elements causing the power system to become unstable.
In this thesis, the effect of the wind turbines modified with grid-forming capability is analysed on the transmission networks as well as on the Offshore VSC-HVDC converter station. The dynamic response of the WTs is studied considering the high share of the power electronic converter interfaced generation.
It is shown when the wind turbine power converters are equipped with the implemented control strategy, they can provide voltage and frequency stability to the system and further upgrades can be added to enhance the system response. The control strategy implemented employs the direct voltage control which is upgraded with voltage dependent active current control for improving the transient voltage recovery of the system. The inertial response based on modifying the machine side converter is also added which extracts kinetic energy from the wind turbine rotor that improves the frequency response of the system following load change.
In the end, an offshore wind farm network is modeled which includes the offshore wind park connected to an offshore MMC HVDC converter station for delivering bulk power to the DC source connected via the HVDC cable. The developed wind turbine model is employed for integration in the offshore wind farms which has shown to eliminate the transient overvoltages occurring in the offshore network during the blocking of the HVDC converter.