Enhancing frequency stability by integrating nonconventional power sources through multi-terminal HVDC grid

The 2050 targets established by the EU will foster both larger penetration of renewable energy, especially wind power, and more cross–border interconnections. Moreover, this new framework requires the non-conventional power sources and power converter-based systems to be responsible for the duties traditionally carried out by conventional synchronous generators as frequency support. This paper presents how different power-electronic based technologies can provide frequency support individually and in a coordinated manner (with different priority given by the deadbands) ensuring a stable operation. The implemented scenarios push the system to the limits to exploit potential bottlenecks, and demonstrating how joint regulation of the power electronic based technologies enhances the frequency stability of the AC synchronous areas. The different control schemes and their interaction are investigated in Cigre DC grid benchmark adapted for frequency stability studies and implemented in Matlab/Simulink simulation tool. This modified grid includes 5-terminal HVDC grid with two offshore wind farms and three AC networks including battery and onshore wind farms