I. Section 4. Frequency control and Low Inertia Systems

The total system inertia (H) is the primary source of electricity system robustness to frequency disturbances which arise due to an imbalance of generation and demand. The traditional large synchronous generators directly connected to the grid are the main sources of inertia, and they play an important role in limiting rate of change of frequency (ROCOF) and provide a natural response to the system frequency changes following an unscheduled loss of generation or demand from the power system. The transition to a low carbon society is the driving force pushing the traditional power system to increase the volume of non-synchronous technologies which mainly use power converters (PCs) as an interface to the power network. The PCs decoupled the primary source from the power network, as a consequence are not able to contribute with “natural” inertia in the same way as classical synchronous generators. During a system frequency disturbance (SFD), the system frequency will change at a rate initially determined by the total system inertia (H). The inertial response of the system might be negatively affected with devastating consequences for system security and reliability. The objective of this seminar is to present the fundamental aspects about system Frequency Control in Low Inertia Systems. This seminar has special emphasis on non-synchronous technologies, mainly using power converters (PCs): (a) High Voltage DC (HVDC) and (b) Wind Power Integration and considers the implications on frequency control.