Distributed vs. concentrated rapid frequency response provision in future great britain system

Abstract

Abstract-Two major sources of rapid frequency response (RFR) to counter the reducing system inertia problem of the Great Britain (GB) system are "synthetic inertia" from wind turbines and fast demand response (FDR). In this paper, we consider a future low inertia scenario to show the effectiveness of RFR provision from the large offshore wind farms (OWFs) planned in the North Sea (concentrated response) against FDR from loads spread across the GB system (distributed response). The spatial variation in transient frequencies, which can be pronounced in the aftermath of a disturbance and is critical for the response activation of these actuators, is accounted. Case studies using a reduced GB system model show the effectiveness of distributed FDR and concentrated support from OWFs in providing RFR when disturbances occur in different areas of the system where different inertia levels are present.

Conditions for Regional Frequency Stability in Power System Scheduling -- Part I: Theory

“…z 1 is real while z 2 and z 3 are complex conjugates in (15) and ( 16). The validity of this proposition is supported by the evidence reported in the literature [2]- [5] and in the dynamic simulations in Section II, which show that the post-fault regional frequencies behave as the COI plus certain inter-area oscillations. As is shown in the next paragraphs, such dynamic behaviour corresponds to one real root and two complex conjugate roots for the denominator in (15).…”

“…3b exhibits extreme RoCoF in that region during the first few seconds, while a 1.8GW loss in England shows a similar behaviour to the COI model. The observation of highest oscillations in the first instants after the fault, for a fault happening in the low-inertia region was also reported in [2] and [3].…”

“…These geographical discrepancies in frequency have been observed after frequency events in recent years by utilities all over the world. Several recent publications and reports [2]- [5] highlight this issue. The authors in [6] propose a method for optimal placement of virtual inertia based on minimising deviation from nominal frequency after an outage.…”

“…At this point a questions arises: given that existing transmission corridors have not significantly changed in recent years, why are system operators observing distinct regional frequencies in recent times, as reported in works such as [2]- [5]? The answer is that there is a second cause for this phenomenon: these renewables located in remote regions also drive a non-uniform inertia distribution, as inertia in the regions dominated by renewable generation can be very low.…”