Containing a Credible Loss to Within Frequency Stability Limits in a Low-Inertia GB Power System

Abstract

There is a reduction in the percentage penetration of synchronous machines within the Great Britain (GB) power system leading to a decrease in inertia, and an increase in system rate of change of frequency (RoCoF) resulting from power imbalances. This raises the challenge of containing frequency deviations to within the relevant operational limits. As a result, steps need to be taken by the system operator to manage the risk to system security. In order to better understand this risk, this paper presents the challenge in light of the changing energy landscape and the current and future frequency response services available to contain frequency deviations. Although the current GB frequency response services may be capable of containing most events within frequency limits, in low inertia scenarios these responses alone are not capable of containing excursions within practical RoCoF limits. Consequently, further action must be taken to ensure system security. The system operator currently employs an interim solution of limiting the largest loss risk, depending on system inertia and the RoCoF limit. While this is suitable in the short-term, it is unlikely that this option will be cost-effective in the future.

Sharing reserves through HVDC: Potential cost savings in the Nordic countries

“…The situation of Ireland is analysed in [21–23]; in particular, authors in [21] compare three mitigation strategies—RoCoF relay setting relaxation, minimum inertia level in the market and provision of synthetic inertia—with dynamic simulations, conveying that relaxing the settings of RoCoF relays has the most influence in minimising the risk of frequency instability. Similar studies have been carried out also for the UK, showing that with the current requirements for FCR the frequency nadir and RoCoF exceed, respectively, 49.0 Hz and 0.125 Hz/s [24, 25].…”

Techno-Economic Analysis and Optimal Operation of a Hydrogen Refueling Station Providing Frequency Ancillary Services

“…The objective function is also subjected to the balance of hydrogen in the storage tanks. Supposing a leakage of 5% for the storage units and having η S1 as the storage efficiency, (11) implies that the available hydrogen in the first storage at any given hour is equal to the remaining hydrogen from the previous time-slot 0.95 • S 1,h−1,s plus the inflow of the compressed hydrogen by the first compressor C 1,h,s . The hydrogen that goes to the first dispenser H b h,s and the share of hydrogen that goes to the high-pressure compressor H C2 h,s are subtracted.…”

“…Apart from selling hydrogen to vehicles, the HRS operators could look for a promising source of extra revenue by providing flexibility to the power system, where growing penetration of intermittent renewable sources has raised the challenge of frequency deviations [11]. In response, grid operators have to let new frequency service providers support the grid stability [12].…”

The Impacts of Demand Side Management on Combined Frequency and Angular Stability of the Power System

“…This study focuses on frequency nadir and RoCoF because the disturbances adopted for MCS always result in a frequency drop. In terms of the stability limits, 47 Hz [16] and ±1 Hz/s [17] have been adopted for frequency nadir and RoCoF, respectively. Furthermore, it is assumed that the time window for RoCoF measurement is 100 ms [18], consequently, RoCoF can be derived according to (3), where 𝑓 𝑡 and 𝑓 𝑡+100 are the frequency values (in Hz) of the start (instant 𝑡) and the end (100 ms after instant 𝑡 ) of RoCoF measurement window, respectively.…”