go to top scroll for more

Projects: Projects for Investigator
Reference Number	NIA_NGSO0034
Title	SHEDD – System HILP Event Demand Disconnection
Status	Completed
Energy Categories	Other Power and Storage Technologies(Electricity transmission and distribution) 100%;
Research Types	Applied Research and Development 100%
Science and Technology Fields	SOCIAL SCIENCES (Business and Management Studies) 20%; ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 80%;
UKERC Cross Cutting Characterisation	Not Cross-cutting 100%
Principal Investigator	Project Contact No email address given National Grid plc
Award Type	Network Innovation Allowance
Funding Source	Ofgem
Start Date	01 May 2020
End Date	01 May 2022
Duration	ENA months
Total Grant Value	£400,000
Industrial Sectors	Power
Region	London
Programme	Network Innovation Allowance
Investigators	Principal Investigator	Project Contact , National Grid plc (99.999%)
	Other Investigator	Project Contact , National Grid plc (99.999%) Project Contact , Western Power Distribution (0.001%)
	Industrial Collaborator	Project Contact , National Grid plc (0.000%)
Web Site	https://smarter.energynetworks.org/projects/NIA_NGSO0034
Objectives	The following deliverables will be explored: Review the year-round performance of the LFDD scheme as the uptake of Low Carbon Technologies (LCTs) increase to identify opportunities to improve its technical and commercial performance in the short and medium term. Consider a range of options for redesign of the current LFDD scheme to maximise its performance in the short term and for a new “smart” alternative to the LFDD scheme in the medium term. Assess those options for redesign, including testing within “war game” simulations to demonstrate performance under simulated HILP events. Identify the optimal solution for both short and medium term improvements to the LFDD scheme, and develop a plan for the way in which it could be rolled out, completed by the necessary technical specifications. Frequency plays a very important role in power transmission and distribution in relation to the balance between the demand and generation requirements of the network. The maintenance of system frequency within set levels is required to maintain stability and prevent a full system collapse. Under normal operating conditions National Grid Electricity System Operator (NGESO) is obligated to maintain the system frequency between 49.8 and 50.2 Hz. Under exceptional circumstances (e.g. loss of a large generator) the frequency should not deviate outside the range 49.5 to 50.5Hz for more than 60 seconds. In order to achieve this, NGESO contracts frequency response to secure the power system for a number of events. There may be certain circumstances where the contracted frequency response may not be sufficient to maintain the system frequency between the statutory limits where the total loss of generation exceeds the amount secured for and a deficit of generation arises.In order to reduce the generation deficit (or excess in demand) to maintain stability, Distribution NetworkOperators (DNOs) have low frequency relays to disconnect demand (LFDD). To comply with the requirements of the Grid Code, Western Power Distribution as a DNO is obligated to install LFDD schemes. The schemes are designed to automatically disconnect at least 60% of the total DNO demand on a stage by stage basis at the time of the forecasted national ET system peak demand. The demand subject to automatic low frequency disconnection is divided into 9 predetermined discrete MW blocks which are disconnected at defined low frequency levels. Each block of demand is distributed across each license area, so far as reasonably practical, so that the demand at different Grid Supply Point (GSP) sites is reduced evenly.The current LFDD schemes do not take into account the growth of distributed generation and decreasing system inertia. The growth of distributed generation connected on DNO networks at voltage levels below where the LFDD relays are installed is likely to impact on the effectiveness of the scheme. If the level of distributed generation output is high when the relay is triggered, the amount of demand disconnected may be lower than expected. In addition, levels of system inertia are decreasing (e.g. due to the closure of traditional generation) along with net transmission system demand. This reduces the effectiveness of LFDD schemes as changes in frequency will be faster and larger. Should the frequency fall at a high rate, more than one LFDD stage could operate resulting in too much demand being disconnected. These increasing changes risk the effectiveness of LFDD, impacting security of supply, unnecessary customer interruptions and price impact. If the LFDD scheme does not deliver the demand reductions required, the whole system is at risk; while if the response results in sub-optimal economic disconnection of customers, the economic impact (and so cost to consumers) of High Impact Low Probability events will be higher than necessary. Furthermore, an ineffective LFDD scheme could increase the risk of rolling brownouts / blackouts.For example:• The LFDD scheme is simplistic in design and overestimates the demand reduction achieved by operating LFDD relays Evidenced by 9 August event Current approach to determining magnitude of demand reduction from each relay is simplistic Unknown what volume of DG is also lost when a relay operates • Load shedding does not take into account the variation in Value of Lost Load (VoLL) for different customer types. • Vulnerable customers and safety critical loads are also not sufficiently protected by the current LFDD scheme.• The performance of the scheme is decreasing as the uptake of Distributed Generation increases, and system inertia falls. This degradation of performance is expected to worsen with time. The objectives of the project is to design and test a new LFDD scheme to maximise its future performance as the network continues to decarbonisation, Distribution Generation (DG) integration increases, and system inertia continues to decrease.
Abstract	The current LFDD schemes do not take into account the move to decarbonize through growth of distributed generation and decreasing system inertia. This reduces the effectiveness of LFDD schemes.The objectives of the project is to design and test a new LFDD scheme to maximise its future performance as the network continues to decarbonisation, Distribution Generation (DG) integration increases, and system inertia continues to decrease.
Publications	(none)
Final Report	(none)
Added to Database	02/11/22