UK National Grid Corporation

Warwick, United Kingdom

UK National Grid Corporation

Warwick, United Kingdom
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Smith C.A.,UK National Grid Corporation
IET Conference Publications | Year: 2017

National Grid Interconnector Holdings (NGIH) develops HVDC interconnector projects and in recent years has been responsible for developing Nemo Link [1], North Sea Link (NSL) [2], IFA2 [3] and Viking Link [4]. Through our experiences we have gained expertise in challenges faced in project consenting. A primary focus of specialist engineers in the field of HVDC is, rightly, the development and implementation of technology to meet the owner/operators requirements. However, another key element is ensuring that consenting is achieved for the scheme. There are a large range of technical specialisms involved in the consenting process. It is not just environmental and engineering experts that need to be actively involved; the integration of the complete engineering team is the key to success. This can provide a number of novel challenges as the relevant stakeholders are often not engineers with the same level of domain expertise and experience.


Milicevic K.,Josip Juraj Strossmayer University of Osijek | Emin Z.,UK National Grid Corporation
International Journal of Circuit Theory and Applications | Year: 2013

The paper presents an analytical and numerical investigation carried out on part of an electrical power network exhibiting ferroresonant behaviour as well as experimental investigation on its physical model. The investigations were carried out in order to estimate the extent of predicting the range of voltage source amplitude values at which the initiation of ferroresonance depends on values of initial conditions and phase shift. For this range of voltage source amplitude values (termed as possible ferroresonant range in the paper), the impact of initial conditions and phase shift of voltage source on the initiation of ferroresonance is determined using a numerical investigation and an experimental set-up. Reasons and consequences of disagreement of parameter values of the original and physical model are determined. © 2011 John Wiley & Sons, Ltd.


Ghassemi F.,UK National Grid Corporation
Electric Power Systems Research | Year: 2014

Excessive sheath voltage limiters (SVL) failures were observed in at least three of the 275 kV circuits in National Grid network, which in turn led to extra cost, more frequent and longer maintenance interventions. The ATP-EMTP programme is used to model a cable circuit with high SVL failure rate. This paper presents results of the investigation. It will be shown that although the SVLs should withstand the surges for normal switching and external fault conditions, but their energy absorption rating is exceeded if the cable is energised while it has high level of trapped charges with opposite polarity to switching voltages. The operational switching log confirmed that the cables with high SVL failures are those which were used as a means of voltage control during light load conditions and that when they are switched daily for this purpose there is no discharge path for the charge drainage. Short and long term remedies are proposed to resolve the issues. © 2014 Elsevier B.V.


Awadallah S.K.E.,University of Manchester | Milanovic J.V.,University of Manchester | Jarman P.N.,UK National Grid Corporation
IEEE Transactions on Power Systems | Year: 2014

This paper presents a probabilistic framework for making decisions about the replacement of ageing power equipment. The framework involves three steps: first, to identify the most important and critical components of the system for overall system reliability; secondly, to perform Pareto analysis to relate the replacement of the components to the effect on system reliability indices; finally, to determine the optimum scenario for replacement based on a comparison between the cost of unreliability due to deferring the replacement and the saving on reinvestment cost. The proposed approach is illustrated on a meshed test system modeled using U.K. transmission system parameters, a representative transformer age profile and regulatory energy not supplied values. The results demonstrate the feasibility of the framework for application in the area of power system reliability, and show its feasibility for informing replacement decisions. © 1969-2012 IEEE.


Dai J.,University of Manchester | Wang Z.,University of Manchester | Jarman P.,UK National Grid Corporation
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2010

This paper presents experimental research of creepage discharge on insulation barriers in power transformers. Using point-to-plate electrode configurations under ac voltages creepage discharge is studied for both single flashover breakdown and partial discharge induced failure modes. It is confirmed that the dielectric strength of oil gap will not be reduced with introducing dry new pressboard surface into the oil gap, indeed the flashover breakdown voltage is hardly compromised by introducing aged pressboard with up to 3% moisture. However, increased moisture content in pressboard reduces partial discharge inception voltage (PDIV) significantly, i.e. ∼30% PDIV reduction for pressboard of ∼3% moisture as compared with dry pressboard. More importantly, high moisture contents in pressboard increase PD activities in oil pores which allow gasses to be trapped inside to develop gaseous channels which eventually lead creepage discharge to breakdown © 2010 IEEE.


Kroll M.E.,University of Oxford | Swanson J.,UK National Grid Corporation | Vincent T.J.,University of Oxford | Draper G.J.,University of Oxford
British Journal of Cancer | Year: 2010

Background: Epidemiological evidence suggests that chronic low-intensity extremely-low-frequency magnetic-field exposure is associated with increased risk of childhood leukaemia; it is not certain the association is causal. Methods:We report a national case-control study relating childhood cancer risk to the average magnetic field from high-voltage overhead power lines at the child's home address at birth during the year of birth, estimated using National Grid records. From the National Registry of Childhood Tumours, we obtained records of 28 968 children born in England and Wales during 1962-1995 and diagnosed in Britain under age 15. We selected controls from birth registers, matching individually by sex, period of birth, and birth registration district. No participation by cases or controls was required. Results:The estimated relative risk for each 0.2 T increase in magnetic field was 1.14 (95% confidence interval 0.57 to 2.32) for leukaemia, 0.80 (0.43-1.51) for CNS/brain tumours, and 1.34 (0.84-2.15) for other cancers. Conclusion:Although not statistically significant, the estimate for childhood leukaemia resembles results of comparable studies. Assuming causality, the estimated attributable risk is below one case per year. Magnetic-field exposure during the year of birth is unlikely to be the whole cause of the association with distance from overhead power lines that we previously reported. © 2010 Cancer Research UK. All rights reserved.


Bunch K.J.,University of Oxford | Keegan T.J.,Lancaster University | Swanson J.,UK National Grid Corporation | Vincent T.J.,University of Oxford | Murphy M.F.G.,University of Oxford
British Journal of Cancer | Year: 2014

Background: We extend our previous study of childhood leukaemia and proximity to high-voltage powerlines by including more recent data and cases and controls from Scotland, by considering 132-kV powerlines as well as 275 and 400 kV and by looking at greater distances from the powerlines. Methods: Case-control study using 53 515 children from the National Registry of Childhood Tumours 1962-2008, matched controls, and calculated distances of mother's address at child's birth to powerlines at 132, 275, and 400 kV in England, Wales and Scotland. Results: Our previous finding of an excess risk for leukaemia at distances out to 600 m declines over time. Relative risk and 95% confidence interval for leukaemia, 0-199 m compared with>1000 m, all voltages: 1960s 4.50 (0.97-20.83), 2000s 0.71 (0.49-1.03), aggregate over whole period 1.12 (0.90-1.38). Increased risk, albeit less strong, may also be present for 132-kV lines. Increased risk does not extend beyond 600 m for lines of any voltage. Conclusions: A risk declining over time is unlikely to arise from any physical effect of the powerlines and is more likely to be the result of changing population characteristics among those living near powerlines. © 2014 Cancer Research UK.


Swanson J.,UK National Grid Corporation
Journal of Radiological Protection | Year: 2013

Epidemiological studies suggest associations between childhood leukaemia and living near high-voltage power lines, but the most obvious potential causative agent, the magnetic fields produced by the power lines, is not supported by laboratory studies or a known mechanism. An alternative hypothesised explanation is if there is greater population mobility near power lines, linking to the findings of Kinlen that population mixing increases leukaemia rates. We used the names recorded in electoral registers to see whether people near power lines move house more often than the population as a whole. We did find variations, but only small ones, and not such as to support the hypothesis. © 2013 IOP Publishing Ltd.


Catterson V.M.,University of Strathclyde | McArthur S.D.J.,University of Strathclyde | Moss G.,UK National Grid Corporation
IEEE Transactions on Power Delivery | Year: 2010

Retrofitting condition monitoring systems to aging plant can be problematic, since the particular signature of normal behavior will vary from unit to unit. This paper describes a technique for anomaly detection within the context of the conditions experienced by an in-service transformer, such as loading, seasonal weather, and network configuration. The aim is to model the aged but normal behavior for a given transformer, while reducing the potential for anomalies to be erroneously detected. The paper describes how this technique has been applied to two transmission transformers in the U.K. A case study of 12 months of data is given, with detailed analysis of anomalies detected during that time. © 2010 IEEE.


Ghassemi F.,UK National Grid Corporation | Koo K.-L.,UK National Grid Corporation
IEEE Transactions on Power Delivery | Year: 2010

There is a global commitment to tackle climate change which is evidenced by a huge surge in the uptake of renewable generation, mainly wind in the energy supply industries. Against this background, the effects of these vast numbers of connections to transmission and distribution system will have a critical impact on the standard and quality of supply in the network. In the U.K., utilities are required to perform harmonic assessments for large nonlinear loads. From an engineering perspective, it is imperative that these assessments are done accurately, efficiently, and effectively to ensure that all present and future connections can be accommodated without any problems. This paper presents a network reduction method for reducing detailed low-voltage wind farms networks to assess the effects of its connection onto a main interconnected transmission system. The rationale and method for this assessment is presented with a comparison of results against current approaches, such as IEC current aggregation, to demonstrate and prove its validity and effectiveness. © 2010 IEEE.

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