A successor to ER P2/6 : existing issues and lessons from "Flexible Networks for a Low Carbon Future"

This note is concerned with a network's ability to meet demand for power. In other words, with 'security of supply' and, in particular, with standards or conventions that drive a distribution network planner’s decisions in respect of ensuring that demand will be met in future. It takes lessons from the “Flexible Networks” Low Carbon Networks Fund project in respect of ‘flexible’ network actions such as dynamic or real-time ratings, network reconfiguration and voltage regulation along with learning from network monitoring, not least to aid better forecasting of demand, and applies them in respect of possible development of a successor to the main standard that drives network investment to provide adequate reliability of supply to distribution connected demand, Engineering Recommendation (ER) P2/6, i.e. the 6th edition of ER P2. This note discusses a number of issues in respect of ER P2/6, its application by Distribution Network Operators (DNOs) and its interactions with other regulatory initiatives, not least the Interruption Incentive Scheme (IIS) and ‘load indices’

Methods and Tools for Planning the Future Power System : Issues and Priorities

This report contributes to discussion of the nature of the future power system in the context of the IET’s ‘Power Networks Joint Vision’ initiative. It summarises a number of future challenges arising from the changing nature of generation and demand and the possibility of greater demand-side participation in electricity markets. It argues that these require significant change in respect of current practice in the assessment, planning and development of power network facilities enabling future system operation. It reflects on methods and tools used by network planners in Britain today and discusses areas in which modelling capability needs to be developed and enhanced data or user competencies are required

Wind generator behaviour in a pay-as-bid curtailment market

A pay-as-bid curtailment market, where Wind Power Plants (WPPs) may offer prices to have their output reduced in the event of network balancing or stability constraints, is one approach towards the market integration of a high proportion of wind energy onto a power system. Such a market aims to procure curtailment at a cost close to the marginal value of the electricity plus renewable subsidies and incentives, reducing risks for WPPs while minimising costs to the Independent System Operator (ISO). Through the use of game theory and market modelling, a key set of bidding strategies are identified that may evolve within such a market, which may act in opposition to the goals of the ISO. These are applied to a variety of network conditions in order to determine their likely impact and the resulting bidding signals provided to market participants. Bidding behaviours and market fluidity may also be affected by factors particular to wind power plants. Through analysis of both ex ante and ex post case studies, the existence of these behaviours is demonstrated, illustrating that a pay-as-bid curtailment market may not be efficient at price discovery in practice

Commercial integration of storage and responsive demand to facilitate wind energy on the Shetland Islands

The Northern Isles New Energy Solutions (NINES) project seeks to implement Active Network Management (ANM) on the Shetland Islands in a manner which reduces customers’ energy consumption, lowers peak demand and facilitates an increase in the proportion of electricity from wind, in order to take advantage of the unique wind resource of the islands. This presentation focuses on the commercial frameworks and trading arrangements necessary to permit additional wind capacity onto the islanded network through the active use of storage and responsive demand technologies. The network is modelled using a Dynamic Optimal Power Flow (DOPF) framework, which allows the unit scheduling of different combinations of generation, storage and demand to be optimised according to different optimisation goals. This is used as a foundation to explore the value of wind energy and storage in meeting the long-term goals of the network, the forms of trading and markets which may be used to contract services, and the potential for responsive demand to facilitate different forms of connection agreements and curtailment strategies for new wind farms. In modelling the Shetland network using Dynamic Optimal Power Flow (DOPF), the optimum unit commitment schedule is determined across a daily horizon for different network topologies, including variable levels of wind generation, storage and demand-side response - primarily storage heaters and water tanks controllable by the Distribution System Operator via Active Network Management. This informs the level of wind generation which may be accepted onto the network, and allows the creation and testing of commercial agreements both for wind generators keen to utilise the unique resource of the islands, as well as allowing third-party operation of storage, and reducing the peak energy demand of domestic consumers. This allows a greater level of demand to be supplied by non-thermal sources through the time-shifting of demand against the availability of the wind resource. Support of the grid through reserve and response is considered in the context of maintaining system stability, with the aim of procuring services through third-party contractual arrangements. Data collected from the operational history of the islands and technology trials demonstrate the feasibility of these approaches and their potential applicability to other constrained distribution networks with the potential for high levels of wind generation. The data from trials of domestic storage equipment and modelling of wind curtailment demonstrate quantitatively the ways in which commercial integration of modern storage and responsive demand can be used to increase the utilisation of wind energy on islanded networks, which may often have increased renewable resources but limited grid capacity. It is shown that there are a number of trading and connection agreements which can be used to contract for generation and ancillary services to meet these goals

Social simulations: improving interdisciplinary understanding of scientific positioning and validity

Because of features that appear to be inherent in many social systems, modellers face complicated and subjective choices in positioning the scientific contribution of their research. This leads to a diversity of approaches and terminology, making interdisciplinary assessment of models highly problematic. Such modellers ideally need some kind of accessible, interdisciplinary framework to better understand and assess these choices. Existing texts tend either to take a specialised metaphysical approach, or focus on more pragmatic aspects such as the simulation process or descriptive protocols for how to present such research. Without a sufficiently neutral treatment of why a particular set of methods and style of model might be chosen, these choices can become entwined with the ideological and terminological baggage of a particular discipline. This paper attempts to provide such a framework. We begin with an epistemological model, which gives a standardised view on the types of validation available to the modeller, and their impact on scientific value. This is followed by a methodological framework, presented as a taxonomy of the key dimensions over which approaches are ultimately divided. Rather than working top-down from philosophical principles, we characterise the issues as a practitioner would see them. We believe that such a characterisation can be done 'well enough', where 'well enough' represents a common frame of reference for all modellers, which nevertheless respects the essence of the debate's subtleties and can be accepted as such by a majority of 'methodologists'. We conclude by discussing the limitations of such an approach, and potential further work for such a framework to be absorbed into existing, descriptive protocols and general social simulation texts

Development of a polyclonal competitive enzyme-linked immunosorbent assay for detection of antibodies to Ehrlichia ruminantium

A polyclonal competitive enzyme-linked immunosorbent assay (PC-ELISA) is described for detection of antibodies to Ehrlichia (Cowdria) ruminantium by using a soluble extract of endothelial cell culture-derived E. ruminantium as the antigen and biotin-labeled polyclonal goat immunoglobulins as the competitor. For goats, the diagnostic sensitivity and specificity were both 100% with a cutoff of 80% inhibition (80 PI), with detection of antibodies for 550 days postinfection. For cattle, diagnostic sensitivity and specificity were 86 and 100%, respectively, with a cutoff of 50 PI and 79 and 100% with a cutoff of 70 PI. Cross-reactions with high-titer experimental or field antisera to other Ehrlichia and Anaplasma species were observed at up to 68 PI in cattle and up to 85 PI in sheep, and therefore to exclude these cross-reactions, cutoffs of 70 PI for bovine serology and 85 PI for small-ruminant serology were selected. Application of the PC-ELISA to bovine field sera from South Africa gave a higher proportion of positive results than application of the murine macrophage immunofluorescent antibody test or indirect ELISA, suggesting a better sensitivity for detection of recovered cattle, and results with bovine field sera from Malawi were consistent with the observed endemic state of heartwater and the level of tick control practiced at the sample sites. Reproducibility was high, with average standard deviations intraplate of 1.2 PI and interplate of 0.6 PI. The test format is simple, and the test is economical to perform and has a level of sensitivity for detection of low-titer positive bovine sera that may prove to be of value in epidemiological studies on heartwater

Probabilistic weather forecasting for dynamic line rating studies

This paper aims to describe methods to determine short term probabilistic forecasts of weather conditions experienced at overhead lines (OHLs) in order to predict percentiles of dynamic line ratings of OHLs which can be used by a system operator within a chosen risk policy with respect to probability of a rating being exceeded. Predictive probability distributions of air temperature, wind speed and direction are assumed to be normal, truncated normal and von Mises respectively. Predictive centres are estimated as a sum of residuals predicted by a univariate auto-regressive model or a vector auto-regressive model and temporal trends fitted by a Fourier series. Conditional heteroscedasticity of the predictive distribution is modelled as a linear function of recent changes in residuals within one hour for air temperature and wind speed or concentration of recent wind direction observations within two hours. Parameters of the probabilistic models are determined to minimize the average value of continuous ranked probability score which is a summary indicator to assess performance of probabilistic models. The conditionally heteroscedastic models are shown to have appropriate sharpness and better calibration than the respective homoscedastic models

Ofgem RIIO-2 Consultation : Response from the UK Energy Research Centre (UKERC)

The RIIO (Revenue=Incentives+Innovation+Outputs) model, introduced in 2013, is designed to ensure that payments to companies running the gas and electricity transmission and distribution networks are fair to network users and permit the recovery of reasonable costs in developing, maintaining and operating the networks. The network licensees’ allowed revenue is linked to their performance and should therefore offer them incentives for securing investment, driving innovation and delivering the service that customers expect. However, some commentators have suggested that the licensees have been making unjustified profits. With network charges making up around a quarter of the average household energy bill, it is anticipated that the new price control framework will be tougher and provide lower expected returns for network licensees. The RIIO-2 framework consultation is welcome. Ofgem’s final view on price control allowances will be published by the end of 2020 with the new network price controls ('RIIO-2') due to be implemented in 2021. General comments In our submission we responded to the individual points raised in the call. We also note the following: We support the proposal to reduce the price control period from 8 to 5 years. The energy system is undergoing unprecedented change, not only with continued transformation of the generation background but also major changes to the way electricity is used, such as for transport and heating. However, the rate and precise locations of these changes is uncertain. A shorter price control period will provide the opportunity for incentives and cost recovery to be adapted to the changing circumstances. Maintenance of acceptable levels of reliability while facilitating the energy system transformation at least cost requires substantial innovation in technologies, business processes and commercial arrangements. The development of new innovations and associated benefits to consumers often takes years to be realised, sometimes beyond a price control period in which network company shareholders would expect a return. We therefore support the proposal to retain dedicated innovation funding but encourage greater clarity on the scope of activities that can make use of such funding and on best practice in the generation and dissemination of evidence on proposed innovations. We welcome moves to increase the accountability of the network companies and would urge Ofgem to concentrate on those measures that have a genuine and positive impact on the network companies’ activities in the context of the whole energy system. We note that this is not restricted to the business plans submitted under RIIO-2 but extends to a whole raft of codes and interactions. These include the evolving responsibilities of the Electricity System Operator (ESO), the relationships between the ESO, the transmission owners and the Distribution Network Operators, and the processes for ensuring that the full set of codes, standards and market arrangements are coherent and fit for purpose. This is a challenging task that requires constant attention to ‘the big picture’ and sufficient resources, commitment and expertise on the part of the network owners, system operators and Ofgem. In applying tighter controls that avoid excessive returns to the network licensees’ owners, the upside and downside risks should be clearly assessed and incentives for managing risk placed on those parties best placed to do so