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

Releasing wind farm equity via post-construction yield analysis

During pre-construction yield analysis, an extrapolated site wind regime is applied to a site model in order to produce estimated yield figures. However, once the site has been operational, many of the uncertainties involved in this modelling, such as electrical losses, wake losses, turbulence and power performance, may be resolved into measured operational parameters. This means that off-site anemometry may be directly related to power production on the site. In a post-construction yield analysis, the pre-construction figures are refined using actual operational data. This allows: a) The initial yield report figures to be reassessed in the light of wind farm performance, and b) The uncertainties associated with annual yield figures to be reduced and understood more fully. This increasing reduction in uncertainty allows improvements in financial modelling to take place over the operational life of the wind farm, releasing equity from the wind farm investmen

Developing networks for the low carbon energy future

This paper discusses various issues associated with the development and operation of networks to facilitate and transfer energy derived from low carbon sources such as renewables, nuclear power and burning of fossil fuels with carbon capture and storage. It starts by briefly describing the limitations of present day networks before moving on to discuss the likely features of a network for low carbon energy and how it should be developed and operated, the facilitation of new connections to the network, the roles of the network licensees, the key technologies and the support of innovation and, before drawing some overall conclusions, some lessons that can be learned from other countrie

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

Modelling the effect of maintenance strategies and reliability for long-term wind yield assessment

Where a number of onshore wind farm locations are being maintained by a single central Operation and Maintenance Contractor, an effective competition exists between those sites for the use of that maintenance resource. Any differentials between those sites in terms of the costs of repair to the contractor, or the potential return to the contractor for improving the site availability under the Operations and Maintenance Contract, may mean a variance in the level of operational availability achieved by each site. A review of UK contract terms illustrates the potential differentials that may occur. A maintenance optimisation model is created which is used to simulate the potential availabilities of a set of wind farms maintained from a central resource in response to typical published failure rates and restoration times. Monte Carlo methods are applied to this simulation to provide an illustrative set of sensitivities which may be used to adjust availability losses assumed during the energy yield analysis of a potential onshore wind farm location

The impact of maintenance contract arrangements on the yield of offshore wind power plants

In the optimisation of maintenance and vessel strategies for the operation of offshore wind plant, it is normally assumed that the off-taker of the power produced may directly control the dispatch of maintenance resources. However, in practice, services such as maintenance technicians and vessels are usually contracted from companies with larger arenas of operation, and so the organisational interfaces between these parties, and the different objective functions involved, need to be considered. This article looks at different current and future models for contracted maintenance, identifies interfaces and conflicts of interest, and constructs a quantified model demonstrating the potential impact on headline energy yields for a set of wind farms with a common contracted maintenance resource. The modelling illustrates that the performance of a site with contracted maintenance operations is not only dependent on the contracts held by that site but also on the effective competition in place with other sites for a centralised resource, and the performance of a site may be highly sensitive to the alignment of contractual incentives, relative travel distances, and the relative size of the site in terms of energy yield

Local pathways to low-carbon domestic heat : exploring the options in the UK

Currently, natural gas is the predominant source of domestic heat provision. Take-up of heat pumps and district heating remains at a minimal penetration of around 0.5%. In total, only around 2.5% of heat comes from low carbon sources, compared with more than 45% of electricity. As heat accounts for around 40% of UK energy consumption and 20% of GHG emissions, the decarbonisation of the heat sector is seen as vital for the UK to reach UK emission reduction targets. Different trajectories in heat provision using parallel energy vectors (electricity, gas, alternative gases, heat networks) imply a range of infrastructure impacts. In order to explore the form of different local energy systems under decarbonisation scenarios, this work seeks to: - Capture the broad forms of ’last-mile’ network: Urban, Suburban, Rural (on/off gas grid ) seen as exemplar of the UK energy system; - Downscale whole system-derived technology mixes and construct demonstrative local energy systems representing key use cases; - Using multi-carrier optimisation, determine the impacts of heat decarbonisation on current and future system actors

Local pathways to low-carbon domestic heat : exploring the options in the UK

Currently, natural gas is the predominant source of domestic heat provision. Take-up of heat pumps and district heating remains at a minimal penetration of around 0.5%. In total, only around 2.5% of heat comes from low carbon sources, compared with more than 45% of electricity. As heat accounts for around 40% of UK energy consumption and 20% of GHG emissions, the decarbonisation of the heat sector is seen as vital for the UK to reach UK emission reduction targets. Different trajectories in heat provision using parallel energy vectors (electricity, gas, alternative gases, heat networks) imply a range of infrastructure impacts. In order to explore the form of different local energy systems under decarbonisation scenarios, this work seeks to: - Capture the broad forms of ’last-mile’ network: Urban, Suburban, Rural (on/off gas grid ) seen as exemplar of the UK energy system; - Downscale whole system-derived technology mixes and construct demonstrative local energy systems representing key use cases; - Using multi-carrier optimisation, determine the impacts of heat decarbonisation on current and future system actors