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- PublicationOptimal charging schedules for thermal electric storage in the absence of communicationThermal Electric Storage (TES) has emerged as a promising power-to-heat technology with the potential of enabling active Demand Side Management (DSM). Optimal exploitation of the DSM capability of TES devices requires twoway communication with the grid. However, several contingencies and/or limitations on communication capabilities would render these storage devices incapable of being of any service to the system. This study presents the development of optimal charging schedules for the distributed TES devices which would determine the operation of these devices in the absence of communication. Different strategies are proposed which determine optimal TES charging dependence on local parameters including time of the day, household power consumption and outside temperature. Performance of the proposed charging schedules is then compared to the optimal communication-enabled and the conventional night-time charging scenarios for the All-Island Power System (AIPS). The results demonstrate the superiority of the proposed strategies as compared to the conventional night-time charging in terms of significant reduction in annual generation costs and energy consumption. Additionally, charging based on the proposed strategies can achieve up to 43% of the total cost savings potential of the communication-enabled scenario.
- PublicationAn integrated Building-to-Grid model for evaluation of energy arbitrage value of Thermal StorageThermal Electric Storage (TES) has emerged as a promising technology for enhancing the flexibility of the built environment to participate in active Demand Side Management (DSM). These devices allow the decoupling of intra-day scheduling of electric power demand from the time of thermal energy end-use. Therefore, if enabled with communication with the grid, these devices can facilitate load shifting and energy arbitrage. This study evaluates the energy arbitrage value of smart TES devices in residential buildings across Ireland. A Building-to-Grid (B2G) model has been developed which integrates the buildings thermal dynamics and end-use constraints with the power systems economic dispatch model. The thermal behavior of the houses and the TES space heater and hot water tank is modeled through linear state space models for three different mid-flat archetypes. The optimization results show the load shifting and arbitrage potential of TES and its impacts on wind curtailment considering various penetration levels of these devices.
- PublicationAssessing Power System Flexibility for Variable Renewable Integration: A Flexibility Metric for Long-Term System PlanningMany countries around the world have instituted policies with the aim of increasing the amount of installed variable generation (VG), such as wind and solar. A consequence of increased penetrations of VG is that changes in their output must be met by the remainder of a system’s resources so that the demand-generation balance is maintained. This paper proposes a highlevel methodology to assess power system flexibility. In this context, flexibility is the ability of a power system to deploy its resources to meet changes in the system demand and that of variable generation. The inclusion of such analysis at the long-term system planning stage will help to ensure that systems are optimally planned and operated with high levels of VG. Two case studies are presented which illustrate the flexibility assessment methodology and highlight some key issues relating to flexibility in the context of long-term planning.
- PublicationWind Power Scenario Tree Tool: Development and Methodology
- PublicationMinimum cost curtailment for distributed generation voltage managementThe penetration of DG is increasing on distribution networks across the world. As a result, networks are being pushed closer to their operating limits. In particular, voltage rise has been identified as a key barrier to further DG capacity. Active management of the voltage constraint may be possible, leading to a form of constraint management at distribution level for the first time. Here a novel method is proposed, which minimises the cost of curtailment. It takes advantage of the dispatchable capability of certain forms of DG, such as biomass, hydro or landfill gas. There are a number of well established methods for congestion management on the transmission network. A number of these are applied to voltage management on the distribution network and used for comparison with the new minimum cost method. The variability of voltage sensitivities andmarket prices is also investigated, with their impact on the cost of curtailment quantified.
- PublicationEvaluating which forms of flexibility most effectively reduce base load cycling at large wind penetrationsIncreasing penetration of wind power on power systems worldwide is resulting in the unconventional operation of base-load generating units. These units which were originally designed for operation at full output are more frequently required to balance the variability of the wind. This results in increased start-stop cycling and hours at low load which causes severe deterioration to the plants components. Interconnection, storage and demand side management increase the flexibility of a power system and can balance variations in the wind power output, thus reducing the onus on thermal plants. This study will attempt to quantify which of these forms of flexibility is most effective at reducing base-load cycling on a thermal test system with a large amount of wind.
- PublicationRenewables Integration, Flexibility Measures and Operational Tools for the Ireland and N. Ireland Power SystemThe Ireland and N. Ireland power system is pursuing ambitious renewable energy (mainly wind generation) targets for 2020. A range of system-wide initiatives are being developed as part of the DS3 (Delivering a Secure, Sustainable Electricity System) programme, and, in particular, a bespoke suite of ancillary services incentivising fast frequency response, dynamic reactive power and ramping margin, and other, (future) system needs. With approximately half of the wind generation connected at distribution level, network development at both distribution and transmission levels is a key challenge for both the transmission system operators (TSO) and distribution system operators (DSO): a wide range of technical options are being examined, including undergrounding, HVDC connection and series compensation, supported by a public and stakeholder engagement programme. The experience gained is highlighted, while also indicating solutions and strategies which have been proposed, and ongoing challenges for the future.
- PublicationThe relationship between base-load generation, start-up costs and generation cyclingDevelopments in the electricity sector such as the integration of increasing levels of renewable power, mainly wind, and the deregulation of electricity markets have resulted in some unconventional operation of base-load units. These units, which were originally designed for continuous operation, are now being forced into more flexible or cycling operation. This cycling operation results in serious physical degeneration of the unit’s components and hence incurs substantial costs to the plant operator. Using a planning tool of the Irish electricity system, the impact of increasing wind penetration on the operation of the base-load units is modelled. The results show that as wind penetration on the system increased, the base-load units were required to start up and shut down more often. However the units found to be cycled the most were not those with the cheapest start-up cost, but in fact those units with the shortest synchronisation time1. On the basis that the resulting cycling costs would increase the start-up costs of the base-load unit to some degree, the effect of increasing start-up costs on the operation of the base-load units was also examined. The results show that by increasing the start-up costs of base-load units, those units will be scheduled to operate in a more conventional base-loaded manner, the extent of which depends on the amount of wind power present.
- PublicationImpacts of large amounts of wind power on design and operation of power systems, results of IEA collaborationThere are a multitude of studies made and ongoing related to cost of wind integration. However, the results are not easy to compare. An international forum for exchange of knowledge of power system impacts of wind power has been formed under the IEA Implementing Agreement on Wind Energy. IEA WIND R&D Task 25 on “Design and Operation of Power Systems with Large Amounts of Wind Power” has produced a state of the art report in October 2007, where the most relevant wind power grid integration studies are analysed especially regarding methodologies and input data. This paper summarises the results from 18 case studies with discussion on the differences in the methodology as well as issues that have been identified to impact the cost of wind integration.
- PublicationDynamic frequency control with increasing wind generationFrequency control is essential for the secure and stable operation of a power system. With wind penetration increasing rapidly in many power systems, ensuring continuous power system security is vital. The frequency response to a disturbance on the all Ireland system is simulated for a range of installed wind capacities under different system conditions. The purpose of this study is to assess the effects of increased wind generation on system frequency, and the security of the system following such disturbances