Now showing 1 - 10 of 71
  • Publication
    Emulated Inertial Response from Wind Turbines: The Case for Bespoke Power System Optimisation
    (Energynautics GmbH, 2012-11-15) ;
    The dynamic characteristics of power systems with increasing wind penetration levels are changing rapidly as the nature of the frequency response capability of these systems develop with the evolving plant mix. Consequently, the protocols for how these systems are operated are changing. While modern variable speed wind turbines do not inherently contribute to the inertial response of the system, they can offer a controlled response to system frequency imbalances, which harnesses the stored rotational energy of the blades. Unlike conventional machines, however, the tunable emulated inertial response of a variable speed wind turbine is dependent on the operating condition of the wind turbine and provides a distinct response to conventional generators. In some cases it is possible that inappropriate tuning of such a response could hinder the recovery of the system frequency following an imbalance. In this paper the emulated inertial response from wind generation on power systems of varying size is optimised, and the impact of system conditions on the response required is examined.
      276
  • Publication
    Utilising time of use surveys to predict water demand profiles of residential building stocks: Irish case study for domestic hot water
    (The WATEF Network, University of Brighton, 2014-09-11) ; ; ;
    The prediction of water consumption patterns is a challenge, especially when water metering is not available at scale. The paper focuses on the prediction of analytical domestic hot water (DHW) demand profiles for detailed building archetype models, using an occupant focused approach based on time-of-use survey (TUS) data. Five dwelling types are considered over different construction periods, representative of the majority of the Irish residential stock, which is used here as a case study. They are modelled at room level using EnergyPlus and converted into archetype models. A bottom-up approach is utilised to develop the required operational data at high space and time resolution. That methodology applies Markov Chain Monte Carlo techniques to TUS activity data to develop activity-specific profiles for occupancy and domestic equipment electricity use. It is extended to DHW demand profiles by combining the probability distributions for particular TUS activities with average daily DHW consumptions, depending on the household size, day type and season. The archetype models are found to be 90% accurate with the Irish standard dwelling energy assessment procedure in estimating the annual energy requirements for DHW heating. Moreover, they capture variations in DHW consumption, heat demand and energy usage for DHW heating, on a national scale and a fifteen-minute basis.
      272
  • Publication
    Evolution of operating reserve determination in wind power integration studies
    The growth of wind power as an electrical power generation resource has produced great benefits with reductions in emissions and the supply of zero cost fuel. It also has created challenges for the operation of power systems arising from the increased variability and uncertainty it has introduced. A number of studies have been performed over the past decade to analyze the operational impacts that can occur at high penetrations of wind. One of the most crucial impacts is the amount of incremental operating reserves required due to the variability and uncertainty of wind generation. This paper describes different assumptions and methods utilized to calculate the amount of different types of reserves carried, and how these methods have evolved as more studies have been performed.
      1321Scopus© Citations 116
  • Publication
    Pumped Hydro and Compressed Air Energy Storage at High Wind Penetrations
    (Energynautics GmbH, 2013-10-24) ;
    Energy storage is a widely used tool for balancing power systems and for providing increased operational flexibility - as such it can assist with the integration of variable renewable electricity generation. Grid-scale energy storage provides potential solutions to some of the technical and economic challenges which arise in systems with high penetrations of variable renewables, particularly on isolated systems. However, capital costs per MW are high, which means that variable renewable penetrations must reach significant levels before the operating cost reductions justify the capital expenditure. Optimum levels of grid-scale storage are explored, considering capital costs and potential operational cost savings for two storage technologies - pumped hydroelectric storage and compressed air energy storage. Grid-scale installations are found to achieve significant cost savings, particularly at high levels of wind generation. While the potential for savings is eroded significantly at high levels of DC interconnection, they remain high when non-synchronous penetration limits are increased.
      304
  • Publication
    Dynamic frequency control with increasing wind generation
    Frequency 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
      1470
  • Publication
    Sub-hour Unit Commitment MILP Model with Benchmark Problem Instances
    Power systems are operated to deliver electricity at minimum cost while adhering to operational and technical constraints. The introduction of smart grid technologies and renewable energy sources offers new challenges and opportunities for the efficient and reliable management of the grid. In this paper we focus on a Mixed Integer Programming sub-hour Unit Commitment model. We present analysis of computational results from a large set of problem instances based on the Irish system and show that problem instances with higher variability in net demand (after the integration of renewables) are more challenging to solve.
      368Scopus© Citations 1
  • Publication
    Quantifying the Aggregate Frequency Response from Wind Generation with Synthetic Inertial Response Capability
    (Energynautics GmbH, 2013-10-24) ;
    Modern variable-speed wind turbines, although decoupled from the system frequency, can respond to significant power imbalances through power electronic controls as synthetic inertial or governor-like droop responses. However, frequency response capabilities from wind power plant cannot be considered a direct replacement for traditional frequency responsive services. Before such capabilities should be in- corporated into systems, their most effective implementation should be considered and a methodology for system operation under high synthetic inertia technology penetration should be identified. This paper considers a possible system frequency response requirement from wind generation and investigates issues surrounding quantification and scheduling of the future system resource, taking the combined Ireland and Northern Ireland system as an example. The distribution of local wind speeds, the variation in the response provided by different control structures, as well as the uncertainty associated with the aggregated capability at any one time, and the implications for the development of ancillary service market incentives or grid code requirements are considered. The impact of uncertainty over the aggregate wind response available is assessed and a strategy for the forecasting, management and coordination of such a resource on future power systems is proposed.
      221
  • Publication
    Demand side management potential of domestic water heaters and space heaters
    (Elsevier - International Federation of Automatic Control (IFAC), 2012-09-02) ;
    Demand side management (DSM) is a viable strategy for facilitating integration of renewable energy into power systems. The demand resource from water and space heating can be used to reduce or delay system demand peaks, and in combination with other flexible loads, reshape the aggregate demand profile and manage system ramping. In this paper, the aggregate power draw profiles for heat pump based water heating and under floor space heating systems for the Irish domestic sector have been synthesized and the effects of daily and seasonal variations, the type of dwelling and control / usage patterns on demand are discussed. The results show a significant seasonal and daily variation of the demand profile for water and space heating, indicating its viability as a DSM resource on the Irish power system, but also the challenges of operation.
      847
  • Publication
    Flexible storage operation in a market environment
    (EnergynauticsGmbH, 2014-11-13) ;
    Future power systems with high penetrations of variable renewables will require increased levels of flexibility from generation and demand-side sources in order to maintain secure and stable operations. One potential source of increased flexibility is large-scale energy storage, which can provide a variety of ancillary services across multiple timescales. In order for adequate investment to take place, it is essential that the correct market signals are present which encourage suitable levels of flexibility, either from storage or alternative sources. This paper explores the changes required in operational practices for storage plant at different levels of installed wind capacity, and the challenges that private storage plant operators will face in generating appropriate bids in a market environment at high penetrations of variable renewables. The impacts on system generating costs are explored under different operating assumptions.
      231
  • Publication
    Developing building archetypes for electrical load shifting assessment: Analysis of Irish residential stock
    Appropriate use of demand side management (DSM) strategies in residential buildings, when placed in a smart grid environment, can help reduce power supplydemand mismatches by shifting electrical loads, thus leading to better integration of renewable energy sources, particularly wind and solar generation. In the current paper, detailed building energy simulation models of residential stock are developed, using an occupant focused approach. Five archetypes are considered over three construction periods, representative of about 82% of the Irish building stock. The archetype models were found to be accurate to within 10% of the Irish standards, as exemplified using the Dwelling Energy Assessment Procedure (DEAP), for space and water heating energy requirements. The proposed approach was found to be more accurate than DEAP to estimate the electricity consumption. By integrating high resolution models for occupancy and electrical equipment use, it can generate more accurate models of the housing stock and expands previous investigations to include occupant behaviour, electrical load shifting and thermal comfort issues.
      597