Now showing 1 - 10 of 88
  • Publication
    Information Gap Decision Theory based OPF with HVDC Connected Wind Farms
    (Institute of Electrical and Electronics Engineers, 2014-12) ; ;
    A method for solving the optimal power flow (OPF) problem including HVDC connected offshore wind farms is presented in this paper. Different factors have been considered in the proposed method, namely, voltage source converter (VSC-HVDC) and line-commutated converter high-voltage DC (LCC-HVDC) link constraints, doubly fed induction generators' (DFIGs) capability curve as well as the uncertainties of wind power generation. Information gap decision theory (IGDT) is utilized for handling the uncertainties associated with the volatility of wind power generation. It is computationally efficient and does not require the probability density function of wind speed. The proposed decision-making framework finds the optimal decision variables in a way that they remain robust against the considered uncertainties. To illustrate the effectiveness of the proposed approach, it is applied on the IEEE 118-bus system. The obtained results validate the applicability of the proposed IGDT-based OPF model for optimal operation of AC/DC power systems with high penetration of offshore wind farms.
      800Scopus© Citations 107
  • Publication
    Impact of high penetrations of micro-generation on low voltage distribution networks
    Due to rising fossil fuel and electricity prices and the overall need to reduce carbon emissions, there is a growing interest in the utilisation of micro-generation amongst electricity consumers and governments alike. Electricity consumers are installing small scale generators on their premises, which are also being connected to existing low voltage (LV) electricity supply networks. High penetrations of micro-generation may present challenges to the planning and operation of LV electricity networks. This is due to LV distribution networks being designed for delivery of electricity from sub-stations to the consumers and not for accommodating generation. The aim of the work presented in this paper is to examine the effect of high penetrations of micro-generation on the voltage levels of a section of existing Irish LV distribution network.
  • Publication
    Challenges posed by the integration of wave power onto the Irish power system
    In order to gauge the potential impact of wave power in Ireland, the capacity factor of theoretical wave farms deployed at various locations around the Irish coast is compared to the system-wide capacity factor of wind power generation over the same period. It is shown that wave power off the coast of Ireland experiences a very significant seasonal variation, but with a lower daily variation. This paper presents the results of that analysis and examines certain challenges that will face the Irish power system if a large portfolio of wave power devices is deployed. Issues such as system adequacy and the capacity value of wave power are discussed.
  • Publication
    Minimum cost curtailment for distributed generation voltage management
    The 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.
  • Publication
    Analysis of the voltage control capability of energy harvesting networks
    (Energynautics, 2010-10) ; ;
    At times of high generation levels from distributed generators (DGs), there may be a paucity of conventional generators still synchronised to the transmission system. These synchronous machines have traditionally been the power system's principal source of controllable reactive power. If DGs are operated at inductive power factors, total reactive power absorption at distribution system bulk supply points may be highest at times when the transmission system is least equipped to supply it. On the Irish power system, new DGs (typically windfarms) may be connected in a clustered fashion to a new transmission node. This paper will show how the aggregate reactive power capabilities of these clustered DGs may be characterised. Of particular importance is how the cluster can respect distribution system operating limits while also providing reactive power support to the transmission system.
  • Publication
    Application of wind generation capacity credits in the Great Britain and Irish systems
    The concept of capacity credit is widely used to quantify the contribution of renewable technologies to securing demand. This may be quantified in a number of ways; this paper recommends the use of Effective Load Carrying Capability (ELCC, the additional demand which the new generation can support without increasing system risk), with system risk being measured using Loss of Load Expectation (LOLE, this is calculated through direct use of historic time series for demand and wind load factor). The key benefit of this approach is that it automatically incorporates the available statistical information on the relationship between wind availability and demand during the hours of very high demand which are most relevant in assessing system adequacy risk. The underlying assumptions are discussed in detail, and a comparison is made with alternative calculation approaches; a theme running through the paper is the need to consider the assumptions carefully when presenting or interpreting risk assessment results. A range of applications of capacity credits from Great Britain and Ireland are presented; this includes presentation of effective plant margin, ensuring that the optimal plant mix secures peak demand in economic projection models, and the Irish capacity payments system. Finally, new results comparing capacity credit results from the Great Britain and Irish systems using the same wind data are presented. This allows the various factors which influence capacity credit results to be identified clearly. It is well known that increasing the wind load factor or demand level typically increases the calculated capacity credit, while increasing the installed wind capacity typically decreases its capacity credit (as a percentage of rated capacity). The new results also show that the width of the probability distribution for available conventional generating capacity, relative to the peak demand level, also has a strong influence on the results. This emphasises further that detailed understanding of risk model structures is vitally important in practical application.
  • Publication
    A sustainability strategy for Ireland’s electricity network
    (Risø National Laboratory for Sustainable Energy, 2009-09) ; ; ; ;
    The electricity system of Ireland is unique as it has no synchronous connections to other systems, while the existing non-synchronous connection provides limited flexibility. When coupled with a target of 40% electricity from renewables by 2020, exceeding any other country, the challenge is truly striking. However, this challenge also gives Ireland the opportunity to be the world leader in this area. The unique experience in solving this problem will provide the technology and knowledge to harness renewable energy sources globally and limit the dependency on petrochemicals. The continued development of the electricity distribution network as a smart network is a critical element of this process which spans electricity generation, transportation and energy end use. This paper described the various elements of ESB Networks’ sustainability strategy and the associated research themes being jointly pursued by ESB Networks, the Electric Power Research Institute (EPRI) and the Electricity Research Centre, University College Dublin.
  • Publication
    Minimising transmission reactive support required by high penetration of distributed wind power generation
    Wind power generation is the fastest growing renewable technology worldwide with large on- and off-shore wind farms being connected to the transmission networks. A significant share of it is, however, still being deployed at distribution levels. While distributed wind generation presents traditionally passive distribution networks with well-established technical challenges, reactive support needed by high penetrations of such new generation capacity might also have an impact on the weak areas of the transmission grid. In this work, a multi-period AC optimal power flow-based technique is proposed to find power factor and substation settings that minimise the transmission reactive support required by variable distributed generation while also considering N-1 contingencies. A section of Irish distribution network is analysed. Results show the significant benefits that a passive approach such as the use of optimal power factor and substation settings can achieve.
  • Publication
    Capacity value of wind power
    Power systems are planned such that they have adequate generation capacity to meet the load, according to a defined reliability target. The increase in the penetration of wind generation in recent years has led to a number of challenges for the planning and operation of power systems. A key metric for generation system adequacy is the capacity value of generation. The capacity value of a generator is the contribution that a given generator makes to generation system adequacy. The variable and stochastic nature of wind sets it apart from conventional energy sources. As a result, the modeling of wind generation in the same manner as conventional generation for capacity value calculations is inappropriate. In this paper a preferred method for calculation of the capacity value of wind is described and a discussion of the pertinent issues surrounding it is given. Approximate methods for the calculation are also described with their limitations highlighted. The outcome of recent wind capacity value analyses in Europe and North America, along with some new analysis are highlighted with a discussion of relevant issues also given.
      2127Scopus© Citations 289