Now showing 1 - 10 of 88
  • 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
    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
    Resiliency Assessment of Electric Power Distribution Systems
    (Nova Science Publishers, Inc., 2017-05-15) ; ; ;
    This chapter discusses the resiliency aspect of electric power distribution systems considering the role of distributed generation. A restoration tool is developed that can emulate the recovery path of the distribution system after a contingency situation, then engineering resiliency assessment framework is applied to (semi)-quantitatively measure the dimensions of resiliency. The proposed procedure is implemented on a test system to demonstrate the key factors affecting the resiliency of a distribution system, including distributed generation.
  • Publication
    Stochastic analysis of the impact of electric vehicles on distribution networks
    Advances in the development of electric vehicles, along with policy incentives, will see a wider uptake of this technology in the transport sector in future years. However, large penetrations of EVs could lead to adverse effects on power system networks, especially at the residential distribution network level. These effects could include excessive voltage drop and thermal loading of network components. A stochastic method is developed to take account of the uncertainties associated with EV charging and the technique is implemented on a residential test network using power system simulation software. The results show how voltage levels, component loading network losses are impacted from EV charging, taking into account the probabilistic behaviour of the EV owners.
  • Publication
    Capacity value of wind power, calculation, and data requirements : the Irish power system case
    The capacity value of wind power indicates the extent to which wind power contributes to the generation system adequacy of a power system. The related data requirements may be subject to difficulties due to the temporal variability and spatial distribution of wind power in connection with the limited databases currently available. This paper presents a methodology to identify the minimal amount of data required for reliable studies. Based on wind power data of 74 stations in Ireland, covering up to ten years, the effects of different numbers of stations and different time periods of data on the capacity value are analyzed. The calculations are performed by means of a fast calculation code. The results show that at least four to five years of data in an hourly resolution are necessary for reliable studies and that 40 to 50 evenly distributed stations give an acceptable representation of the total wind power generation in Ireland.
      1286Scopus© Citations 94
  • 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.
      630Scopus© Citations 96
  • Publication
    Optimal voltage control settings for wind power
    (Institution of Engineering and Technology, 2009) ; ; ;
    High penetrations of wind power on distribution networks are causing voltage rise on many networks. This voltage rise is limiting the permissible penetration levels of wind. Numerous active control schemes have been proposed to solve this issue, but widespread adoption of active management by network operators has yet to occur. Here, the fixed power factors of the generators' and the tap setting of the transmission transformer are optimally determined such that the voltage rise barrier is overcome and more wind can connect. The impact on the transmission system is becoming increasingly important and is also taken account of in the method. The method is tested on a sample section of distribution network illustrating that the optimal selection of voltage control settings can deliver some of the benefits of active management without any of the expense or perceived risk.
      487Scopus© Citations 5
  • Publication
    Transmission System Impact of Wind Energy Harvesting Networks
    (Institute of Electrical and Electronics Engineers, 2012-10) ; ;
    The increasing emphasis placed upon renewable sources of energy requires that power systems accommodate a roll out of variable, asynchronous generators throughout transmission and distribution networks. High penetration levels of such generation will displace synchronous plant and may cause a challenging scarcity of ancillary service providers, notably in the area of reactive power provision. Consequently, the onus must increasingly be laid upon renewable generators to provide the ancillary services necessary to operate the power system. An emerging practice is to connect adjacent distributed generators in a clustered fashion to a dedicated transmission node, an arrangement that offers rich possibilities for participation in transmission-level control. Performance characterizations of such networks will be helpful in planning transmission system development for reduced synchronous plant availability. This work will examine the effect of increasing penetration of wind generators on transmission system voltage levels and voltage security.
      535Scopus© Citations 23
  • Publication
    A study of operation strategy of small scale heat storage devices in residential distribution feeders
    Passive operation of thermal energy storage devices is a well established concept in Europe; this paper looks at active operation of thermal storage devices and their role in providing demand response from residential distribution feeders. It co-simulates the power system and the thermal performance of buildings to investigate the effect of operation strategy of thermal energy storage devices on the network and thermal comfort of households. A realistic residential feeder is used to demonstrate the applicability of the presented methodology. It is shown that the operation strategy of the thermal storage devices can affect the realizable reserve from these devices, house temperature and network variables such as losses and voltage. The realizable demand response found by the presented methodology can be used for market operation to avoid underestimation and overestimation of the demand response.
      323Scopus© Citations 6