Now showing 1 - 9 of 9
  • Publication
    A small - signal stability analysis of DFIG wind generation
    This paper examines the small-signal stability impacts of high penetrations of doubly-fed induction generator (DFIG) wind turbines on power systems. It provides a basic overview of small-signal stability concepts and then examines the response of DFIG generation to two local contingency event. Using the New England 39 bus test system, this paper will demonstrate the stability implications of DFIG turbines utilizing terminal voltage control and fixed power factor control in response to reactive and active power loss events. By implementing terminal voltage control strategies in DFIG wind turbines, system stability is improved and allows for increased levels of wind penetration levels while maintaining a high level of system security.
  • Publication
    Transient stability impacts from distribution connected wind farms
    (Institute of Electrical and Electronics Engineers, 2012-07) ; ;
    Wind generation penetration levels are increasing in power systems across the world. Along with transmission connected wind farms, distribution connected wind farms are becoming more prevalent in power systems. How these distribution connected farms control reactive power is of concern to the transmission system operator. This paper examines a hybrid system, where the transmission system is modeled with a significant penetration level of radial distribution feeders connected to a collection of small wind farms. By varying control strategies at the distribution farms the impacts of the reactive power control strategy implemented by the wind farms are observed. It aims to show that the additional impedance of the distribution system will have unintended consequences on the transmission system and the application of voltage control is less critical.
      690Scopus© Citations 4
  • Publication
    Enhanced utilization of voltage control resources with distributed generation
    Distributed Generation (DG) is increasing in penetration on power systems across the world. In rural areas, voltage rise limits the permissible penetration levels of DG. Another increasingly important issue is the impact on transmission system voltages of DG reactive power demand. Here, a passive solution is proposed to reduce the impact on the transmission system voltages and overcome the distribution voltage rise barrier such that more DG can connect. The fixed power factors of the generators and the tap setting of the transmission transformer are determined by a linear programming formulation. The method is tested on a sample section of radial distribution network and on a model of the all island Irish transmission system illustrating that enhanced passive utilisation of voltage control resources can deliver many of the benefits of active management without any of the expense or perceived risk, while also satisfying the conflicting objectives of the transmission system operator.
      1284Scopus© Citations 170
  • Publication
    A steady-state voltage stability analysis of power systems with high penetrations of wind
    As wind generation begins to contribute significantly to power systems, the need arises to assess the impact of this new source of variable generation on the stability of the system. This work provides a detailed methodology to assess the impact of wind generation on the voltage stability of a power system. It will also demonstrate the value of using time-series AC power flow analysis techniques in assessing the behavior of a power system. Traditional methods are insufficient in describing the nature of wind for steady-state analyses and as such a new methodology is presented to address this issue. Using this methodology, this paper will show how the voltage stability margin of the power system can be increased through the proper implementation of voltage control strategies in wind turbines.
      4054Scopus© Citations 229
  • Publication
    Rotor angle stability with high penetrations of wind generation
    This paper explores the relationship between wind generation, particularly the control of reactive power from variable speed wind turbine generators, and the rotor angle stability of the conventional synchronous generators in the system. Rotor angle stability is a dynamic phenomenon generally associated with changes in active power flows that create angular separation between synchronous units in the system. With larger penetrations of wind generation being introduced into power systems, there will be large flows of active power from asynchronous generation in the system. These asynchronous active power flows can aid in maintaining the rotor angle stability of the system. However, the manner in which wind generation injects reactive power into the system can be critical in maintaining angular stability of the synchronous units. Utilizing wind generation to control voltage and reactive power in the system can ease the reactive power burden on synchronous generators, and minimize angular separation in the system following a contingency event and can provide a significant level of support which will become increasingly important in future power systems.
      3464Scopus© Citations 203
  • Publication
    Varying penetration ratios of wind turbine technologies for voltage and frequency stability
    This paper examines the ability of a power system to accommodate wind generation with varying ratios of doubly fed induction generator and fixed speed induction generator turbines from both static and dynamic aspects. By controlling the ratio between the two types of turbines, voltage stability is maintained for steady-state conditions for a large range of varying wind speeds. Using the ratio determined from the static analysis, the dynamic analysis explores the voltage and frequency characteristics of the system under contingency conditions. An initial analysis was carried out on the IEEE 30 bus test system. The results of this analysis are presented in this paper and detail how by varying the ratio of the turbine types the frequency stability and voltage stability can be improved.
      1355Scopus© Citations 37
  • Publication
    Impact of wind turbine control strategies on voltage performance
    This study examines the 2013 Irish electricity network and its ability to accommodate large levels of wind generation while maintaining appropriate voltage levels across the system. The network provides a fully functional test system that is suitable for large scale power flow and dynamic simulations. In the next decade, wind generation is expected to constitute large percentage of the country’s new renewable generation portfolio due to the rich wind resource available in Ireland. As wind penetration grows, larger levels of conventional generation will be displaced and there will be an increased need to provide both voltage and frequency stability support. Many wind turbines have the capability to perform certain mitigation tasks such as reactive power support; in particular, this study will examine the wind turbine’s ability to provide terminal voltage control in order to improve the system’s voltage performance. This will be achieved using steady-state power flow analysis with historical loading patterns while taking into account the inherent variability of the wind resource. It will show that increased application of terminal voltage control strategies will allow for more robust voltages both locally and systemically.
      1624Scopus© Citations 9
  • Publication
    Synchronizing Torque Impacts on Rotor Speed in Power Systems
    Renewables are increasingly replacing power from conventional generators. Renewable power injected through power electronic converters lacks the fundamental electric torque components. Electric torque components have an important role in determining the behavior of conventional machines in the network. The influence of this factor becomes more notable in power systems with reduced inertia. Hence, questions arise on, how can synchronizing torque basically contribute to the rotor speed deviation and eventually the system frequency and if there is a potential for using the steady state synchronizing torque coefficient (STC) to achieve acceptable frequency operating points. This paper calculates the steady state STC matrix by using the multi-machine Heffron-Philips model in conjunction with the network admitance matrix. Accordingly, it investigates the impact of the generator location and reactive power output on the STC matrix. It demonstrates how this impact manifests in the generator rotor speed deviation. Eventually, the significance of the STC from the system frequency perspective is assessed.
      965Scopus© Citations 10