Now showing 1 - 10 of 33
  • Publication
    The relationship between base-load generation, start-up costs and generation cycling
    (International Association for Energy Economics, 2008-12) ; ;
    Developments 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.
      2678
  • 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.
    Scopus© Citations 38  1447
  • Publication
    Multi-mode operation of combined-cycle gas turbines with increasing wind penetration
    As power systems evolve to incorporate greater penetrations of variable renewables, the demand for flexibility within the system is increased. Combined-cycle gas turbines are traditionally considered as relatively inflexible units, but those which incorporate a steam bypass stack are capable of opencycle operation. Facilitating these units to also operate in opencycle mode can benefit the power system via improved system reliability, while reducing the production needed from dedicated peaking units. The utilization of the multi-mode functionality is shown to be dependent on the flexibility inherent in the system and the manner in which the system is operated.
      1084Scopus© Citations 39
  • Publication
    Optimal firm wind capacity allocation to power systems with security constraints
    Many countries have declared future renewable energy penetration targets. Wind power connection to power systems is delayed by limited transmission system capacity as attractive wind sites are often located in weakly designed transmission areas. Optimal use of existing transmission system resources should be made in the allocation of capacity connection permits. The volume of wind power connection applications and their power production statistical inter-dependencies suggest that they should be assessed in a collective probabilistic manner. This paper uses a sequential probabilistic load flow method in tandem with a linear programming computational geometry constraint redundancy approach to optimally allocate wind capacities given the transmission system capacity that is securely available.
    Scopus© Citations 17  1987
  • Publication
    Improved system operations with high penetration of wind power : a dialog between academia and industry - Ireland
    This is a submission to a panel session at the 2010 IEEE PES General Meeting. It discusses effective collaboration between academia and industry.
      392
  • Publication
    Quantifying reserve demands due to increasing wind power penetration
    With wind power penetration increasing in many systems worldwide, operational issues are beginning to emerge due to the uncertain nature of wind power. One of these issues is the provision of reserve for system security. To analyse this, one must consider generator outage rates, system load forecast errors and wind power forecast errors in such a way as to directly relate the system reserve level to the security of the system. In this paper a new methodology is proposed for the analysis and provision of system reserve levels. The methodology considers the provision of both reserve (on-line) and replacement reserve (offline). The proposed methodology is then applied to the IEEE reliability test system incorporating other influencing factors like wind farm size and numbers and forecast periods. Results illustrate the impact increasing wind power penetration has on reserve.
      1125Scopus© Citations 71
  • Publication
    Aspects of wind energy characteristics in transmission related optimisation models : invited panel discussion paper
    This invited panel paper discussion will outline a number of aspects of wind energy characteristics relevant to the optimal wind/transmission model formulation task. Optimal placement of wind capacity on a constrained transmission network is a typical example of this type of problem. In particular the relevance of advanced and computationally intensive stochastic unit commitment to the model formulation will be debated. Optimization constraint matrix structure and techniques to exploit it will be shown to be of considerable importance for this type of problem. The relative merits of different model dimensionality reduction schemes, either through multivariate component analysis and probability discretisation or indeed scenario reduction, will be discussed. A pragmatic acceptance of the imprecise impact of long-term power system uncertainties will be maintained throughout, and wherever possible generality to different types of power systems will be considered.
    Scopus© Citations 1  475
  • Publication
    A flexible power system operations simulation model for assessing wind integration
    With the advent of wind power generation on worldwide power systems, many operators and researchers are analyzing the impacts that higher future amounts may have on system operations. Many of the tools are analyzing longer term impacts on the steady-state operations of power systems and are primarily using cost as a metric. They are also using tools that are often inflexible to accommodating different market designs or operational structures. In this paper a model was developed to mimic operator behavior using a combination of security-constrained unit commitment, security-constrained economic dispatch, and automatic generation control programs. New metrics are used to compare reliability in terms of energy imbalance for different systems or different market and operational structures at very high time resolution. Finally an example application of the tool and results for a test system are shown.
      550Scopus© Citations 28
  • Publication
    Rolling unit commitment for systems with significant installed wind capacity
    As wind power penetration grows, the amount of reserve needed on the system also grows, due to the increases in the uncertainty of wind power, which grows larger as forecast horizon increases. By scheduling the system more often the amount of extra reserve to be carried to cater for wind uncertainty decreases, depending on the flexibility of plant on the system. This reduces the costs of operating the system. There is a trade off between reduced costs due to more frequent commitment, the ability of wind forecasts to be made more accurately, and the increased costs of more flexible plant. This paper examines the benefits of committing the system more frequently, and how different factors such as reliability of the system, accuracy of the forecasts and plant mix impact on this.
    Scopus© Citations 53  690
  • Publication
    Base-load cycling on a system with significant wind penetration
    Certain developments in the electricity sector may result in suboptimal operation of base-load generating units in countries worldwide. Despite the fact they were not designed to operate in a flexible manner, increasing penetration of variable power sources coupled with the deregulation of the electricity sector could lead to these base-load units being shut down or operated at part-load levels more often. This cycling operation would have onerous effects on the components of these units and potentially lead to increased outages and significant costs. This paper shows the serious impact increasing levels of wind power will have on the operation of base-load units. Those base-load units which are not large contributors of primary reserve to the system and have relatively shorter start-up times were found to be the most impacted as wind penetration increases. A sensitivity analysis shows the presence of storage or interconnection on a power system actually exacerbates base-load cycling until very high levels of wind power are reached. Finally, it is shown that if the total cycling costs of the individual base-load units are taken into consideration in the scheduling model, subsequent cycling operation can be reduced.
    Scopus© Citations 210  1098