Conference programme

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Wednesday, 18 November 2015
11:30 - 13:00 Wind power supporting the grid
Integrating wind power into the electricity market  
Onshore      Offshore    


Room: Belleville

The aim of the session is to present advances on techniques that permit to wind farms to support the grid both in terms of frequency and voltage.  The ability to provide such services is one of the challenges today for increasing wind penetration. The session addresses also the potential of increasing wind penetration when considering smart grid problematics.

Learning objectives

  • Advances in techniques enabling wind turbines to comply with emerging grid codes for system services
  • Insight to the possibility offered by wind farms to contribute to frequency control
  • Advances in voltage management in grids with high wind penetration
  • How the control capabilities of wind farms can be used to mitigate any negative impacts on grid stability
  • How to increase wind penetration considering complementarity with demand with focus on electric vehicles
Lead Session Chair:
Alfredo Parres, ABB Group, Spain
George Kariniotakis, Professor, Centre for Processes, Renewable Energies and Energy Systems (PERSEE), MINES Paris Tech, France
Kevin Johnstone University of Strathclyde, United Kingdom
Co-authors:
Kevin Johnstone (1) F Keith Bell (1) Campbell Booth (1)
(1) University of Strathclyde, Glasgow, United Kingdom

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Kevin Johnstone is a PhD researcher at University of Strathclyde, Glasgow, UK. He studied Aero-Mechanical Engineering at Strathclyde before working at Airbus for two years as a graduate engineer. After this role he returned to Strathclyde to pursue his PhD with a focus on power system stability and wind energy.

Abstract

The impact of post-fault active power recovery ramp rates of wind turbines on transient stability in Great Britain

Introduction

As the growth of renewable power generation continues as a consequence of the push towards renewable energy targets, dramatic changes are expected in the dynamic characteristics of power systems. The replacement of synchronous power plants with converter-interfaced generation produces three key changes in the grid, each of which affects stability: (i) alterations in steady-state power flows through transmission corridors, (ii) erosion of the overall system inertia and (iii) alterations in the characteristics and capability of stabilising controllers. The question remains over how the unique control capabilities of wind farms themselves can be used to mitigate any negative impacts on grid stability which come about as a result of their increased penetration. It is imperative that such growth is not unduly impeded by preventable limitations such as transient stability limits.

Approach

A reduced dynamic model of the GB transmission system is used to simulate critical scenarios for transient stability, such three-phase-to-earth faults on key transmission boundaries while the grid is operating during periods of high wind power output in the northern region. Scotland is modelled with varying amounts of synchronous generation online and the effect of wind penetration level and geographical distribution of the generators on overall grid transient stability – in terms of key boundary transfer limits and critical clearing times – is analysed. Sensitivity studies are carried out to identify the impact of post-fault active power ramp rates of wind farms on the grid transient response.

Main body of abstract

Future power systems may include significantly large areas of predominantly converter-interfaced power plants. In the GB context, future scenarios are predicted where there is very little conventional synchronous generation connected to the transmission network in Scotland, while increasing amounts of wind power plants are integrated in place of the decommissioned synchronous plant. It is increasingly important to develop an understanding of the nature of the transient response such a future system may have to large disturbances, such as three-phase short-circuit faults on critical transmission circuits. The aim of the study is to examine the potential benefits of tailored post-fault active power recovery ramp rates of wind turbines, in terms of their impact on the transient response of the remaining synchronous generation, to several network fault events in the GB system.

Conclusion

The implementation of slower post-fault active power ramp rates of wind turbines in exporting regions, as well as faster ramp rates in importing regions, is expected to provide an increase in transient stability limits for large faults, particularly those occurring on the boundaries between exporting and importing regions. Current grid code requirements for wind farms may require modification in order to force wind farm operators and manufacturers to provide services which will improve grid transient behaviour. The findings could also have an impact on how the power system is operated in future high wind scenarios.


Learning objectives
The study provides a qualitative assessment of the underlying dynamic behaviour resulting from altered active power recovery rates on GB transient stability, for a variety of fault conditions. Broad conclusions from the work will be applicable to other power systems around the world which are experiencing similar unprecedented growth in converter-interfaced generation. The work feeds into a larger PhD project which aims to assess a range of strategies which can be used to mitigate the negative impacts on power system transient stability from high wind penetrations, including the use of FACTS devices (e.g. STATCOMs) and the provision of reactive power support from wind farms.