Investigation of sub-synchronous between wind turbine generators and series capacitors

Completed

Renewable Energy Sources(Wind Energy)
Other Power and Storage Technologies(Electricity transmission and distribution)

Applied Research and Development

ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering)

Not Cross-cutting

Project Contact
National Grid Electricity Transmission

Network Innovation Allowance

Ofgem

01 March 2014

01 July 2016

28 months

£305,000

Power

London

Network Innovation Allowance

Project Contact, National Grid Electricity Transmission

The objectives of this research project are to: Highlight any potential SSI issues that can occur between series capacitors and wind turbine generators Establish a control system that could be implemented as part of the wind turbine converters to mitigate any SSI issues The project will be deemed successful if the above-mentioned objectives are delivered and when the full report detailing the research, modelling and results is delivered upon completion of the project.

Series compensation will be implemented on the GB transmission network in the near future in order to enhance the transfer capability of the Anglo-Scottish boundary. A possible risk associated with series capacitors is the occurrence of Sub-Synchronous Interactions (SSI) which are oscillations involving generator shafts and power electronic controllers. If not damped, these oscillations can potentially lead to component fatigue, life-time reduction of equipment and failures of both synchronous and induction generators. These affected generators will have to be withdrawn from the network thereby reducing the overall generation availability to meet the demand, compromising the security of supply and possibly delaying the achievement of renewable energy and carbon emissions targets. In 2009 a Sub Synchronous Control Interaction (SSCI) event occurred in Texas, where a wind turbine generator was connected directly with a series compensated line during an outage. During this event the wind turbines were damaged through excessive current. The risk of occurrence of sub-synchronous interactions (SSI) in the future GB network as a result of increasing onshore series compensation can neither be confirmed nor ruled out unless in-depth technical studies are carried out. The GB network is very unique in nature with respect to its topology, the location of the series capacitors and that of the wind farms. The standard IEEE benchmark models are not suitable to provide an accurate representation of possible SSI in the GB system. An alternative approach consisting of developing specific models is therefore required. Research The Method that has been proposed for this project include: An investigation and analysis of the possible interactions of wind turbine generators (DFIGs and FCIGs) with series compensation in the GB system. This would involve the modelling of relevant network components in MATLAB and Simulink. A literature research into the mitigation of sub-synchronous interaction using a damping controller at the grid side converter of wind turbine generators with close proximity to synchronous generators suffering from sub-synchronous oscillationsNote : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above

21/08/18