33kV Shunt Reactor | A TRV Study for a UK Offshore Windfarm
Published 18 Aug 2020
33kV Shunt Reactor
A TRV Study for a UK Offshore Windfarm
Enspec Power have released a case study of a TRV assessment for a UK Wind Farm.
This assessment was done to ensure the 33kV Circuit Breaker was sufficiently rated for the sites 2.5MVAr shunt reactor.
Enepec Power carried out full modelling of the medium voltage network, site and shunt reactor to investigate the peak TRV and RRRV values and compared these against the breaker ratings.
The full case study can be found via download. The full redacted paper is available on request from Thorne & Derrick.
This report was produced by Enspec Power Ltd – it details a Temporary Recovery Voltage (TRV) study carried out for ABC Wind Farm in order to assess TRV ratings of the shunt reactor circuit breaker.
The following events have been investigated: De-energisations of the shunt reactor, credible single phase-to-ground and three phase-to-ground faults, simulations of the worst case TRV peak and Rate of Rise Recovery Voltage (RRRV) values of the vacuum circuit breaker (VCB), with a comparison of the results with the switching capability of the VCB according to IEC 62271-100, and finally a discussion of the possible solutions in order to reduce the TRV to below VCB ratings.
In conclusion, the investigations found that the TRV values for the de-energisation of the shunt reactor and the fault interruption of a three phase-to-ground and single phase-to ground fault at the reactor terminals were not compliant with the corresponding envelopes described in IEC 62271-100 (T10 / T60).
The probability of a fault between the VCB and shunt reactor terminal is low. Nevertheless, the de-energisation of the shunt reactor would be considered as frequent. Thus, a TRV / Overvoltage suppression / mitigation method should be considered. It is essential not only for the TRV requirement, but also for protecting the reactor against over voltages.
An RC snubber with appropriately sized SAs, or controlled switching with appropriately sized SAs are considered to be the best solutions to suppress the TRV to below the breaker ratings, minimise/eliminate probability of reignition phenomena and reduce the overvoltage stress at the reactor terminals. Note that independent pole operation is required for the solution of controlled switching.
About Enspec Power
Enspec Power help organisations to make money and to save money – professional engineers can do this! They’ve been making businesses more profitable since 1998 when their sibling founders, fed up with the bureaucracy of larger organisations, decided to go it alone and set up Enspec as a friendly, flexible engineering company.
Two decades on, they’re still a friendly bunch and one of the UK’s leading independent specialists in power quality engineering. They really understand electrical power systems and are passionate about what we do and what’s happening in the wider world of technology.
They are progressive members of The Institution of Engineering and Technology (IET) with links to academia – so if they don’t have the immediate answers, chances are they know somebody that does. They offer specialist engineered products and services such as Power System Studies, Power Factor Correction, Harmonic Filters, Reactive Compensation, Point-on-Wave Switching and Site Services. They’re here to help all manner of heavy electricity users such as utilities and renewables, oil and gas, manufacturing and other industries.
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