With National Grid’s recently-published Future Energy Scenarios (FES) 2019 report highlighting the challenge of reacting to renewable energy and electric vehicle adoption, Darren Jones, Technology Manager for ABB Power Grids, explains how an innovative combination of technology and economic models has potential to support grid stability.
As the UK strives to reduce its carbon dioxide emissions and minimise climate change, it is shifting towards greater reliance on renewable energy at the same time as switching off traditional thermal power generation. However, this energy transition has consequences for grid operators.
Operators were previously able to rely on the momentum inside large rotating generators to absorb and inject power to stabilise voltage and frequency within a tightly controlled window. This spare capacity on the network is called inertia or spinning reserve as the momentum of the generators has inertia that keeps generators spinning even when unpowered.
However, wind and solar plants do not provide this inertia. They may deliver a sudden step change in output due to changing cloud or wind conditions that may add to varying conditions on the grid. In addition, the FES report has highlighted that we’re likely to see greater adoption of electric vehicles (EVs) and this may also lead to more variability on the grid due to changing patterns of timing, location and frequency of EV charging.
The net result is that grid operators will need to find alternative sources of inertia. One solution that has already been adopted widely is battery energy storage but it’s well worth exploring alternatives.
That is SP Energy Networks’ objective for the Phoenix project, which has received funding from Ofgem under the Network Innovation Competition (NIC).
First of a kind hybrid-synchronous condenser
During the innovative four-year project, SP Energy Networks is working with ABB, alongside the University of Strathclyde and the Technical University of Denmark to support the development plan to deliver the world’s first hybrid-synchronous condenser (H-SC).
This combines traditional motor technology with power electronics and a hybrid control system to create a hybrid system that is capable of delivering a combination of fast reaction, spinning capacity and short circuit control. These are all essential for delivering ancillary services such as frequency regulation and voltage control.
As well as creating a model for the technology itself, the project will create a commercial template and business case for operators across the UK to roll out the technology as ‘business as usual’.
The H-SC’s two main physical components will be a traditional Synchronous Compensator (SC) and a power electronic static compensator
(STATCOM). The SC is a type of synchronous motor that uses a voltage regulator device to either generate or absorb power. SC devices have been in use for over a century and the unit in the H-SC will provide inertia and short circuit level control.
It will be paired with a power electronic STATCOM, which is part of ABB’s flexible alternating current transmission system (FACTS) portfolio. The STATCOM’s role in the H-SC will to absorb or inject power fast, which is essential for frequency control.
Together, the SC and STATCOM provide the scale and speed to create an alternative to traditional inertia from a thermal generator. However, they will also require a hybrid control system to manage both technologies seamlessly as a single solution for grid stability.
Wider benefits
According to SP Energy Networks’ forecasts, the H-SC will achieve operational cost savings of £42 million by 2030, as well as saving more than 62,000 tonnes of carbon dioxide emissions and releasing additional network capacity by enabling accelerated connection of Distributed Energy Resources (DER) sources such as wind turbines and solar photovoltaics.
The project will also act as a model for other operators to follow – including technical arrangements, as well as commercial mechanisms and cost benefit analysis. This will support the roll-out of H-SC technology on a larger scale, ultimately supporting the UK’s energy transition at the same time as protecting the security and quality of supply.
Neilston 275 kV substation
Having initiated the project in 2018, ABB is currently installing the H-SC at Neilston substation, a strategic 275 kilovolt (kV) on SP Energy Networks’ transmission network substation near Glasgow. Development of the control system and commercial packages have been underway at the same time. The project partners will then evaluate its capability to enhance system stability and security while maintaining power quality.
Once commissioned at the end of 2019, the H-SC will inject or absorb energy into the network to maintain the voltage within the required limits. In effect, it will provide spinning reserve over a few seconds until other resources such as a battery energy storage system (BESS) or a reserve generator can be brought online.
The project partners will evaluate the installation’s performance in a year-long trial phase that is due to start in early 2020.
