A selection of the projects we’ve delivered — across renewables, storage, data centres, transmission and heavy industry. Filter by service or sector to explore our work.
Independent UK power systems consultancy — modelling, compliance studies and technical analysis for complex grid-connected projects.
Powered by Morson Praxis →Full earthing design for a new private 33/11 kV substation
Arla was building a new private 33/11 kV substation to serve its own site and needed a complete earthing design, with the supporting studies to demonstrate a safe installation.
We carried out a full design of the new earthing system and all the associated studies, covering soil resistivity analysis, EPR and touch and step voltage calculations, together with the substation layout and earthing schematic drawings.
Condition survey of the existing earthing infrastructure across the campus
The Culham campus has an extensive HV distribution network built up over many years, and the condition and integrity of the existing earthing infrastructure needed to be established before further development.
We carried out a site-wide earthing investigation and survey to assess the condition of the existing earthing infrastructure. This included soil resistivity tests and earth continuity tests within each substation and between the individual substations, validating the earth return paths and sheath bonding across the site.
400 kV onshore substation earthing for an offshore wind connection
A new 400 kV onshore substation connecting an offshore wind farm needed a full earthing design. At 400 kV the earth fault current and resulting earth potential rise are high, so the earthing system has to be proven to keep touch and step voltages within safe limits.
We carried out the soil resistivity analysis measurements and modelled the site in CDEGS, then prepared a detailed earthing study to assess the overall EPR and the associated touch and step voltages across the substation.
49 MW onshore wind at 132 kV — full BoP studies and 33 kV cable sizing
Crystal Rig IV is a 49 MW onshore wind farm connecting at 132 kV in a heavily congested location. Alongside the full balance-of-plant compliance and protection package, the constrained routing meant the 33 kV collector cables had to be sized carefully across many different trench and crossing arrangements without oversizing.
We delivered the full balance-of-plant study suite — load flow, system losses, short circuit, P28 (RVC/SVC), G5.5 harmonics, TGN 288E insulation coordination, earthing, protection coordination and arc flash. Alongside this we produced detailed 33 kV cable sizing calculations, analysing current ratings for 8 unique cable trench sections and 4 complex cable crossing / HDD sections to keep every section within its thermal limit.
132 kV cable rating over legacy 1960s fluid-filled circuits
A new road was to be constructed directly over a set of NGET legacy 1960s fluid-filled cables connecting the SGTs to the local NGED 132 kV substation. Additional ground cover changes the thermal environment of a buried cable, and on ageing fluid-filled circuits any loss of rating has to be understood before construction is allowed to proceed.
We developed a detailed 132 kV cable sizing calculation, first building a baseline model of the original fluid-filled cables to reproduce their existing rating, then running a series of optioneering studies to assess the impact of different road cover depths and backfill materials on the achievable circuit rating. The output gave a defensible basis for the road installation without derating the legacy circuits.
Rolling survey and modelling exercises for 8 sites across the South East Water area
Aurora was contracted by South East Water to carry out a rolling site survey programme across critical water treatment works (WTW) sites in the southern region, to support preparation for future PV and BESS upgrades.
Aurora’s scope was to attend each site, gather the existing site data, produce an overall single line diagram and identify the existing system configuration and operation. Once this was complete, we carried out loadflow and fault level studies to facilitate the planned upgrade of the sites for solar and battery storage schemes.
200 MVAr 400 kV shunt reactor, TOV/SOV and TRV/RRRV
Aurora Power Consulting was contracted by Mersey Reactive Power to carry out an urgent TOV/SOV study for a new 200 MVAr 400 kV reactor due for energisation onto the National Grid network.
The work combined two studies. First, a detailed PSCAD model assessed temporary and switching overvoltage behaviour against TGN 288E. Second, a TRV and RRRV study confirmed that the circuit breaker would operate correctly when switching the reactor under both routine loading and fault conditions. Reactor switching is a known driver of severe TRV cases, so the breaker selection needed to be supported by simulation evidence rather than catalogue assumptions alone.
A full suite of studies for two iDNO private networks
Aurora was approached by Thameswey to undertake power system studies to support and develop a detailed understanding of the Woking and Milton Keynes town centre private iDNO networks.
Aurora’s first tranche of work was to carry a full review of the existing 11 kV and 400V power distribution system and protection settings for the Woking town centre as part of the Victoria Square development, using the ETAP modelling package. Aurora developed an overall electrical model of the entire electrical network in ETAP from the main DNO incomers down to the largest outgoing LV circuit, and then ran a series of short circuit studies to validate that all the switchgear is within the correct fault rating duty. Once completed, Aurora then carried out a detailed protection coordination study to assess each of the main 11 kV substations on the network for correct discrimination to ensure that the correct protection elements trip in order.
Aurora’s second tranche of work was to develop a detailed CDEGS earthing model to assess Earth Potential Rise (EPR), touch and step voltages at a number of substations. This involved creating a MALZ model and then using TRALIN/SPLITS to determine fault current return paths through a complex series of interconnecting cables.
The final tranche of work was to carry out a similar exercise for Milton Keynes town centre, including a full survey, loadflow and short circuit study, protection coordination study and subsequent CDEGS earthing study.
A full suite of studies for an onshore gas storage plant
Aurora was approached by Storengy to undertake power system studies to support the connection of two new 9.5 MW VSD compressors, along with additional studies to assess system performance following faults and subsequent arc flash requirements.
We began by developing an ETAP model of the whole power system, including the existing and new equipment and the associated solution mining loads. Once the model had been created and validated against existing site operation, Aurora undertook loadflow and short circuit studies to confirm the system operating parameters. Aurora then re-evaluated the existing protection coordination settings across the whole plant, from LV up to the 132 kV connection, before undertaking a new grading exercise for the new VSDs and associated auxiliary loads.
Aurora was subsequently tasked with carrying out an arc flash investigation using the new protection settings, to determine incident energy levels and required PPE for operatives.
A full suite of studies for an onshore oil field
Aurora was approached by GSYS to carry out a full set of power system studies for a new greenfield oil field development in Kurdistan. The project required full modelling of the generation and distribution system, along with design support for the protection system and CT selection and sizing for main and differential protection.
We began by reviewing the initial site documentation and detailed design deliverables before creating an ETAP model for client validation. Once complete, a full suite of studies was carried out covering loadflow, short circuit, motor starting, protection coordination, arc flash, harmonics and transient stability. Aurora also supported several aspects of the system design, including CT sizing calculations, earthing configuration advice and protection relay configuration.
A full suite of studies for an offshore rig
Aurora was approached by Archer to carry out a full set of power system studies for an upgrade of the Topaz offshore platform with a new modular drilling unit (MDU). The project required a full modelling exercise for the generation and distribution system.
We carried out a full review of the existing site data, documentation and studies before building a full network model. Once the model was created, Aurora carried out simulations for loadflow, fault level, motor starting, harmonics, transient and dynamic stability, followed by a protection coordination study for the whole installation.
A detailed protection study for a large hospital
Aurora was approached by Southampton NHS Trust to carry out a protection study for Southampton Hospital. The site was very large, with two main 11 kV intakes, a complex interconnected distribution system and a series of embedded generators.
We carried out a full site survey of the hospital distribution system, checking relays and settings to establish an up-to-date baseline. We then carried out loadflow and short circuit studies to validate the system design before developing a detailed protection coordination study for the entire network, covering overcurrent and earth-fault coordination.
A detailed protection study for a large university campus
Aurora was approached by SSE to carry out a protection study for Exeter University campus. The site is large and consists of three distinct rings, two of which operate normally closed using Translay cable differential protection.
We carried out an initial short circuit study to validate the system design before developing a detailed protection coordination study for the entire network, covering overcurrent and earth-fault coordination and updating the Translay differential settings.
A detailed loadflow, short circuit and protection study for a secure data centre
Aurora was approached by ICE to carry out power system analysis and an overall protection study for a key London data centre handling financial trading between the London and New York stock exchanges. The site had been developed over several years and lacked an up-to-date protection coordination study and arc flash study.
We carried out a full loadflow and short circuit study to validate the system design and confirm that all equipment was correctly rated for the required duty. This included both main and failover supplies, sustained operation from backup diesel generator sets and the performance of the rotary UPS under fault conditions. We then undertook a detailed protection coordination study for the entire network, covering the HV, LV and UPS systems, cable differential and transformer differential protection, and generator protection settings.
LT2029 tender for 3x existing power stations to provide ESR services
RWE wished to submit tenders to provide Electricity Restoration Services (ERS) for three existing power stations: Didcot B, Staythorpe and Pembroke. Some site models existed, but they were simple static models and did not contain the generator control systems: AVR, OEL, UEL, SCL and PSS. All three sites needed to be modelled and the ERS simulations completed within a month.
We reviewed the available data for each site and expanded the existing DIgSILENT models to include the generator control systems: AVR, OEL, UEL, SCL and PSS. We then checked that the models behaved as expected before executing the RMS simulation tests required by NESO to identify SCL behaviour, inertia delivery and plant stability under the specified test conditions.
SSO studies for 2x 49 MW BESS sites connected at 33 kV
NESO had recently introduced a new requirement for SSO studies on new generation sites connected to the transmission network, catching many developers by surprise. Aurora was tasked with reviewing the guidance, taking the existing EMT models and undertaking an SSO study.
We reviewed the initial NESO guidance and challenged the validity and practicality of the requirements, since a literal interpretation would have required more than 10,000 simulation studies. Even with scripting and automation, the processing and analysis time would have been unrealistic. We discussed the requirements with NESO and agreed a simplified set of requirements and a more appropriate method, while liaising directly with the inverter and PPC manufacturers to understand the system response.
49 MW Hybrid Solar and BESS at three sites, 132 kV DNO connection
Solar sites at 132 kV require the full suite of G99 Type D studies, along with ENA P28, ENA G5.5 and HV cable sizing studies. Individually the sites were relatively straightforward; the challenge came from delivering three sites simultaneously on a tight programme.
Aurora delivered the three sites simultaneously to meet the client’s tight programme. For each site, a full ENA G99 Type D package, P28 assessment and HV cable sizing calculation package was provided to allow the client to meet the aggressive construction schedule required by the developer.
Policy development for large-scale BESS integration on distribution networks
Aurora was approached by Northern Powergrid (NPg) to help develop its policy and understanding of how large-scale BESS integration could affect distribution network operation and performance. The project was undertaken as part of a Network Innovation Allowance (NIA) programme.
We reviewed the existing NPg policy documents and discussed potential shortcomings in assessing BESS operating at fixed non-unity power factor, unity power factor and voltage control modes. In parallel, we considered the impact of aggregated disturbances associated with coincident BESS behaviour responding to similar market signals from the Balancing Mechanism or Dynamic Containment, Dynamic Regulation and Dynamic Moderation services. Finally, we developed a DIgSILENT PowerFactory tool to allow simple RMS simulations and network assessments of BESS performance before an offer is made.
A detailed loadflow, short circuit and protection study for a secure data centre
Aurora was approached by Capita to carry out power system analysis and an overall protection study for a secure classified data centre in Cornwall. The site was undergoing a significant expansion and needed a full independent review and protection coordination study on a critical and challenging network.
We carried out a full loadflow and short circuit study to validate the system design and confirm that all equipment was correctly rated for the required duty. This included both main and failover supplies, as well as sustained operation from backup diesel generator sets. We then undertook a detailed protection coordination study for the entire network, covering the HV, LV and UPS systems and the cable differential protection network. The coordination was unusually complicated because of the multiple operating configurations, closed-ring HV and LV systems, directional protection and alternative setting groups.
A series of Concept Studies for 2x sites for private wire Energy From Waste plants
Vital Energi was developing several sites to receive an alternative private-wire supply from nearby energy-from-waste (EfW) plants. Aurora was tasked with developing the initial concepts and assessing loadflow, short circuit levels, protection impacts, automatic changeover operation, break-before-make or make-before-break transition requirements, UPS behaviour and LV backup arrangements.
We carried out a full concept study for each site, ensuring that the scheme was ready to progress and that many of the usual pitfalls were addressed before gate approval. This included the impact of the alternate supply on the network voltage profile and fault levels under different operating modes, how the break-before-make transition would affect site operations and continuity of supply, post-transfer re-energisation of the network transformers, and constructability of the overall scheme.
A series of Concept Studies for 7x sites of EHV connected BESS
Gresham House was developing a series of grid applications for large-scale BESS sites connected to the transmission network across Scotland. Aurora was tasked with developing the initial concept ideas into worked-up proposals covering transformer rating and standardisation, fault ratings, operability, modularisation and transformer energisation.
We carried out a full concept study for each site, ensuring that the scheme was ready to progress and that many of the usual pitfalls were addressed before gate approval. This included confirming transformer sizing, impedance and tap-changer requirements, ensuring sufficient inverter capacity for the required MW and MVAr range, checking fault levels against standard switchgear ratings, assessing transformer energisation and identifying any need for point-on-wave switching controllers. A key part of the assessment was constructability and the cost-benefit trade-off between bespoke transformer ratings and standardised equipment.
400 kV Full cable design including bonding, joints and route
The client needed a complete 400 kV cable design package to support a design and installation project as part of a key substation upgrade. Aurora was tasked with optimising the route design and cable size and advising on the most suitable bonding technique.
We delivered a complete 400 kV cable design package covering current rating calculations, sheath voltage calculations, bonding scheme design, pulling force calculations, joint bay drawings and cable route layout drawings. The bonding scheme was the key design issue, because it directly affected sheath voltage during faults, induced voltage during normal operation and the protection arrangement to be agreed with the connecting party. Additional challenges included optimising the HDD section depth to keep cable thermal ratings within limits and confirming acceptable pulling forces along the final route.
4x Earthing Studies and Design for Gretna, Neilston, Rothienorman and Thurso
The client had four EHV-connected sites that needed detailed earthing designs to support NESO’s stability pathfinder programme. All four sites were under tight time pressure and required full earthing designs for the new EHV yards, including safe management of high EPR contours without transferring unacceptable risk onto the 15 kV synchronous condenser machines and buildings.
Aurora delivered the earthing design for four NESO Stability Pathfinder synchronous compensator sites for Welsh Power. Each site received a detailed CDEGS model to calculate EPR, touch and step voltages for local and transfer faults, followed by a Fall of Potential test after construction to verify the model. Transfer voltage and fault return path calculations were taken into PSCAD where simplified analytical methods did not give a defensible answer. The four sites were Gretna, Neilston, Rothienorman and Thurso.
1500 MW offshore wind, onshore HVDC and HVAC cable system
This was a cable containment and initial sizing study for one of the largest offshore wind farm projects in the UK pipeline. The onshore route involved approximately 50 km of 320 kV HVDC cable feeding into 5 km of 400 kV HVAC cable, with complex sections including HDD and cable crossings. The HVDC cable selection was still open, with different cable types offering different temperature gradient limits and therefore different achievable ratings.
We worked through the trade-off between cable types, assessing how the temperature gradient limit interacted with the achievable current rating along the full route. The complex HDD sections and crossing points were treated as separate derating problems, with mutual heating and separation distances optimised to keep the route deliverable without forcing an oversized cable on the easier sections. The output gave the project team a defensible basis for the cable specification ahead of detailed design.
Concept Study for upgrade of the Isle of Sark Electrical System
The Isle of Sark is a small island adjacent to Guernsey, with an islanded electrical network whose assets in places date back more than 50 years. Following several operational challenges, the island was considering whether to expand and upgrade the existing network or undertake a wholesale replacement, while also integrating solar PV, wind, grid-forming BESS and diesel generator backup.
We carried out a full concept study considering upgrade and replacement options for the existing 6.6 kV network. The study considered the most suitable operating voltage, network topology and redundancy, protection requirements, control systems, operation as a 100% renewables island using grid-forming BESS control, and black-start capability.
Concept Study for upgrade of the existing power station to add new rotating stabilisers
Saltend Power Station is a large, mature existing site that was looking to expand its service offering to NESO through the addition of new rotating stabilisers. Aurora was tasked with reviewing the initial outline ideas, developing a concept design for connecting the proposed stabilisers, and then completing an LT2029 submission.
We carried out a full concept study considering options for adding new rotating stabilisers to the existing network. This included cut-in options to the existing generator IPBs and the development of a new 275 kV bay and transformer compound, considering fault level, loadflow and constructability limits. Once the final option had been selected, Aurora prepared the LT2029 stability tender submission, including the detailed RMS simulation studies for the rotating stabilisers.
grid-forming BESS, Synchronous Condensers and 400 kV NGET connection
As part of the LT2029 stability tenders, Field Energy required support to understand how different OEM grid-forming inverter solutions compared against each other before selecting a preferred bidder. Aurora also carried out separate LT2029 submission studies for synchronous condenser options.
We carried out a side-by-side comparison of three OEM grid-forming inverter solutions, looking at performance under the LT2029 tests for fault contribution, inertia contribution and phase angle jump withstand. We also reviewed the quality of the PSCAD models, supporting documentation and the technical competence of each OEM to support the projects through detailed design.
In parallel, we completed two sets of classical synchronous condenser studies for LT2029 submissions at High Marnham and New Woolavington. The studies required optimisation of the design to maximise fault contribution while staying within the maximum headroom allocated by NGET.
250 MW Onshore Wind Farm, 132 kV SPT connection
Sanquhar II is one of the largest onshore wind farm developments in the UK, at a scale that attracted close interest from both SPT and NESO. The site was unusually challenging because of the low system fault level, which created potential P28 compliance issues for voltage trips and array transformer energisation. A detailed insulation coordination study was also required to assess switching and lightning overvoltages and optimise surge arrester selection and location.
We developed detailed DIgSILENT PowerFactory and PSCAD models of the wind farm and used them to support the Grid Code compliance evidence, including RMS and EMT studies. The low fault level made P28 RVC/SVC assessment particularly important, especially for site voltage trips and transformer energisation cases.
Alongside the compliance package, Aurora delivered G5.5 harmonics, TGN 288E insulation coordination, DRC schedules, protection coordination and a detailed CDEGS earthing study for the 132 kV and 33 kV infrastructure.
We also completed a detailed earthing study covering the 132 kV substation, the associated 33 kV substation and over 44 individual wind turbine locations. This included site EPR, touch and step voltages for local and transfer faults, and the full site layout earthing drawing for construction.
Large 11 kV Industrial Network with islanded generation
Large islanded networks are relatively uncommon and require detailed analysis to ensure the system performs correctly across all operating conditions. Mount Pleasant Airbase is a large complex, with over 70 substations, five ring feeders and a partially closed distribution system.
We built and validated an ETAP model of the 11 kV islanded network, covering the main generation sources, ring feeders and major substations. The study work included loadflow, short circuit, protection coordination and arc flash assessment across the credible operating configurations. Particular care was needed because conventional distribution assumptions do not always hold on an islanded industrial network with limited generation and variable fault contribution.
135 MW gas (diesel) turbines with decoupling clutch, 400 kV connection
A 135 MW gas turbine, dual-fuelled to run on diesel and fitted with a decoupling clutch for synchronous condenser operation, is a key asset on the final leg of the transmission system. Aurora has provided ongoing support for upgrades, rework and modifications, and for assessing the site’s suitability for extension through the stability pathfinder programmes.
We have supported the Indian Queens site over a number of years across a wide range of studies. The work has included options for additional synchronous compensators to provide fault contribution and inertia, MV protection coordination, upgrade of the station transformer, reconfiguration of the overall differential protection, system fault level checks and generator circuit breaker (GCB) performance assessment.
50 MW grid-forming BESS, 275 kV NGET connection
Coylton was a grid-forming inverter project at a voltage and scale where the relevant compliance evidence is still maturing. Grid-forming behaviour changes how a BESS responds to network disturbances compared with a conventional grid-following inverter, so the standard demonstration approach for fault calculations, fault ride through, frequency response and inertia provision had to be adapted. The high DC component associated with faults at this connection also meant that fault level analysis was not a routine exercise.
We developed detailed site models in both DIgSILENT PowerFactory and PSCAD, with the two models cross-checked across the full set of compliance scenarios. The PSCAD model carried the EMT compliance evidence to GC0141 and PC.A.9 and was also used for the detailed fault level analysis, where the high DC component had to be properly captured to assess plant duty. The protection scope included the 275/33 kV transformer differential and REF schemes, 275 kV cable differential, breaker failure, 33 kV busbar differential, IDMT overcurrent and earth-fault coordination, and overall reliability calculations.
Alongside the core compliance package the site received the full P28 RVC/SVC assessment, G5.5 harmonics, TGN 288E insulation coordination, DRC schedules and a full protection coordination study.
We also completed a detailed earthing study covering both the 275 kV substation and the associated 33 kV substation in the BESS compound. This included site EPR, touch and step voltages for local and transfer 275 kV faults, and the full site layout earthing drawing for construction. The transfer fault case was critical, because EPR on the 275 kV side can appear on the 33 kV compound in locations that the local fault case alone would not identify.
275 kV Full cable design including bonding, joints and route
The client needed a complete 275 kV cable design package to support a design and installation project as part of a key substation upgrade. Aurora was tasked with optimising the route design and cable size and advising on the most suitable bonding technique.
We delivered a complete 275 kV cable design package covering current rating calculations, sheath voltage calculations, bonding scheme design, pulling force calculations, joint bay drawings and cable route layout drawings. The bonding scheme was the key design issue, because it directly affected sheath voltage during faults, induced voltage during normal operation and the protection arrangement to be agreed with the connecting party. Additional challenges included optimising the HDD section depth to keep cable thermal ratings within limits and confirming acceptable pulling forces along the final route.
49 MW onshore wind, SSEN connection at 33 kV
Onshore wind brings a different dynamic profile to a BESS or solar site, with turbine behaviour, pitch control and the wind farm controller all influencing the response that Grid Code studies need to demonstrate. The compliance evidence has to reflect that site-specific behaviour rather than relying on a generic inverter-based generation template.
We delivered the full Grid Code compliance package for the site, including RMS and EMT simulations to GC0141 and PC.A.9, P28 (RVC/SVC), G5.5 harmonics, TGN 288E insulation coordination, DRC schedules, a full protection coordination study and an SSO study.
We also completed a detailed earthing study for the associated 33 kV substation. This included site EPR, touch and step voltages for local and transfer faults, and the full site layout earthing drawing for construction.
57 MW BESS, NGET 400/132 kV SGT tertiary at 33 kV
Connecting at 33 kV onto a Super Grid Transformer tertiary winding is unusual and brings its own complications. The tertiary is electrically close to the transmission network, making the system stiff and the protection coordination more sensitive than a typical distribution connection, while still being treated as a Grid Code site for compliance purposes.
We delivered the full Grid Code compliance package, with RMS and EMT simulations to GC0141 and PC.A.9, P28 (RVC/SVC), G5.5 harmonics, TGN 288E insulation coordination and DRC schedules. The protection coordination study was carried out in detail because the proximity to the SGT made conventional rule of thumb settings unsuitable.
2 x 334 MVA gas turbines, 1x 346 MVA steam turbine, 400 kV connection
Synchronous plant at 400 kV is a different proposition to inverter-based generation. The dynamic behaviour of the unit is dominated by the governor, AVR and limiter response, and standard off-the-shelf models do not cover everything the Grid Code asks for. In particular, the OEL, UEL and SCL behaviour had to be represented at a level of detail that the standard model libraries did not provide.
We built detailed DIgSILENT PowerFactory and PSCAD models of GT11, GT12 and ST12. The machine governor was implemented using a GGOV1 model partially developed within PSCAD, the AVR was an ST9C, and the OEL, UEL and SCL were all written as custom models tuned to the actual plant characteristics. The models were used to deliver Grid Code compliance evidence covering GC0141 and PC.A.9 requirements for both RMS and EMT analysis, with results cross-checked against earlier site commissioning tests.
50 MW BESS, 33 kV NGET connection
A 50 MW BESS connecting directly to a 33 kV NGET owned substation is a more demanding compliance environment than a typical 33 kV distribution-connected system. The studies have to be carried out against a stiffer system with tighter tolerances, and any error in the dynamic behaviour is correspondingly more visible.
We developed the full suite of power system studies needed to demonstrate Grid Code compliance, covering RMS and EMT simulations to GC0141 and PC.A.9, P28 (RVC/SVC), G5.5 harmonics, TGN 288E insulation coordination and DRC schedules. A complete protection coordination study was completed in parallel so that the protection settings were consistent with the dynamic behaviour shown in the compliance models.
We also carried out a full sub-synchronous oscillation (SSO) study in PSCAD, liaising directly with the inverter manufacturer and PPC manufacturer to validate the system response and impedance profile.