High Voltage Direct Current (HVDC) valve halls are inaccessible to staff due to the hazardous environment. Monitoring of the equipment is currently performed using static cameras however these do not provide full visibility of equipment, particularly monitoring gauges and floor level machines. Because of these restrictions condition monitoring and maintenance is performed on a periodic timeframe (annually) and requires a shutdown of the system.

This project proposes to install an autonomous robot within the confined space of a HVDC valve hall to monitor equipment status and need for maintenance. This innovation would allow for any faults or need for maintenance to be identified without causing unplanned downtime of the system and allowing for engineers to perform condition-based maintenance.

Benefits

If the system can reduce the number of unplanned maintenance outages, then this will have a saving to the consumer in the form of reduced costs. By monitoring SF6 gauges, leaks can be observed earlier meaning less loss of SF6 to the environment and reduced penalty charges.                                                                                                                                                                                                                               

The analysis considers only robot use on converter stations where restricted areas exist and each converter station, irrespective of its capacity and size, will be able to be served by one robot if the charging station can be installed within the halls. 

Based on the use of a robot calculated to reduce the O&M cost by up to 61% until 2072, reaching an identified benefit of £6.28m per single converter pilot station, an analysis of the scaled benefit was conducted to reflect the innovation at more stations. Indicative costs were used for the purpose of the Cost Benefit Analysis (CBA) with an assumption that a further nine stations may benefit from installation of an autonomous robot considering site placements by 2032. There is no need to consider substations without restricted areas as these can be accessed by technicians freely. The base case included remote inspection using installed cameras only. The potential benefits have been calculated as follows – 

Single robot install at single pilot site:

·        Base cost for converter station maintenance at pilot site: £10.33m

·        Method cost with robot installed at pilot site: £4.06m

·        Lifetime Saving per single pilot site: £10.33m - £4.06m = £6.28m

Scaled cost savings from additional projects are as follows - 

Base cost for converter station maintenance at ten sites: £72.38m
Method cost with one robot installed at each of the ten sites: £23.28m
Saving up to 2072: £72.38m - £23.28m = £49.11m
 

These projects will be carried out through the asset life of the substations (45 years), and we used as estimation’s cut-off year 2072 following a consistent methodology for our analysis. The capital budgeting method of Net Present Value (NPV) is used to account for the time value of money and expressed in 2018 real values based on Ofgem’s CBA template. The initial investment cost for purchasing the robots for these projects is £1.26m and cost savings as expected to start after 2030. The short-term cost savings on key regulatory milestones is estimated as below for the ten substations identified as long as a long-term saving until 2072.

·        RIIO-T2 (FY 2025/26): - £9,685

·        RIIO-T3 (FY 2026/27 – 2030/31): - £11,501

Long term (up to FY 72/73): £49.11m