Running Cool seeks to challenge current Active Network Management (ANM) curtailment arrangements by creating a new post fault capability for overhead lines and a new ANM architecture which will help to avoid curtailment. An improved system of short term dynamic OHL ratings (informed by real-time conductor temperatures) and a new corresponding ANM control system architecture will be the key outputs of this work.
Benefits
Running Cool seeks to challenge current Active Network Management (ANM) curtailment arrangements by creating a new post fault capability for overhead lines and a new ANM architecture which will help to avoid curtailment. An improved system of short term dynamic OHL ratings (informed by real-time conductor temperatures) and a new corresponding ANM control system architecture will be the key outputs of this work. By improving the overall capacity of the distribution network WPD can look to accommodate more clean embedded generation connections, which would lead to a reduction in the overall carbon intensity of energy delivered to customers and thereby help to deliver and achieve ‘decarbonisation and Net Zero’ – a priority area in our Innovation Strategy.
Learnings
Outcomes
Running Cool project has produced a number of documents in alignment with the objectives of the study:
- Technical Specification and Implementation for ANM System Architecture Changes required to embed STPFR capability within existing ANM systems. The document specified different implementation strategies for transferring STPFR values from the source of STFPR system to ANM.
- Technical Specification of how to derive STPFR using a live temperature of the conductor and accompanying risk assessment that specifies each process and component of the STPFR solution, identify how it may fail and propose mitigation solutions to manage the failure modes.
- Report detailing network use cases and detailed information of where the temperature monitoring equipment was installed, methodology for capacity uplift, methodology for curtailment analysis (new ANM connections), results of the uplift analysis and curtailment analysis (observed and modelled).
- Engineering Specification for retrofit OHL temperature monitoring equipment that enables STPFR calculation.
- Documented Cost Benefit Analysis of the STPFR capability and qualitative discussion of the impact of STPFR on OHL conductor design life.
- Recommendations for amendment to the relevant NGED policies relating to OHL ratings and installation and maintenance of the monitoring equipment.
The documentation specified above is available upon request.
Lessons Learnt
Methodology for short-term post-fault rating (STPFR) calculation
- The calculation of STPFR, based on CIGRE Technical Brochure 601, is not dependent on convective cooling, solar heating and radiative heating/cooling. The conductor temperature measurement is the only parameter required to be monitored in real-time to provide a rating to cover STPF generation curtailment events.
- A functional specification for STPFRs builds upon the learnings of the previous NGED NIA project “Overhead Line Power Pointer”.
Active Network Management and system architecture
- NGED has different ANM arrangements depending on a licence area. Implementation of the STPFR capability will require all vendors to be able to accommodate acceptance of dynamic ratings within their power system analysis and decision making.
- The ANM system would require the rating values to be sent to the ANM system every 5 seconds or greater. The ANM system requires the rating to be in either Amps or MVA.
- There are multiple ways of passing STPFR values from the system that would derive the values to the ANM. The preferred implementation method is for the STPFR system to send values directly to the NGED Control System (PowerOn). This arrangement will eliminate a need for multiple interfaces with the ANM system. It will reduce undesirable IT maintenance burden and future proof the system if/when ANM functionality is taken in house (i.e. implemented within PowerOn).
- It is expected that the STPFR will be delivered to ANM in the same ICCP transfer as the network measurements. Additionally, the ANM system will have access to a set of static ratings that are used by default if the STPFR is unavailable via the ICCP transfer set.
OHL temperature monitoring equipment
- Equipment used for the temperature monitoring (Smart Navigators 2.0 or SN2.0) uses sim cards for information transfer. During the course of the project there had been a few issues with sim cards to stop communicating with iHost and therefore loss of data for a period (up to 3 months). If STPFR capability is implemented within ANM such comms failure will be critical; therefore, further consideration should be given into failover arrangements by ANM providers and alternative comms solutions.
- The existing NGED Standard Technique for installation of SN2.0 on OHL was not detailed enough for 132kV OHLs. This has caused minor confusion across operational staff. As a result, feedback from operation personnel was sought and standard techniques updated (in draft).
- SN2.0 devices used during this study for live temperature measurements have been proven efficient. Along with temperature monitoring, SN2.0 provides visibility of real-time voltage, current and directional power flow which is not required for STPFR capability. There is an opportunity to explore alternative technologies with a sole purpose of temperature monitoring if they are proven to be a cheaper option. (Functional specification for that equipment was prepared as part of the project). It is worth mentioning, however, that at the time of writing SN2.0s are relatively cheap devices and when combined with additional visibility can provide for control operation there is an opportunity to optimise the installation of the devices for both ANM and control use hence derive additional financial benefit.
Qualitative benefits of STPFRs: capacity uplift and potential for avoided curtailment
- The increase in available capacity when using STPFR has been assessed and compared against the static post-fault rating.
- For the 175 mm2 Lynx conductor rated at 50°C results demonstrated that the potential yearly uplift in capacity of OHL circuit using STPFR is 6,842 MWh on average when compared to the static post-fault rating. For 175 mm2 Lynx conductor rated at 75°C the results indicate potential yearly uplift in capacity of 2,961 MWh on average. The greatest uplift is produced during cooler months.
- A common hourly uplift profile was identified by this study amongst all sites which produced the minimum uplift during peak sunlight hours and the bulk of the uplift during the evenings and mornings. This uplift profile would benefit generators that have a constant energy output irrespective of meteorological conditions. This is a result of the adiabatic methodology used to obtain the STPFR which is dominated by ambient temperature, which has a bell curve profile, and conductor load. Generators such as PV connections that have an output profile similar to the ambient temperature profile will not be capable of reaping the full benefits of STPFRs.
- The benefits of the STPFR capability can only be realised under a condition when uplift is present at the time of a circuit being thermally constrained.
- The results of this study demonstrate that the implementation of STPFR offers a “little but often” benefit with significant aggregate energy volume that will further unlock latent capacity within the distribution network.
- Financial benefit derived from STPFR capability is mainly associated with avoided curtailment for ANM curtailable connections subject to a cap. This study provides an indication of financial benefits associated with reduction in flexibility procurement where the indicative figure for MWh is available (£300/MWh):
- Annual reduction in flexibility procurement of 341MWh or ~£102,300 for a highly loaded circuit (ALVE 305) with limited headroom, six sets of SN2.0 installed.
- Modelled annual reduction is flexibility procurement of £96,483 with one set installed (for future pipeline ANM sites)
- There is no additional impact on OHL conductor design life associated with the implementation of the STPFR. Static post-fault ratings use a 9% exceedance value, which signifies higher thermal stresses could be sustained by the conductor in the event of a prolonged fault. The deterministic nature of STPFRs and the 10-minute interval for ANM response does not increase any currently accepted risk of exceedance. However, the preserved level of risk exceedance relies on the ANM system’s ability to react within the 10-minute STPFR window.
