The GB power system is rapidly evolving as conventional synchronous generation is decommissioned and ever greater levels of renewable sources are connected leading to a much lower level of system inertia and lower short circuit levels. At the same time there are increasing numbers of HVDC links and Flexible AC Transmission systems (FACTs) devices being connected in close proximity in parts of the system. The potential for adverse control interactions between these devices is rising and needs careful consideration within the context of a potentially weaker GB system.
Conventional phasor-based RMS simulation tools have limitations in studying weak, low inertia systems due to the level of detail that is represented. A move to developing more detailed electromagnetic transient (EMT) based models which will address these concerns is proposed as a solution and is seen as a key way of de-risking the integration of the technologies described above.
Objectives
The objectives of the project are as follows:
Build and validate a PSCAD model of the GB transmission network and from that derive separate models for each of the three TO licence areas;
Deliver tools for PSCAD model manipulation and analysis that will support the TOs in their use of the GB model;
Provide the GB TOs with the knowledge and understanding required to adopt the models and put them into use; and
Establish shared computing resources for running the most complex models.
Learnings
Outcomes
The project has positively developed;
- A multi-Party Agreement which enables the GB Transmission Owners to work together to acquire and validate a new system model that will enhance, as well as de-risk the integration of new technologies.
- MHI have completed the build of the PSCAD models for both Scottish TOs.
- Computing resource for GB TOs has been selected and procured.
Lessons Learnt
The learning captured during this project is outlined below:
- Developing the 4-Party Agreement, which required finding common ground between the individual GB TOs, has emphasised the different contracting approaches that each of the GB TOs use. The deliverables associated with this Project are highly technical and require the procurement of specific computing equipment to sit internally within each of the GB TO Parties premises. Given the surrounding complexity of the Project it was not suitable for placement with an external third-Party to project manage. Using a third-Party to co-ordinate would have enabled a simpler interface contractually i.e. each of the GB TOs would have contracted separately with the third-Party project management organisation, then the third-Party would have contracted the PSCAD model supplier.
- This was the first time MHI had undertaken a whole scale network PSCAD build with a combination of different TOs. The task turned out to be more complex than originally anticipated, leading to the extension of project timescales. It is important to enter a modelling contract providing as much clarity as possible in the early stages to enable a realistic timescale. If possible, initial sharing of the network data (e.g. Electricity Ten Year Statement (ETYS) network model) with potential suppliers at precontract stage is suggested to ensure proper understanding of the project scope. Once under contract any additional information needs to be provided as soon as possible, to enable the contractor to provide a realistic timescale and, where possible, share how it could be accelerated.
- Covid has had unexpected impacts such as the computer chip shortage. The last 2 years has highlighted the importance of the unforeseen circumstances Clauses in any contract and the inability to cover all possible eventualities. To turn the event into a positive it has been a test of resilience and continual open dialogue to maintain the course of the project across multiple parties.
- The PSCAD software is more complex than other tools currently used for power system analysis and requires greater flexibility and control over the computing environment it runs in. For example, it is necessary to be able to install and link to different fortran compilers according to the specific models being used. This presents challenges for the IT infrastructure and support in the TOs that may have to develop new approaches to support the use of this type of software. In establishing a high-power computing resource, the project is exploring and confirming the requirements that can be applied in future projects.
