Renewable generation has been growing at historically high rates over the last decade in GB as well as other parts of the world. This rapid growth is predicted to continue at an increasing pace in order to achieve legally binding 2050 climate change targets as agreed for the UK. One important characteristic of this new generation is that it is connected through power electronic convertors and subsequently does not present any inertia to the power system. The aim of the F2P project is to accurately observe and consequently predict frequency fluctuations at an operational level across the GB power system.
Objectives
The aim of the F2P project is to accurately observe and consequently predict frequency fluctuations at an operational level across the GB power system. The following objectives are being targeted:
- Gather PMU data for GB power system incidents of interest;
- Develop a visualisation approach for overlaying such gathered data on the GB power system;
- Explore the variation of frequency phenomena with power system location and characteristics;
- Explore and evaluate whether existing power system modelling software can comprehensively explain the observed phenomena. Make recommendations as appropriate for any improvements to National Grid’s data, models or processes.
- Implement a range of models in the OPAL-RT software (RT-LAB 11 + ePHASORSIM), from simple test models up to the full GB system.
- Demonstrate simulation of actual incidents in the OPAL-RT software, validating results at the PMU level.
Learnings
Outcomes
The following has been delivered as part of this project:
- Data Gathering, Visualization and Investigation: Developed a powerful Matlab 2D/3D visualization tool to show the change of frequency, RoCoF and vector shift in past system events.
- Modelling & Validation using OLTA: Model post system events in OLTA and engage DigSilent and DNOs/DERs to explore both Tx & Dx modelling issues.
- Modelling & Validation using OPAL-RT: “hardware-in-the-loop” testing using 36-zone model and the full GB model. Importing NG-specific controller models is a particular area of focus. Relay responses will be tested across 36-zone and full models.
Lessons Learnt
The significant shortfall in functioning PMUs has hampered these investigations. Gaining access to LV recorders from WPD constituted a major breakthrough for the project, but in terms of system coverage this was still very limited. Future work can include the following:
- Collection of more PMU data;
- Working with DNOs to access a wider range of PQM devices and ensure that these are configured to capture transmission-level events, notably;
- As and when the above data becomes available, examine whether electromechanical phenomena are modified as they propagate into the distribution network;
- Investigate the modelling techniques required to accurately reproduce Vector Shift phenomena for off-line studies and HIL studies;
- Investigate whether the reduced model can be modified, for example with the insertion of circuits dedicated to a particular fault event, so that it can be used for VS studies.
Review of benefits case
There is no change to the benefit case of this project. The project worked towards to understand the fast frequency phenomena in a low inertia system, figure out ways to improve of the modelling of frequency response and seek opportunities to improve the frequency management.
