ROCOF algorithms: selection, optimization, and performance characterization
Algorithms for rate-of-change-of-frequency (ROCOF) are selected, optimised, and tested, with the objective of meeting the use case requirements and power quality scenarios laid down previously in the project. To do this, the few most promising ROCOF measurement techniques are selected from literature, and representative versions are implemented in software. The algorithms are optimised for each use case identified in the project, at least in the selection of window-length and frequency-domain performance, to values appropriate for the allowed latencies. The potential to make algorithms more immune to spurious events such-as faults, is also investigated.
Once the algorithms are selected and optimised, they are tested comprehensively in simulation against the library of waveforms previously developed and the viable measurement configurations are assessed against each use case, considering the suitability for inclusion in a ROCOF-standard. For the use cases where it is not possible to meet end-user requirements with any algorithm/configuration, the implications for future network control are highlighted.
Simulation testing is important as a precursor to future hardware testing and has the advantage that the vagaries of real electrical signals and imperfect hardware do not confuse the performance assessment of the trial algorithms. But it is also vital that the algorithms can be implemented in hardware; effects such as digitisation word lengths (quantisation), timing errors, and noise are not readily simulated and are often overlooked in the modelling environment. For these reasons, it is considered crucial that real digitisers and waveform generators are used to make ROCOF measurements, using the proposed algorithms to assess practicality and accuracy as previously proposed. This has the added benefit of prototyping the compliance testing procedures for future instrumentation, which is helpful to form a draft Annex to a future ROCOF-standard.
For more information, see the project webpage >>
Short Name:ROCOF,Project Number:15NRM04
University of Strathclyde (United Kingdom)