A “use case” is defined as a particular situation in the grid where a utility would like to perform a ROCOF measurement. This maybe under normal operating conditions or during an exceptional event such as the sudden disconnection of a large load or generator.

The “wish list” will define the desired specification of accuracy the measurement latency (or measurement update rate) and cost-effectiveness from an end-user point of view for the given use cases.

In order to develop a ROCOF standard, this pre-normative project will address the following scientific and technical objectives:

  1.  To evaluate the problem of ROCOF measurement in the context of actual use cases and the “wish list” from an end-user point of view. To develop a library of standard-test-waveforms representative of typical PQ events on electricity networks, including extreme events, in order to adequately test ROCOF algorithms and instrumentation containing these algorithms.
  2.  To review, develop and optimise algorithms to reliably and accurately measure ROCOF over the full range of network conditions, specifying any use cases where this is not achievable.
  3.  To implement and test selected ROCOF algorithms utilising the standard waveform library via computer simulations as well as in instrument hardware that will be tested using precisely generated electrical waveforms in the laboratory. This will lead to compliance verification protocols for ROCOF instruments suitable for inclusion in a ROCOF standard (new or pre-existing).
  4.  To specify a reference signal processing architecture for a ROCOF instrument suitable for inclusion in a ROCOF standard. To use sensitivity analysis to determine the uncertainty specification for each element of the measurement chain (this could include: transducers, analogue signal processing, filtering, analogue to digital convertors, digital signal processing, computational processing) required to manufacture an instrument to implement the selected algorithms and be capable of compliant accuracy measurements for each of the use cases.
  5.  To work closely with the European and International Standards Developing Organisations, in particular CENELEC TC8X and the working-group/technical committee responsible for IEEE/IEC 60255 118-1, and the users of the standards they develop, to ensure that the outputs of the project are aligned with their needs, communicated quickly to those developing the standards, and in a form that can be incorporated into current standards and used to develop a new internationally accepted standard at the earliest opportunity.