WG C4.27 Benchmarking of Power Quality Performance in Transmission Systems


Benchmarking is receiving growing interest from both transmission companies and electricity regulators. This proposed work aims at developing guidelines for technical performance benchmarking by combining the input from specialists in C4 (System Technical Performance) and C5 (Electricity Markets and Regulation). Technical performance here refers to: interruption performance (reliability), availability, voltage dips, and voltage waveform quality (harmonics, unbalance, magnitude, and flicker). The work undertaken by C4 (publication TB 261) identified that various transmission companies are using widely different indices for technical performance reporting, especially in the case of voltage dips, system reliability, and availability reporting. Various commercial benchmarking companies also use very different indices, and in some cases the manner in which common indices are defined and applied can vary greatly – making comparisons between the performance reported by these different companies difficult. The peer groups for which such benchmarks are determined are also often not well selected, and characteristics of the systems are not included with the benchmarking information. Furthermore the implementation of exclusions is not consistent among transmission companies making comparisons difficult (e.g. third party caused incidents).


The scope of the working group is to develop a set of guidelines for transmission technical performance benchmarking based on: • A review of the practical application and definitions of the indices proposed by the C4 TB 261 for Transmission and Sub-Transmission systems. (This report on Power Quality Indices and Objectives has provided an in-depth analysis of possible indices, and provides proposals on indices and the manner in which these indices are calculated). These proposed indices may be used as a starting point, but may well need to be adapted or further defined for application to benchmarking. • The definition of important “internal” indices such as circuit availability and line fault rates. • Consideration of the implications on monitoring and reporting systems. • Recommendations on how systems can be described (important characteristics to be identified as part of the benchmarking information) to assist transmission companies, regulators, and benchmarking companies in the identification of a suitable peer group. • Highlight what historical data, system descriptions, and calculation methodologies need to be in place for effective benchmarking to be undertaken (or alternatively highlight cases where benchmarking is not an appropriate tool for decision making).


A technical report/ brochure providing practical guidelines for undertaking benchmarking of system technical performance in the case of Transmission systems.

Convener: D. Vujatovic (UK) 

Progress Report 2015 (pptx, 142kB)

Progress Report 2016 (pptx, 138kB)