Diagnostic capabilities of voltage fluctuation indices - a case study

There are a number of measures used to describe voltage fluctuations and their obnoxiousness. Some are suggested by the standards and legal acts of different countries, others are used because of their theoretical or practical advantages. The most popular measures include: P_st/P_lt indicators, voltage fluctuation indices, ΔV₁₀ index, max and min rms values. Their diagnostic capabilities depend on their distinctive characteristics. To use them in an effective manner it is necessary to understand their measuring process and to define the information one is able to obtain with the process. The paper includes a brief description of a selection of voltage fluctuation measures. On the basis of measuring results recorded in a real LV circuit a study on voltage fluctuation has been performed. At different stages of the study, diagnostic abilities of specific measures have been illustrated and the type of information on voltage variation which can be obtained through their application has been identified.