Power Quality Analysis in non-stationary mains frequency conditions

The increasing volatility of the mains frequency sets new requirements to Power Quality Analyzers, especially when it comes to the harmonic composition of voltage and current, e.g. to analyze power flows. Frequency transients or static off-nominal frequency conditions can render PQ measurements partly unusable. One way to deal with these effects is mains frequency synchronous sampling. In this paper, the chances and risks of this method will be discussed and quantified on a test case, using data from a Power Quality Measurement System especially designed for that purpose.