This example shows a method to compute short-term flicker severity of a phase-to-ground voltage taken from one feeder of a given remote community.
The statistical analysis of instantaneous flicker level is performed on a phase-to-ground voltage taken from one feeder of a given network. The analyzed signal comes from a phasor simulation of 650 sec of duration of a detail model of a remote community (not discussed here).
We can observe in the analyzed signal (Signal with flicker) that a large and relatively slow voltage fluctuation is superimposed on small voltage fluctuations induced by distributed thermal storage systems. It is apparent that the slow moving voltage fluctuation did not induce significant flicker compared to the small voltage fluctuations.
The magnitude of the phasor signal is used to regenerate a 60 Hz sinewave voltage that is connected at the input of the Digital Flickermeter block. Doing so, the block can compute the instantaneous flicker level present in the voltage. The signal is saved in the S5 workspace variable. The statistical analysis module of the flickermeter is used to analyze the S5 signal.
1. Run the simulation. When completed, click the Open statistical analysis button of the flickermeter block.
2. In the Statistical Analysis of Instantaneous Flicker Level window, load the S5 signal from workspace. The instantaneous flicker level signal is then displayed in the upper diagram.
3. In the analysis section, set the start time value to 50 seconds to exclude from the analysis the initial spike in amplitude in the instantaneous flicker level.
4. Click the Compute button.
The cumulative probability function (CFP) is then displayed in the lower diagram. The short-term flicker severity value Pst is displayed along with the P0s, P1s, P3s, P10s, and P50s percentiles corresponding to the flicker levels exceeded for 0.1%, 1%, 3%, 10% and 50% of the time during the observed period.