Intermittent Clouds and Their Impact on Power Quality
The rapid rise in PV installation globally and in India, has created a new series of power quality challenges for users of PV generators.
Her are some examples and graphs taken from measurement in one of our PQ assessment of Solar Installation.
Variation in Currents:
Variation in Power Generation:
Voltage Variations:
?Voltage delivered to customers is dependent upon two things 1. The voltages set in substation 2. Customer load currents.
The current load affects the customer’s voltage on the distribution. This is due to V=IR losses in the distribution wiring and losses in the transformer.
The graphs show the voltage variation through the day.
Harmonics: The low order harmonics are minimum at maximum to 60 %?of capacity, harmonic levels increases steadily as the Solar radiation slows down. However, what is visible is the high frequency voltages increasing as much as 40v in certain High frequencies. This may not comply with IEEE-1547 the Harmonic standard for solar installation. They are also called supra Harmonics; this may affect the performance of the PV inverters and the PV panels. The issues of interoperability may be a problem in some installation especially the other Electric power system in parallel is rich in harmonics.
It is also our experience that along with a Active Harmonic filter may not be compatible with the solar inverter and may affect the performance of Active Harmonic filter.
The issues of Reverse Power Flow (RPF) is not uncommon in many installation especially when operating with Diesel generators.
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Conclusion:
?A power flow assessment is recommended to avoid these issues and for seamless operation of the PV installation.
In some installation static VAR generators are deployed, Static voltage restorer are deployed to surmount these vexatious issues.
The deployment of Zero sequence Harmonics Mitigation Transformers, and LCL filters for filtering low order frequencies, EMC filters are recommended to improve the reliability and productivity of the PV installation.
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