Republic of Georgia uses SEL meters to solve power quality challenges caused by harmonics

Schweitzer Engineering Laboratories, Inc. (SEL) announced that Georgian State Electrosystem (GSE)—the high-voltage transmission system operator for the Republic of Georgia—recently chose to standardize on the SEL-735 Power Quality and Revenue Meter for transmission power quality measurement. The new equipment enables GSE to control harmonics in the Georgian power grid, improving overall power quality and extending the life of their critical power transmission equipment.
GSE faced a serious challenge in their power system. Harmonic distortion in the power grid was causing overheating and damage to GSE’s critical power transmission infrastructure and was negatively impacting power quality. Left unchecked, the harmonic distortion could have led to sudden equipment failure, threatening the stability of the power grid.
To solve the harmonics problem, GSE first needed to identify the sources of higher-order harmonics on their 220 kV and 500 kV transmission systems and document them for government regulators.
After researching possible solutions to pinpoint the problem source(s), GSE chose the SEL-735 based on its advanced harmonics functionality: detection up to the 63rd harmonic, fast harmonic update rate, visualization of inter-harmonics, and harmonic data trending.
The SEL-735 helped GSE quickly determine two harmonic sources that were causing the overheating of their autotransformers and shunt reactors. One source was the ac-to-dc converters used in the HVDC station for interties with neighboring Turkey. The second harmonics source originated from several industrial plants.
GSE used low-pass filters to remove harmonics introduced by the ac-to-dc converters, but enough got through to cause problems. With the documentation that the SEL 735 provided, GSE contacted the industrial plants and requested that they take steps to minimize harmonics.
“The SEL-735 truly is the key in identifying some of the subtle sources of harmonics,” said Gakha Makharoblidze, GSE’s department head for relay protection maintenance.

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