Power quality measurements improve security of supply

In early June, Fingrid provided its customers with a new extranet service for quality information, thus giving the company’s customers an even more detailed and descriptive picture of electricity quality at their connection points. This makes it easier to monitor the state of the electricity grid and further improve the security of electricity supply.

The security of electricity supply has become increasingly important as society has become more dependent on electricity. Weather-related phenomena, such as storms and lightning, cause the greatest number of quality problems for main grid customers. Disturbances in the customers’ own equipment or an exceptional load can also lead to deviations in power quality.

Electricity loads and electricity production connected with frequency converter technology increase the need for more accurate monitoring of power quality.

“Frequency converter technology is used with wind and solar power. This presents challenges for power quality that can be better monitored with new energy meters,” states Specialist Antti Kuusela from Fingrid Oyj’s Grid Services unit.

In addition to security of supply, power quality involves ensuring that voltage fluctuations in the grid occur as rarely as possible and remain as small as possible. The new quality information extranet service developed by Fingrid means that the process of locating and monitoring these swells and dips in voltage is now more comprehensive and flexible.

The service is made up of graphic screens, tables and event logs. Service users can check the time series and log data for voltage level and flicker at their main grid connection points. Log data allows customers to examine local swells and dips in voltage at different times.

“This ensures that quality deviations in the electricity grid are accurately recorded, which also helps with grid planning and operation and makes it possible to plan and forecast the need for outages and maintenance measures,” explains Kuusela.

More than 1,000 new meters

The replacement of Fingrid’s energy meters made it possible to implement this new type of service. The company has recently changed a total of 1,000 energy meters, which have power quality measurement features in addition to their main purpose.

“In other words, these meters have sufficient measurement capacity to provide us with a large amount of big data for processing. Powerful information systems play a key role when it comes to compiling measurement data about voltage fluctuations and other power quality properties throughout the main grid,” says Energy Measurement Specialist Olli Taipale from Fingrid.

Taipale also reminds us that the metering point of the energy meter must be taken into account when examining quality information. It can also be located in the distribution grid rather than at the main grid connection.

The actual energy meters represent the best possible energy measurement accuracy class of 0.2S. When measuring power quality information, the same energy meter represents Class B of the power quality measurement standard (IEC610000-4-30). With regard to time series for power quality measurements, approximately 4.3 million events per day are currently collected in the database.

Power quality information from energy meters provides extensive monitoring material related to power quality at the connection points. If significant deviations in power quality are detected at a connection point, a thorough power quality measurement is performed with a separate analyser brought to the site. •