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Netcon RPS helps electric utilities manage their reactive power balance

Since the beginning of 2017, the Finnish transmission grid company, Fingrid, has imposed access-point-specific reactive power limits on its customers, the nation’s electric utilities. The move comes as the extent of reactive power within the electricity grid continues to grow. Reactive power puts a strain on the grid, increasing the risk of disturbances.

There is a limit for both negative and positive reactive power, that is, the reactive power that the customer feeds into the transmission grid and the reactive power that it draws from the grid. The two limits form the reactive power window. They depend on the active power: the window widens at high active power levels and is shifted slightly downward at negative levels (i.e. when the customer is actually supplying active power to the transmission grid).

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If it exceeds the reactive power limits, a utility must pay a monthly tariff. The fifty largest hourly violations are waived, but the rest will be charged. The tariffs are based the absolute extents of the violations and the corresponding amounts of energy. They are going to rise in the next few years:

By monitoring the balance of reactive power at its access points, a utility company can apply compensatory measures and thus minimise the tariffs that it has to pay. While compensation costs money too, neglecting it involves a risk because it contributes to the increase of reactive power within the transmission grid. It may therefore motivate Fingrid to keep raising the tariffs in the future.

Cyber secure cloud service

Netcon RPS is a modern cloud-based service helping utilities supervise their reactive power balance. A secure SSL/VPN connection is used to transfer power measurement data from the customer’s SCADA to Netcontrol’s RPS server. The communication protocol is ELCOM, the same one that Fingrid itself uses, which helps the customer make use of Fingrid’s own data (this is subject to a separate contract).

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The Netcon RPS server stores the customer’s power data in an SQL database. The interface is browser-based and can be integrated with most modern SCADA systems supporting web components. User accounts make it possible to grant different users the access to different sets of measurement points as desired. Even the employee of an end client, such as an industrial or power plant, may be given access to certain points in the grid.

The crucial benefit of this centralised, cloud-based service managed by Netcontrol is that any changes, e.g. those due to Fingrid’s rules, are automatic from the utility’s point of view. This reduces the resources needed for SCADA configuration and therefore saves money as well.

Versatile user interface

The Netcon RPS interface offers the user a comprehensive range of tools for analysing their power data. The history and the costs are available both separately for each point and for the entire network. The observed point may also be the sum of two or more actual measurement points, so that it can be configured to reflect an access point with no measurements of its own.

To facilitate compensatory actions, Netcon RPS calculates a reactive power prediction for the current hour. The interface has two configurable alarm stages for impending limit violations. These are given as percentages of the distance form the window midpoint.

The user may view an up-to-date summary table of each point in their network, colour-coded according to the last hour’s measured value, including any violations of the limits as well as a prediction for the current hour. A separate tab has a more detailed monthly table for the violations that have occurred. It separates the 50 largest violations, to be waived, from the rest, showing the total number and the extent of the largest violation. The costs incurred are also listed. The last tab shows the user a scatter diagram of active versus reactive power for the selected point as well as a trend view of the two kinds of power hour by hour.

 

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Feedback into SCADA

Netcon RPS also supports an ELCOM connection back to the utility’s SCADA. This enables the customer to get reactive power alarms, and even to implement automatic control of compensation.