WA-MSR mesh current controller, FLOW-R

FLOW-R Research Project: Development of
the WA-MSR Mesh Current Controller

 

FLOW-R, synonymous with the WA-MSR mesh current controller, was developed jointly by TU-Kaiserslautern, Pfalzwerke, Pfalzwerke Netz, PPC, and Walcher.

The mesh current controller, FLOW-R, has the task of controlling the current flows in meshed low-voltage networks or ring mains in such a way as to balance out strong fluctuations in current flows in parallel mesh lines.

The two Kirchhoff laws are implemented by FLOW-R to form the basis for the controller.

For this, within a mesh, the currents and the phase voltages and angles are cyclically queried at technically relevant measurement points approximately every ten seconds and evaluated in the WA-MSR.

If there is a need for action by the controller, it becomes active and sends suitable dynamic compensating current through the monitored mesh by connecting or disconnecting adapted tap-changing transformers.

The WA-MSR also determines the direction of flow of the compensating current within the ring main; with this, the rated current at all points of the mesh can be influenced.

The WA-MSR can also assume the task of voltage control within certain limits.

The WA-MSR can optionally be monitored from the master display and, if necessary, parameterized via telecontrol protocol IEC 60870-5-104.

Operating Principle

Masche ohne ReglerMasche mit Regler

The figure to the left shows the current flow through the mesh without the WA-MSR.

The figure to the right shows the same mesh with installed WA-MSR. It can be seen that the compensating current of 100 A injected by FLOW-R (WA-MSR) counteracts overloading of the right circuit with 220 A at the time. Through this, the current that would theoretically flow without the WA-MSR is reduced from 220 A to 120 A. Because the injected compensating current must flow back to FLOW-R, the relatively poorly loaded parallel branch is better utilized than before. Network conversion can hence be avoided or at least considerably delayed.

The WA-MSR is installed in a cable distribution cabinet for easy mounting on a concrete plinth.

Maschenstromregler WA-MSR

The figure shows the opened FLOW-R with the very maintenance-friendly arrangement of components.

The arrangement of input and output fuses enables rapid switching to a bypass.

Maschenstromregler Aussenansicht

Closed WA-MSR (left cabinet) in the local network.

Deployment in test network

Testnetz FLOW-R

Diagram showing test network of Pfalzwerke with measurement points and transformer station as well as the location of the FLOW-R (WA-MSR) marked.

The data are exchanged via power line.

The control principle can be derived more easily in a simplified equivalent circuit diagram.

Diagramm Strom ungeregeltDiagramm Strom geregelt

 

Comparison of representative measurement curves recorded at different times in the same mesh once without and once with FLOW-R. The mode of operation of the WA-MSR can clearly be seen in the curve in Figure 7. The current Ilimit = 40 A shown in blue is well maintained.

As soon as this current wants to rise, it is compensated for by the current injected by FLOW-R
(shown in red). The green curve (tap) given below shows the transformer tap changes at the given times.

 

With the WA-MSR, completely new, low-cost equipment that can avoid the often very expensive network expansion required in many application cases is available.

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