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6.3. TESTING - SCALED PHYSICAL NETWORK
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Naturally a construction like this is expensive, nor built overnight. The best
solution is to cooperate with other parties who would have interest in using such
a scaled network for testing on other, similar fields. At NTNU, such a scaled
network exists in the form of a renewable energy/smart grid/wind power lab (SG
Lab). The lab is quite comprehensive, and includes several types of generator
models, a distribution network model (lines, transformers, loads), energy storage
capabilities and a short circuit emulator, as shown in Figure 6.8.
Figure 6.8.: One Line Diagram of SG Lab at NTNU
The lab provides several opportunities for relay testing, the short circuit emulator is especially of importance. It allows the emulation of different fault scenarios, i.e phase-to-ground and three-phase faults, with corresponding fault currents
flowing in the network. However, traditional CTs and VTs does not exist in the
lab today. Transducers outputting current values scaled as a mV /A signal is installed. The currents from these transducers are also sampled and used for other
purposes than protective relaying today. Traditional CTs and VTs could possibly
be installed, however the amount of space in the switchgear cabinet is limited.
Because of this, using the sampled values in an IEC61850 compliant lab system
might be a good idea. This is a possible future step for the relay lab and not the
focus of this report. Any further studies of this opportunity will not be made in
this report.