Different test-benches are required to do practical experiments and test the developed system to determine in what way the IEC 61850-9-2 sampled values can be implemented for protection, monitoring and control of the power transformers.
7.2.1 Test-bench A
The first test-bench is used where the power system with the power transformers is simulated in the RTDS. The test-bench is shown in Figure 7.1. The RTDS simulated instrument transformers analogue signals are sent to an Omicron CMS 156 amplifier outside the RTDS. These analogue signals, proportional to the real-time secondary voltage and current signals are sent to an Analogue Merging Units (AMU). The AMU converts the CT and VT signals to one IEC 61850-9-2 Sampled Value (SV) stream and publishes it on the Process Bus Ethernet network. Two Omicron amplifiers and two AMUs are used, one set for the CT and VT analogue signals on the High Voltage (HV) 132kV side of the power transformer and the second is used for the Medium Voltage (MV) 11kV side.
The AMUs are connected to a network switch which is connected to the fibre optic LAN. Another switch is connected to the LAN and the protection IED. The MiCOM P645 IED subscribes to both SV streams. A laptop computer connected to the Ethernet network is used to configure the RTDS, the IED and the network switches. The AMUs cannot be configured over the network, the laptop is connected directly to an AMU to configuration it.
Figure 7.1 Test-bench A
The following configuration is done on this test-bench:
• Configuring the RTDS to produce analogue VT & CT signals out of the RTDS. • Configurate the AMUs to receive analogue VT & CT signals and produce SV
streams.
• Configure the network switches. • Configure the P645 IED
The following investigations are done on this test-bench:
• Measure SV streams on the Ethernet network using software tools and the computer.
• Measure SV streams with the IED.
• Determine if SV values are consistent with the power system current and voltage values.
7.2.2 Test-bench B
In the second test-bench shown in Figure 7.2, the RTDS GTNET_SV-9−2 component is replacing the Merging Unit of the first test-bench. The GTNET SV-9-2 component produces IEC 61850−9−2 Sampled Values which are sent to the Ethernet network. The developed power system is simulated in the RTDS. The RTDS simulated instrument transformers analogue signals are converted to IEC 61850-9-2 Sampled Value (SV) streams. One GTNET_SV9-2 component can produce 2 SV streams at 80 samples/cycle.
The Sampled value streams are measured and captured to analyse. The MiCOM P645 IED subscribes to the SV streams. Different current transformer burdens can be
simulated to compare the use conventional current transformers, analogue signals and copper wiring with AMU, SV and Fibre Optic (FO) networks.
Figure 7.2 Test-bench B
The following configuration is done on this test-bench:
• Configuring the RTDS to produce analogue VT & CT signals internal to the RTDS.
• Configurate the RTDS SV9-2 component to receive analogue VT & CT signals and produce SV streams.
• Configure the network switch. • Configure the P645 IED
The following investigations is done on this test-bench:
• Measure SV streams on the Ethernet network using software tools and the computer.
• Measure SV streams with the IED.
• Determine if SV values are consistent with the power system current and voltage values.
7.2.3 Test-bench C
The third test-bench has the structure shown in Figure 7.3. The RTDS developed system in Test-bench B is expanded to include transformer differential and over current protection relay components. The RTDS/RUNTIME case is shown in Figure 7.40. The
RTDS simulated instrument transformers analogue signals are converted to IEC 61850- 9-2 sampled value (SV) streams.
The following configurations are done on this test-bench:
• Configure the RTDS RSCAD transformer differential and over current protection components,
• Configure the RTDS RSCAD SV9-2 component to produce SV streams.
The following investigations are done on this test-bench:
• Measure SV streams on the Ethernet network using software tools and the computer.
• Apply different type of faults at different positions in the system with parallel power transformers and measure the fault currents.
• Test the RTDS RSCAD software transformer protection components.
Figure 7.3 Test-Bench C
The RTDS and computer are connected using Fibre Optic (FO) cables to the network switch.
7.2.4 Test-bench D
The fourth test-bench shown in Figure 7.4 is the same as Test-bench C but the modelling inside the RTDS is different. The power system is simulated in the RTDS. The RTDS developed system includes transformer differential and over current protection relay components. The RTDS simulated instrument transformers analogue signals are converted to IEC 61850-9-2 sampled value (SV) streams. The SV streams are used inside the RTDS/RSCAD software for experimentation.
The LAN is used to connect the computer to the RTDS hardware with the RSCAD software to configuration, execution, and analysis the real-time simulations
This test-bench compares a system using SV streams to a system that only uses conventional instrument transformers. Copper wires are modelled and are used in both cases, but the length of copper wires is different. The copper wires from the instrument transformers (IT) to the IED, in the control room, measuring analogue signals are much longer compared to the wires from the IT to the merging units in the yard.
The burden on the IT is much less when using MU. The burden effect on the IT when using merging units was simulated in the RTDS. The IT burden when merging units are used is discussed in 2.3.1.1 Current transformers.
The following configuration is done on this test-bench:
• Configure the RTDS RSCAD transformer differential and over current protection components,
• Configure the RTDS RSCAD current transformer component
• Configure the RTDS RSCAD SV9-2 component to produce SV streams.
The following investigations are done on this test-bench: • Measure SV streams in the RTDS/RSCAD software.
• Compare the burden on current transformers when a system using AMUs is compared to a system not using AMUs.
Figure 7.4 Test-bench D