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COMMUNICATION PROTOCOLS

Connect to external devices with ease via Ethernet

Connecting an RTDS Simulator via Ethernet
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Exchange data in real time

The RTDS Simulator can exchange data with external hardware or software devices in real time through many different communication protocols. Input and output via Ethernet (though standard-compliant data packets) allows the closed-loop testing of digital substations and other non-wires alternatives.

The hardware that gets it done: Network Interface Card

The RTDS Simulator’s GTNETx2 Network Interface Card provides a real-time communication link to and from the simulated network via different Ethernet-based protocols.

Two powerful processors

Each GTNETx2 card has two processors which run simultaneously, meaning that two different communication protocols can be run at the same time with one card. Many GTNETx2 cards can be used at once for simulations that may require many streams of the same or different protocols.

Supported Communication Protocols

  • The GTNET-SKT firmware is included with every GTNETx2 card. This protocol allows the user to interface the simulation with external software and physical equipment over a Local or Wide Area Network connection using Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) sockets.
  • The communication is bidirectional and asynchronous. GTNET-SKT is capable of sending up to 300 data points per packet, with each point defined over 4 bytes. The data transmitted can be of either integer or floating-point (IEEE 754) type.
  • FPGA-based Sampled Values streaming allows up to 16 simultaneous publish/subscribe streams.
  • The GTNET-MODBUS firmware provides Modbus communication over TCP/IP networks. The firmware supports Modbus TCP, Modbus RTU over TCP, and Modbus ASCII over TCP. The MODBUS protocol is a widely used in legacy and modern automation applications.
  • Using this protocol, the RTDS Simulator operates as a Modbus server (slave) communicating to a Modbus master station. This master station can be either an IED on dedicated hardware or a computer workstation running a Modbus master API.
  • The GTNET-SV firmware provides IEC 61850-9-2 sampled value messaging for power system voltages and currents in substation automation applications. In order to timestamp the sampled values, a one pulse per second (1PPS) signal can be input to the GTNETx2 via a BNC coax connection or fibre-optical port. Alternatively, the GTNETx2 can provide the master 1PPS signal to the IED(s) being tested.
  • When used in conjunction with a GTSYNC card to synchronize the simulation timestep, the GTNET-SV firmware is able to transmit up to two data streams for up to 4 current and 4 voltage channels at a rate of 80 samples per cycle, or one stream at 256 samples per cycle. It can also be configured to receive sampled data from one Merging Unit (4 x V and 4 x I) at either 80 or 256 samples per cycle.
  • In non-9.2LE mode, based on IEC 61869-9 and the Chinese National Standard for SV merging units, one GTNET-SV can publish 1 data stream for up to 24 voltages or currents at a rate of 80 samples per cycle, with < 10 μs jitter between samples as is required by the standard.
  • The GTNET-GSE firmware option provides IEC 61850 GOOSE Messaging, often used for breaker status and commands in protection and control applications. The firmware can be used to model 1-4 individual IEDs. Each model is capable of sending and receiving up to 64 points (or 32 points with associated quality bitmap). For each GSE firmware installed, GOOSE messages can be received from a total of 16 unique external IEDs.
  • RSCAD contains a built-in ICT editor which helps the user to easily and conveniently configure the publication and subscription of GOOSE messages.
  • IEC GOOSE fields such as the Test mode, Needs Commissioning, and individual Quality bitmaps can be dynamically changed and monitored for both transmit and receive messages during a simulation, allowing many scenarios to be thoroughly tested and verified.
  • The GTNET-PMU firmware option for the provides P-class or M-class synchrophasor output data streams according to IEEE standard C37.118.1aTM-2014. Two PMU streaming options are available for GTNET-PMU. This standard is widely used for standalone PMUs or as embedded functions within relays or disturbance recorders.
  • A single GTNET-PMU firmware can represent and provide output for up to 8 PMUs with symmetrical component information related to 3-phase sets of voltage and current. The reporting rate of each PMU can be set individually from 1–240 frames per second.
  • Alternatively, a single GTNET-PMU can represent and provide output for up to 24 PMUs containing only positive-sequence data. Frame rates up to the system frequency (50/60 Hz) are supported.
  • The GTNET-PMU output is synchronized to an external 1PPS, IRIG-B or IEEE 1588 signal via the GTSYNC card.
  • The GTNET-DNP firmware option allows the GTNETx2 to act as a DNP slave using the DNP 3.0 protocol, to communicate with an external DNP master. DNP3 is a SCADA protocol commonly used in substations.
  • For each DNP3 protocol operating, the GTNETx2 can communicate with one DNP3 master and accommodate the following maximum communication capacity:
    • 1024 binary simulation status points (i.e. breaker position) at a scan rate of 1000 Hz
    • 512 binary simulation control points (i.e. breaker commands) at a scan rate of 1000 Hz
    • 500 analogue status points (i.e. output from simulator) at a scan rate of 10 Hz
    • 100 analogue control (i.e. input to simulator) at a scan rate of 10 Hz
  • The GTNET-104 firmware option allows the GTNETx2 to act as a slave using the IEC 60870-5-104 protocol, to communicate with an external master. IEC 60870-5-104 is a commonly used SCADA communication protocol.
  • For each 104 protocol operating, the GTNETx2 can accommodate the following maximum communication capacity:
    • 1024 binary simulation status points (i.e. breaker position) at a scan rate of 1000 Hz
    • 512 binary simulation control points (i.e. breaker commands) at a scan rate of 1000 Hz
    • 500 analogue status points (i.e. output from simulator) at a scan rate of 10 Hz
    • 100 analogue control (i.e. input to simulator) at a scan rate of 10 Hz
  • The GTNET-PB firmware option is used to read large data files stored on a PC hard drive and allow them to be played back into the simulated environment. Sampling frequencies as high as 20 kHz can be maintained in a true real-time simulation.
  • COMTRADE files with up to 8 channels can be played back on the RTDS Simulator. Because the COMTRADE data file is stored remotely on a PC, file sizes of several gigabytes can be handled easily. The component also allows for independent pre- and post-fault looping.
  • The primary application of GTNET-PLAYBACK has been to inject currents recorded at an actual installation (e.g. arc furnace or rolling mill) in a real-time simulation. It is very difficult to accurately simulate the behavior of such installations so the recorded waveforms are often the best representation of the on site dynamics. By injecting the recorded current into the plant simulation, the performance of compensation equipment (e.g. SVC or STATCOM) can be accurately evaluated for the expected operating conditions. Simulation/playback times in excess of 30 minutes allow even the flicker (PST) reduction factor to be observed.