COMMUNICATION PROTOCOLS

Connect to external devices with ease via Ethernet

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

TCP/UDP Sockets

The GTNET-SKT firmware 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.
GTNET-SKT is capable of sending up to 300 input and output 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.
When communicating with multiple external devices (to a maximum of 10), GTNET-SKT is capable of managing up to 30 input and 30 output data points for each channel.

MODBUS

The GTNET-MODBUS firmware provides Modbus communication over TCP/IP networks. The firmware supports Modbus TCP, Modbus RTU over TCP, Modbus ASCII over TCP, and Modbus UDP. 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.
Each instance of the GTNET-MODBUS firmware is capable of simulating up to 10 Modbus outstations simultaneously, each with independent data mapping. Each GTNET Modbus outstation can maintain two concurrent communication channels with two different clients, using two different TCP ports (20 connections in total).

IEC 61850 Sampled Values

The GTNET-SV firmware provides IEC 61850-9-2 / IEC 61869-9 sampled value messaging for power system voltages and currents in substation automation applications.
When used in conjunction with a GTSYNC card to synchronize the simulation timestep, the GTNET-SV firmware is able to transmit 2 independent SV streams simultaneously. Each IEC 61869-9 stream can have up to 24 channels at sampling rates of 80 and 96 samples/
cycle and 4800 Hz. Each stream can have up to 9 channels at sampling rates of 256 samples/cycle and 14,400 Hz.
In input mode, GTNET-SV can subscribe to one SV stream (with the same sampling rate and channel limits as written above). GTNET-SV can be configured to publish/subscribe regular SV or routable SV (R-SV).
GTNET-SV also supports connection-oriented IEC 61850 MMS client/server communication, acting as a service device. A client can connect to GTNET-SV as an MMS server and access, view, and control the data objects in the model.

IEC 61850 GOOSE Messaging

The GTNET-GSE firmware provides IEC 61850 Ed 2.0 and 2.1 GOOSE communication and MMS server services. GTNET- GSE can simulate 1-4 IEDs, which can be configured to publish/subscribe regular or routable GOOSE.
Each GTNET-GSE firmware can publish up to 16 GOOSE message streams and receive GOOSE messages from up to 32 unique external IEDs. Each firmware can publish up to 512 data items (of types integer, Boolean, double position, float or quality) and can receive up to 512 data items.
The GTNET GOOSE configuration is done via a companion software tool within RSCAD called the IED Configuration Tool.
IEDs simulated by GTNET-GSE component can include standard IEC 61850 data models obtained from the ICTs’ Logical Node (LN) database. In addition, the GTNET-GSE supports simulated switch-objects to represent and test switchgear operations, test (simulated) GOOSE messages, and GOOSE subscription monitoring.

PMU / Synchrophasor Data

The GTNET-PMU firmware provides P-class or M-class synchrophasor output data streams according to the IEC/IEEE 60255-118-1 standard. 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.

DNP3

The GTNET-DNP firmware option allows the GTNETx2 module to act as a DNP slave using the DNP 3.0 protocol, to communicate with external DNP masters.
Each instance of the GTNET–DNP firmware supports simulation of up to 10 outstations, with a maximum of 2 masters connected per outstation simultaneously (20 connections total), with a maximum polling rate of 5 Hz.
Each firmware 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

IEC 60870-5-104

The GTNET-104 firmware option allows the GTNETx2 module to act as a slave using the IEC 60870-5-104 protocol, to communicate with external masters.
Each instance of the GTNET-104 firmware can be configured to simulate 10 independent outstations, and each outstation can communicate with up to 2 IEC 104 client stations simultaneously (20 connections in total).
For each 104 protocol operating, the GTNETx2 module 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

Playback

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.
Up to 48 channels of floating point data can be imported from an external data file (COMTRADE or ASCII).
Because the data file is stored remotely on a PC, file sizes of several GB 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.