Test Case 21

21

Felipe Castro

1

ERIGrid 2.0

04/12/2020

Performance characterization of new equipment and communication technologies

The aim of this test case is to assess the performance of equipment used for communication in smart grids and power systems, such as Remote Terminal Units (RTU). The characterization of this performance is one of the major goals of this test case, taking into account the different communication technologies that could be supported in such devices (e.g. communication protocols) and the stochastic nature of communication effects.

In particular, the experiments in the test case allow characterizing the performance of communication equipment by means of communication delay calculation and the rate of dropped packets between two RTUs. Through this experiment, it is possible to determine the mean value and the standard deviation of the communication delay between two devices, together with the packet loss rate for different polling times.

The characteristics of two communication devices exchanging information. The delay of the information transmission and the loss packet rate, for different communication protocols.

At least two communication components connected together.

Information and Communication Technology (ICT)

Verify whether the performance of the devices is adequate for the applications for which their use is intended. Specifically, verify that the mean delay and packet loss rate of the communication complies with the minimum expected requirements for the application for which they will be used.

In order to execute this test, the following components are needed:

• Real time simulator, such as OPAL-RT
• At least two communication devices, such as remote terminal units (RTU)
• One communication emulator, such as ATTERO
• Ethernet connection cables (RJ45)

The test consists in the connection of the Real Time simulator to both communication devices, and the connection of these devices to the communication emulator.

• Capability of the real time simulator to transmit data under different communication protocols (e.g. MODBUS, IEC 60870-5-104, IEC 61850)
• Capability to generate and transmit data by the real time simulator with different characteristics (data profiles)
• Data transmission from real time simulator to the OuI.
• Capability of Communication protocol translation by OuI.
• One communication emulator, such as ATTERO
• Ethernet connection cables (RJ45)

• The real time simulator needs to send a data profile periodically using a certain pre-defined communication protocol.
• Due to the stochastic nature of communication phenomena, the data profile needs to be sent periodically enough times to be able to obtain statistically valid results.
• The real time simulator needs to register the time for which data is sent and for which data is received, in order to calculate the communication delay of each data value.

Data profile:

• The data profile needs to be arranged in a way that it is possible to determine the communication roundtrip time (delay) of each data value. A series of increasing integer values is proposed with an increasing value change periodicity. For example:

In the previous figure, the constant α represents the reduction of the time during a particular value is sent. It is noted that the polling time of the devices must be less than the time duration of a sent value.

• The delay and the lost packages have to be registered:

• The delay for each successfully transmitted data value can be used to create a normal distribution of the delay probability (obtaining the mean delay value and its standard deviation):

• The successful transmission rate can be calculated for each value sent from the profile, allowing to determine the minimum periodicity that can be 100% successfully transmitted

• Periodicity for which a data value changes.
• The delay between the OuI devices set in the communication emulator.
• The amount of repetitions of the experiment to obtain statistically valid results.
• The communication protocols involved between the real time simulator and the OuI devices, and between each of the OuI devices.

For delay calculation, at least have a packet loss rate less than 1%