Applying a New On-line Tool to Easily Set Protection Function for Commercial Relays

Nowadays, there are numerous protection relays manufacturers on the market, with countless input parameters, which implies different ways to calculate the protection settings even for a specific protection function. Based on this, the present paper shows an online tool, under development, which provides an easy way to set protection elements of commercial relays. Therefore, the tool claims to contribute to the academy and to assist professionals in the protection field of electrical power systems as the tool can be used by anyone for free. The present paper introduces the tool which returns a bunch of specific data based on short-circuit and the protection function of a specific relay manufacturer to help the configuration of the protection relay function desired.

To accomplish that, information on the power system where the relays will be placed is provided to the tool. The proposed system has two Thevenin equivalents and a transmission line, which can be simple or parallel and of any length. It is also possible to insert shunt reactors in the lines. The systems solution method used by the tool is developed based on the two-port networks theory and is based in Python language.

After the system configuration, it is necessary to provide the protection function and relay manufacturer under analysis. Currently, the program features three models from well-known relay manufacturers, they are: SIEMENS, model SIPROTEC 7SJ62; SWCHEITZER, model SEL-311L; GE, model D90Plus. Other relays with the same protection function can be also analyzed. Based on those data, the tool performs fault calculations along the entire line and also behind the line terminal relays. Afterward, the tool presents graphical results with all fault positions, guiding the user to find the best setting for each parameter of that particular protection function.

In the paper, it is presented the whole process to set the system, to choose the relay, and to choose the desired protection function. For example, it will be set the overcurrent direction elements from two manufacturers. As an example, a system with two long parallel lines was chosen. As the lines are long, shunt reactors were also necessary. The paper will show, briefly, the solutions process based on two-port networks for parallel transmission lines. Also, the results of the tool will be shown and how it can help protection engineers to set the overcurrent direction elements based on the tool output for different fault types, with or without fault resistance.

In conclusion, using a more dedicated and practical tool, it was possible to verify which parameters are critical for a particular application depending on the type of relay involved. As the market provides several relays for the Protection, Control, and Supervision Systems, we seek to bring a tool that can help to set these relays in a much simpler and visual way.