OverCurrent Tutorial

DIgSILENT PowerFactory Application Guide

Over-current Protection Tutorial DIgSILENT Technical Documentation

DIgSILENT GmbH Heinrich-Hertz-Str. 9 72810 - Gomaringen Germany T: +49 7072 9168 00 F: +49 7072 9168 88 http://www.digsilent.de [email protected] r995

Copyright ©2013, DIgSILENT GmbH. Copyright of this document belongs to DIgSILENT GmbH. No part of this document may be reproduced, copied, or transmitted in any form, by any means electronic or mechanical, without the prior written permission of DIgSILENT GmbH. Over-current Protection Tutorial (DIgSILENT Technical Documentation)

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Contents

Contents 1 Introduction

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2 Network Modeling

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3 Using Standard Protection Elements from the Library

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4 Modeling Protective Elements in Cubicles

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5 Modeling a New Fuse Type

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6 Testing the 300 A Fuse

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7 Modeling the Motor Protection

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8 Setting the Motor Protection Relay

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9 Modeling the Transformer Protection

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10 Modeling the Feeder Cable Protection

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11 Creating an Overcurrent Path

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12 Exporting Settings to a Tabular Output

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13 Performing a Short Circuit Trace

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Over-current Protection Tutorial (DIgSILENT Technical Documentation)

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Using Standard Protection Elements from the Library

Introduction

This tutorial demonstrates the modeling and editing of over-current protective devices typically found in distribution and industrial networks. The tutorial has been designed for a user who has already used, and is familiar with the basic functions and structure of PowerFactory .

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Network Modeling

A network model has already been prepared for use. The tutorial comes with five different .pfd files, where each one of them represent a specific stage of what is presented in this tutorial as to be done. The first model includes all primary elements, but does not include CT’s, VT’s or any other protective devices. First of all, import the .pfd project files to PowerFactory , and then activate the “OC Prot Tut Start” project from the DataManager. Once activated, note that short sections of cables have been modeled between the transformer terminals and those buses that they are connected to. Not only is this a more realistic model, it also presents the opportunity of simulating faults between protective devices of the respective transformer HV and LV relays and the transformer itself. Similarly, cables have been added for loads. The user should first perform a load flow of the network to check that all model elements are defined (this is a normal ’first order of business’ step for any newly opened project).

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If at all possible, it is recommended that available protective elements from the Global Library are utilized, rather than the creation of new relays from scratch. More advanced users should then edit existing types before finally creating new types. A number of standard protective devices will be used from the library. These devices are: • an ABB SPAJ 140C type relay, used as the Feeder Cable protection relay. • a GE Alstom MCGG63 type relay, used as the Transformer HV protection relay. • a Siemens 7SJ70 type relay, used as the 100 kW Asynchronous Machine protection relay. • a 250 A fuse, used as the LV Load protection. These relays are available in the Global Library and must be copied over to the project library for use. Though it is not a requirement, it is often useful to keep specific type models together in a library sub folder inside the project library. To do this, such a sub folder must first be created. • Right click on the tutorial project library folder (named Library). A drop down menu appears. • Select New → Folder. The dialog shown below opens. Name the folder Protective Devices. • Select Library under the Folder Type field. • Click OK. A library sub folder should now appear in the project library.


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A destination folder has now been created for the protective devices to be copied to from the Global Library. As stated before, these devices could also have been copied directly into the project library folder. Now the type models in the Global Library must be selected: • Open the Data Manager by left clicking on it. • Move to the top of the database tree. • Left click on the plus sign next to moneLibrary. A list of library folders will drop down. • Open the Relays Library folder. The Data Manager should appear as shown below:

The protective devices required for this study will be found in the Fuses and the Relays sub folders. Start by searching for the correct fuse type model. Opening the Fuses sub folder, by left clicking on the plus sign next to it, opens the dialog shown below. The LV fuses are found in the VDE0636/IEC60269-2 sub folder. Our intention is to copy the total range of LV fuses into the Project Library folder called Protective Devices, therefore, right click on this VDE0636/IEC60269-2 fuse sub folder and select Copy. Over-current Protection Tutorial (DIgSILENT Technical Documentation)

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The Project Library sub folder called Protective Devices must now be selected to paste this set of fuse characteristics into. This is done with a right click on the Protective Devices folder; then select Paste. Now the relay types must be copied to the Project Library. This is done using the same copy and paste operation as used for the fuses, except that relays are now individually selected (as opposed to the whole Relay folder being copied). Starting from the top, first select the SPAJ 140 relay as shown below. Note that the path to find this element is, Library → Relays→ Relays→Overcurrent Relays → ABBWestinghouse→ SPAJ140C. Right click on the SPAJ140C relay type and select Copy as shown below.


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• Go to the project library and right click on the Protective Devices folder. Select Paste. Follow the same steps to Copy and Paste over the GE Alstom MCGG63 and Siemens 7SJ70 relay types to the Protective Devices folder. Relay types are modeled using what are known as Relay Frames. The types that we have copied over from the Global Library are presently still referenced to frames saved in the Global Library. Similarly, characteristics such as the Current-time curves may be stored outside of the relay type folder. The reason for this is that the frame or the curves may be used by several different relays in the same ’family.’ The type then refers to these common characteristics, in the same way that an objects element data refers to type data when we draw a network. Should we export this project, the relay frame references, and the characteristic curve references, would be lost, because these are not saved in the project itself, only in the Global Library. To correct this, we could copy the frames and characteristics over from the Global Library, and then we would have to re-select the new addresses of the frames and characteristics into the relay type. However, this all seems rather complicated for a user only wanting to use standard relay types. To make this process very simple, a special feature called Pack is available. Thus, it is important that the following steps be taken whenever relays are copied from the Global Library: • Open the project Protective Devices folder. • Double click the icon of the SPAJ 140C (or right click Edit; or select Edit Object on the Data Manager toolbar) to view the type data of the relay that has been copied. The dialog shown below should open:


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• Select Pack. • You may be asked “Do you really want to copy all used objects into this model?” Select Yes. • Press OK on the relay type dialog. Note that not all relay type will have ’missing’ references so not all relays will need to be packed. Once packed you will notice that a plus sign is visible next to the relay type model in the library (if this is there before packing takes place it is not indicative that the relay has been packed). This is because all of the objects that were externally referenced have now been brought into the relay type itself. Repeat the same steps for the MCGG 63 relay model. Note that the 7SJ70 relay comes “packed”. This is because all the referenced objects for this relay are already saved in the relay type. You can see if the relay has been packed or not by whether the Pack button is greyed out or not.


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Modeling Protective Elements in Cubicles


In the same way that Circuit Breakers and isolator Switches are held/located in a Cubicle, so Relay elements, Current Transformers, Voltage Transformers and Fuses are also located in cubicles. These cubicle elements are in turn either located within station models (for busbars), or within Terminals. To demonstrate this we will start with the modeling of a Load Fuse element: • Right click on the cubicle for the cable feeding the General Load on the 415 V busbar named Industrial/B2 (the cable is named Load Cable, as it happens). The cubicle itself is not a selectable object on the canvas, but the area of the line between the busbar/ terminal and the results box is the defined ’cubicle area,’ and right clicking in this area will produce the relevant menu. • This drop down menu now appears, as shown. • Select New Devices → Fuse Note: that if these options do not appear on the drop down menu, the right click was probably not within the cubicle area. It is sometimes better to first enlarge the view of the cubicle area in order to perform the right click on the cubicle and not the line or the back-ground.

• A fuse element dialog appears. • Name the fuse element “Load Fuse”. • The fuse type must be defined. Using the selection button at Type, go to Select Project Type. Over-current Protection Tutorial (DIgSILENT Technical Documentation)

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• In the Protective Devices folder, select the gL-200 A fuse type. • Press OK. • Tick the box Open all 3 Phase Automatically. • Below the option Compute Time Using, select Total Clear Curve. • Press OK. Note: The Device Number is used for documentation and is an unique identifier for the protection devices stored in the cubicle. To see the fuse characteristic, press the Plot button.

Initially we would want to make sure that the fuse has been properly selected with respect to the nominal load current. For this we need to display the load current in a time-current plot where the fusing characteristic of the fuse is also shown. We can use a standard time-overcurrent plot for this, but first we must calculate the nominal current for the load. Perform a Balanced Load Flow, ensuring that you have selected all from the list next to Consider Protection Devices, on the Advanced Simulation Options submenu. For the time-overcurrent plot: • Right click on the cubicle containing the newly created fuse. • Select Create Time-Overcurrent Plot. • A new graphic should be created, showing the calculated load current as a vertical line (the default colour of this line is normally red) and the fusing characteristic of the fuse.


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Should we decide that the fuse curve appears too close to the load current value we could then select a new fuse type from the library, however, this would be time consuming. Instead we can easily and quickly select an appropriate fuse by following the next few steps: • Double left click anywhere in the plot, but not on the fuse curve or load current value. • The plot editing dialog opens. At the bottom of the plot, under the heading Relay, we notice the Load Fuse. • Double click in the box Split Relay so that a tick appears in the box. • Press OK. Note: this action may also be achieved by right clicking on the envelope (that is, the edge) of the fusing characteristic, but accurate mouse positioning is required. • Now left click on the fuse curve, making sure you either click on the melting curve or total clearing time curve (on the envelope). • It is now possible to change the curve tripping value by holding the cursor down on the curve and moving it side-ways. Notice how the curve will ’jump’ from one position to the next. The reason for this is that you are effectively selecting different fuses from the library. Since these have discrete fusing characteristics the envelope must jump from one to the other. This method is used later to adjust settings on protective relays as well. • Once the appropriate fusing characteristic is selected double click on the shifted fuse curve to reveal that the Load Fuse element now has a new Fuse type. This new Fuse type has been selected from within the range of fuses that we copied over to the Protective Devices library earlier; which hopefully makes it clear why we copied the whole library over- the fuse can only be chosen from those available in the library folder. • Note that the load vertical line has disappeared when we shifted the fusing characteristicthis is because PowerFactory interprets this as a change to the system, making the calculated results invalid. Say we want to keep the load value as a fixed reference to enable us to better select the fusing characteristic. Over-current Protection Tutorial (DIgSILENT Technical Documentation)

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• Perform a load flow with Consider Protective Devices enabled again (this can be done directly from the overcurrent plot by pressing on the Calculate Load Flow button in the toolbar). • Now right click on the vertical current line. A drop down menu appears. • Select Set User Defined and Yes to the question that follows. It is now possible to change the fuse value while the load current indication line remains. Also notice that if the fuse curve is moved left over the current line the time value at which the two curves intersect appears automatically. Notice that the load current indication line and the fusing characteristic are both the same colour. When several overcurrent plots are laid above one another this tool is used to distinguish which current each device is looking at.


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Modeling a New Fuse Type


Let us assume that we want to include a unique fuse type to the list of available fuses in our library. We shall model this fuse by creating a new fuse type. Using the manufacturers fuse catalogue, for the fuse we want to consider, we see that the fusing characteristic curve points are as follows: Operating Current (A) 795 955 1160 1270 1590 2700

Operating Time 40 13 6 3 0.9 0.1

Table 5.1: Fuse Characteristics

The normal PowerFactory fuse model allows for a minimum melt curve and total fault clearing curve. In this case, however, we only have one set of characteristic curve points. The fuse is thus modelled as follows: • Using a Data Manager, select the fuse library subfolder in the project library. Left click on this VDE0636/IEC60269-2 subfolder. • The third button from the left on the Data Manager toolbar is the New Object button. Press the New Object button. The dialog shown below appears. • Select Special Types and search in the list for Fuse Type (TypFuse) type. Left-click on it and click OK. Note: The selection for a new fuse type can be found under the Net Element Types set; in older versions of PowerFactory you will notice a TypFus marked as obsolete. In other versions the TypFuse is found in the Other object set in the New Object dialogue the Filter must have “Typ*” entered to access this (type this in if it is not available as a selection).


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• A fuse type dialog appears as is shown below. We name this fuse type “300 A Fuse”.

• The Rated Voltage must be defined as “0.415” kV; the rated current is “300” A; and of course the Rated Frequency is “50” Hz. • A new Melt Curve must be created and defined. Press the down (select) arrow next to Melt Curve and Select Project Type. The program automatically searches the project library for a fuse curve type, and finds the list of curves that were copied earlier. However, we wish to use a new and unique curve. Here we can use the present dialogue to go straight to the appropriate type target by pressing the New Object button- the program knows what is required as the Data Manager is ’focused’ on the Melt Curves field. A fuse curve type data sheet now opens. Alternatively, we can create a new Melt Curve from scratch. A new fuse curve type can be created by pressing the New Object button and choose an I-t Characteristic (TypChatoc) in the Net Element Types menu. A fuse curve type data sheet now opens. Before pressing this button


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make sure that the active folder in the Data Manager is the one that you wish to store the curve in. Normally we will want to store the curve in the same folder as that of the Fuse Type. Once the curve has been edited as described below the curve type must be linked to the fuse type using the normal selection button for the Melt Curves field in the Fuse Type dialogue. • The fuse curve type object must be named. We will simply call it a “300 A Fuse Curve”. Because characteristic curves can be used in both fuses and relays, be sure that the Usage is defined as Fuse. • Open the drop down menu next to Function. By defining the fuse curve in terms of plot values, either the Linear Approximation or Hermite Polynomial functions can be used for interpolation of the fuse curve points. We will use the Hermite Polynomial. • As stated before, a fuse curve would typically consist of two curves defining minimum (Melt) and maximum (Total fault clearing) values. In our case, the fuse curve is only a single curve, with the values as described in Table 5.1, thus we choose the No. of Curves to be “1”. • Initially only one set of X and Y values is catered for in the dialogue. To create more lines for X and Y fuse curve values, right click on the first row (on the ’1’ button) and select Insert Cells. Various options are available, such as Insert Cells, Append Cells, Append n Cells and so forth, which are chosen depending on user requirements. • Fill in the appropriate cell data from Table 5.1.


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• The fuse curve type data sheet now appears as shown above. By pressing the Plot Curves button, the fuse curve will be shown (please note that the X row values must be always in ascending order). • Select OK to return to the Fuse Type dialogue and then OK once more to finish editing the new fuse type- you will see that the new fuse has now been created in the library. By moving the fuse plot on the Time-Overcurrent slowly in a horizontal direction across the plot the new fuse and its characteristic will be selected. If this proves to be difficult (it may since our new characteristic is markedly different to the others in the library) you can select the fuse type in the normal manner by double clicking on the fuse characteristic envelope. It will be noticed that the fuse curve become shorter and changes into a single line when the newly created fuse type is selected. Use the new 300 A fuse for the next few steps. Another way of creating a new fuse type would of course be to copy and paste an existing type in the Data Manager.


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Testing the 300 A Fuse

Testing the 300 A Fuse • To test the newly created fuse, a 3-phase fault is simulated on the terminal to which the LV load is connected (T-Lod). Right click this terminal and select Calculate → Short Circuit. • On the Basic Options page of the Short Circuit command, select a fault impedance with Resistance, Rf = “0.1” ohm and Impedance, Xf = “0” ohm as is shown below.

• Select the Advanced Options page of the Calculate Short Circuit command. Make sure to select all from the list next to Consider Protection Devices, as is shown below.


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Testing the 300 A Fuse

• Press Execute. • The fuse fault clearing time of 0.179 s is shown on the time-overcurrent plot. If a different result has been calculated, repeat the simulation of the short circuit ensuring that it has been correctly simulated. The complete method should be used for fault calculations as this does not use any approximations and is a far more accurate method of calculating the fault currents. It presents an ’actual world’ picture to the engineer, as opposed to the IEC, VDE and ANSI methods, which have certain safety margins built in. Note: This concludes the first stage of the tutorial. Now, please activate the project named “OC Prot Tut Step 2”.

Note: You should notice that the current activated project includes all the changes that were made before. If you want to make a more detailed comparison, you can do it by means of using the DIgSILENT PowerFactory commands Select as Base to Compare and Compare to “BaseProject” (where the name of the project selected as base will appear instead of “BaseProject”). For more detailed information, please refer to the DIgSILENT PowerFactory User´s Manual.


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Modeling the Motor Protection


The next element to model is the motor protection relay. As stated before, we will use a Siemens 7SJ70 relay for this protection element. The following steps need to be performed: • Right click on the Industrial/B2 415 V busbar cubicle to which the Motor Cable is connected. A drop down menu appears. • Select New Devices → Relay Model as shown below.

• A relay data input dialog appears. Firstly we name this relay “Motor Relay”. • Click on the arrow down next to Relay Type. Press Select Project Type. The library automatically opens and shows the list of available relays. • Left click on the 7SJ70 relay and click OK. The relay data dialog now appears as shown below.


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The next logical step is to create a CT element that drives this relay. To do this; • Press Create CT. A CT dialogue box appears. • The only data required is the CT type and if the type is a multi-ratio CT, the selected CT ratio. To select the CT type, press the selection arrow, next to Type on the CT element dialog, and Select Project Type on the drop down menu that appears. • The data manager automatically opens the project library looking for CT types, but finds none. Press the New Object button in the data manager while making sure the object is created in the Protective Devices folder (meaning that you must ensure that the folder “Protective Devices” is the focus of the Data Manager ). • A CT type dialog opens. Name the CT type “Multi-Ratio CT Type”. • Right click on the first (and only) row inside the Primary Taps dialog. Select Insert Row(s). There will now be two rows of Primary Tap cells. Repeat this two create three rows of Primary Tap cells- the Append n Cells could also be used. • Enter the values “75”; “150”; and “300” A respectively for the Primary Taps. Change the Secondary Tap from “5” A to “1” A. The CT Type dialog should appear as shown below.


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• Press OK to return to the Select Current Transformer Type dialogue and notice that the new Multi Ratio CT Type has been created in the library, and that it is highlighted for selection, and press OK again to return to the Current Transformer Element dialogue. • In this CT element dialogue box, select the ratio to be 150/1 as shown next.

• Press OK. • Press OK on the relay element dialogue and OK again on the cubicle dialogue. The motor protection has now been completely modeled, but not set.


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Setting the Motor Protection Relay


First a load flow is performed, considering all Protective Devices. Now the following steps are followed: • Left click on the Edit Relevant Objects for Calculation button (this also known as the object filter button), which is the second tool on the toolbar. A small screen appears with different element (green) and type (red) symbols. • Left click on the green Relay Model (*.ElmRelay) symbol. A list of all used relays will appear. Note that there is only one relay in our current list. • Double left click on the relay symbol next to Motor Relay. Note that you can also get to this point by right clicking on the cubicle where the relay is and then select Edit Devices. • The relay editor appears again. Double click on the field to the right of the (look under The Relay Model in the help index for more information on how relays are modelled) I> symbol (in the net elements column) and set the relay Pickup Current to “3.9” p.u. and Time Setting to “5.0” seconds. The convention used for the overcurrent symbols is fairly widespread and is explained below for clarity of purpose: The “>” symbol is used to indicate the designed chronological sequence of the tripping characteristics used by the relay, so that increased use of the “>” symbol may mean, for example:

’’I>’’ overcurrent with inverse tripping characteristic (slowest acting tripping element) ’’I>>’’ instantaneous tripping with a time delay (mid term tripping element) ’’I>>>’’ instantaneous tripping without a time delay (fastest acting tripping element)

Where a relay has only a moderate inverse characteristic and an instantaneous characteristic the “>>”indicates the instantaneous characteristic since this is of course the fastest characteristic that the relay has.

• Press OK. • Double click on the I>> field and set the Pickup Current to “15” p.u. Press OK.


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• Lastly double click on the IE> symbol and set the earth fault Pickup Current to “0.5” p.u. Press OK to return to the relay dialogue box and OK again on the relay editor/ dialogue box to return to the Object Filter. Close the Object Filter. • Perform a load flow with the consideration of all Protective Devices. • Right click on the cubicle containing the newly created motor protection. • Select Add to Time-Overcurrent Plot. • The time-overcurrent plot should appear as shown next.

The red current value and red curve represent the current and characteristic fuse curve for the LV load. The green current and green curve represent the current and curve/s of the newly created motor protection. To be able to see a larger current range on the time-overcurrent curve, the following steps are taken. • Double click anywhere on the plot, but making sure it is not on either protection curve or current values. • The time-overcurrent curve editor opens as shown below.


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• Change the Maximum Limit value on the x-Scale to 100,000. • Press OK. • A larger section of the green curve is visible. • You can also instruct the program to automatically scale the axes by pressing the Scale x-Axes automatically, or, Scale y-Axes automatically, buttons. Next we want to make sure that the motor protection relay will not trip under motor starting conditions. • Go to the network view and right click on the motor. • On the drop down menu, select Show → Add to Time-Overcurrent Plot.


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A blue motor starting curve appears on the time-overcurrent plot. We can see that the protection setting is higher than the motor starting plot. However, we may wish to increase the time setting for the I> part of the curve. • Double click anywhere on the plot, but not on any curve or current value. • The plot editor opens. • Click in the Split Relay box next to Motor Relay and press OK. This may also be achieved by right clicking the relay time characteristic line and selecting Split. • Left click on the horizontal part of the I> curve (hover the cursor over the line to determine which one is the I> curve if you are unsure). Note that the relay curve can be moved by holding down the cursor on it and dragging the curve up and down. Drag the curve to the maximum time setting available- this maximum time is determined by the relay type that we have selected. • Double click on the plot again (or right click on the I-t characteristic line) and “unsplit” the Motor Relay. Press OK. Now we want to make sure that the protection is sensitive enough to operate for overcurrent conditions. To do this: • Right click on the terminal to which the motor is connected. • Select Calculate → Short Circuit as shown below.


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A three phase short circuit is modeled with the same values that were selected before when the 300 A fuse was tested. Set the fault resistance to Rf = “0” ohm. • Press Execute and look at the time-overcurrent plot.

We have set the relay to be sensitive to maximum fault conditions, whilst being stable under motor starting and load flow conditions. Note: This concludes the second stage of the tutorial. Now, please activate the project named OC Prot Tut Step 3.


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Modeling the Feeder Cable Protection

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Modeling the Transformer Protection

For this project, we model only the transformer HV protection, using a MCGG63 type relay. The steps should by now be familiar, but are briefly repeated. • Right click on the cubicle feeding the HV side of the transformer from the Industrial/B1 substation busbar. • Select New Devices → Relay Model. • Name the new relay element “Transformer Relay”. • Select the MCGG63 relay type from the project library. • Press Create CT and name the CT “Transformer CT”. • Select the “Multi-Ratio CT” type from the project library. • Choose the CT ratio to be 75/1. • Press OK. • Double click on the Toc Ph element and set it to a Current Setting value of “2.2” p.u. and Time Dial of “0.8”. Press OK. • Double click the Ioc Ph element and set the Pickup Current to “7” p.u. and the Time Setting to “0.095” s. Press OK. • Press OK on the relay editor and OK on the cubicle editor.

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As stated before, the Feeder Cable protection that we will use is an ABB SPAJ140C type relay. This is modeled as follows: • Right click on the cubicle feeding the Feeder Cable from the Intake/Incomer substation busbar. • Select New Devices → Relay Model. • Name the new relay element “Feeder Relay”. • Select the SPAJ140C relay type from the project library. • Press Create CT and name the CT “Transformer CT”. • Select the “Multi-Ratio CT” type from the project library. • Select the CT ratio to 300/1. • Press OK. • Double click on the I> element and set it to a Current Setting value of “1” p.u. and Time Dial of “1”. Press OK. • Double click the I>> element and set the Pickup Current to “5.3” p.u. and the Time Setting to “0.36” s. Press OK.


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• Double click the Io> element and set the Current Setting to “0.2” p.u. and the Time Dial to “0.3”. Press OK. • Double click the Io>> element and set the Pickup Current to “0.4” p.u. and the Time Setting to “0.4” s. Press OK. • Press OK on the relay editor and OK on the cubicle editor.


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Creating an Overcurrent Path

Creating an Overcurrent Path

It is useful to create paths for ease of creating and editing overcurrent relay settings. To do this, multi-select all busbars, lines/cables, terminals etc. in the desired path and right click the multi-selection as shown below.

• Select Path → New. • In the path dialog, name the path “Red Path”. Click OK. • We can now right click anywhere on the path and select Path → Create Time-Overcurrent Plot (the path must first be de-selected by clicking anywhere outside of the path). A new time-overcurrent plot appears. We can again reset relays by first splitting relay curves and then by dragging the curves. If we would like to confirm that the transformer is adequately protected from thermal damage due to overcurrents, follow the next steps: • Right click on the transformer. • Select Show → Add to Time-Overcurrent Plot. • A window appears listing the two curves created so far. We can now select on which plot the transformer damage curve should be added. • Select the second plot- Time-Overcurrent Plot(1), and press OK. • We note that the transformer damage curve is only just above the transformer protection relay curve.


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Exporting Settings to a Tabular Output


PowerFactory v15 introduces a completely new tabular reporting format which vastly improves the protective device setting reporting capability of the software. With the previous approach ASCII reports for protection settings were generated in the output window which were not able to deal with the structure of complex relay models. Furthermore the settings could not easily be exported to other software environments like Microsoft Word or Excel. The new tabular report command (ComTablereport) overcomes these problems by generating pre-configured tabular outputs customized to the protective device class. A report command specifically for protection can be accessed by either clicking on the Output of Protection Settings icon on the Protection toolbar or alternatively selecting from the main menu Output → Protection→ Output of Protection Settings, as is shown below.

A dialog will appear, showing the options to generate several reports. By default, PowerFactory comes with the selection of the Instrument Transformers and Overcurrent Protection reports. For each option selected, PowerFactory will generate a dialog, including all the chosen data. For now, please leave only the Overcurrent Protection box ticked. In the field of Protective Devices are two options presented: you could rather choose to have a tabular report of all the protection devices or to make a selection of them. To do this: • Left click on the Edit Relevant Objects for Calculation icon, and select the green Relay Model (*.ElmRelay) symbol. A list of all used relays will appear. Note that there should be 3 relays on the list. • Select the “Transformer Relay” and the “Feeder Relay”, holding the CTRL button while doing right click on the corresponding green icons. • Left click on any part of the selection and choose Define → General Set. • A dialog appears. Right click on Close button and close the Object Filter dialog. • Return to the Output of Protection Settings dialog, as stated before. Over-current Protection Tutorial (DIgSILENT Technical Documentation)

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• Select User Selection in the Protection Device field. • Select the down arrow button next to Selection and right click on Select. • On the dialog, go to Study Cases → Study Case and make sure to select the item General Set on the right pane. Press OK.

Now go to the Common Options submenu. Here you can specify the number of decimal digits you want to have in the tabular output, as well as the Layout Options for the report. The three selected columns in the Layout Options field will appear at first of the tabular output dialogue. You can rearrange the order of the columns by means of using the >> and << buttons. For the last four options below, please tick on the Show Instrument Transformers box and leave the others as is. This will result in having the information about the Instruments Transformers which are associated with each corresponding relay, while showing only the settable blocks in a vertical arrange for each protection stage. If you want the ANSI codes to be shown together with IEC codes, you can also tick this box. For now, leave it as is. Press Execute. Now we have a tabular output for the relays, including the Instrument Transformers information. Please note that the settings information are listed horizontally while the relay models are listed vertically. This data can be copied and pasted if required, with or without column headers, or also can be exported to HTML format or in excel spreadsheet format, by means of clicking the downward pointing triangular icon and selecting the option desired.


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You can also access to the main dialog of the relay element through the tabular output. Left click on the cell “Transformer Relay”. As you can see, a new dialog is shown but is the same dialog from which you can access to the relay settings.


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Performing a Short Circuit Trace


Sometimes is desired to have a quick look over the performance of the protection scheme, taking into account the dynamic behavior of relay tripping under shortcircuit conditions. PowerFactory introduces a new tool named Short Circuit Trace based on the calculation of the fault currents through the complete method, for a single or a group of faults, to determine the relays tripping time due to the measured current that flows through the associated branches. Note: Please activate the project named “OC Prot Tut Step 3”

Now, as you can see below, there has been a slight change on the topology of our test system. We have added a new “Feeder Cable” with its corresponding relay, which has the same settings as the relay created before (“Feeder Relay”). Our goal is to simulate a fault near the “Intake/Incomer” busbar, in order to observe what happens with the behavior of the protection scheme.

To perform the Short Circuit Trace, please do the following: • Left click on the center of the “Feeder Cable”. A menu appears. Select Calculate → Short Circuit Trace. • A new dialog is shown. Right click on the “Short-Circuit Event” cell and select Edit. • You will notice that the “Feeder Cable” is already selected as the element to be faulted. Left click on the arrow button right next to the “Feeder Cable” element.


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• Go to the Complete Short-Circuit submenu and enter “5” in the Short-Circuit Location field. Press OK.

• Now the Fault Location is defined to be at “5”% from the Intake/Incomer busbar. Press OK. • Press Close. • The Short Circuit Trace dialog appears. Left click on the arrow next to Command. Go to the Advanced Options submenu and select Mixed Mode from the Calculate relay tripping with field. Define the Sub-Transient Time to be as “0,5” s. • Press Close. • Now, we have all prepared for the Short Circuit Trace calculation. Press Execute. The first stage of the fault calculation is shown as next.


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As you would notice, the simulated 3-Phase fault is not only being fed through the Feeder Cable, but also from the New Feeder Cable as well. For the Next Time Step, please left click on the black left arrow, in the Protection toolbar.

Now the Feeder Cable relay has tripped at 0,36 s, as you will notice a red circle surrounding the cubicle area. Nonetheless, the fault is still being fed, but now all the current is going through the New Feeder Cable. At this point, PowerFactory has recalculated the 3-Phase fault, using the initial conditions which are the same as the final values at the end of the first stage, but with a new topology condition, thus showing the new current distribution.


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For the last step, observe that the relay associated to the New Feeder Cable has now tripped.


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OverCurrent Tutorial

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