App of CFC Logic in Intel Devices

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10/18/99

Protective Relays

Application of CFC Logic in IntelligentDevices.

1 Abstract

Relays being the most intelligent devices within a substation are beingused for a large number of functions other than protection. Protectiverelays are being used as PLCs. No not Power Line Carrier, butProgrammable Logic Controllers. Perhaps because of this confusion inacronyms a better acronym would be CFC, or Continuous FunctionChart. CFCs have been used very successfully in the industrial marketand luckily there is a world wide standard on how the charts arecreated. This standard is the IEC1131 standard for PLCs.

With a multiprocessing platform a protective device can do both itsprotection functions as well as giving the user flexibility to create anunlimited number of users defined functions. Combine this CFCflexibility with the increasing RTU functions of protective relays todayand the user has the ability to reduce costs by removing control handlesand create a safer substation.

This paper is intended to show the user how to realize some commonfeeder functions used by just about every utility in the United States.The realization of these functions will reduce cost and create a safersubstation.


2 Different CFC Functions

This paper will deal with 4 major control handle related items used on a per-feederbasis. The following functions will be examined and implemented in a Siemens 7SJ63relay. The functions will vary from one utility to the next due to different philosophiesbetween utilities.- Recloser On/Off- Ground On/Off- Hot Line Tag Applied/Normal- Trip/Close

As you can see if all of these were to be preformed from the faceplate of the protectivedevice utilizing CFCs the cost savings would be enormous.

The SIPROTEC 4 7SJ63 relay offers 4 user definable function keys and aTrip/Close button on the front of the relay. Along with these function keys therelay also offers a graphical display for displaying metering values, breakerstatus, and the 3 other functions mention above.

3 Functionality Abstract

The functions will be defined first to eliminate any confusion on how they arebeing implemented in this paper. Also the reader should understand that thefunctions could be implement in any form that they desire. Different interlockingof functions can be realized by the flexibility of the device.

3.1 Recloser On/Off (Enable/Disable) Functions

The first function that will be examined is recloser On/Off. This function in anutshell allows the user to turn the recloser functionality of the relay On or Off. Asingle function key will be utilized for this function. It will act to toggle betweenthe On and Off functions. Also the status of this function will be displayed on thefront of the relay by means of the programmable LED indicators and also on thegraphical display.

3.2 Ground On/Off Functions

This function is identical to the Recloser On/Off function except that the relay willblock the 50N/51N functions. Some user only block the 50N this can beaccomplished with the same CFC but blocking just the 50N element.


3.3 Hot Line Tag Applied/Normal Function

The functionality of this particular function varies from one utility to another. Below arelisted the steps that will be implemented for the purpose of this paper.

Upon the application of the Hot Line Tag the relay will do the following:1. Turn off the recloser.2. Not allow the user to turn the recloser ON while the tag is applied.3. Do not allow the user to close the breaker locally or remotely.4. Change to a different group that has more sensitive settings.

3.4 Trip/Close Functions

This function is universal, Trip and Close the breaker when the particular button isselected on the front of the relay.

4 Configuration Notes

The CFC implementations require the user to configure points from one part of the relaysystem to another. What this means is that the protective function elements like block50N/51N or the recloser functions On/Off must be mapped to other functions such as theCFC, Front Display, or the event log. This has two purposes. One is to eliminateunwanted data from the selection list for each function like the CFC or the display, andsecond is to avoid sending information that does not need to be sent between functions.This is done in what is called the configuration matrix.

4.1 Configuration Matrix

In the 7SJ6X series relays the device gives the user the ability to send information fromone function to another. This configuration is done in the Configuration Matrix. Asample of this page is shown below in Figure 4.1. Figure 4.1 shows the basic layout ofthe configuration matrix. On the far-left column the different function groups are defined.Within each function group the different tags are defined. In the example the50/51Overcurrent function has been expanded to show the different tags in that group.On the top row there is a source location that the tags can be mapped to and adestination location. The sources that can be configured are from hard wired binaryinputs , function keys on the front of the relay, and from the CFC. Destinations includehardwired binary outputs, LED on the front of the relay, event buffers, system interfaceon the rear of the relay, the CFC, the display on the front of the relay, and to thecommand menu within the relay.


Figure 4.1 Configuration Matrix

Configuration is simple. On the left is the function and in each column is a source or adestination. Simple click the intersection of the function tag and the appropriate sourceor destination. For example, if we wanted to block the 50/51 function with binary input 1,click the intersection of the binary input 1 and the 50/51 BLK, see Figure 4.2. so for anyfunction listed the user can easily send information to any part of the relay.

Source Destination

Groups

Tags


Figure 4.2 Configuration Matrix 50/51 Block example.

5 Function Implementations

5.1 Recloser

Items to be configured into the configuration matrix are as follows:

1. >79 ON -- Turn Reclose On. (Mapped as Source into CM)2. >79 OFF Turn Recloser OFF. (Mapped as Source into CM)3. 79 ON Recloser Status. (Mapped as Destination into CM)4. F2_Key F2 Key pressed. (Mapped as Destination into CM)

The > on Any tag indicates a command to be sent to the function. All others are status.

When the Function key is depressed it is of very short duration when seen by the > 79ON and >79 OFF functions. So it will be necessary to capture this pulse and make itlonger. Using the function key to trigger a timer that will hold the pulse to the recloserfunctions longer will accomplish this. The ladder logic will be as shown in figure 5.1.

Blocks 50/51 Function when Binaryinput 1 is High (Voltage applied).


Figure 5.1 Recloser CFC

Shown above is how to use a function key to toggle the recloser On or Off. The functionreceives the Function key pulse which is AND with the status. If the status is theopposite of the function to be performed then the pulse is sent through to the timer whichholds the pulse long enough for the recloser element to read it.

5.2 Ground On/Off


1. >BLK 50/51N -- Blocks the 50N/51N Elements. (Mapped as Source into CM)2. F4_Key F4 Key pressed. (Mapped as Destination into CM)

The > on Any tag indicates a command to be sent to the function. All others are status.

So what need to be accomplished here is to block the ground overcurrent elements.This is done by asserting a logic one 1 to the >BLK 50N/51N element. The actualladder logic is shown in figure 5.2 below.

Timer for 79OFF Function

Check if Status of 79 is On.Send F2 Key to Timer if it is

Check to see if 79 is Off.Send Command to timer ifit is.

Timer for 79 OnCommand.


Figure 5.2 Ground On/Off

Figure 5.2 shows how this function is realized. The Function key is fed into the clockinput of a d flip-flop. The input of the flip-flop is fed from a negate function block thatinverts the status of the output of the D flip-flop. The output is then tied to the protectionfunction by the >BLK 50N/51N tag. So when function key 4 is depressed the tag of theBLK 50N/51N is toggled.

5.3 Hot Line Tag Enable/Disable


1. >Set Group bit 1 -- Changes the group settings from Group A to Group B. (Mapped as Source into CM)2. F2_Key F2 Key pressed. (Mapped as Destination into CM)3. HotLineTag Nothing more than a status tag to be mapped to a LED. (Mapped as

Destination into CM)The > on Any tag indicates a command to be sent to the function. All others are status.

A D-Flip Flop is used to latchthe opposite state of the ofthe status of the 50N51NBlock is

This block negates the status of theoutput of the flip-flop into the input ofthe flip-flop so the toggling of thefunction is realized.

The function key clocks theopposite status into theoutput of the flip-flop.


There are several goals to this particular fuction. If review the following must beaccomplished:

1. Turn off the recloser.2. Not allow the user to turn the recloser ON while the tag is applied.3. Do not allow the user to close the breaker locally or remotely.4. Change to a different group that has more sensitive settings.

The ladder logic for the funtion is identical to that of the Ground On/Off function insection 5.2 but the status of this function will be feed into the recloser function, groupchange tag, and the block breaker control. Figure 5.3 shows the ladder logic. Again ituses the same D flip-flop logic as the Ground On/Off function in section 5.2.

Figure 5.3 Hot Line Tag function

The HotLineTag tag status is used within the relay to block the closing of the breakerwhile the tag is applied. This is done in special place in the relay designed for thispurpose. Figure 5.4 shows this unique option of the SiProtec version 4 relays.

Changeto GroupB settings

Hot Line Tag status. For usefor LED status and blockbreaker control

Sent to recloser function toblock user from turningrecloser on while Hot LineTag is enabled


Figure 5.4 Blocking Controls for Hot Line Tag

This unique configuration option allows the user to block control on either the Opencommand or the close command. In the case shown in figure 5.4, only the closecommand will be blocked. The open command can be issued freely.

The reclosing CFC will need to be reevaluated to turn the recloser Off when the tag isapplied and also to block the recloser On function when the tag is applied. Figure 5.5shows the revised recloser function.

Interlocking Option. The HotLine Tag is place here to blockcommands from SCADA andlocal controls.


Figure 5.5 Recloser function revised.

To block the recloser if the Hot line tag is applied an extra gate was added to the ANDgate. This extra gate was attached to the opposite status of the Hot Line Tag. So if theTag was applied the value into the and gate would be a zero 0 and would not allow anypulses pass into the timer block. Therefor not allowing the recloser to turn on.

The OR gate was added to the Off function to allow the hot Line tag function F2_key toturn the reloser Off. So if the F2 key is pressed and the recloser is ON this would meanthe hot line tag was just applied and would turn off the recloser.

5.4 Breaker Open/Close

The 7SJ63 relay has an intergrated Open and Close button on the front on the relay.Figure 5.6 shows this.


Figure 5.6 7SJ63 Relay

The graphic display can be utilized to create any type of graphics or text as shownabove. The Trip and Close function only need to be mapped to a point on the graphicscreen to be realized. Figure 5.7 shows how easy this is to do.

Trip/CloseOn/OffButtons

ProgrammableFunction Keys


Figure 5.7 Configuring the Open/Close

With a simple click of a button the point that is displayed on the screen is nowcontrollable by the user via the front trip and close buttons. Figure 5.8 shows breakerpoints are mapped to the above object.

Status Overview.Different states ofthe breaker

Select this for the point to becontrolled by the buttons onthe front of the relay.

A and Bcontacts areutilized todisplay status


Figure 5.8 Tag configuration

Simple select the controllable point from a list and bolth the status for the breaker andthe associated controls are mapped. The object only has controls if the checkmark infigure 5.7 is selected.

6 Conclusion

The above application of the 7SJ63 relay gives the user the ability to save money onswitching hardware, wiring, and testing of each feeder. The device takes the place ofseveral expensive switches. Trip/Close switch, Reclose On/Off, Ground On/Off, HotLine Tag On/Off, and even a function built onto the front of the relay Local/Remote. Allthese switches can add up to thousands of dollars depending on the switches used.Wiring is another realized savings. All of the functions above are done within the relay.So other than wiring the CTs, PTs, Breaker status, and LAN to the RTU your done.Testing is done with one unit and the ladder logic is copied to each unit and just theprotection settings are changed. This allows the user with total confidence, to downloadthe settings and start operating the unit. Most utilities would test each feeder and thesavings would then be realized in not chasing down wiring problems.


In conclusion, the 7SJ63 is a powerful Relay, RTU, PLC, SOE recorder, Fault Recorderand controller unit that can do pretty much anything the user imagines.

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App of CFC Logic in Intel Devices