IEC 61850 : How to refurbish serial protection relays

Oct 15, 2015

The number of IEC 61850 projects in the world is increasing year by year, and most of these projects involve retrofit and expansion of current substations.

Because pro­tec­tion relays are being main­ly cho­sen by its reli­a­bil­i­ty per­form­ing its pro­tec­tive func­tions, many already installed relays can­not be replaced. And still, many pro­tec­tion relays cur­rent­ly being sold in the mar­ket, or cur­rent­ly cer­ti­fied by util­i­ties do not sup­port IEC 61850. These facts com­pro­mise the upgrade/expand of old sub­sta­tions to IEC 61850 sub­sta­tion automa­tion sys­tems, main­ly in High Voltage.

iGrid T&D iGW allows these relays to con­nect to the IEC 61850 net­work, as if they were anoth­er IEC 61850 relay. iGW com­mu­ni­cates with the IED through any of most com­mon­ly used pro­to­cols in ener­gy sec­tor such as IEC 60870–5‑101, IEC 60870–5‑103, IEC 60870–5‑104, DNP3.0, Profibus, Pro­come and Modbus.

iGW collects all information from relays and maps it to IEC 61850 Logical Nodes.

 

iGW sup­ports any kind of Log­i­cal Node(LN) and Com­mon Data Class (CDC), both stan­dard and cus­tomized. All this infor­ma­tion is avail­able through IEC 61850 with all required features:

  • Read and discovery.
  • Gen­er­al Interrogation
  • Report­ing
    • Buffered Report Con­trol Blocks (BRCB)
    • Unbuffered Report Con­trol Blocks (URCB)
  • Dynam­ic dataset and report con­trol block creation.
  • Log ser­vices
  • Any IEC 61850 con­trol mod­el is sup­port­ed, regard­less of the con­trol mode used by the IED.
  • SCL files support
  • IEC 61850 Edi­tion 1 and Edi­tion 2 full support
  • Con­fig­u­ra­tion of RFC 1006 lay­er parameters
  • GOOSE pub­lish­ing

Some IEC 61850 data can­not be obtained direct­ly from the IED, and need to be cal­cu­lat­ed by the iGW :

  • Sta­tus points. Some inputs in the IED must be com­bined into a sin­gle sta­tus point in IEC 61850. Such us the phys­i­cal capa­bil­i­ties of the break­er to oper­ate ‘CBOp­Cap’, which reflects the switch­ing ener­gy as well as addi­tion­al block­ing due to some local problems.
  • Mea­sures cal­cu­la­tion. iGW can com­plete IEC 61850 data mod­els cal­cu­lat­ing new mea­sures based on the ones pro­vid­ed by the IED.
  • IEC 61850 spe­cif­ic data. There are some spe­cif­ic IEC 61850 attrib­ut­es that need to be com­put­ed also, such us ‘Beh’, ‘Health’, dead­band and others.

Sev­er­al IEDs can be added to the same IEC 61850 serv­er iGW by means of Log­i­cal Devices (LD), where each LD rep­re­sents a phys­i­cal IED. In any case, any oth­er mod­el struc­ture is also possible.

Note that though iGW can pro­vide GOOSE pub­lish­ing, this may not be suit­able for all pro­tec­tion schemes. Because, if com­mu­ni­ca­tion with IED is being done by ser­i­al links with low band­width, this would com­pro­mise time respons­es to be fast enough to meet some pro­tec­tion scheme tim­ing requirements.

iGW is the best way to inte­grate an exist­ing relay into an IEC 61850 net­work as any oth­er IEC 61850 relay. The iGW adds to the IED a com­plete set of IEC 61850 fea­tures addi­tion­al­ly to the cur­rent­ly pro­tec­tive func­tions offered by the relay. This allows these relays to be includ­ed into new IEC 61850 projects while extend­ing their live cycle, and with­out com­pro­mis­ing IEC 61850 deploy­ment inside the utility.