The Role of the SCADA RTU in Today’s

SubstationCraig Wester, Terrence Smith, Noel Engelman

GE Digital Energy

Bob Anderson, Joe ReillyOrlando Utilities Commission

Texas A&M Relay Conference 2015

Content

Traditional Hardwired SCADAMerger of SCADA and P&CAnalog Input, Digital Input and Control ConsiderationsRedundancy ConsiderationsRemote I/O ConsiderationsRTU Operating System ConsiderationsCommunication ConsiderationsConclusions

Introduction

Supervisory, Control and Data Acquisition (SCADA)Protection and Control (P&C)

PROTECTIVE RELAYSYSTEM

PRIMARY EQUIPMENT

Contact Outputs

Digital Inputs

Transducer Inputs From

CT

s and P

Ts

Contact Inputs

Currents (from CTs)

Voltages (from PTs)

Control Outputs

SUBSTATION SCADA RTU

Serial or Ethernet Communications

SCADA MASTER

Various Trips and Alarms (Relay Tripped/Operated, Loss of Potential, Loss of DC, Channel Alarm, Relay

Disabled, etc)

Historically…………Status only

Historically……….A CommonConnection Point....

Introduction

Typical concerns of a SCADA technician are:

Is SCADA or P&C staff responsible for IED data maps?When new protective relay settings are downloaded to IED, who is responsible for the effects these changes have on SCADA system?How can the substation be operated if an IED output contact is not operational?

Traditional Hardwired SCADA

Analog Inputs

32 Transducers

Digital Inputs

64 Statuses

Control Outputs

32 Trip/ Close Pairs

h)

Peri p

heral B

oard s

( Si n

gl e or Mul ti pl e U

ni ts o f Ea

c

Serial or Ethernet Communications

SCADA MASTER

SUBSTATION SCADA RTU

Analog InputsQuantity and cost of wire connectionsCost and reliability of discrete transducer hardwareTransducer maintenance

Digital InputsCostly and congested wiring often to redundant devicesEvery status point has clear indication LED

Control OutputsQuantity and cost of wire connections and discrete control relay hardwareAbility to provide critical control in event of IED failure

Benefits of Discrete I/OHot swappable modules without disturbing wiring or RTU configurationAllow quick removal for troubleshooting and maintenance purposes

Merger of SCADA and P&C

PRIMARY EQUIPMENT

Contact Inputs

Currents (from CTs)

Voltages (from PTs)

Control Outputs T/C #1

Serial or Ethernet Communications

SUBSTATION SCADA RTU

SCADA MASTER

Serial or Ethernet Communications

Remote Peripheral Board or Protective Relay

Transformer Alarms & Temperatures, Breaker

StatusesSerial Fiber Optic

MICROPROCESSOR BASED PROTECTIVE RELAY SYSTEM

Contact Outputs T/C #1

Serial or Ethernet communications between P&C System and RTU

Configurable data maps in IEDs & RTU

Configurable control points in IEDs (momentary or latched)

Analog signals scaled in IEDs

Consider using IED native protocol

Remote I/O mounted in primary equipment

Redundancy Considerations

SCADA RTU can be configured with redundant I/O functionality

RTU simultaneously polls analog and digital values from IED-A and IED-B. If IED-A stops responding or goes off-line, analog or digital values are replaced with values from IED-B.

AdvantagesSignals are continuously transmitted in event that IED-A or IED-B were taken out of service for maintenanceRedundancy and reliability of the signalSCADA RTU can transmit alarm when IED is off-line

SUBSTATION SCADA RTUIED-A

IED-B

Redundancy Considerations

SCADA RTU redundant I/O functionalityDistribution station - redundant analog signals could be obtained from separate feeder meter and protective feeder IED

Distribution station - redundant digital signals could be obtained from protective feeder IED and separate terminated status points to RTU

SUBSTATION SCADA RTUFDR IED

FDR METER

SUBSTATION SCADA RTUFDR IED

RTU TERMBOARD

Redundant Control Considerations

SCADA RTU can be configured with redundant control functionality

Method A - Operate internal latches and/or discrete output contacts of protective IEDMethod B - Operate discrete RTU termination boards with control relaysDistribution substations - methods A & B combinationTransmission substations:

Redundant protective IEDs (IED-A and IED-B)Recommend different IED contacts for SCADA control & protection

Discrete breaker control IED with separate protective IEDs

Remote I/O Considerations

Remote I/O exist that need monitoringStatus and analogs not wired into IEDs because not necessary to IED or difficult to route to IED

Door alarms, motion and loss of or low power (DC) sensors, health status points for IEDs, copper theft alarms, transformer/breaker alarms, temperatures, pressures (low SF6 gas), other critical status/analog points, sudden pressure relay, motor operated disconnect status, circuit switcher status, etc.

For example, RTU remote I/O mounted in the primary equipment located in the substation switchyard

SUBSTATION SCADA RTU

Remote Peripheral Board or Protective IED

Transformer Alarms & Temperatures, Breaker

StatusesSerial Fiber Optic

Operating System Considerations

SCADA RTU has real time operating system (RTOS) developed as proprietary software, such as VxWorksRTOS is designed for use in embedded systems which require real time and deterministic performanceRTOS is not open to network modification and, therefore, is not affected by viruses or require security patchesPC-based gateways or RTUs are affected by Microsoft Windows obsolescence, Microsoft Windows software, security patches and viruses

Communication Considerations

Protocol conversion by SCADA RTU

SCADA RTU serves as a data concentrator

Communications bandwidth limitations may exist to substation

SCADA communication redundancy to master using redundant RTUs

A Proposed Architecture

PRIMARY EQUIPMENT

Contact Outputs

Contact Inputs

Currents ( from CTs)

Voltages ( from PTs)

SCADA MASTER

Transformer Alarms & Temperatures , Breaker

Statuses

UTILITY WAN

MICROPROCESSOR BASED PROTECTIVE RELAY SYSTEM

Secure Access

ENGINEERING ACCESS

Secure Access

SUBSTATIONHMI

Secure AccessSUBSTATION LAN

Serial ( Copper or Fiber)

Ethernet

Control Outputs

Secure Access

SUBSTATION SCADA RTUSecure Access

Redundant I/OAnalog valuesDigital inputsControl outputs

Secure RTU access and IED access using

Role Based Access ControlRADIUS authenticationSys LogsComply with NERC CIPEngineering access for fault analysis troubleshooting or configuration

Optional

Conclusions

The merger of SCADA and P&C is continuously evolvingRTUs are hardened, secure devices with real time operating systemsMust balance metering, statuses and control considerations for SCADA, P&C and operationsRedundancy with RTU hardware and P&C hardware can be accomplishedSecure access is always important

Thank You

Questions?