Presentation on “Substation Automation System (SAS)”

Presented by-Abu Isha Md. Sajed Arefin

Deputy ManagerSystem Protection & Metering Circle

Power Grid Company of Bangladesh Ltd.

Definition Substation Automation System (SAS)

The most straightforward definition of SAS is that it can perform-

Local & remote access to the power system

Consisting of Manual & automatic functions

Consisting of communication links & interfaces to the switchgear objects within the substation and to the

Network Control & Management Center.

Traditional SAS architectureStation PC

Control Centre

Engineering PC

Router

Station Bus

Relay ABay Controller

Conventional Switchgear

ConventionalCT / VT's

Relay B Relay ABay Controller

Conventional Switchgear

Relay B

ConventionalCT / VT's

Brief History of SAS-

To dig out the history of SAS, lets go back more than 100 years when protective relays were introduced in power system for the first time.

Microprocessor based Remote Terminal Units came into picture in 1984.

Then in 1994 Intelligent Electronic Devices (IEDs) were introduced in the power system.

And finally universal SAS standard IEC 61850 was introduced in 1997 to build the modern SAS architecture.

From RTU to SAS Architecture

Development of SAS over Time-

Basic Functions of SAS-

Basic Functions Typical Examples of Functions

Monitoring Functions

Monitoring of switchgear status, transformer tap position & tap changer status etc.

Monitoring of control & protection equipment soundness. Monitoring of electrical quantities, e.g. current, voltage,

frequency, MW, MVAR etc. Monitoring of station auxiliary supply and DC system.

Control Functions

Controlling of circuit breakers & disconnecting switches. opening & closing.

Synchronization checking. Maintaining switchgear operational interlocking. Controlling of voltage regulation. Controlling of reactive power.

Recording Functions

Recording of monitoring data. Fault, disturbance and event recording.

Protection Functions

Protection of generator, transmission line, power transformer, busbar, RPC bank, distribution feeders, shunt capacitor, shunt reactor etc.

Major Benefits of SAS-

Increases reliability and flexibility of the power system. Integrated protection & control accelerates response to

problems.A new approach to predict voltage instability.Comparatively easy and cost effective maintenance. Intelligent under frequency initiated load shedding to

avoid blackouts.Disturbance recording for fault location and power

quality assessment.Power system condition assessment for better

knowledge.

Communication in SAS-

Communication between the switchyard equipments to IEDs and communication between local SAS to network control centers are the backbone of modern SAS.

Proper & flexible communications is the key feature to achieve the perfect score and reliability for SAS.

Communication structure of SAS

Communication in SAS- (cont.) Communication with network control centers- Proprietary Protocols- RP570/571 (ABB) 8fW (Siemens) DNP3.0 (GE-Harris. DNP User Group) Modbus (Different users specially in power plants) Standard Protocols- IEC 60870-5-101 IEC 60870-5-104 IEC 60870-6 IEC 61850

Communication in SAS- (cont.) Communication within the substation- Proprietary Protocols- SPA (ABB) LON (ABB) Profibus (Siemens) DNP3.0 (GE-Harris. DNP User Group) UCA.2 (Utility communication architecture by

EPRI/IEEE ) Standard Protocols- IEC 60870-5-103 IEC 61850

Thank you