Power system automation involves using microprocessor-based intelligent electronic devices to automatically control power systems through data acquisition, supervision and control. Common communication protocols for power system automation include Modbus, DNP3, IEC-60870-5, and IEC-61850. These protocols define specifications for communication layers, data models, and transmission services to enable communication between master stations and remote terminal units or intelligent electronic devices in an automated power system.

1. Power System Automation

2. AGENDA
• Power System
• Power System Automation
• Communication Protocol
– Modbus
– DNP 3.0
– IEC-60870-5
– IEC-61850

3. Power System

4. Electrical Substation
• transform voltage from high to low, or the reverse
– Transformer
– Circuit Breaker
– Capacitor Banks

5. Power System Automation
• Automatically controlling the power system via
instrumentation and control device
– Data acquisition
– Supervision
– Control
• Intelligent Electronic Device
– Microprocessor-based controllers
• circuit breaker, protective relay
– Receive digitalized data
– Issue control commands
• tripping circuit breakers

6. Power System Automation

7. Communication Protocol
• Modbus
• DNP3
– North America, Australia, South Africa
• IEC-60870-5
– Europe & Middle East
• IEC-61850

8. Modbus
• Modbus Series

9. Modbus

10. Modbus
• Frame

11. DNP3.0 (Distributed Network Protocol)
• a set of communications protocols used
between components in process automation
systems
– electric and water companies
– communications between a master station and
RTUs or IEDs

12. DNP3.0
• Layered Architecture
– Physical Layer
• Serial (RS232, RS485), Ethernet
– Data Link Layer
• CONTROL : ACK, NACK, link needs reset, link is reset,
request data, link confirm of frame, request link status,
link status reply

13. DNP3.0
• Layered Architecture
– Pseudo-Transport Layer
• Add function code to indicate frame sequence
– Application Layer
• control code
• function code (Confirm, read and write, select and
operate, direct operate, freeze and clear, restart,
enable and disable unsolicited messages, assign class)
Master
Station
Slave
StationResponse
Request
Master
Station
Slave
StationUnsolicited
Response

14. DNP3.0
• Data Object Library
– Object Group (data group)
• Binary input, output
• Analog input, output
• Counter, Time & date, File, other…
– Data point (value)
– Object Group Variation (data type)
• 16bit int, 32bit int, 32bit float in analog input
• Reporting Model
– Class 0 : static data
– Class 1 ~ 3 : change data
– Integrity Poll : Get all class data

15. IEC 60870-5
• Standards
– IEC 60870-5-1 Transmission Frame Formats
– IEC 60870-5-2 Data Link Transmission Services
– IEC 60870-5-3 General Structure of Application Data
– IEC 60870-5-4 Definition and Coding of Information Elements
– IEC 60870-5-5 Basic Application Functions
– IEC 60870-5-6 Guidelines for conformance testing for the IEC 60870-5
companion standards
• Implementation Agreement
– IEC 60870-5-101 Basic telecontrol tasks
– IEC 60870-5-102 Transmission of integrated totals
– IEC 60870-5-103 “Informative interface” of protection equipment
– IEC 60870-5-104 Network access for IEC 60870-5-101

16. IEC 60870-5
• Layered Architecture
– Physical
• Serial : 101 ~ 103
• Ethernet : 104
– Data Link Layer
• fixed-length frame (request & response)

17. IEC 60870-5
• variable-length frame (data
transfer)
– RES/ DIR (balanced)
» Master - Slave
– PRM (primary)
» Primary or secondary
– FCB
» Frame count bit
– FCV
» frame count bit valid
– ACD/ RES (unbalanced)
» Class 1 events
– DFC (secondary)
» Data flow control

18. IEC 60870-5
• Balanced Transmission
• Unbalanced Transmission

19. IEC 60870-5
• Application Layer
– single-function message = as a single data link
frame
– Sector address
• Multiple, unrelated to link address
– Cyclic Data Transmission
• Eliminates static data poll message form master
• Unbalanced mode

20. IEC 61850
• Standards

21. IEC 61850
• Substation Architecture

22. IEC 61850
• Class Model

23. IEC 61850
• Protocol Mapping Profile