Application of a RTU for load tap changer monitoring and controlECE 504Alejandro SchnakofskyRaleigh, NC

Content

• Motivation and objectives

• What is an RTU

• What is a load tap changer

• Components

• The DNP3 protocol

• Signal list

• Functionality

• Demo

Motivation and objectives•Learn about RTUs and their application•Program RTU to:

▫Monitor LTC▫Control LTC▫Serve LTC data via a communication

protocol▫Automatic voltage adjustment logic

What is an RTU?

•A remote terminal unit is a device that collects information regarding a process▫Voltage▫Current▫Status indications (position of a breaker)

•It then reports that information to a higher level system such as SCADA, DCS, etc

What is an RTU?Inputs:

-Binary- mA- RTD

Outputs:

- mA- Contact

Communications:

- DNP- Modbus- IEC61850- Profibus- Spa- RS232- RS485- Modem- Ethernet

What is Load Tap Changer?

•Load tap changer is a device that has the capability of changing the turns ratio of a transformer or auto transformer

•By varying the turns ratio the voltage at the load terminal can be adjusted.

What is Load Tap Changer?

•Load tap changer is a device that has the capability of changing the turns ratio of a transformer or auto transformer

•By varying the turns ratio the voltage at the load terminal can be adjusted.

What is Load Tap Changer?

Components

•ABB RTU 560▫Binary input card▫mA input card▫Binary output card▫DNP protocol and PLC licenses

•Howard Industries SVR-1 voltage regulator

•ASE2000 DNP protocol test set•Laptop

The DNP3 protocol

•A master-slave protocol for data acquisition and control applications

•3 Layers▫Link▫Transport▫Application

•Functions▫Read▫Select▫Operate

The DNP3 protocol

•Data is divided into objects ▫Object 1: binary inputs▫Object 30: analog inputs▫Object 60: class data▫Object 12: operate relay

•Several indexes inside objects representing data

The DNP3 protocol

Signal ListBinary InputsSignal Name Board Location DNP Object DNP Index Class Notes USEDAuto/Manual_Input BE01 BI 10 11=Auto 0=Manual NOBlock_Ind BE02 BI 11 1 NOButton Lower BE04 BI 12 1 YESButton Raise BE05 BI 13 1 YESLR Switch BE06 BI 14 11=Local 0=Remote YESMax Pos Reached BE07 BI 15 1 NOMin Pos Reached BE08 BI 16 1 NOSpare13 BE09 BI 17 1 NOTapB1 BE10 BI 18 1 YESTapB2 BE11 BI 19 1 YESTapB3 BE12 BI 20 1 YESTapB4 BE13 BI 21 1 YESTapB5 BE14 BI 22 1 YESAuto/Manual_Ind BI 23 11=Auto 0=Manual YESBlock_Ind BI 11 1 YES

Signal List

Binary Outputs

Signal NameBoard Location

DNP Object

DNP Index Class Notes USED

Lower cmd BA05 BO 1NA YESRaise cmd BA06 BO 2NA YESAuto-Manual BA03 BO 3NA YES

Analog Inputs

Signal NameBoard Location

DNP Object

DNP Index Class Notes USED

Voltage 23AE23 AI 1 2 YES

Functionality

•Report status signals via DNP3•Handle commands from DNP3•Handle commands from local interface•Local/Remote Logic•Auto/Manual Logic•Determine tap position•Automatic tap change logic•WebHMI interface to easily view status

information of tap changer