Application of a RTU for load tap changer monitoring and control ECE 504 Alejandro Schnakofsky Raleigh, 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 - IEC 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 List Binary Inputs Signal NameBoard LocationDNP ObjectDNP IndexClassNotesUSED Auto/Manual_InputBE01BI1011=Auto 0=ManualNO Block_IndBE02BI111NO Button LowerBE04BI121YES Button RaiseBE05BI131YES LR SwitchBE06BI1411=Local 0=RemoteYES Max Pos ReachedBE07BI151NO Min Pos ReachedBE08BI161NO Spare13BE09BI171NO TapB1BE10BI181YES TapB2BE11BI191YES TapB3BE12BI201YES TapB4BE13BI211YES TapB5BE14BI221YES Auto/Manual_IndBI2311=Auto 0=ManualYES Block_IndBI111YES

Signal List Binary Outputs Signal Name Board Location DNP Object DNP IndexClassNotesUSED Lower cmdBA05BO1NAYES Raise cmdBA06BO2NAYES Auto-ManualBA03BO3NAYES Analog Inputs Signal Name Board Location DNP Object DNP IndexClassNotesUSED Voltage23AE23AI12YES

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