Developing a Virtual Simulation and Data logging and Supervisory Control System for a Laboratory-Based Mini Thermal Power Plant

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"The new system, based on the NI platform, monitored the plant with the complete automatic panel, which included indicators and a valve controller."

- Bindu Pillai, Chandubhai .S.Patel Institute of Technology

The Challenge:
Conducting a feasibility study to automate a mini thermal power plant and creating virtual simulation; identifying the required sensors and actuators, installation, and testing; and implementing a data logging and supervisory control system.

The Solution:
Developing an automated plant layout with the LabVIEW Datalogging and Supervisory Control (DSC) Module; converting this into a virtual simulation with NI LabVIEW software; and using the NI cDAQ-9178 chassis, the NI 9219 universal analog input module, and the NI 9403 digital I/O module to acquire data and perform real-time measurements.

Author(s):
Bindu Pillai - Chandubhai .S.Patel Institute of Technology
Dhara Trivedi - Chandubhai .S.Patel Institute of Technology
Vishal Mehta - Chandubhai .S.Patel Institute of Technology
Nilam Patel - Chandubhai .S.Patel Institute of Technology

About the Department

The CHAMOS Matrusanstha Department of Mechanical Engineering offers a bachelors, masters, and doctorate degrees in mechanical engineering. The department is equipped with sophisticated laboratory equipment for various areas such as tribology, reverse engineering, unconventional machining, control and automation, and machine vision.

Introduction

Virtual laboratories can facilitate the teaching and learning process in higher engineering education. The mini thermal plant automation project provides students with ideas about a working power plant. Our goal with this project is to show students the benefits of virtual simulation in practical laboratories, explain the different types of sensors and actuators used in power plant instrumentation, and create remote access to the lab.

Automating a Mini Thermal Power Plant Setup

Figure 1 shows the original manual mini thermal power plant. It lacked the following features:

  • Pumps to feed diesel into the diesel storage tank
  • An indicator to check water and diesel levels in the tanks
  • Power plant valve automation
  • Accurate devices for process parameter measurements
  • Ability for unskilled workers to operating the complete power plant
  • A monitoring system available at the power plant setup

We simulated the entire automated setup of the mini power plant with LabVIEW using the LabVIEW Datalogging and Supervisory Control (DSC) Module. Figure 2 shows the layout of the automated setup and Figure 3 shows the front panel of the virtual simulation of the entire mini thermal power plant.

Operation

The power plant starts by pushing a toggle switch. One of four level sensors (S2) senses if the tank is empty at the initial stage and passes a feedback signal to the NI CompactRIO  system, which actuates Valve 1 to fully open so the water can feed into the water tank from Pump 1.

S1 senses when the level reaches 1,000 mm and passes feedback to the CompactRIO system so that Pump1 immediately stops. Simultaneously, Valve 2 fully opens. It remains fully open throughout the whole operation because it continuously provides water to the boiler through Pump 2.

The oil circuit follows the same process. If the oil tank is empty initially, then S4 senses the signal and gives feedback to the CompactRIO system, which actuates Valve 3 to fully open. As the oil level reaches 700 mm, S3 senses the signal and passes it to the actuator of Valve 4 so it closes. When the level goes below 200 mm, Valve 3 opens again. When  steam generates in the boiler, its initial temperature is 29 °C. The bypass valve remains fully open until the boiler temperature reaches 135 °C and rises up to 190 °C, which can be observed on a monitoring panel.

At this temperature, the bypass valve closes and Valve 5 opens fully. Now the steam passes to the turbine valve where one pressure transmitter and one temperature sensor (T1) are mounted on the pipeline to sense the steam’s pressure and temperature.

Steam from the turbine valve passes to the turbine, which connects to the alternator. Dry steam is supplied to the turbine, which makes the rotor of the turbine move at 3,000 rpm. The monitoring panel provides the status of the valves, pumps, and sensors.

LEDs show the status of the virtual instruments—red indicates off and green indicates on. The output panel shows three sets of bulbs. The bulb is on when the alternator connected to the turbine generates electricity up to 3 KW, where 1 KW is used to illuminate the bulbs.

The used steam goes to the condenser to convert into water. Here, temperature sensors T2 and T3 sense the inlet and outlet water temperature and thermocouples sense the temperature.

System Benefits

Virtual simulation is useful for understanding the real-time power plant operation. The simulation can be used as a virtual lab to train students and professionals.

We replaced the manual valves of the existing setup with automatic valves. We used sensors to determine the level, pressure, and temperature. We modified pipelines and integrated the whole system with PID controllers. Figure 4 illustrates the implementations.

Benefits of the power plant instrumentation include:

  • Improved boiler operation safety by acknowledging the water and diesel levels inside the tank with a level sensor
  • Reduced plant operating time with automatic valves
  • Performed globe and bypass valve control with the PID controller
  • Enhanced process monitoring
  • Used power produced to charge an internal combustion engine battery to run the pump and recirculate water and fans for the thermal engineering laboratory
  • Improved efficiency
  • Eased PID controller power plant operation with control valve automation

Data Logging and Supervisory Control


We used the LabVIEW DSC Module for plant control and to transfer data in real time from remote locations to control equipment and conditions. We needed to develop a system to monitor the plant and help reduce the errors caused by humans by automating the plant and minimizing human intervention.

Similar systems are widely used in plant automation to provide an efficient tool to monitor and control equipment in manufacturing processes online. Our system can handle a wide range of errors and safely shutdown various components in a reliable and effective way. It supports a sophisticated range of mechanisms for integration, reporting, and recording of errors, events, and alarms. The system is flexible enough to integrate additional industry standard I/O devices in the existing system. A client computer performs high-speed data acquisition to synchronize data capture with a signal triggered by a specific event.

The mini thermal power plant system includes on-off condition for various valves of the plant, on-off condition for various pumps, and low and high levels for water and diesel. It also includes the mini thermal power plant layout and monitoring of steam and water temperature and steam pressure. Figure 5 shows supervisory control of the mini thermal power plant.

Data Acquisition 

The main objective of this system was to acquire data from the temperature, pressure, and level sensors of the mini thermal power plant. We used the NI cDAQ-9178 chassis, the NI 9219 universal analog input module, and the NI 9403 digital I/O module for this. Figure 6 shows the mini thermal power plant data acquisition system. Figure 7 shows sensor monitoring and Figure 8 shows valve position.

Historical Data

We included a historical data viewing feature as shown in Figure 9. The operator can view previously acquired data in the form of plots of various process parameters such as steam temperature, water temperature, and steam pressure.

Overall Outcome

The new system, based on the NI platform, achieved these benefits:

  • Improved system efficiency from 22% to 28%
  • Lowered fuel consumption from 40 liters per hour to 33 liters per hour
  • Reduced manpower since power plant operation could be monitored through the HMI
  • Improved operational efficiency with automatic valves, sensors, and PID controller
  • Monitored the plant with the complete automatic panel, which included indicators and a valve controller
  • Used power produced during power plant operation
  • Saved 0.575 kW/hr in power consumption over the old setup

Author Information:
Bindu Pillai
Chandubhai .S.Patel Institute of Technology
Charotar University of Science and Technology, Changa
Anand 388421
India
bindupillai.me@charusat.ac.in

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