Analysis and implementation of dip based online control and monitoring system for displacement in control valves
G. Rajakumar, P. Manimegalai · 2010
Process industries require supervisory control and data acquisition systems (SCADA) or distributed control systems (DCS) depending upon geographic distribution of the plant instrumentation. Remote operation of the hazardous field needs quite a good amount of instrumentation support for control as well as monitoring purposes. The various parameters to be monitored are pressure, flow, level, displacement, speed etc. Sensors are to be installed at hundreds of locations to bring the details of signals to the operator station. Along with this signal remote field images are taken by analog cameras to be received at operator station for field view. This separate arrangement of signal acquisition from sensors for signal conditioning, A/D conversion, Engineering unit conversion, limit checking and report/control signal generation at computer as well as separate field images view at operator station can be overcome with the latest technique Digital image processing(DIP). Separate image view at the computer monitors may produce erroneous results for control signal generation. Only web (Digital) cameras are installed at various parameter measuring points. Let us consider a case of level measurement. A digital camera installed near the boiler drum in a Thermal power station takes continuous photographs of water levels and forward the digital image signal to the computer at regular interval. These images are compared with standard image stored inside the computer with suitable algorithm. When received image matches the standard image, control action is initiated. This paper proposes a FPGA based new architecture for high-speed comparison of image according to the threshold value. This method exploits compare the sample image with reference image, if changes occur control signal will generate to monitor the parameters. The design based on using FPGA for the hardware implementation of the architecture using VHDL. FPGA Spartan 3E starter Kit has been used for the hardware implementation. The proposed method is an improvement over traditional software package based approaches in that of image comparison. This system gives real time display of various field images super imposing on the animated mimic diagrams in computer monitor, which is not possible in the old environment with analog sensors.