Figure 1. System Block Diagram
From many years in order to maximize the working productivity of the industrial equipment, the control and data acquisition systems have always been available for modernized industrial architecture. However, to increase the reliability of the plant/process, these systems have always tended to be expensive on small and medium scale purposes. Similarly, electric drives find many applications in industries as well as household purposes. Also, for a greater productivity of electric drives, control becomes necessary and will always benefit the end user. This paper presents a microcontrollerbased control and data acquisition system for electric DC drives that is low cost, modular, and can be installed in stages determined by budget constraints or process requirements. The presented system includes a supervisory desktop computer with specifically developed Data Acquisition software. Arduino UNO Microcontroller Development Board is used for drive speed and directional control using Pulse Width Modulation (PWM) technique. Data transfer from desktop to controller and controller to desktop is done using the Serial Port Connectivity (SPC) of the microcontroller. Microsoft Visual Studio is used to develop the necessary GUI Software System. VB.NET is used as the backend programming language for drive control and data acquisition. The data acquired can be stored into Microsoft Excel Workbook for further analysis and the speed v/s voltage characteristics can be saved as an image file.
Electric drives are used on a large scale in industries as well as domestic purposes as they are an efficient method of energy conversion. Supervisory Control and Data Acquisition (SCADA) systems are currently employed in many applications, such as home automation, greenhouse automation, and hybrid power systems. The designed system uses low-cost yet effective sensors, an Arduino Uno microcontroller development board, and custom developed SCADA software. The Arduino Uno microcontroller collects data from sensors and communicates with a computer through Serial Port Connectivity (SPC). Uno has been programmed to transmit data to the PC. The results of the experiments demonstrate that SCADA works in real time and can be effectively used in monitoring an electric DC drive system. As per the current design, the system can be used in small scale industries, upcoming electric drive based electric vehicles and in electric drives and on renewable energy sources. Also, the hardware and software designed is best suited for DC Drives. Yet making some minor changes the software and the controller can be used to control and acquire data of AC Drives.
From several years, Electric Motors have been the backbone of any industry and many other processes. A study shows that the greatest load on any power system are the motors. To get the desired output from these motors in terms of speed and power, mechanical methods were adopted which resulted in energy wastage and inefficiency (Jones, Hammond, & Thurston, 1990). As a result, the working lives and health of equipment were greatly affected. Modern techniques known as drives develop power electronic converters that are useful in increasing efficiency by newer means. High end drives manufactured by Tesla and other drives manufacturers provide sophisticated SCADA systems for their users (Sagi & Varga, 2017; Youngblood, 2015). But low-cost drives with same performances as high end drives does not come with embedded SCADA software. There are number of SCADA software commercially available for monitoring and controlling of drives (Youngblood, 2015). But as described above, cost of such software would be more than 10,000 USD. Therefore, it is a requirement to develop low cost SCADA for small control system with most of the features offered by commercial SCADA service providers. The interface between SCADA and the drive can be considered as the most important part of this development because different manufacturers use different protocols and this interface should be capable to communicate in any protocol. Therefore, selecting a capable and low-cost device is also important. Hence a microcontroller board Arduino was considered. There were number of options available when developing a SCADA system for an electric drive (Yin, Jia, Ma, & Wang, 2018; Guozhen, Changsong, & Shanxu, 2009). The main objective of the paper is to use the best available method among all. The main approaches were tested for the client side and, considering all those pros and cons Visual Basic based system can be recognized as the best option. As the next part four major approaches of speed control were tested to identify the best approach. Pulse Width Modulation was selected as best method.
Initially, the block diagram of the system was prepared as shown in Figure 1. Then the presented idea was simulated using computer software Lab center Electronics Proteus as shown in Figure 2. Further depending upon the simulation results obtained making some changes in the microcontroller code, the complete drive system was set up in laboratory. L293D Motor Driver was used to power interface for a smaller rating DC Motor. The voltage and speed values of motor are sent to remote PC (configuration server). Figure 3 shows the image of monitoring interface of SCADA system. Before operating in this interface, the user must enter his/her user ID, password, and priority. If either user ID or password is wrong or incorrect, the user will be refused to access the system.
Figure 1. System Block Diagram
Figure 2. Simulation Circuit Diagram
Figure 3. The User Interface of SCADA after the System is Operational
In this work, the proposed SCADA system monitors a DC Motor Drive system and several experiments can be carried out. These experiments cover the measurement error of the sensor systems, which are installed to measure motor voltage, motor speed, and SCADA features. The sensors that are used contain errors, so these errors are rectified with calibrated instruments, this is done by slight modifications in microcontroller code. The monitoring tasks are displayed on the PC. They include the motor parameters as a graph and values of voltage and speed. Figure 3 shows the user interface of SCADA after the system is operational. The SCADA system is designed to make an update in every two seconds. As shown in Figure 4, motor speed and direction can be controlled remotely from PC.
Figure 4. Graph Data Saved as Image
SCADA system has the feature of enabling all data to be easily saved on a computer as an Excel file and Image File. To save the data, the user just has to hit the Export Button and also the graph is saved in image format. In this report, a low-cost SCADA system was designed and built using Visual Studio and Arduino Uno. The SCADA system was applied to a DC Drive to monitor the speed and voltage of drive. Figure 4 shows the image file of the motor speed and voltage characteristics.
The presented system finds its applications in Small- Medium Scale Industries (SMSI). Making some modifications, the system can be readily adapted to renewable energy based Micro-Grids, Hybrid Electric Vehicles, and Traction Systems. Also, it being used as a Experimental Lab setup for Control System and Electric Drives Lab.
The paper proposes a system designed to control speed and direction of a PMDC Motor. The software application developed can save motor parameters to an excel file and characteristics to an image file. The presented system is cost effective and yet it delivers the desired performance. The presented system is suitable to use for personnel who need not have a professional computing background. Improvements can be made in presented system to make it more acceptable to different control strategies of electric drives. Personal computers or laptops used as HMI can be replaced by lower cost computing devices like Raspberr y Pi. Wireless Communication Interface can be introduced between Microcontroller and PC for increased system steadfastness. Increased options like speed control of induction motors and BLDC motors can be incorporated. Online data acquisition and control using IoT also can be incorporated for universal adaption.