Real-Time Control and Monitoring of Photovoltaic Arrays Using RTDS and BeagleBoard Technology
^††thanks: Md Fazley Rafy is with the LCSEE, WVU, doing his Ph.D. in Computer Science. Corresponding author: Md Fazley Rafy (E-mail: mr00065@mix.wvu.edu)

The increase in environmental pollution and scarcity of fossil fuels is raising concerns with the exponential growth of technology and development in the 21st Century. A net-zero initiative of governments worldwide has led to the consideration of alternate energy solutions, such as renewable generation. Renewable generation includes power and energy generated from energy conversion from heat, mechanical power, water flow, wind, biomass gas emission, etc. The resulting technologies that facilitate such conversion to generate essential energy-based electricity include PV solar arrays, wind turbines, battery storage systems, bio-mass gas emitters, and many more. Among these, the prevalent one is solar power conversion through PV to generate solar-based electricity. United States Department of Energy reported to have generated 5,259,595 MWh electricity by renewable energy of which 31.5% was from Solar PV alone [1]. The inclusion of PV-based sustainable energy resources is widely used due to its ubiquity, abundance from sunlight, and sustainability. The source of this technology is the sole impact of solar energy from sunlight, which makes it free of cost and desirable. As the PV arrays are made of semiconductor materials, the integrated devices are static, complete, and liberated from moving parts. These characteristics make a solar panel easy to maintain, operate, and scale. The operation of solar panels generally relies on solar irradiance, the temperature of the solar cells, operating voltage, surrounding temperature, dust, humidity, wind intensity, etc. Among all these factors, insolation and temperature are the most critical ones that influence the output power and voltage of the panels which proportionately influence the generation of electricity [2]. This paper considers these two factors to control the output voltage and current of the PV arrays that provide electricity to the loads, which can be small residential or large commercial facilities. However, with the increasing integration of PV array-based distributed energy resources (DERs), the evolving landscape of modern power systems is becoming more complex and multimodal [3]. Energy management of such systems requires effective control of the solar operations to maintain grid stability and meet consumer demands. This complexity necessitates a comprehensive testing of different system components. Real-time simulation with a hardware-in-the-loop (HIL) can validate the performance of these intricate mechanisms without concern of losing essential power or damaging expensive components in PV panels. The need for an efficient HIL-based real-time simulation is the core focus of this report which dictates the control of multiple factors that facilitate the PV to function constructively. There are different simulation tools to assess the performance of solar PV, and comparison between PVGIS, PV Watts, and PV Syst dictates how real-time PV data monitoring can increase efficiency [4].

Digital simulators like RTDS and Opal-RT are also used to validate the performance of the sliding mode controller and the Perturb & Observe (P&O) controller for a solar panel [5]. RTDS perform power flow and other computation at the microsecond level to simulate a real-time environment for PV arrays that requires dynamic behavior representation under various conditions. This real-time simulation is a useful resource for education and training on power electronics for solar PV system integration. The Opal-RT on the other hand is another competitive simulator due to its ability to offer a flexible platform for experimentation on all aspects of a PV-integrated system [6]. Both of these provide a practical and efficient way to develop and test multiple scenarios in real time, which is crucial for both research and educational purposes in the rapidly evolving field of solar PV systems. To include the HIL in the Rea; Time System (RTS), black BeagleBoards are used as a controller for PV parameters. Among different types of BeagleBoards, the black version is the most common one as it has both wired and wireless capabilities. In Internet-of-Things (IoT) based technology, these boards are used considering their powerful processing capabilities, suitability, and usability to implement ModBus protocol, competence to manage OPC USA server-client, and integration capability with diverse IoT applications [7]. Regardless of the type, BeagleBoards are used for academic support for their cost-effectiveness, versatility in software and hardware integration, and other appropriateness in teaching data analysis and acquisition. These boards, like PocketBeagle, offer pragmatic solutions, and experimental capabilities for learning embedded systems and programming, which is an ideal device in technical fields [8]. Compared to Arduino Boards or Raspberry Pi, black BeagleBoards are better for control systems for PV as they can manage more extensive data with complex algorithms, making them suitable for sophisticated monitoring devices. However, their higher cost and potential limitations in processing power for very large-scale data need to be considered for larger implementation [9]. To objectify the necessity of efficient PV control for beneficial power system management of DERs, this paper scratches the surface of the control mechanism to improve PV performance. Section II presents the details of the design, operation, and data flow of the model. Software and Hardware setup for the experiment in RTS is explained in Section III. SCADA performance and illustration of the control through discussion are shown in Section IV. Finally, the overall contribution and summary of the paper are in Section V.

The core operation for this RTS is guided by the RSCAD design as shown in Figure 1. GTNET-SKT card and Beagle boards, as explained in Section III further articulate the RTS process with hardware inclusion to control the parameters of the PV array. With the varying measurement for insolation and temperature with varying environmental conditions, a PV controller, as shown in Figure 1 uses this information to adjust the operation of the PV array. The adjustment provides optimization of output power under those varying different environmental conditions. BeagleBoards are acting as two factors of the environment that are changing with time and affecting the performance of the PV. The complete steps of RTS operation with PV and Beagle boards are demonstrated in Algorithm 1 for better exposition.

With the help of RTDS, the real-time system is modeled as the simulator is able to perform computation with synchronized clock time. The larger number of input-output channels and dynamic processing power enable experiments with hardware-in-the-loop simulations. Facilitating that function, beagleboards were possible to integrate with the software design in RTDS through a special transducer, GTNET-SKT, that enables a versatile interface between different external communication devices and system models in RSCAD. As demonstrated in Figure 2, RTDS is controlled through RSCAD software, and PV design and controller are modeled in the RSCAD. Inside the model, the GTNET-SKT module refers to the actual hardware device in RTDS, which is also known as the GTNET card, and connects the router to create a local network. In that local network, beagle boards are also connected and can establish communication through the GTNET card with the help of a router. The details of the device’s configurations and performance monitoring of the overall system are provided in the subsequent sections.

The SCADA results shown in Figure 3, demonstrate the effect the environmental conditions like insolation and temperature on solar panel performance. The use of RTDS as a digital simulator allows for the modeling, control, and monitoring of PV arrays with connected dynamic loads to realize the RTS. The GTNET-SKT further assist in the control of these factors through the controllers to adjust the different rate of insolation and degree of temperature throughout the day. The SACADA shows how current and voltages change over time. The current changes proportionately with the increasing insolation and constant temperature. While the increase is less during temperature changes with constant insolation. With varying loads, and increasing insolation high flow of power is observed from the solar panel. However, improved efficiency is observed with lower temperatures and higher insolation that can help meet varying load demands more effectively.

The HIL-based PV controller in RTS demonstrates a significant advancement in the field of renewable energy management and monitoring, particularly in photovoltaic (PV) systems, by leveraging Real-Time Digital Simulation (RTDS) integrated with BeagleBoard technology. The developed system, as outlined through Algorithm 1, offers several key commercial and technical benefits that are crucial in today’s energy landscape:

Future smart grid technology with the increasing integration of PV arrays demands efficient analysis and operation of PV controllers to balance the demand from load consumption and response from the solar power generator. This paper demonstrates the impact of varying environmental factors, such as insolation and temperature to realize the need for proper PV control mechanisms for efficient power consumption and generation. RTDS and Beagle boards were used to develop a HIL testing environment to validate the performance of solar power generators under the influence of different external environmental factors. The real-time control and monitoring system for PV arrays presented in this paper not only advances the technical capabilities of solar energy management but also offers tangible benefits for commercial applications, research, and education. This system stands as a testament to the potential of integrating modern control technologies into renewable energy systems, paving the way for a more sustainable and efficient energy future.