Physics
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/3750
Browse
35 results
Search Results
Item Smart System Using Lora Technology to Connect Rural Areas Underserved By Existing Internet and Telecommunication Technologies(The Electrochemical Society, 2022) Jayasekaraa, L.D.P.S.; Gurusinghe, T.N.; Wijesooriya, H.E.; Seneviratne, J.A.; Ranaweera, A.L.A.K.; Jayathilaka, K.M.D.C.; Wijesundera, L.B.D.R.P.; Kalingamudali, S.R.D.LoRa, Sigfox, and Narrowband-Internet of Things (NB-IoT) are some of the long-distance, low-power wireless communication technologies developed in the recent past. The proposed system consists of mainly nodes and a gateway as the fundamental system architecture. Nodes only communicate with the gateway individually and the gateway communicates with all the nodes separately and wirelessly. System in this proposed study, uses long range low power RF wireless communication technique for primary data communication, where an Internet connection will not be required for the communication between the gateway and the nodes. Any number of nodes can be paired with the gateway, and the gateway can individually communicate with each and every node. Furthermore, gateways have the ability of storing real-time data. Due to its unique design, the proposed system in this study, can achieve addressable, bidirectional, and continuous data communication even without the Internet connection. The bidirectional communication design of this proposed system facilitates real time and uninterrupted simultaneous handling of monitoring/sensor devices and controller devices without the need of a separate controlling system. As this system consists of those unique features, it is recommended to use in the rural areas underserved by current internet and telecommunication technologies. Furthermore, with the in-built option to get connected to the Internet, this system can be further expanded to an IoT based addressable data communication, processing, and visualization systems by eliminating the major technical problems in typical IoT systems such as interrupted communication and data losses during an Internet connection failure, power concerns and customization issues. This system is highly customizable, and the nodes and the connected devices can be controlled through the gateway or remote dashboard by assigning automated or user defined custom commands. These features together improve the robustness of the system and facilitates enhanced data recovery in case of a failure in the Internet connectivity.Item Efficiency Optimization of Supercapacitor Assisted Low Dropout (SCALDO) Regulators(IEEE, 2020-12) Jayasekara, L. D. P. S.; Piyumal, P. L. A. K.; Ranaweera, A L A K.; Kalingamudali, S.R.D.This study was primarily focused on presenting a novel method to enhance the efficiency of Supercapacitor Assisted Low Dropout (SCALDO) regulators. The main objective was to study SCALDO regulators under a specifically controlled condition where supply voltage is less than twice of the required minimum voltage for Low Dropout (LDO) regulators. Furthermore, design modifications to the switching controlling algorithm were performed to optimize number of capacitors with respect to the supply voltage in order to enhance the efficiency of SCALDO regulators. It was theoretically proven that the efficiency decline can be successfully reduced by varying the number of capacitors connected, according to the supply voltage and the minimum input voltages. The theoretical efficiency calculated for the proposed SCALDO technique falls within 81.5% - 88% range, which is well above the previously reported values. This was verified experimentally with the prototype developed using 2.7 V, 10 F supercapacitors, 5-3.3 V LDO. © 2020 IEEE.Item Analysis of Impedance Matching Technique for Novel Supercapacitor Assisted PV Systems(IEEE Computer Society, 2020-10) Piyumal, P.L.A.K.; Ranaweera, A.L.A.K.; Kalingamudali, S.R.D.; Kularatna, N.To extract the maximum power from a photovoltaic (PV) system, the maximum power point (MPP) of the PV array must be tracked continuously. A directly coupled load with the PV array does not track the MPP of the PV array because the load has a constant resistive value. Therefore, to track the MPP of the PV array, a technique called impedance matching is used. This is done by continuously matching the load impedance to the instantaneous impedance of the PV array. Switch mode DC-DC converters are widely used for this purpose which also helps to interface the DC output of the PV array with power distribution systems in order to deliver the power to the consumer end. However, the efficiency of these converters lies around 90% which degrade the end to end efficiency of the PV system. In this context, novel supercapacitor (SC) assisted PV systems have been introduced, which were able to enhance the end to end efficiency of PV systems. However, existing impedance matching technique is no longer valid for SC assisted PV systems. Therefore, still it is a challenge for these systems to track MPP of the PV array continuously while in operation. This paper presents a study on impedance matching technique for the novel SC assisted PV systems. Previously, it has been experimentally shown that a series connected SC bank between PV array and DC-DC buck converter of a PV system could deliver higher end to end efficiency than typical systems. This study validates the impedance matching technique for SC assisted PV systems by connecting a SC bank in series with buck, boost, and buck-boost converters. Simulation results indicate that this can be achieved by carefully designing the system with given parameters. © 2020 IEEE. https://ieeexplore.ieee.org/document/9254315Item Smart Automation System for Controlling Various Appliances using a Mobile Device(IEEE Xplore Digital Library, 2019) Gunarathne, S.B.M.S.S.; Kalingamudali, S.R.D.This paper outlines the methodology of designing and developing a smart control system for controlling light, air conditioning and ceiling fans in a room. This system considers the requirements of the users appropriately and makes a comfort zone for the users. An android application with a user friendly Graphical Interface, which is easy to communicate with the smart control system, has been developed. The application is connected with the control system through Wi-Fi across a cloud network and it can respond quickly. RGB LED panel light system that controls the color, color temperature and luminance was designed by considering the requirements of the instances and lighting conditions. Although there are RGB LED panel lights available, there are no systems defined for the activity based color modes. An IR Remote module controller system was built for controlling inverter type air conditioners by giving commands from a smart phone application. This system considers the mean value of the preferences of many users to control the air conditioning system. The running mode of the air conditioner is chosen from the data given through the application by many users in a same place. Although the inverter type air conditioners continuously regulate the temperatures, the fan does not do it. Because of this problem, a ceiling fan controlling system with two modes, automatic and manual, was designed. Automatic mode utilizes the users skin moisture related hybrid system to set the room temperature. Manual mode works according to the suggestions given by the crowd just as the air conditioning system. This air conditioning and ceiling fan control system that works according to the suggestions of crowd is better than the individual preference system using a conventional remote controller.Item Improving the Energy Storage of Standalone PV Systems while Enhancing the Charging Efficiency using Supercapacitors(IEEE Xplore Digital Library, 2019) Piyumal, P.L.A.K.; Ranaweera, A.L.A.K.; Kalingamudali, S.R.D.; Kularatna, N.Usually a battery is used as the energy storage device in typical standalone solar photovoltaic (PV) systems. It is charged by a solar charge controller. The charging efficiency of the system depends on the efficiency of the DC-DC converter of solar charge controller. However, a considerable amount of usable energy is wasted during the charging process. In this work, a method is proposed to utilize this wasted energy and thereby to enhance the charging efficiency. In the case of an empty capacitor being charged by an external source, it stores only half of the energy delivered by the source as compared to that of an electrochemical battery. Therefore, it wastes 50% of useful energy. A portion of this wasted energy can be collected and utilized if a useful resistive load is connected in series to this capacitor charging loop. In this study, a DC-DC converter and battery bank is connected as the useful resistive load in the capacitor charging loop. A supercapacitor (SC) bank is used replacing the conventional capacitor. Therefore, total energy loss in capacitor charging loop can be minimized by storing energy in both battery bank and SC bank. This concept is introduced into a typical PV system for reducing its energy losses. Experimental results show an enhancement in charging efficiency when this new method is employed. The energy stored in the SC bank could be used for driving loads with required electronics.Item Novel Approach for Harnessing Maximum Energy from PV Systems using Supercapacitors(IEEE Xplore, 2018) Piyumal, P.L.A.K.; Ranaweera, A.L.A.K.; Kalingamudali, S.R.D.; Kularatna, N.Typical standalone solar photovoltaic (PV) systems use battery bank as the energy storage device. The battery bank is charged by using a solar charge controller connected to a solar array. For similar PV systems, charging efficiency mostly depends on the efficiency of DC-DC converter available inside the charge controller. However, considerable amount of usable energy will be wasted during the charging process. In this work, a method is proposed to utilize this wasted energy while enhancing the end to end efficiency of standalone PV systems. When an empty capacitor is charged by an external source, it stores only a half of the energy delivered by the source as compared to the case of an electrochemical battery. As a result, 50% of useful energy is lost in the charging loop of a capacitor. If a useful resistive load is connected to this loop, some amount of energy can be utilized by doing a beneficial work. In this study, a DC-DC converter and battery bank has been chosen as the useful load in the capacitor charging loop, and a supercapacitor (SC) bank is used replacing the conventional capacitor. Therefore, total energy loss can be minimized by storing energy in both battery and SC bank. The energy stored in the SCs could be used for driving loads with required electronics. Consequently, it leads to an improvement of end to end efficiency of the PV system.Item Simultaneous control of multiple line-loads each connected separately in series with a designed unit (Control using Radio Frequency and a Mobile device)(2016) Cooray, B.N.P.; Perera, W.S.K.; Kalingamudali, S.R.D.A unit which can be connected separately in series with each load to control multiple line-loads simultaneously using Radio Frequency (RF) and a mobile device has been developed during this study. Series connected remotely controllable regulators are not widely available commercially and the few available do not have the facility to control the multiple line loads using a mobile application along with a RF remote controller and also they are very expensive and even require an alternative wiring system. The designed regulator provides the convenience of controlling the current flow through appliances connected to a single line power supply. A triac is used to control the power supplied to the load, since it can control the current flow in both halves of an AC current. The gate terminal is triggered by using a diac. A Switch Mode Power Supply, powers the active components of the regulator using the voltage drop across the triac. The Bluetooth (HC-06) and RF (315 MHz RF receiver) modules are programmed to receive inputs from the user to switch ON/OFF or control the voltage supplied to appliances such as fans and light bulbs. The Graphical User Interface enables the user to control the appliances easily and much faster than in normal usage of mechanical switches. The timer which allows the user to define time intervals for predefined output levels, can set desired levels of outputs for the appliances. This feature is not currently available in normal regulators. The suggested method facilitate simultaneous use of RF and the mobile devices as well as the ability to control several appliances with a single unit enabling energy conservation and ease of use. The cost of designing the unit with discrete components being less than US$ 17, it can be concluded that the model is cost effective since this method suggests two modes of control of the appliances along with timer settings. [1-9].Item Effects of lightning and possible health hazards due to the erection of telecommunication towers(Wayamba University of Sri Lanka, 2016) Maduranga, J.A.K.; Kalingamudali, S.R.D.; Jayaratne, K.P.S.C.The health hazards due to lightning and electromagnetic radiations in the neighbourhood of telecommunication towers were studied. Six tower sites were selected for the investigations from the areas covering the Sri Lankan lightning belt in Gampaha (Delgoda, Gonawala, Madarawa and Udupila) and Kaluthara (two in Poruwadanda) districts. Initially, a survey was conducted with a questionnaire based interviews. The earth resistance was measured using a digital earth tester according to the fall of potential method inside the region of 15m from the tower for studying the contribution to the lightning effects. The electromagnetic radiation power density was measured using a broadband field metre. The readings were obtained at 10m intervals along the direct line-of-sight of the antennas from the tower to about 80m distance. According to the literature and from the observations it was revealed that the most important factors related to the induced lightning current effect are the earthing systems utilised at the tower site, locations of the power feeding transformer and the houses in the neighbourhood. It was also observed that the earth resistance was near to threshold value in the Kaluthara district, and severe lightning hazards were prevented by installing the Surge Protection Devices (SPD) by the service providers. However, installing SPDs into houses was a temporary solution for the induced lightning current effects. The results of power densities showed that they were significantly below the recommended threshold values according to the guidelines of Telecommunication Regulatory Commission of Sri Lanka; such that the maximum and minimum were 0∙001% and 0∙0001% respectively. The measurements also revealed that distance from the tower is not the sole criteria to determine radiation hazards. In some regions the power density was independent from the distance from the tower because it was not proportional to the distance. In rural areas, the radiation power density emitted by the telecommunication towers is considerably low compared to that emitted by in-use mobile phones. Also, the radiation pattern is critically dependent on inclination and tilting direction of antennas. Thus, this study revealed that the effects of radiation emitted from telecommunication towers are negligible in the immediate neighbourhood.Item Remotely Controllable Regulator Connected in Series with Resistive and Inductive Loads(Institute of Physics, Sri Lanka, 2015) Perera, W.S.K.; Kalingamudali, S.R.D.This work presents a simple design and implementation of a series connected remotely controllable regulator which can be used for both resistive and inductive type loads driven by AC power. Commonly available remote controlled regulators require access to both live and neutral connections. The designed regulator enables the single line power controlling which offers a high level of convenience to the user. The power supplied to the load is controlled by a Triac, because it can control the current flow over both halves of an alternating cycle. The trigger on the gate terminal is set by a diac. The active components of the regulator are powered by a Switch Mode Power Supply (SMPS) using the voltage drop across the Triac. Radio Frequency (RF) remote control module controls the device and improved user satisfaction at a much better range. RF does not require the typical IR point-and-shoot action. The regulator includes a timer which enables the user to control both the level and the period of power. A seven segment display unit is included in the design to indicate the supplied power level and the timersetting. PICmicro® 16F873 microcontroller is used to drive the system and the timer. When compared with remote controlled regulators which require alternative additional electrical wiring system, the designed regulator is much more user friendly. It has many advantages such as low power consumption, small in size and low manufacturing cost and etc.Item Remotely Controllable Regulator for Line-Loads(Tech. Sess. Inst. Phys., Sri Lanka, 2014) Gunawardana, K.D.B.H.; Kalingamudali, S.R.D.