ICAPS 2023
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/26832
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Item Comparison of different methods for generating SPWM signal for the development of a pure Sine wave inverter(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Hemal, S. B. N. H.; Dilshan, G. K. D.; Karunarathna, M. A. D. D. S.; Morawakaarachchi, K. N.; Senanayake, S. V.; Premasiri, R. H. M. D.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.An inverter is an electronic device which is used for converting Direct Current (DC) to Alternating Current (AC) because AC is the predominant form of electrical power used in homes, businesses, and most electrical appliances. Inverters can be categorized based on the type of waveform that they produce, such as Pure Sine Wave Inverters, Modified Square Wave Inverters and Square Wave Inverters. This paper discusses the development of a Pure Sine Wave Inverter with an output voltage of 230 VRMS and a frequency of 50 Hz using the Sinusoidal Pulse Width Modulation (SPWM) technique. Three SPWM signal generation methods, including analogue comparator, microcontroller, and SPWM driver module methods, were tested. This study presents a method to obtain a 230 VRMS, 50 Hz output sine wave in three steps. The first step involves the generation of an SPWM signal with frequency control, utilizing the DC source supply. The analogue comparator method uses op-amps as the analogue comparator. Then, it compares a reference sinusoidal wave with a high-frequency (in kHz range) carrier triangular wave. The output of the op-amp comparator is SPWM. The frequency of this reference sinusoidal wave is chosen based on the required inverter output frequency (50 Hz). In that process, the comparator gives out a pulse when the voltage of the sine waveform is greater than the triangular voltage, and this pulse is used to trigger the respective inverter switches. When designing a circuit that involves op-amps, the slew rate of the op-amp is a critical consideration. To generate an SPWM signal using an ATmega328p microcontroller, the microcontroller was used to generate a series of PWM signals by digital high and digital low. The corresponding time of each pulse's delay is added using the microsecond function. Increasing and decreasing duty cycle, and then a series of PWM signals. As the pure sine wave inverter SPWM driver module EGS002 was used and, that method was the more accurate method, and a clean SPWM signal was generated with less harmonics. Although this type of inverter board has more features, the circuitry was not complex because of the module. Secondly, we employ the MOSFET H-bridge stage to obtain the desired sine wave output. Finally, the third step focuses on supplying a high DC voltage to the H-bridge circuit, which the DC-DC PWM boost converter generates. Several circuit protections were included to ensure the device's safety and reliability. In the process of SPWM generation, although in the analogue comparator method, op-amps offer a low-cost option, a microcontroller is favoured for its superior precision and ability to handle high-power applications effectively. However, the EGS002 module stands out as the preferred method due to its user-friendly nature, comprehensive protection features, and ability to provide valuable feedback, making it a more economically efficient choice in the overall design.Item Development of an off-grid solar PV system with battery-supercapacitor hybrid energy storage(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Pitigala, P. A. S. P.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.In off-grid photovoltaic (PV) systems, the charge controller is a significant device since the system's end-to-end efficiency depends on its efficiency. Currently, the commercially available MPPT charge controllers have an average efficiency of 90%. Supercapacitors' (SCs’) high energy density compared to traditional capacitors makes them used as energy storage devices. But theoretically, 50% of energy loss will occur in the capacitor charging loop if we charge it directly connecting to a power supply. According to the supercapacitor-assisted loss management (SCALoM) theory, inserting a useful resistive load into the capacitor charging loop, a portion of the above wasted 50% of energy can be utilised for beneficial work. This paper proposes a novel off-grid PV system with a battery-SC hybrid energy storage. This system utilises the SCALoM theory using the combination of a charge controller and battery as the useful load in the capacitor charging loop, while PV panels are used as the external power source. To achieve maximum use of the SCALoM theory, the SC must be kept under partially charged condition. An electronic switching network consisting of nine electronic switches was designed to realise this. Two SC banks, SC-1 and SC-2 were embedded in the prototype system. The proposed system operates in four different modes: SC-1 charging mode, SC-2 charging mode, SC bypass mode, and night mode. These modes are defined by the state of each switch in the switching network and the voltage of both SC banks. In SC-1 and SC-2 charging modes, the relevant SC bank is connected in series with the PV panels and charge controller while a DC load is connected in parallel to the SC bank. In this mode, the remaining SC bank is discharged through another DC load. In SC bypass mode, the operation of the system is the same as the typical off-grid PV system because both SC-1 and SC-2 are disconnected from the system so that the PV panels are connected in parallel with the charge controller. In this mode, DC loads are connected to the battery. In night mode, an SC bank is connected in series to the PV array and the charge controller and DC loads are connected to the battery again. For maximum utilisation, this system must be operated in SC- 1 and SC-2 charging modes as much as possible throughout the day. The overall operation of the system is controlled by microcontroller-based control circuitry. This system achieved end-to-end efficiencies of 87.36%, 87.50%, 75.68%, and 93.28%, respectively, for SC-1 charging, SC-2 charging, SC bypass, and night modes, respectively. Therefore, it can be concluded that the endto- end efficiency of an off-grid PV system can be increased by implementing a supercapacitor in a series configuration to the solar panel and to the charge controller.Item Optimising energy efficiency in a PV-enabled base transceiver station(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayasooriya, J. A. T. D.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.The need for green energy sources has become paramount in the modern world due to the environmental hazards of non-green alternatives. Essential services, including the telecommunication industry, must also align with this goal. As foundational elements of the telecommunications network, base transceiver stations offer a ripe opportunity to integrate green energy solutions. However, the prevalent scenario reveals that many of these stations continue to rely on conventional grid-based power sources, with only a limited fraction equipped with standalone photovoltaic (PV) systems. This study addresses a pressing challenge in integrating standalone PV systems with base transceiver stations. Central to this challenge is the conundrum of power generation backups, specifically during the morning hours, when the battery reserves charged by the PV systems are frequently depleted. This operational gap necessitates the deployment of supplementary power generators, imposing substantial operational costs that diminish the cost-efficiency advantages anticipated with the introduction of PV systems. The methodology involved a detailed analysis of the selected base transceiver station's total DC power consumption patterns from 15th May 2023 to 21st May 2023. These insights guided the design of an efficient energy harvesting system enriched with a supercapacitor-battery hybrid energy storage arrangement. A Maximum Power Point Tracking (MPPT) controller was acquired to optimise system performance; its effectiveness was verified through efficiency calculations and PV array emulator Irradiance Profiles, and its efficiency exceeded 90%. An intelligent power management strategy was implemented, automatically switching to consume supercapacitor (SC) energy when the voltage level exceeds a threshold, conserving battery bank energy, ensuring uninterrupted operation, and extending battery lifespan. The prototype's operational modes, including neutral, SC charge recovery, and SC bypass, have been successfully demonstrated. Results indicate that the suggested photovoltaic system prototype effectively tracks the PV array's maximum power point (MPP), comparable to standard systems using traditional MPPT algorithms. This novel system promises to not only obviate the need for extensive generator backups but also potentially reduce their capacity compared to conventional configurations. Realising a green energy-powered telecom network is a vast and complex process, demanding guaranteed performance and cost-effectiveness for a period of at least about 15 years. This research marks a significant milestone in advancing green energy solutions and highlights the crucial role of base transceiver stations in establishing a sustainable telecommunication infrastructure. Embracing eco-friendly technologies is essential in safeguarding our planet and ensuring a brighter future for generations to come.