Modified Series-Parallel Photovoltaic Configuration to Enhance Efficiency under Partial Shading

Partial shading is a phenomenon where photovoltaics (PV) array experiences irregular level of irradiances. Such mismatch can cause a significant reduction in power yield. To mitigate the effect of partial shading, PV modules in an array are connected in various configurations namely Series-Parallel (SP), Total-Cross-Tied (TCT), Bridge-Linked (BL) and Honey-Comb (HC) etc. However, all these techniques introduce redundancy and complexity while improving the performance by very little. In this paper, a new PV configuration is proposed to solve the limitations of the existing PV configurations. The proposed configuration is a modified version of SP, hence referred as MSP configuration. To justify the performance of the proposed scheme, several experiments have been carried in MATLAB Simulink. Total 14 partial shading cases are simulated to compare the output performance between generic SP and proposed MSP configuration. The proposed MSP configuration is validated to be superior compared to normal SP configuration under majority of the cases. Depending on shading pattern, the efficiency of the PV array can be enhanced up to 37%, if MSP configuration is implemented

A review of available hybrid renewable energy systems in Malaysia

The utilization of conventional sources of energy releases harmful pollutants to the environment causing global warming and acid rain. For that reason, it becomes necessary to use a non-depletable, sustainable and eco-friendly renewable energy as a mean of producing electricity. Malaysia is tropical country rich in resources beneficial in electricity generation as it is in equatorial region therefore it has an abundance of solar irradiance of average annually. In addition, Malaysia’s demand in electricity is increasing to 124,677 GWh by 2020. Therefore, the electricity generation from renewable sources in Malaysia is anticipated to grow in the future alongside the government endorsement due to its clean, eco-friendly and free source of energy which can highly reduce the dependency on oil and gas that emits harmful pollutants to the environment. This paper gives a comprehensive review on the renewable projects and researches in Malaysia, challenges that affect popularity of renewable energy in Malaysia and available and successful renewable energy system in Malaysia

A comprehensive scientometric analysis on hybrid renewable energy systems in developing regions of the world

Energy crises, increasing electricity prices, and having no access to the grid electricity are the leading issues in developing countries of Asia, the Middle East, and Sub-Saharan Africa. Developing hybrid renewable energy systems in off-grid or grid-connected modes is the best way to overcome developing countries' economic and energy crises. However, the development of hybrid renewable energy systems faces severe technical and related economic challenges. This article provides an updated and comprehensive resource and economic overview of developed hybrid renewable energy systems in different locations in these aforementioned regions. The resource assessment shows that for economical hybrid energy system the average annual wind speed and average annual solar radiation should be 5 m/s and 5 KWh/m^2 respectively. This paper also provides a big picture of renewable energy impacts, challenges in the architecture of hybrid systems, and key organizations working in this domain in the developing regions. According to our review, hybrid optimization model for electric renewable, particle swarm optimization and genetic algorithm are frequently used tools for the optimization and sizing of hybrid energy systems. The map of hybrid renewable energy system research in developing regions is not available. Our study gives energy scenario and clear map of hybrid energy in developing regions of the world. The scientometric review of 2000 bibliographic data obtained from the Scopus database to perform co-author and co-occurrence analysis in this study. The data is used to trace the research pattern and thus to identify the most impactful authors, institutions, and countries in the hybrid renewable energy systems domain to obtain recommendations and make policies for the future uninterrupted and carbon dioxide emission free energy systems. The results of scientometric analysis shows that the Wang X. is the most prolific author, while India and Tanta University are the most productive country and institution in this domain. The scientometric analysis result will be beneficial in determining the future research directions in the hybrid renewable energy systems field

Sizing and economic analysis of stand-alone hybrid photovoltaic-wind system for rural electrification: A case study Lundu, Sarawak

Energy Consumption has been increasing at an alarming rate due to the growing energy need. More and more non-renewable sources are harvested to fulfill the energy demand resulting in and rising environmental health issues. However, harvesting Solar and Wind energy is considered as the best alternative in generating energy as these resources are renewable. Hybrid Renewable Energy System (HRES) has been grabbed the attention recently, as it involves with renewable, environmentally friendly sources to generate energy. The limitation of single Renewable Energy (RE) system is overcome by systems such as HRES. Even though it has been introduced different sizing and optimization techniques, due to the lack of system function, it had posed issues in calculating the optimized cost of a hybrid system considering the solar, wind resources and load demand as the optimization of the system cannot be predicted accurately. The aim of this research was to obtain optimization of a Hybrid PV-wind system in term of sizing and cost over the 20 years of the period of interest. The simulation of the PV-Wind Hybrid system using MATLAB for the verification purpose. This work includes detailed calculation using the Life Cycle Cost method for identifying all possible combinations. The combination of eleven Solar Panels, one Wind Turbine and nine Batteries was identified as the optimal Combination with LCC of RM 221,329.97 and has been verified using simulation results. Lastly, a sensitivity test was carried out using the exiting results of verified by the simulation to identify the most deterministic system in affecting LCC of the Hybrid system. Further, total Cost distribution for the Optimized hybrid PV-Wind system was conducted and identified that 50% of system cost was contributed by the Wind turbine. Determination of LCC, was done as a combination of Component and Operation costs. It was identified that Replacement cost contributed the highest while Wind turbine showed the highest Operation cost from the system cost. Thus, this work was included with the sensitivity test assuming 10% price increment for each component and it was concluded that price changes in Wind turbine results the greatest difference in LCC while further verified with the results of the simulation

Comprehensive review on the feasibility of developing wave energy as a renewable energy resource in Australia

The facts are that increasing energy demand, depletion of fossil fuel, and greenhouse gas emissions have increased the world's interest in renewable energy. Out of all RE options, Wave Energy (WE) is the least harnessed one despite the availability of WE Resource (WERs) in many countries and with the potential to cover a significant proportion of the world's energy needs. Australia, mainly in the southern part of the country, has plenty of this resource. Although recently, the Australian Government has started to focus on WERs as a Renewable Energy Source (RES) to cope with the energy crisis, research suggests that the country's progress in the WE generation to meet the energy demand is well below the potential generation capacity. However, insufficient research and studies address the issues and technologies in detail. This study examines the viability of further developing WE as a renewable energy source in Australia by evaluating the current constraints and challenges to achieving a satisfactory level of WE generation in the country. As a result, this study emphasizes the trustworthiness of WE in terms of several criteria. The availability of WERs within Australia and the status of producing WE are reviewed in this study. It also highlighted certain Australian technologies and devices that are now being tested or deployed in real-time. Moreover, this review is expanded by comparing the key developers in the WE sector to Australia to uncover some of the contributing elements in other countries that may have contributed to the growth of the WE generation in other nations. Finally, some of the barriers identified are lack of high-resolution data and social & environmental challenges. Some recommendations are given in the latter part of the review to accelerate WE production in Australia

Techno‐economic analysis of direct combustion and gasification systems for off‐grid energy supply: A case for organic rankine cycle and dual fluidized‐bed

Biomass is one of the most versatile sustainable energy sources. This versatility allows utilization of different biomass feedstock using a verity of conversion techniques. Often, a biomass-to-bioenergy conversion method is selected depending on the application, end-use product, and the type of feedstock. In many applications such as residential energy supply, it is possible to select amongst various technologies. Although, there exist several challenges such as cost-effectiveness and sustainability that constrains bioenergy development. To this end, this research elaborates on the impacts of different conversion methods on techno-economic performance of bioenergy systems for residential energy supply. In this context, Organic Rankine Cycle based on direct combustion, and Dual Fluidized-Bed technology based on gasification were selected for that purpose. A techno-economic comparative analysis illustrates that the primary product of the system and fuel cost are the two most important factors in feasibility assessment. The negative impact of feedstock price was more severe on the Organic Rankine Cycle. For wood chips prices below 55$/t, Organic Rankine Cycle could be the better option due to lower capital and maintenance costs. In contrast, Dual Fluidized-Bed could better tolerate the variation of feedstock price; offering 8$/t wood chips

Simulation of lightning flash and detection using time of arrival method based on four broadband antennas

Various methods are used to locate cloud-toground lightning flash. The accuracy of the methods depends on the number of sensor stations, station topology, mathematical model adopted for the analyses, and the type of measuring equipment. For a single station with the configuration of short baseline in a measuring system, the accuracy of analysis is mostly based on the chosen mathematical equations (and assumptions) which can be solved in either linear or nonlinear mode. This paper concentrates on the simulation of a lightning flash and its detection based on the Time of Arrival (TOA) method by utilizing four broadband antennas. The accuracy of the TOA method is also evaluated in this work. A Matlab based simulation of the measuring system is implemented to construct a randomly located lightning flash with its corresponding electromagnetic radiation. Then, suitable mathematical models used as measurement systems based on the 3-antenna TOA method to determine the azimuth and elevation angles, which in turn can be used for the calculation of flash coordinates in term of (X,Y,Z) with the help of the fourth antenna. © 2011 IEEE

Discriminating cloud to ground lightning flashes based on wavelet analysis of electric field signals

Lightning discharges produce electromagnetic radiation in a wide frequency range, but its propagation in a certain frequency range are usually used by lightning detection networks. Investigation of lightning activities in time-frequency domain can be obtained by using the wavelet transform. This study proposes a new approach using the discrete wavelet transform (DWT) algorithm to classify the detected lightning strikes. The measuring station would capture lightning electric field in 500 ms time scale and then utilizes a wavelet based recognizer algorithm to duly differentiate the cloud to ground flash from other cloud activities. Wavelet transform allows the expansion of transient events into a small number of coefficients. A total of 200 lightning flashes were randomly selected among the captured lightning discharges in South of Malaysia in one year. Initially, the cloud to ground and other cloud activities were manually analysed and discriminated. Then, these lightning flashes were analysed using different mother wavelets such as Haar, symmlet, Coiflet, and Daubechies by means of MATLAB program. Haar mother wavelet gives the best result for CG decomposition analysis. A total of 24 decomposition layers were chosen and the energy level of each layer was calculated to obtain the correlation between energy fluctuation and type of signal. The investigations reveal that the CG discharges have higher energy in 17th to 20th layers compared to the rest. However, the opposite results were obtained for the case of other cloud activities. To increase the accuracy of the wavelet transform approach algorithm, another filter was added to the algorithm flowchart. The proposed CG discrimination algorithm successfully classified 92% of the randomly selected flashes

Three-dimensional potential and electric field distributions in HV cable insulation containing multiple cavities

Cross-linked polyethylene is widely used as electrical insulation because of its excellent electrical properties such as low dielectric constant, low dielectric loss and also due to its excellent chemical resistance and mechanical flexibility. Nevertheless, the most important reason for failure of high voltage equipment is due to its insulation failure. The electrical properties of an insulator are affected by the presence of cavities within the insulating material, in particular with regard to the electric field and potential distributions. In this paper, the electric field and potential distributions in high voltage cables containing single and multiple cavities are studied. Three different insulating media, namely PE, XLPE, and PVC was modeled. COMSOL software which utilises the finite element method (FEM) was used to carry out the simulation. An 11kV underground cable was modeled in3D for better observation and analyses of the generated voltage and field distributions. The results show that the electric field is affected by the presence of cavities in the insulation. Furthermore, the field strength and uniformity are also affected by whether cavities are radially or axially aligned, as well as the type of the insulating solid. The effect of insulator type due the presence of cavities was seen most prevalent in PVC followed by PE and then XLPE