Hybrid bypass technique to mitigate leakage current in the grid-tied inverter

The extensive use of fossil fuel is destroying the balance of nature that could lead to many problems in the forthcoming era. Renewable energy resources are a ray of hope to avoid possible destruction. Smart grid and distributed power generation systems are now mainly built with the help of renewable energy resources. The integration of renewable energy production system with the smart grid and distributed power generation is facing many challenges that include addressing the issue of isolation and power quality. This paper presents a new approach to address the aforementioned issues by proposing a hybrid bypass technique concept to improve the overall performance of the grid-tied inverter in solar power generation. The topology with the proposed technique is presented using traditional H5, oH5 and H6 inverter. Comparison of topologies with literature is carried out to check the feasibility of the method proposed. It is found that the leakage current of all the proposed inverters is 9 mA and total harmonic distortion is almost about 2%. The proposed topology has good efficiency, common mode and differential mode characteristics.

Validation of photovoltaics powered UPQC using ANFIS controller in a standard microgrid test environment

The power quality improvement becomes one of the important tasks while using microgrid as main power supply. Because the microgrid is combination of renewable energy resources. The renewable energy resources are intermittent in power supply and at the peak loading condition it has to supply the required power. So, the power quality problems may increase in that time. Out of all power quality issues the voltage drop and harmonic distortion is considered as the most serious one. In recent years unified power quality conditioner (UPQC) is emerged as most promising device which compensates both utility as well as customer side power quality disturbances in effective way. The compensating potentiality used in the UPQC is limited by the use of DC link voltage regulation and the conventional proportional integral (PI) controller. In this paper the compensating potentiality of the UPQC device is controlled by an adaptive neuro fuzzy inference system (ANFIS) control and it is powered from the available photovoltaics (PV) power generation. The effect of adding an intelligent UPQC is tested in the standard IEEE-14bus environment. MATLAB 2017b is used here for testing and plotting the simulation results.

THE EFFECT OF FLY ASH UTILIZATION IN REINFORCEMENT CONCRETE: A REVIEW

Indonesia signed the Paris Agreement on facing climate change. Carbon dioxide is the main issue contributing to the greenhouse effect. Most power plant in Indonesia uses non-renewable energy to generate electricity. Increasing demand for electricity makes increasing coal consumption for steam power plants and directly contributes to greenhouse gasses from coal combustion and produces fly ash as a waste product. Otherwise, fly ash from Steam Power Plant is classified as pozzolanic materials being a part of substitution ordinary portland cement (OPC) on making reinforcement concrete. Many Researchers studied reinforcement concrete from fly ash composition and others development using renewable energy resources such as biomass. This paper presents a literature review on focus studying the properties of various types of fly ash and their effect on the performance of concrete, including corrosion resistance.

Challenges, Trends and Solutions for Communication Networks and Cyber-Security in Smart Grid.

Power grid is one of the most important manifestations of the modern civilization and the engine of it where it is described as a digestive system of the civil life. It is a structure has three main functions: generation, transmission lines, distribution. This concept was appropriate for a century. However, the beginning of the twenty-first century brought dramatic changes on different domains: media, human growth, economic, environmental, political, and technical etc. Smart grid is a sophisticated structure including cyber and physical bodies hence it reinforces the sustainability, the energy management, the capability of integration with microgrids, and exploiting the renewable energy resources. The quantum leap of smart grid is related to the advanced communication networks that deal with the cyber part. Moreover, the communication networks of smart grid offer attractive capabilities such as monitoring, control, and protection at the level of real time. The wireless communication techniques in integration frame are promised solution to compensate the requirements of smart grid designing such as wireless local area networks, worldwide interoperability for microwave access, long term evolution, and narrowband- internet of things. These technologies could provide high capacity, flexibility, low-cost maintenance for smart grid. However, the multi-interfaces in smart grid may exploit by persons or agencies to implement different types of cyber-attacks may lead to dangerous damage. This research paper reviews the up-to-date researches in the field of smart grid to handle the new trends and topics in one frame in order to offer integration vision in this vital section. It concentrates on the section of communication networks the mainstay of smart grid. This paper discusses the challenging and requirements of adopting the wireless communication technologies and delves deeply into literature review to devise and suggest solutions to compensate the impairments efficiently. Moreover, it explores the cyber security that representing the real defiant to implement the concept of smart grid safely.

SSNN-Based Energy Management Strategy in Grid Connected System for Load Scheduling and Load Sharing

The proposed research work focused on energy management strategy (EMS) in a grid connected system working in islanding mode with the connected renewable energy resources and battery storage system. The energy management strategy developed provides a balancing operation at its output by utilizing perfect load sharing strategy. The EMS technique using smart superficial neural network (SSNN) is simulated, and numerical analyses are presented to validate the effectiveness of the centralized energy management strategy in a grid connected islanded system. A SSNN prediction model is unified to forecast the associated household load demand, PV generation system under various time horizons (including the disaster condition), EV availability, and status on EV section and distance. SSNN is one the most reliable forecasting methods in many of the applications. The developed system is also accounted for degradation battery model and its associated cost. The incorporation of energy management strategy (EMS) reduces the amount of energy drawn from the grid connected system when compared with the other optimized systems.

Prediction and Optimization of the Cost of Energy Resources in Greek Public Hospitals

The continuous operation and the specialized conditions needed for safely delivering healthcare services make hospitals among the most expensive buildings. Several studies in different countries have investigated the potential role and contribution of macroscopic indices of hospitals in total energy requirements. In this work, we tried to investigate the energy requirements of Greek hospitals in terms of cost. We collected data from all public hospitals in Greece over a 2 year period (2018–2019) and evaluated the contribution of various factors in the total energy cost. The data revealed large variability by region and by hospital, even regarding structures of the same category and size. The analysis also showed that structural and operational data of each hospital differently influence the hospitals’ energy requirements. Using regression methods, we developed two models for calculating annual energy costs. One only contains hospital structural data (number of beds, type of hospital, number of employees, and the non/use of alternative energy sources such as natural gas), and it reached an R² of 0.84. The second model contains not only structural but also operational data from each hospital (number of the internal patients, number of surgeries and number of medical imaging tests), and it reached an R² of 0.87. The former model is easier to compute since it only relies on data that can be easily gathered, but the latter has slightly better performance. These tools can help the Ministry of Health and hospitals’ management to identify the factors that contribute to the energy cost in order to plan targeted interventions, be well-prepared regarding budgeting, and be able to progressively measure, monitor, and improve the environmental footprint of hospitals by investing in renewable energy resources.

Renewables will be slow to take off in Algeria

Significance The country has abundant renewable energy resources and substantial potential for green energy exports, but development to date has been minimal. Domestic firms are focused on the gas sector and foreign investors have been deterred by a hostile business environment. However, Algiers has taken steps recently to incentivise investment. Impacts The lack of development to date means the country’s emissions reduction targets are at risk of being missed. The December tender is likely to attract more interest than previous efforts because of changes to foreign investment conditions. Competition from new developers may prompt greater interest from Algeria’s state energy companies, in part to ward off challenges.

Modelling of Liquid-Liquid Equilibria Using NRTL and UNIFAC Equations in the Extraction of Bio-Oil-Based Phenolics Produced from the Pyrolysis of Sugarcane Bagasse

An exploration on renewable energy resources has been paid more attention due to the depletion of the fossil-based energy resource. In addition, their safe and environmentally friendly properties have attracted experts’ interest. One of the renewable energy resources is the bio-oil produced from sugarcane bagasse. The bio-oil was produced through a pyrolysis at 500°C. However, the produced bio-oil showed a high content of phenolics, c.a. 40-60%. A liquid-liquid extraction to remove the phenolics using methanol-chloroform solvents would be beneficial to improve the stability of the bio-oil as well as to obtain high purity phenolics. Modelling of the liquid-liquid equilibria in the extraction was then developed using NRTL and UNIFAC equations. The empirical quantitative data of phase equilibrium system were calculated on both the extract and raffinate phases. The lowest RMSD value of 0.043160 was obtained from the calculations using NRTL equation at an extraction temperature of 50°C. Thus, the most suitable model was achieved using NRTL equation.

Exchange Rate Dynamics, Energy Consumption, and Sustainable Environment in Pakistan: New Evidence From Nonlinear ARDL Cointegration

Pakistan's local currency has been devalued during different exchange regimes, which may substantially affect energy consumption and CO2 emissions. Therefore, this study investigates the effects of exchange rate depreciation on Pakistan's CO2 emissions and energy consumption from 1990–2018. We apply the nonlinear autoregressive distributed lag (ARDL) cointegration approach for the empirical analysis and found that exchange rate depreciation increases CO2 emissions and energy consumption in both the short and long runs. These results suggest that currency devaluation has an expansionary effect which enhances economic growth at the cost of high energy consumption and CO2 emissions. Therefore, the government needs regulations along with an exchange rate policy to control CO2 emissions. Moreover, the government should search for alternate energy resources such as renewable energy resources that meet the country's energy needs and mitigate CO2 emissions.