Huan Ma¹, Linlin Ma², Zengwei Wang^3,*, Zhendong Li³, Yuanzhen Zhu¹, Yutian Liu³

Energy Engineering, Vol.121, No.11, pp. 3133-3160, 2024, DOI:10.32604/ee.2024.055051 - 21 October 2024

Abstract With the increasing penetration of renewable energy in power system, renewable energy power ramp events (REPREs), dominated by wind power and photovoltaic power, pose significant threats to the secure and stable operation of power systems. This paper presents an early warning method for REPREs based on long short-term memory (LSTM) network and fuzzy logic. First, the warning levels of REPREs are defined by assessing the control costs of various power control measures. Then, the next 4-h power support capability of external grid is estimated by a tie line power prediction model, which is constructed based More > Graphic Abstract

Weigang Jin¹, Lei Chen^2,*, Shencong Zheng², Yuqi Jiang², Yifei Li², Hongkun Chen²

Energy Engineering, Vol.121, No.11, pp. 3161-3179, 2024, DOI:10.32604/ee.2024.054068 - 21 October 2024

Abstract Investigating flexibility and stability boosting transmission expansion planning (TEP) methods can increase the renewable energy (RE) consumption of the power systems. In this study, we propose a bi-level TEP method for voltage-source-converter-based direct current (VSC-DC), focusing on flexibility and stability enhancement. First, we established the TEP framework of VSC-DC, by introducing the evaluation indices to quantify the power system flexibility and stability. Subsequently, we propose a bi-level VSC-DC TEP model: the upper-level model acquires the optimal VSC-DC planning scheme by using the improved moth flame optimization (IMFO) algorithm, and the lower-level model evaluates the flexibility More >

Chunxue Wen, Yaoquan Wei^*, Peng Wang, Jianlin Li, Jinghua Zhou, Qingyun Li

Energy Engineering, Vol.121, No.11, pp. 3241-3261, 2024, DOI:10.32604/ee.2024.051810 - 21 October 2024

Abstract A modular system of cascaded converters based on model predictive control (MPC) is proposed to meet the application requirements of multiple voltage levels and electrical isolation in renewable energy generation systems. The system consists of a Buck/Boost + CLLLC cascaded converter as a submodule, which is combined in series and parallel on the input and output sides to achieve direct-current (DC) voltage transformation, bidirectional energy flow, and electrical isolation. The CLLLC converter operates in DC transformer mode in the submodule, while the Buck/Boost converter participates in voltage regulation. This article establishes a suitable mathematical model More >

Saif Serag^1,*, Adil Echchelh², Biagio Morrone¹

Energy Engineering, Vol.121, No.10, pp. 2719-2741, 2024, DOI:10.32604/ee.2024.054424 - 11 September 2024

Abstract Renewable energy sources are essential for mitigating the greenhouse effect and supplying energy to resource-scarce regions. However, their intermittent nature necessitates efficient storage solutions to enhance system efficiency and manage energy costs. This paper investigates renewable and clean storage systems, specifically examining the storage of electricity generated from renewable sources using hydropower plants and hydrogen, both of which are highly efficient and promising for future energy production and storage. The study utilizes extensive literature data to analyze the impact of various parameters on the cost per kWh of electricity production in hybrid renewable systems incorporating… More > Graphic Abstract

Ganesh There^*, Rohit Sharma^*

Energy Engineering, Vol.121, No.10, pp. 2851-2892, 2024, DOI:10.32604/ee.2024.049506 - 11 September 2024

Abstract This analysis investigates the widespread use of solar drying methods and designs in developing countries, particularly for agricultural products like fruits, vegetables, and bee pollen. Traditional techniques like hot air oven drying and open sun drying have drawbacks, including nutrient loss and exposure to harmful particles. Solar and thermal drying are viewed as sustainable solutions because they rely on renewable resources. The article highlights the advantages of solar drying, including waste reduction, increased productivity, and improved pricing. It is also cost-effective and energy-efficient. The review study provides an overview of different solar drying systems and… More > Graphic Abstract

Wentao Li¹, Jiantao Liu², Yudun Li³, Guoxin Ming¹, Kaifeng Zhang¹, Kun Yuan^1,*

Energy Engineering, Vol.121, No.9, pp. 2479-2503, 2024, DOI:10.32604/ee.2024.050852 - 19 August 2024

Abstract With the large-scale development and utilization of renewable energy, industrial flexible loads, as a kind of load-side resource with strong regulation ability, provide new opportunities for the research on renewable energy consumption problem in power systems. This paper proposes a two-layer active power optimization model based on industrial flexible loads for power grid partitioning, aiming at improving the line over-limit problem caused by renewable energy consumption in power grids with high proportion of renewable energy, and achieving the safe, stable and economical operation of power grids. Firstly, according to the evaluation index of renewable energy… More >

Kaicheng Liu^1,3, Chen Liang², Naiyue Wu^1,3, Xiaoyang Dong², Hui Yu^1,*

Energy Engineering, Vol.121, No.9, pp. 2621-2637, 2024, DOI:10.32604/ee.2024.050001 - 19 August 2024

Abstract This paper presents a novel approach to economic dispatch in smart grids equipped with diverse energy devices. This method integrates features including photovoltaic (PV) systems, energy storage coupling, varied energy roles, and energy supply and demand dynamics. The system model is developed by considering energy devices as versatile units capable of fulfilling various functionalities and playing multiple roles simultaneously. To strike a balance between optimality and feasibility, renewable energy resources are modeled with considerations for forecasting errors, Gaussian distribution, and penalty factors. Furthermore, this study introduces a distributed event-triggered surplus algorithm designed to address the More >

Anggara Ridho Putra¹, Apri Heri Iswanto^1,*, Arif Nuryawan¹, Saptadi Darmawan², Elvara Windra Madyaratri², Widya Fatriasari², Lee Seng Hua³, Petar Antov^4,*, Harisyah Manurung¹, Ade Pera Amydha Sudrajat Herawati Pendi²

Journal of Renewable Materials, Vol.12, No.6, pp. 1103-1123, 2024, DOI:10.32604/jrm.2024.051077 - 02 August 2024

Abstract The increased valorization of renewable and cost-effective lignocellulosic feedstocks represents a viable, sustainable, and eco-friendly approach toward the production of biopellets as alternative energy sources. The aim of this research work was to investigate and evaluate the feasibility of using various lignocellulosic raw materials, i.e., raru (Cotylelobium melanoxylon), mangrove (Rhizophora spp.), sengon (Paraserianthes falcataria), kemenyan toba (Styrax sumatrana), oil palm (Elaeis guineensis), manau rattan (Calamus manan), and belangke bamboo (Gigantochloa pruriens) for manufacturing biopellets with different particle sizes. The raw materials used were tested for their moisture content, specific gravity, ash, cellulose, and lignin content. In addition, thermal analyses, i.e., calorific values,… More >

Chia-Nan Wang, Thuy-Duong Thi Pham^*, Nhat-Luong Nhieu

Energy Engineering, Vol.121, No.8, pp. 2039-2064, 2024, DOI:10.32604/ee.2024.050224 - 19 July 2024

Abstract Geothermal energy is considered a renewable, environmentally friendly, especially carbon-free, sustainable energy source that can solve the problem of climate change. In general, countries with geothermal energy resources are the ones going through the ring of fire. Therefore, not every country is lucky enough to own this resource. As a country with 117 active volcanoes and within the world’s ring of fire, it is a country whose geothermal resources are estimated to be about 40% of the world’s geothermal energy potential. However, the percentage used compared to the geothermal potential is too small. Therefore, this… More >

Yirui Li¹, Dongliang Xiao^1,3,*, Haoyong Chen¹, Weijun Cai¹, Josue Campos do Prado²

Energy Engineering, Vol.121, No.8, pp. 2093-2127, 2024, DOI:10.32604/ee.2024.049232 - 19 July 2024

Abstract Currently, both regulated and deregulated power trading exist in China’s power system, which has caused imbalanced funds in the electricity market. In this paper, a simulation analysis of the electricity market with wind energy resources is conducted, and the calculation methods of unbalanced funds are investigated systematically. In detail, the calculation formulas of unbalanced funds are illustrated based on their definition, and a two-track electricity market clearing model is established. Firstly, the concept of the dual-track system is explained, and the specific calculation formulas of various types of unbalanced funds are provided. Next, considering the More >