Non-intrusive load monitoring is a vital part of an overall load management scheme. One major disadvantage of existing non-intrusive load monitoring methods is the difficulty to accurately identify loads with similar electrical characteristics. To overcome the various switching probability of loads with similar characteristics in a specific time period, a new non-intrusive load monitoring method is proposed in this paper which will modify monitoring results based on load switching probability distribution curve. Firstly, according to the addition theorem of load working currents, the complex current is decomposed into the independently working current of each load. Secondly, based on the load working current, the initial identification of load is achieved with current frequency domain components, and then the load switching times in each hour is counted due to the initial identified results. Thirdly, a back propagation (BP) neural network is trained by the counted results, the switchin... [more]

Hybrid Renewable Energy Systems (HRESs) have been touted as an appropriate way for supplying electricity to remote and off-grid areas in developing countries, especially in sub-Saharan Africa (SSA), where rural electrification challenges are the most pronounced. This study proposes a two-step methodology for optimizing and analyzing a stand-alone photovoltaic/wind/battery/diesel hybrid system to meet the electricity needs of Fanisua, an off-grid and remote village of northern Nigeria. In the first step, the MATLAB environment was used to run simulations and optimize the system via the genetic algorithm. Then, techno-economic and emissions analysis was carried out in the second step to compare the proposed system to the existing traditional modes of rural electrification in sub-Saharan Africa, namely, the grid-extension and diesel generator. The break-even distance parameter was adopted in the comparison with grid-extension. Besides, the hypothetical project of replacing the diesel gene... [more]

One of the most important problems of operating solar heating systems involves variable efficiency depending on operating conditions. This problem is more pronounced in hybrid energy systems, where a solar installation cooperates with other segments based on conventional carriers of energy or renewable sources of energy. The operating cost of each segment of a hybrid system depends mainly on the resulting efficiency of solar installation. For over 40 years, the procedures of testing solar collectors have been undergoing development, testing, comparison and verification in order to create a procedure that would allow determining the thermal behavior of a solar collector without performing expensive and complicated experimental tests, usually based on the steady state condition. The proper determination of the static and dynamic properties of a solar collector is of key significance, as they constitute a basis for the design of a solar heating installation, as well as a control system. I... [more]

A solar tracker can be defined as an electromechanical system capable of following the apparent path of the Sun, in order to orient an array of solar panels and/or collectors directly to the solar rays, maximizing the collected energy. Accordingly, the present work describes the process of building and automating a micro-controlled solar tracker. Two mobile structures were built, one equipped with high-precision step motors and four luminosity sensors separated in quadrants by a cross structure, and the other equipped with DC motors and the 275 Wp solar panel, allowing the design and evaluation of the behavior of each structure separately. The control and automation system is centralized in an Arduino MEGA2560 microcontroller, which runs the tracking and positioning algorithms. The built prototype allows us to carry out studies of solar tracking strategies based on sensor and control systems applied to DC motors.

In a moderate, transitory climate, to prevent freezing of outdoor pipes and collectors in solar thermal systems, anti-freezing fluids are commonly used. There is little experience of using water without any additives as a solar thermal fluid in such a climate. Based on these findings, to fill the knowledge gap this article presents the long-term results of thermal performance and anti-freeze protection of a solar heating system with heat pipe evacuated tube collectors with water as a solar thermal fluid. The operation of this system under real conditions was analysed for five years in southern Poland. The annual value of solar insolation ranged from 839 to almost 1000 kWh/m2. The monthly efficiency of the solar collectors from March to October was usually higher than 25%, and the lowest was between November and January. The anti-freeze protection system consumed annually from 7 to 13% of the heat generated by the collectors in the installation. Supporting the operation of the central h... [more]

The accuracy and reliability of solar tracking greatly impacts the performance of concentrator photovoltaic modules (CPV). Thus, it is of utmost significance to know how deviations in tracking influence CPV module power. In this work, the positioning characteristics of CPV modules compared to the focus points were investigated. The performance of CPV modules mounted on a dual-axis tracking system was analysed as a function of their orientation and inclination. The actual experiment was carried out with CPV cells of 3 mm in diameter. By using a dual tracking system under real weather conditions, the module’s position was gradually modified until the inclination differed by 5° relative to the optimal position of the focus point of the CPV module. The difference in inclination was established by the perfect perpendicularity to the Sun’s rays. The results obtained specifically for CPV technology help determine the level of accuracy that solar tracking photovoltaic systems are required to h... [more]

The environmental impact of the road transport sector, together with urban freight transport growth, has a notable repercussions in global warming, health and economy. The need to reduce emissions caused by fossil fuel dependence and to foster the use of renewable energy sources has driven the development of zero-emissions powertrains. These clean transportation technologies are not only necessary to move people but to transport the increasing demand for goods and services that is currently taking place in the larger cities. Full electric battery-powered vans seem to be the best-placed solution to the problem. However, despite the progress in driving range and recharge options, those and other market barriers remain unsolved and the current market share of battery electric vehicles (BEVs) is not significant. Based on the development of hydrogen fuel cell stacks, this work explains an emerging powertrain architecture concept for N1 class type vans, that combines a battery-electric confi... [more]

To improve the sustainable development ability of logistics parks, this study constructs a sustainability evaluation method of logistics parks based on emergy; analyzes the input (energy, land, investment, equipment, information technology, and human resources) and output (income and waste) of logistics parks from the perspective of emergy; studies the characteristics of the emergy flow of logistics parks; and constructs the function, structure, ecological efficiency, and sustainable development indexes of logistics parks. The basic situation, resource efficiency, and environmental friendliness of the logistics parks are comprehensively evaluated from the emergy point of view. On this basis, targeted decision suggestions are provided for the sustainable development of logistics parks. Finally, the feasibility and effectiveness of the method are verified by an example. This study reveals the internal relationship among economic, environmental, and social benefits of logistics parks thro... [more]

The photovoltaic (PV) industry is an important part of the renewable energy industry. With the growing use of PV systems, interest in their operation and maintenance (O&M) is increasing. In this regard, analyses of power generation efficiency and inverter efficiency are very important. The first step in efficiency analysis is solar power estimation based on environment sensor data. In this study, solar power was estimated using a univariate linear regression model. The estimated solar power data were cross-validated with the actual solar power data obtained from the inverter. The results provide information on the power generation efficiency of the inverter. The linear estimation model developed in this study was validated using a single PV system. It is possible to apply the coefficients presented in this study to other PV systems, even though the nature and error rates of the collected data may vary depending on the inverter manufacturer. To apply the proposed model to PV systems wit... [more]

Active seismic faults in the Pacific Northwest area have encouraged electric utilities in the region to deeply contemplate and proactively intervene to support grid resilience. To further this effort this research introduces Monte Carlo (MC)-based power system modeling as a means to inform the Performance Based Earthquake Engineering method and simulates 100,000 sample earthquakes of a 6.8 magnitude (M6.8) Portland Hills Fault (PHF) scenario in the Portland General Electric (PGE) service territory as a proof of concept. This paper also proposes the resilience metric Seismic Load Recovery Factor (SLRF) to quantify the recovery of a downed power system and thus can be used to quantify earthquake economic risk. Using MC results, the SLRF was evaluated to be 19.7 h and the expected economic consequence cost of a M6.8 PHF event was found to be $180 million with an annualized risk of $90,000 given the event’s 1 in 2000 year probability of occurrence. The MC results also identified the eight... [more]

This study’s primary goal is to evaluate the performance of a large thermal energy storage tank installed in a Gas District Cooling (GDC) plant. The performance parameters considered in this study include thermocline thickness (WTc), Cumulated Charge (Qcum), and Half Figure of Merit (½ FOM). The operation sensor data of a large Thermal Energy Storage (TES) tank was acquired for this analysis. The recorded temperature sensor from the 1st to 7th January and from 12th to 17th October 2019 was considered in this research. GraphPad prism computer software was deployed for analyses, and the temperature distribution data were analyzed to determine the four temperature parameters (hot water temperature (Th), cool water temperature (Tc), cool water depth (C), and slope gradient (S)) using a non-linear regression curve fitting technique and sigmoid Dose Responses function as integrated with the software. At the end of this research, the relationship between the growth of the determined performan... [more]

A common denominator in the vast majority of processes in the food industry is refrigeration. Such systems guarantee the quality and the requisites of the final product at the expense of high amounts of energy. In this regard, the new Industry 4.0 framework provides the required data to develop new data-based methodologies to reduce such energy expenditure concern. Focusing in this issue, this paper proposes a data-driven methodology which improves the efficiency of the refrigeration systems acting on the load side. The solution approaches the problem with a novel load management methodology that considers the estimation of the individual load consumption and the necessary robustness to be applicable in highly variable industrial environments. Thus, the refrigeration system efficiency can be enhanced while maintaining the product in the desired conditions. The experimental results of the methodology demonstrate the ability to reduce the electrical consumption of the compressors by 17%... [more]

This paper proposes an efficient power management approach for the 24 h-ahead optimal maneuver of Mega−scale grid−connected microgrids containing a huge penetration of wind power, dispatchable distributed generation (diesel generator), energy storage system and local loads. The proposed energy management optimization objective aims to minimize the microgrid expenditure for fuel, operation and maintenance and main grid power import. It also aims to maximize the microgrid revenue by exporting energy to the upstream utility grid. The optimization model considers the uncertainties of the wind energy and power consumptions in the microgrids, and appropriate forecasting techniques are implemented to handle the uncertainties. The optimization model is formulated for a day-ahead optimization timeline with one-hour time steps, and it is solved using the ant colony optimization (ACO)-based metaheuristic approach. Actual data and parameters obtained from a practical microgrid platform in Atlanta,... [more]

It is well accepted that combined heat and power (CHP) generation can increase the efficiency of power and heat generation at the same time. With the increasing penetration of CHPs, determination of economic dispatch of power and heat becomes more complex and challenging. The CHP economic dispatch (CHPED) problem is a challenging optimization problem due to non-linearity and non-convexity in both objective function and constraints. Hence, in this paper a novel meta-heuristic algorithm, namely improved artificial bee colony (IABC) algorithm is proposed to solve the CHPED problem. The valve-point effects, power losses as well as the feasible operation region of CHP units are taken into account in the proposed CHPED problem model and the optimal dispatch of power/heat outputs of CHP units is determined via the proposed IABC algorithm. The proposed algorithm is applied on three test systems, in which two of them are large-scale CHPED benchmarks. The obtained results and comprehensive compa... [more]

Nowadays, distributed power generation is highly valued and fully developed since the energy crisis is worsening. At the same time, the distribution system operator is becoming a new stakeholder to take part in the dispatch of the active distribution network (ADN) with the power market being further reformed. Some new challenges to the dispatching of the ADN are brought by these distribution system operators (DSO), which break the traditional requirement of the lowest operating cost. In this paper, the relationship between the maximum revenue and the minimum operating cost of the ADN is fully considered, and the model of the bi-level distributed ADN considering the benefits and privacy protection of multi-stakeholder is established precisely. Further, the model is solved by using the alternating direction method of multipliers (ADMM) in which the safety and economy of the ADN are fully considered. Finally, the validity of the model and the feasibility of the algorithm are verified by u... [more]

This paper is focused mainly on the production simulation method of a regional integrated energy system under random scenarios for optimal configuration. First, the cooling, heating, and electric load demand of the regional integrated energy system is described quantitatively in the form of time series, as well as the power characteristics of renewable energy, such as wind power and photovoltaic power generation. Then, a typical scenario set of regional integrated energy system configurations considering the random probability characteristics is established through scene clustering. Second, considering the power output characteristics and cost factors of different types of distributed energy, the corresponding technical and economic quantitative model is established. Third, a multi-objective production simulation model of a regional integrated energy system considering configuration constraints and operation constraints is proposed with economic and environmental protection as the main... [more]

In order to improve fuel economy and enhance operating efficiency of fuel cell hybrid vehicles (FCHVs), fuzzy logic control (FLC) strategies are available and suggested for adoption. In this paper, the powertrain of a fuel cell hybrid vehicle is designed and the parameters of the motor, battery, and fuel cell are calculated. The FLC strategy and the power following control (PFC) strategy are designed for the studied FCHV. A secondary development for Advanced Vehicle Simulator (ADVISOR) is implemented based on the standard driving cycles, and a Chinese typical city driving cycle is imported. Simulation results demonstrate that the proposed FLC strategy is more valid and reasonable than the traditional PFC strategy. The proposed FLC strategy affects the vehicle characteristics significantly and contributes to better performance in four aspects: fuel economy, efficiency of battery and fuel cell system, battery state of charge (SOC), and battery life. Hence, the FLC strategy is more suitab... [more]

Some of today’s modern life challenges include addressing the increased waste generation and energy deficiencies. Waste tyres have been identified as one of the key environmental concerns due to their non-biodegradable nature and bulk storage space demand. Pyrolysis is a thermochemical process with the potential to address the growing waste tyre problem, energy deficits, and material recovery by converting waste tyres to pyrolysis oil that can be used as a fuel. This study seeks to critically evaluate the feasibility of constructing and operating a waste tyre processing facility and then subsequently marketing and selling the pyrolysis secondary end products by developing a financial business model. The model encompasses costing, procurement, installation, commissioning, and operating a batch pyrolysis plant in Gauteng, South Africa. To achieve the study objectives, an order of magnitude costing method was used for model construction. The results showed the feasibility and sustainabili... [more]

Non-intrusive load monitoring (NILM) is an effective way to achieve demand-side measurement and energy efficiency optimization. This paper studies a method of non-intrusive on-line load monitoring under a high-frequency mode of electric data acquisition, which enables the NILM to be automated and in real-time, including the short-term construction of a dynamic signature library and continuous on-line load identification. Firstly, in the short initial operation phase, load separation and category determination are carried out to construct the load waveform library of the monitoring user. Then, the continuous load monitoring phase begins. Based on the data of each user’s signature library, the decomposition waveforms are classified by convolutional neural network models that are constructed to be suitable for each signature library in order to realize load identification. The real-time power consumption status of the load can be obtained continuously. In this paper, the electricity data... [more]

In order to solve the capacity shortage problem in power system frequency regulation caused by large-scale integration of renewable energy, the battery energy storage-assisted frequency regulation is introduced. In this paper, an adaptive control strategy for primary frequency regulation of the energy storage system (ESS) was proposed. The control strategy combined virtual droop control, virtual inertial control, and virtual negative inertial control. The virtual inertial control was used to reduce the frequency change rate, and the virtual droop control was used to reduce the steady-state frequency deviation. The virtual droop control and the virtual inertia control were adopted in the frequency deterioration stage to slow down the frequency drop. While in the frequency recovery stage, the virtual negative inertia control worked together with the virtual droop control to accelerate the frequency recovery. Besides, the coefficients of the control methods were related to the state of ch... [more]

This paper aims to compute the performances of a smaller version of Solana power plant, with half the solar field, and 1 of 2 turbines in the power cycle, that can be built in Amman or Ma’an in Jordan. The climate conditions for both Amman and Ma’an are discussed thoroughly in the paper. Furthermore, a preliminary validation exercise performed by using measured monthly average values of electricity production from existing plants, a system advisor model (SAM) is used to predict the performances of the proposed Solana-like plants in Ma’an and Amman. The validation shows a good agreement with the measured data for different existing power plants. The simulation results including the monthly capacity factors suggest the annual operation in Ma’an maybe even better than the operation in Gila Bend, for an annual average capacity factor of about 41% for Ma’an vs. a capacity factor of about 39% for Gila Bend. This is mainly due to the best combination of direct normal irradiance (DNI) and the... [more]

Steam network operation stability and reliability is vital for any industrial branch. A combined steam network model comprising a balance and a coupled thermo-hydrodynamic model, including seasonal variations impact and system specificities, is presented. A balance model can readily be used by a refinery’s operators. The thermo-hydrodynamic model identifies system bottlenecks and cold spots and evaluates proposed operation and investment measures including heat loss reduction. A three-pressure levels refinery steam network served for model testing and validation. Balance model results reveal significant misbalance in steam production and consumption, reaching 30.5% in the low-pressure steam system, and heat balance differences in the range of 9.2% to 29.5% on individual pressure levels, attributable both to flow measurement accuracy issues and to heat losses. The thermo-hydrodynamic model results differ from the measured steam parameters by less than 5% (temperature) and by less than 4... [more]

In this paper, a small-area and high-efficiency single-inductor multiple output (SIMO) boost converter with digital pulse-width modulation (DPWM) is proposed. The DPWM comprises a delay line using interlaced hysteresis delay cells (IHDCs) that occupy a small area while consuming a low power amount. These proposed IHDCs are applied to replace the conventional delay cells of the prior works for both the power and area reductions. Regarding the DC-DC converter, this technique comprises fewer digital blocks in the feedback path compared with the conventional DC-DC converter, and the DPWM architecture uses IHDCs. The purpose of the digital limiter block is to concede some helpful code for the DPWM. The IHDC topology used for delay in DPWM is of the simplest architecture. The high-side power switch gate drivers need individual phases which are generated by phase control. The Complementary Metal Oxide Semiconductor (CMOS)-fabrication process is 55 nm, with a standard supply voltage of 1.8 V a... [more]

In this paper, a centralized control strategy for the efficient power management of power converters composing a hybrid AC/DC microgrid is explained. The study is focused on the converters connected to the DC bus. The proposed power management algorithm is implemented in a microgrid central processor which is based on assigning several operation functions to each of the generators, loads and energy storage systems in the microgrid. The power flows between the DC and AC buses are studied in several operational scenarios to verify the proposed control. Experimental and simulation results demonstrate that the algorithm allows control of the power dispatch inside the microgrid properly by performing the following tasks: communication among power converters, the grid operator and loads; connection and disconnection of loads; control of the power exchange between the distributed generators and the energy storage system and, finally, supervision of the power dispatch limit set by the grid ope... [more]

Due to the complex configuration and control framework, the conventional microgrid is not cost-effective for engineering applications with small or medium capacity. A stand-alone modular microgrid with separated AC bus and decentralized control strategy is proposed in this paper. Each module is a self-powered system, which consists of wind and solar power, a storage battery, load and three-port converter. The modules are interconnected by three-port converters to form the microgrid. Characteristics, operation principle, control of the modular microgrid and the three-port converter are analyzed in detail. Distributed storage batteries enable power exchanges among modules to enhance economic returns. Economic dispatch of the stand-alone modular microgrid is a mixed-integer programming problem. A day-ahead operation optimization model including fuel cost, battery operation cost, and power transmission cost is established. Because there are so many constraints, it is difficult to produce a... [more]