Hybrid Generation System Research Articles

Exergo-economic optimization of concentrated solar photovoltaic and thermoelectric hybrid generator

Exergo-economic analysis of a concentrated photovoltaic–thermoelectric generator (CPV-TEG) hybrid system is investigated. The specific exergy costing is employed to study the cost effectiveness of the CPV-TEG system. A multi-dimensional single-objective optimization is carried out to optimize the CPV-TEG hybrid system. The performance of the CPV-TEG system is found to be better than that of the concentrated photovoltaic (CPV) system alone in terms of overall energy and exergy efficiencies. From an exergo-economic standpoint, the CPV-TEG system is more cost effective as compared to the CPV system alone. The low value of the exergo-economic factor of the system indicated that the associated cost was mostly due to irreversibilities in the system. A compromise is made by optimizing the CPV-TEG system for maximum exergy efficiency using an optimum thermal resistance of the thermoelectric generator (TEG). For the operating conditions and the geometry considered, integration of CPV and TEG is not found to be feasible (in terms of exegetic performance) below certain values of heat transfer coefficients (< 2500 Wm−2 K−1). A minimum value of heat transfer coefficient of 5266 Wm−2 K−1 is determined for a water-cooled heat sink to limit the cell temperature to 100 °C under the studied set of operating conditions and the geometric configuration. Optimization results yielded exergy efficiencies of 42.22% and 43.48% for the stand-alone CPV system and CPV-TEG system, respectively. The minimum costs of electricity under the optimum conditions were obtained as $$0.57\;\$ \; {\text{kW}}\,{\text{h}}^{ - 1}$$ and $$0.53\;\$ \; {\text{kW}}\,{\text{h}}^{ - 1}$$ for the stand-alone CPV system and CPV-TEG system, respectively.

Optimal tracking control of switched systems applied in grid-connected hybrid generation using reinforcement learning

The paper presents a reinforcement learning approach for optimal tracking control of switched systems with application to a grid-tied hybrid generation system. To enhance interaction with the irregular environment, reference trajectory is learned via controller from states to optimal control. The main issue is to solve the optimal tracking control problem for a hybrid generation system consisting of multiple switched subsystems, and reinforcement learning can seek the globally optimal solution well without knowing accurate system dynamics. The investigated learning algorithm is used to generate an optimum map based on the learned ultimate value without knowledge of system parameters and obtains the optimal control law via deriving of algebraic Riccati equation (ARE) with unnecessary knowing of command generator dynamics. The optimal control solution can converge the online learning algorithm well based on policy iteration as verification in the simulation.

The investigation of the optimization based on market mechanism to the operation of a thermal‐wind‐photovoltaic hybrid generation system

The renewable energy hybrid generation system in the area with renewable energy and land source plays a key role in improving the application of the renewable energy in China, with the rapid development of the extra high voltage (EHV) and ultra-high voltage (UHV) grids to transmit the electricity. The suitable plan and decision-making mechanism has a significant influence on the utilization of the renewable energy. The output of thermal power, wind power and photovoltaic are respectively simulated in the plan period of a hybrid generation system, and then all the output are comprehensively studied with the consideration of some constrains. However, the experience of the applications of the renewable energy hybrid generation system with thermal power revealed an obvious disadvantage that to maintain the competitiveness of the power output without the guidance of the price signals in the electricity market is difficult. The dispersed areal distribution and discontinuous power output of the renewable energy may be responsible for this disadvantage. The investigation to improve the consumption of the renewable energy hybrid generation system is meaningful to solve the renewable energy curtailment problems. In the present study, the investigation to the operation of a thermal-wind-photovoltaic hybrid generation system with market mechanism was conducted to optimize the consumption of the renewable energy. These results are beneficial to the operations of the similar hybrid generation systems.

Energy performance investigation of nanofluid‐based concentrated photovoltaic / thermal‐thermoelectric generator hybrid system

Nanofluid can be used in a CPV/T solar collector to boost electrical and thermal performances as this technology has drawn great attention from researchers over the last decades. In a CPV/T system, the amount of collected heat could be significantly higher than the amount of electrical power. Combining thermoelectric generator (TEG) and nanofluid-based CPV/T system may result in better electrical performance than CPV/T system alone. In the present work, a nanofluid-based CPV/T-TEG hybrid system with a cooling channel was designed and tested, and the obtained performance was compared with conventional cooling methods [ie, natural cooling (CPV/TEG) and water cooling (WCPV/T-TEG) methods]. At the optimum value of solar concentration, C = 14.6, the electrical performance of the nanofluid-based concentrated photovoltaic/thermal-thermoelectric generator (NCPV/T-TEG) configuration was found to be ~89% higher than the standard PV modules. For the same concentration, the electrical performance of the above configuration was found to be ~13.9% and ~8.4% higher than CPV/TEG and WCPV/T-TEG configurations, respectively. In addition, the overall thermal energy of the NCPV/T-TEG was found to be higher by 4.98% compared to WCPV/T-TEG hybrid system. The NCPV/T-TEG configuration was found to produce 92.47%, 41.06%, and 8.8% higher daily exergy compared to standard PV cell, CPV/TEG, and WCPV/T-TEG, respectively. Overall, the proposed design of the NCPV/T-TEG hybrid system has the potential for further development in high-concentration solar systems.

Enhanced PLL (EPLL) Synchronization and HBCC Controlling of Grid-Interactive (PV-SOFC) Hybrid Generating System

Objective: In a grid-interactive (PV-SOFC) generation system, the inverter is the main constituent. Further, the quality of the injected signal in utility depends upon inverter control and synchronization. Thus, the main objective of thispaper is to control the single-phase inverter for a hybrid DC generation system and obtain synchronization between the grid signal and hybrid renewable energy source (RES) inverted output signal. Methods/Statistical analysis: This paper suggests software modeling of the grid-interactive hybrid photovoltaic array (PV) and solid oxide fuel cell (SOFC) power generation system to supply continue load demand. The enhanced phase locked loop (EPLL), and hysteresis band current controller (HBCC) utilize to control single-phase inverter for hybrid generation system. The main benefit of EPLL configuration beyond traditional PLL’s is to compose and keep up phase change zero between input and output of voltage controlled oscillator (VCO). So, the EPLL tracks thephase angle and amplitude of the signal. The incremental conductance based MPPT technique is implemented in the proposed architecture to enhance the system’s efficiency by maximizing extracted power from the PV configuration. In addition, the synchronization between the grid signal and hybrid RES inverted output signal is obtained with EPLL. The simulation results with system design parameters are carried out in MATLAB 2015. Findings: The efficacy of the proposed synchronization circuit of EPLL is confirmed through the compensation of twice time-frequency error, which is introduced in traditional PLL. Further, from the simulation results, it is observed that smooth frequency is obtained with the proposed EPLL. Moreover, the performance index parameter (%THD) of current in the presence of EPLL and HBCC is smaller than the traditional PLL. Novelty: This paper introduces a hybrid EPLL and HBCC approach to control the single-phase inverter for a hybrid PV-SOFC generation system. Keywords: Photovoltaic array (PV); incremental conductance based maximum power point tracking (INC-MPPT); synchronization; solid oxide fuel cell (SOFC); hysteresis band current controller; enhanced phase locked loop (EPLL); grid

Recent progress in thermoelectric materials, devices and applications

<p indent=0mm>Thermoelectric materials have the capability of directly converting heat into electricity, and vice versa. They play an important role in a global sustainable energy solution because they can convert a fraction of the heat into useful energy. Moreover, this conversion does not produce carbon dioxide, toxic or hazardous substances. However, due to its low energy conversion efficiency, thermoelectric power generation never comes into large scale applications. A lot of efforts have been done to understand the physics of this effect after its first observation by Seebeck in the early nineteenth century. About one hundred years later, thermoelectric figure-of-merit has been defined, which is a crucial parameter for estimating the performance of thermoelectric materials. Since then, looking for materials with high figure-of-merit becomes one focus of thermoelectric community. Till now, most of the thermoelectric materials in practical use and studied intensively are alloys. In recent years, thermoelectric properties of oxide and organic materials attracted much attention. Due to their high thermal and chemical stability, oxides-based ceramics are of the most promising thermoelectric materials at high temperatures. Hence, the development of oxide thermoelectric with both high performance and environmental stability is of significance. More recently, oxide materials, such as calcium manganite and delafossite structure compounds, show very interesting thermoelectric property at high temperature conditions. Calcium manganite CaMnO₃ is an n-type semiconductor oxide with perovskite structure. For delafossite compounds, their layered crystal structure usually possesses a low thermal conductivity, which is good for thermoelectric property. Quite a few reports on thermoelectric property of delafossite are on CuFeO₂ compound. It seems difficult to obtain pure phase samples, due to its complicated phase structure. Different synthesis methods have been adopted, including microwave, aerosol-deposition, etc. to synthetize this compound. Till then thermoelectric investigation of delafossite is far too enough. To reach high energy conversion efficiency, material with high thermoelectric figure-of-merit is necessary. On the other hand, good module geometry design or new geometry module is very important for energy conversion efficiency. Moreover, to meet different application requirements and improve the power output, module geometry design is necessary either. Finite element method is powerful for simulating the performance of thermoelectric devices. Using this method, the geometry of the traditional thermoelectric module has been optimized. Novel types of thermoelectric devices, such as multilayer composite structured thermoelectric module and uni-leg module as well as thin film structures, are designed and simulated. Besides applications on cooling and power generation for space energy, investigations are also extended to combination with other power generation types. For instance, performance of a dye-sensitized solar cell and thermoelectric hybrid power system is established and studied. The performance of solid oxide fuel cell-thermoelectric generator hybrid system is designed and optimized. With the rapid development of technology and the increasing demand for wearable electronics, more attention has been moved towards the self-power and maintenance-free systems. Flexible thermoelectric generators can tightly adhere to human skins, and may generate maintenance-free electricity based on the direct conversion of the temperature difference between the human body and ambient temperature. The market of internet of things expands at a very rapid rate. Thermoelectric energy conversion from environment seems to be a natural and intuitive candidate for power supply of internet of things. It is economically attractive and energetically efficient alternatives for powering internet nodes. As final remarks, more efforts have to be taken to understand thermoelectric phenomenon as coupling effects, to explore thermoelectric materials with high performance, and to design devices with novel architecture for potential applications.

A Short-Term Optimal Scheduling Model for Wind-Solar-Hydro Hybrid Generation System With Cascade Hydropower Considering Regulation Reserve and Spinning Reserve Requirements

In order to meet the challenges brought by the high penetration of intermittent and fluctuating wind and solar power, a short-term optimal scheduling model for wind-solar-hydro hybrid generation system with cascade hydropower is established with the objective of minimizing the amount of abandoned wind, solar and hydro power and maximizing the stored energy of hydro stations. Cascade hydropower is considered to provide spinning reserve and regulation reserve to ensure the security of system. Mixed Integer Linear Programming (MILP) method is used for the short-term optimal schedule of wind-solar-hydro hybrid generation system. The case studies show that spinning reserve and regulation reserve are beneficial to the hybrid generation system, and verify the practical applicability of the proposed model.

An optimal operation method of cascade hydro-PV-pumped storage generation system based on multi-objective stochastic numerical P systems

To take full advantage of the complementary characteristics of various renewable energy sources, hybrid generation systems (HGSs) are used to accommodate the increased variability and uncertainty. In southwest China, there are many small cascade hydropower stations (CHSs) and PV power stations, which have spatial and temporal correlation characteristics and complementary characteristics. Pumped-storage units are considered as ideal large-scale energy storage elements for HGSs due to their fast response and long life. The purpose of this study is to increase the system reliability and water power utilization rate and maximize the economic benefits of a cascade hydro-PV-pumped storage (CH-PV-PS) generation system. Considering the reliability, economy, and water power utilization rate of the system, the CH-PV-PS system model with multiple objectives and multiple constraints is established. Then, a multi-objective stochastic numerical P system (MOSNP) is proposed. The external storage set and correction method in the MOSNP algorithm are introduced to ensure the diversity of the solution and improve the efficiency of the algorithm. The CH-PV-PS system is introduced in Sichuan Province, Southwest China. The simulation results show that (1) the MOSNP method can obtain robust and effective optimization results for the hybrid system; (2) the use of pumped storage units has increased the daily economy by 1018 CNY, and the total fluctuation of CHSs has been reduced by 29.3%, which makes the hybrid system safer and more economical; and (3) the uncertainty of PV and runoff will lead to frequent dispatching of CHSs, thus reducing the economic benefits of the system.

Effective Design and Implementation of Three Port Hybrid Converter for Hybrid Power Sources

With the improvement in the power electronics innovations, a bigger amount of PV panels are integrated as power energy sources into distributed power generations systems leads to the betterment of hybrid renewable energy systems. Enhancement in a renewable hybrid generation system is required because it is the future origin of power where we are expected to produce a lot of yield voltage. It tends to be finished by utilizing the plan of the converter design. In recent days, the developing method on hybrid power generation systems makes it more beneficiaries on the power systems domain. So, an integrated three port converter with combinations of PV cell/fuel cell/battery systems is proposed here. We need to effectively increase the generation to meet up with the power demand by boosting output power. To build the effective yield power by a blend of photovoltaic (PV)/Fuel cell energy unit with the assistance of the structure strategies of the three-port converter dependent on five switches connect DC-DC support converter. Along these lines, we could accomplish a superior productivity is verified with MATLAB/SIMULINK simulation results and scale down the model is developed.

Integral Backstepping Based Nonlinear Control for Maximum Power Point Tracking and Unity Power Factor of a Grid Connected Hybrid Wind-Photovoltaic System

This paper proposes a novel integral backstepping-based nonlinear control strategy for a grid-connected wind-photovoltaic hybrid system. Firstly, detailed three-phase models of the hybrid system elements are presented, and then an overall state-space model is derived. Secondly, nonlinear control laws for the hybrid system’s converters are developed with the aim of ensuring maximum extraction of the available renewable energy, stabilizing the DC bus voltage and guaranteeing the operation of the hybrid system at unity power factor. The overall stability of the closed-loop system is demonstrated on the basis of Lyapunov’s stability theory. Comprehensive simulations, using the MATLAB/Simulink software environment, are carried out to assess the effectiveness of the proposed control methodology. The simulation results obtained confirm that the proposed control strategy offers high efficiency in various operating modes of the hybrid generation system.

Integral Backstepping Based Nonlinear Control for Maximum Power Point Tracking and Unity Power Factor of a Grid Connected Hybrid Wind-Photovoltaic System

This paper proposes a novel integral backstepping-based nonlinear control strategy for a grid-connected wind-photovoltaic hybrid system. Firstly, detailed three-phase models of the hybrid system elements are presented, and then an overall state-space model is derived. Secondly, nonlinear control laws for the hybrid system’s converters are developed with the aim of ensuring maximum extraction of the available renewable energy, stabilizing the DC bus voltage and guaranteeing the operation of the hybrid system at unity power factor. The overall stability of the closed-loop system is demonstrated on the basis of Lyapunov’s stability theory. Comprehensive simulations, using the MATLAB/Simulink software environment, are carried out to assess the effectiveness of the proposed control methodology. The simulation results obtained confirm that the proposed control strategy offers high efficiency in various operating modes of the hybrid generation system.

In situ and tunable structuring of semiconductor-in-glass transparent composite.

SummarySemiconductor-in-glass composites are an exciting class of photonic materials for various fundamental applications. The significant challenge is the scalable elaboration of composite with the desirable combination of tunable structure, high semiconductor loading ratio, and excellent transparency. Here we report that the topological engineering strategy via hybridization of the glass network former enables to surmount the aforementioned challenge. It not only facilitates the in situ precipitation of (Ga2-xAlx)O3 domains with continuously tunable composition but also allows to simultaneously refine the grain size and enhance the crystallinity. In addition, the composites exhibit excellent transparency and can host various active dopants. We demonstrate the attractive broadband optical response of the composite and achieve the pulse laser operation in mid-infrared waveband. The findings are expected to provide a fundamental principle of in situ modification in hybrid system for generation of high-performance semiconductor-in-glass composites.

Optimal configuration of hybrid PV-generator (diesel/GPL) for a decentralized production of electricity in Algeria

The absence of electricity in rural areas is one of the major challenges faced by many developing countries like Algeria. This work has been devoted to the design of an off-grid renewable hybrid power system for a rural village in the region of Tindouf located in south Algeria. The main objective of this study is to determine the optimum size of the hybrid power system able to fulfill the requirements of 709 kWh/day primary load with 66 kW peak load for a remote area of 230 households. This study is based on simulation and optimization of a (PV-Diesel) and (PV-GPL) hybrid system with a technical-economic analysis. Simulation results showed that electrifying using a PV/GPL generator hybrid system is more advantageous when compared to the PV/diesel generator hybrid system as it has lower operating costs and emissions. The comparison is based on per unit cost of electrical energy production, operating cost of conventional fossil fuel-based energy sources and pollutants gases reduction.

Optimization with excess electricity management of a PV, energy storage and diesel generator hybrid system using HOMER Pro software

Optimization with excess electricity management of a PV, energy storage and diesel generator hybrid system using HOMER Pro software

Optimization with excess electricity management of a PV, energy storage and diesel generator hybrid system using HOMER Pro software

In this research, a standalone microgrid power system is proposed to electrify a small agricultural community in Palestinian territories. The load includes residential load and water pumping load. The community comprises about 30 households with some service buildings in addition to the water pumping system. The average load energy demand is 300kWh/day and the average power demand is 12.5kW, in the same context, the average energy demand for water pumping is 49kWh/day. The region has abundant solar radiation potential with a daily average of 5.4 kWh/m&lt;sup&gt;2&lt;/sup&gt;. The optimum design was achieved using the HOMER Pro software. It took into consideration real incident solar radiation data, electrical demand profile for the community and water pumping system and market cost of all equipment. The optimization results showed that the best hybrid system among all feasible configurations is a PV system with an energy storage system combined with a diesel generator. The net present cost of the system is USD636,150 and the cost of energy (COE) produced is USD0.438/kWh. Sensitivity analysis is considered to study the impact of variations in PV cost, diesel fuel price, and maximum annual capacity shortages (MACS), the results showed that MACS has no effects. Energy management procedure is followed to reduce the excess electricity from 10.6% to 6.24% which in turn reduces the COE from 0.438 to USD 0.416/kWh.

A microbial electrochemical hybrid system for simultaneous sludge treatment, acid production, and desalination

Excess sludge production from wastewater treatment plants has significantly increased, and sludge disposal has become a serious social and environmental problem. In this study, we constructed a microbial electrochemical hybrid system (MEHS) for simultaneous electricity generation, acid and alkali production, desalination, alkali pretreatment, and degradation of sludge. The alkaline solution generated in the MEHS was used for in situ sludge pretreatment. Owing to the efficiency in alkali pretreatment, a higher sludge degradation efficiency was obtained by the MEHS (Total chemical oxygen demand (TCOD) removal efficiency of 57.2%) than by the SMFC (TCOD removal efficiency of 51.7%). Moreover, the MEHS (0.165C) could recover more electricity from the sludge than a traditional single-chamber microbial fuel cell (SMFC, 0.133C). Additionally, the MEHS exhibited excellent performance in desalination (> 50%) and acid production. The system developed in this study provides a new solution for sludge degradation and multifunctional utilization.

Optimization of a PV-Wind Hybrid Power Supply Structure with Electrochemical Storage Intended for Supplying a Load with Known Characteristics

An important aspect of the off-grid utilization of hybrid generation systems is the integration of energy storage facilities into their structures, which allows for improved power supply reliability. However, this results in a significant increase in the cost of such systems. Therefore, it is justified to use optimization resulting in the minimization of the selected economic indicator taking into account the most important technical constraints. For this reason, this work proposes an algorithm to optimize the structure of a hybrid off-grid power distribution system (with electrochemical energy storage), designed to supply a load with known daily energy demand. The authors recommend genetic algorithm utilization as well as a modified criterion for evaluating the quality of solutions based on the Levelized Cost of Energy (LCOE) index. Several technical and economic analyses were presented, including unit costs, power distribution of the wind and solar sections, nominal battery capacity, SSSI index (System Self-Sufficiency Index), etc. The model of the system includes durability of the elements which have a significant impact on the periodic battery replacement. The tests were carried out for two types of loads and two types of electrochemical batteries (NMC—Lithium Nickel Manganese Cobalt Oxide; and PbO2—Lead-Acid Battery), taking into account the forecast of an increased lifetime of NMC type batteries and decreasing their price within five years. The proposed synthesis method of photovoltaic-wind (PV-wind) hybrid off-line systems leads to limiting the energy capacity of electrochemical storages. Based on the analyses, the authors proposed recommended methods to improve (reduce) the value of the criterion index (LCOE) for PV-wind off-grid systems while maintaining the assumed level of power supply reliability.

Comprehensive Review of Methods and Instruments for Photovoltaic–Thermoelectric Generator Hybrid System Characterization

Finding new sustainable energy sources or improving the efficiencies of the existing ones represents a very important research and development direction. The hybridization approach is one solution for increasing the efficiency of the existing energy sources. In the case of photovoltaic technology, the hybridization of the photovoltaic panels (PV) with thermoelectric generators (TEGs) has become a more interesting solution for the research community in the last decade. Thus, a comprehensive review of the characterization methods and instruments used in PV-TEG hybrid system study represents the objective of this work. PV and TEG equivalent circuits are presented. The instruments and software applications used for the measurements and simulations are presented and analyzed. The analysis of the literature reveals that there are many papers that offer partial or no information about the instruments used or about the measurement quality (accuracies, uncertainties, etc.). In hybrid system modeling, the preferred software applications are MATLAB (MathWorks, Natick, MA, USA) and COMSOL Multiphysics (Comsol, Burlington, MA, USA), while for experimental studies based on computers, LabVIEW (NI, Austin, TX, USA) is preferred. This review work could be interesting for researchers and engineers who are interested in finding solutions for characterizing or monitoring hybrid system components, but it is not limited to these.

Dynamic simulation of a hybrid PV/Wind/Diesel system using power factory

Economic growth is one factors driving the need for expansion of the electricity system. However, power systems in some isolated areas are found to be unreliable because of some issues such as the transportation of components of the power system and fuel. The potential of local renewable energies can be the alternative for the development of power plants in these areas. However, most renewable energy sources produce relatively unstable voltage and power due to fluctuating primary energy sources conditions. This study proposes a hybrid generation system that utilizes the potential of local RES such as a PV system and a wind turbine generator, combined with existing diesel generators and equipped with a battery energy storage system. Simulations are carried out to observe and study the dynamic response of each component in response to the system frequency using PowerFactory software. The result shows the proposed hybrid system still operate well and stably due to the dynamic performance and coordination control between diesel generators and the battery energy storage system.

Multi-objective evolutionary optimization with genetic algorithm for the design of off-grid PV-wind-battery-diesel system

With the increasing hazard to the environment and progressions in renewable energy technologies, hybrid renewable energy systems can meet the energy demand. Total dependability can be attained by adding battery banks to hybrid systems. This paper aims to optimally design a multi-source grid isolated hybrid generation system for future smart cities in the state of Tamil Nadu, India. This off-grid power generation consists of wind turbine generators, photovoltaic panels, inverters, diesel generators, and batteries. The design intents at minimizing Net Present Cost, Unmet Load, and CO2 emissions which are conventionally contradictory to each other. This paper analyzes the optimal off-grid combination of components and control strategies, utilizing improved Hybrid Optimization using the Genetic Algorithm. The results obtained portrays that a mix of hybrid renewable energy generators at off-grid locations without diesel generators can be a cost-effective choice of new smart cities, and it is sustainable, environmentally viable, and techno-economically feasible. Subvention is imperative to take on the large-scale system due to the high capital cost.