In this paper, a stand-alone hybrid microgrid consisting of wind turbines, photovoltaic (PV) arrays and storage battery banks is developed for use in Qinghai Province, China. With the help of Software Homer and Matlab...In this paper, a stand-alone hybrid microgrid consisting of wind turbines, photovoltaic (PV) arrays and storage battery banks is developed for use in Qinghai Province, China. With the help of Software Homer and Matlab, different variables such as annual average wind speed, annual average load demand, and annual capacity shortage are considered. The net present value is then used during an entire project lifetime for the optimization solution.展开更多
This paper presents a design for a stand-alone photovoltaic (PV) system to provide the required electricity for a single residential household in rural area in Jordan. The complete design steps for the suggested house...This paper presents a design for a stand-alone photovoltaic (PV) system to provide the required electricity for a single residential household in rural area in Jordan. The complete design steps for the suggested household loads are carried out. Site radiation data and the electrical load data of a typical household in the considered site are taken into account during the design steps. The reliability of the system is quantified by the loss of load probability. A computer program is developed to simulate the PV system behavior and to numerically find an optimal combination of PV array and battery bank for the design of stand-alone photovoltaic systems in terms of reliability and costs. The program calculates life cycle cost and annualized unit electrical cost. Simulations results showed that a value of loss of load probability LLP can be met by several combinations of PV array and battery storage. The method developed here uniquely determines the optimum configuration that meets the load demand with the minimum cost. The difference between the costs of these combinations is very large. The optimal unit electrical cost of 1 kWh for LLP = 0.049 is $0.293;while for LLP 0.0027 it is $0.402. The results of the study encouraged the use of the PV systems to electrify the remote sites in Jordan.展开更多
Renewable energy sources(RESs)are considered to be reliable and green electric power generation sources.Photovoltaics(PVs)and wind turbines(WTs)are used to provide electricity in remote areas.Optimal sizing of hybrid ...Renewable energy sources(RESs)are considered to be reliable and green electric power generation sources.Photovoltaics(PVs)and wind turbines(WTs)are used to provide electricity in remote areas.Optimal sizing of hybrid RESs is a vital challenge in a stand-alone environment.The meta-heuristic algorithms proposed in the past are dependent on algorithm-specific parameters for achieving an optimal solution.This paper proposes a hybrid algorithm of Jaya and a teaching–learning-based optimization(TLBO)named the JLBO algorithm for the optimal unit sizing of a PV–WT–battery hybrid system to satisfy the consumer’s load at minimal total annual cost(TAC).The reliability of the system is considered by a maximum allowable loss of power supply probability(LPSPmax)concept.The results obtained from the JLBO algorithm are compared with the original Jaya,TLBO,and genetic algorithms.The JLBO results show superior performance in terms of TAC,and the PV–WT–battery hybrid system is found to be the most economical scenario.This system provides a cost-effective solution for all proposed LPSPmax values as compared with PV–battery and WT–battery systems.展开更多
This paper describes the characteristics and optimal methods for the planning of stand-alone microgrid system, in order to improve the power supply reliability, increase the coefficient of utilization of renewable ene...This paper describes the characteristics and optimal methods for the planning of stand-alone microgrid system, in order to improve the power supply reliability, increase the coefficient of utilization of renewable energy and reduce the cost of investment and operation. Next, the problems in the optimal planning for a stand-alone microgrid system are summarized, including the unique operational control targets, the flexible combination approaches and the operation strategies of distributed generation energy supply system, and the special requirements of the reliability of power supply quality factor from the different users. And then, centering on the operational control and the advanced energy management strategy, the optimal mathematical models and the solving methods, the reliability assessment approaches and the improvement measures of a stand-alone microgrid system, an overview of the general situation of the recent research at home and abroad and the limitations of the study are summarized. Finally, several problems, existing in the optimal planning of stand-alone microgrid system, to be urgently solved, are put forward.展开更多
Application of a DFIG （doubly-fed induction generator）, which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supp...Application of a DFIG （doubly-fed induction generator）, which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine eogeneration system. In the case of conventional constant speed of synchronous generator, the amount of the allowed step load is limited to around 30% of the rated power. On the other hand, DFIG is expected to increase the amount of step load during the stand-alone operation. In this paper, it has been demonstrated that an increase in the gas engine speed resulted in an increase in the maximum amount of step load using experimental equipment with a real gas engine. It has been concluded that the proposed system can improve the performance of an emergency power supply at step-loading.展开更多
This paper deals with control method related to a wind system operating in stand-alone applications. The stand-alone wind system is composed of three energy transfer subsystems： wind generator subsystem （wind turbin...This paper deals with control method related to a wind system operating in stand-alone applications. The stand-alone wind system is composed of three energy transfer subsystems： wind generator subsystem （wind turbine and electrical generator）, energy storage subsystem, respectively, specific local network subsystem （controlled loads）. This wind power system performs in the same time the maximization of wind energy conversion and the power balance between produced and required power. Three structures of the energy storage subsystem, based on buffer battery operation and/or capacitor voltage control, are discussed. The simulation results show that the proposed stand-alone wind power system ensures a good management of the local energy request. The design of the structures is analyzed in Matlab/Simulink environment, using PowerSim toolbox.展开更多
Introduction: Bracket debonding is a frequent issue that clinicians encounter, leading to increased chair time, lost revenue, and material usage. In addition to patient compliance with their diet recommendations, the ...Introduction: Bracket debonding is a frequent issue that clinicians encounter, leading to increased chair time, lost revenue, and material usage. In addition to patient compliance with their diet recommendations, the preparation and conditioning of teeth for bonding significantly influence bond strength and consequently impact orthodontic treatment success and efficiency. Because of OBA-MCP’s (orthodontic bonding adhesive with modified calcium phosphate) decreased shear bond strength (SBS), the purpose of this study was to evaluate the effects of conditioning with 5.25% sodium hypochlorite (NaOCl) before etching in the bonding protocol. Materials and Methods: 90 extracted teeth were divided into 3 groups to be bonded with orthodontic brackets with different bonding protocols: 1) Transbond XT with regular bonding protocol (etch + prime + adhesive);2) OBA-MCP with regular bonding protocol;and 3) OBA-MCP with NaOCl prior to acid etching in the regular bonding protocol. SBS (in Newtons) were measured using an MTS universal testing machine with a custom jig to apply a vertical force onto the bracket and ARI (adhesive remnant index) scores were recorded for each sample after de-bond to rate the amount of adhesive remaining. Results: The addition of NaOCl to the bonding protocol statistically significantly increased the SBS of OBA-MCP to comparable levels to Transbond XT. The ARI scores showed that when NaOCl was added, more adhesive remained. Conclusion: The addition of NaOCl to the bonding protocol can increase the SBS of adhesives with historically weaker bond strengths. However, the increased amount of adhesive remaining and the increased time spent during bonding must be considered. Further testing can be done in vivo to demonstrate the practicality of this new procedure.展开更多
文摘In this paper, a stand-alone hybrid microgrid consisting of wind turbines, photovoltaic (PV) arrays and storage battery banks is developed for use in Qinghai Province, China. With the help of Software Homer and Matlab, different variables such as annual average wind speed, annual average load demand, and annual capacity shortage are considered. The net present value is then used during an entire project lifetime for the optimization solution.
文摘This paper presents a design for a stand-alone photovoltaic (PV) system to provide the required electricity for a single residential household in rural area in Jordan. The complete design steps for the suggested household loads are carried out. Site radiation data and the electrical load data of a typical household in the considered site are taken into account during the design steps. The reliability of the system is quantified by the loss of load probability. A computer program is developed to simulate the PV system behavior and to numerically find an optimal combination of PV array and battery bank for the design of stand-alone photovoltaic systems in terms of reliability and costs. The program calculates life cycle cost and annualized unit electrical cost. Simulations results showed that a value of loss of load probability LLP can be met by several combinations of PV array and battery storage. The method developed here uniquely determines the optimum configuration that meets the load demand with the minimum cost. The difference between the costs of these combinations is very large. The optimal unit electrical cost of 1 kWh for LLP = 0.049 is $0.293;while for LLP 0.0027 it is $0.402. The results of the study encouraged the use of the PV systems to electrify the remote sites in Jordan.
文摘Renewable energy sources(RESs)are considered to be reliable and green electric power generation sources.Photovoltaics(PVs)and wind turbines(WTs)are used to provide electricity in remote areas.Optimal sizing of hybrid RESs is a vital challenge in a stand-alone environment.The meta-heuristic algorithms proposed in the past are dependent on algorithm-specific parameters for achieving an optimal solution.This paper proposes a hybrid algorithm of Jaya and a teaching–learning-based optimization(TLBO)named the JLBO algorithm for the optimal unit sizing of a PV–WT–battery hybrid system to satisfy the consumer’s load at minimal total annual cost(TAC).The reliability of the system is considered by a maximum allowable loss of power supply probability(LPSPmax)concept.The results obtained from the JLBO algorithm are compared with the original Jaya,TLBO,and genetic algorithms.The JLBO results show superior performance in terms of TAC,and the PV–WT–battery hybrid system is found to be the most economical scenario.This system provides a cost-effective solution for all proposed LPSPmax values as compared with PV–battery and WT–battery systems.
文摘This paper describes the characteristics and optimal methods for the planning of stand-alone microgrid system, in order to improve the power supply reliability, increase the coefficient of utilization of renewable energy and reduce the cost of investment and operation. Next, the problems in the optimal planning for a stand-alone microgrid system are summarized, including the unique operational control targets, the flexible combination approaches and the operation strategies of distributed generation energy supply system, and the special requirements of the reliability of power supply quality factor from the different users. And then, centering on the operational control and the advanced energy management strategy, the optimal mathematical models and the solving methods, the reliability assessment approaches and the improvement measures of a stand-alone microgrid system, an overview of the general situation of the recent research at home and abroad and the limitations of the study are summarized. Finally, several problems, existing in the optimal planning of stand-alone microgrid system, to be urgently solved, are put forward.
文摘Application of a DFIG （doubly-fed induction generator）, which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine eogeneration system. In the case of conventional constant speed of synchronous generator, the amount of the allowed step load is limited to around 30% of the rated power. On the other hand, DFIG is expected to increase the amount of step load during the stand-alone operation. In this paper, it has been demonstrated that an increase in the gas engine speed resulted in an increase in the maximum amount of step load using experimental equipment with a real gas engine. It has been concluded that the proposed system can improve the performance of an emergency power supply at step-loading.
文摘This paper deals with control method related to a wind system operating in stand-alone applications. The stand-alone wind system is composed of three energy transfer subsystems： wind generator subsystem （wind turbine and electrical generator）, energy storage subsystem, respectively, specific local network subsystem （controlled loads）. This wind power system performs in the same time the maximization of wind energy conversion and the power balance between produced and required power. Three structures of the energy storage subsystem, based on buffer battery operation and/or capacitor voltage control, are discussed. The simulation results show that the proposed stand-alone wind power system ensures a good management of the local energy request. The design of the structures is analyzed in Matlab/Simulink environment, using PowerSim toolbox.
文摘Introduction: Bracket debonding is a frequent issue that clinicians encounter, leading to increased chair time, lost revenue, and material usage. In addition to patient compliance with their diet recommendations, the preparation and conditioning of teeth for bonding significantly influence bond strength and consequently impact orthodontic treatment success and efficiency. Because of OBA-MCP’s (orthodontic bonding adhesive with modified calcium phosphate) decreased shear bond strength (SBS), the purpose of this study was to evaluate the effects of conditioning with 5.25% sodium hypochlorite (NaOCl) before etching in the bonding protocol. Materials and Methods: 90 extracted teeth were divided into 3 groups to be bonded with orthodontic brackets with different bonding protocols: 1) Transbond XT with regular bonding protocol (etch + prime + adhesive);2) OBA-MCP with regular bonding protocol;and 3) OBA-MCP with NaOCl prior to acid etching in the regular bonding protocol. SBS (in Newtons) were measured using an MTS universal testing machine with a custom jig to apply a vertical force onto the bracket and ARI (adhesive remnant index) scores were recorded for each sample after de-bond to rate the amount of adhesive remaining. Results: The addition of NaOCl to the bonding protocol statistically significantly increased the SBS of OBA-MCP to comparable levels to Transbond XT. The ARI scores showed that when NaOCl was added, more adhesive remained. Conclusion: The addition of NaOCl to the bonding protocol can increase the SBS of adhesives with historically weaker bond strengths. However, the increased amount of adhesive remaining and the increased time spent during bonding must be considered. Further testing can be done in vivo to demonstrate the practicality of this new procedure.
