This research appraises comparative analysis between single diode and double diode model of photovoltaic (PV) solar cells to enhance the conversion efficiency of power engendering PV solar systems. Single diode model ...This research appraises comparative analysis between single diode and double diode model of photovoltaic (PV) solar cells to enhance the conversion efficiency of power engendering PV solar systems. Single diode model is simple and easy to implement, whereas double diode model has better accuracy which acquiesces for more precise forecast of PV systems performance. Exploration is done on the basis of simulation results and MATLAB tool is used to serve this purpose. Simulations are performed by varying distinct model parameters such as solar irradiance, temperature, value of parasitic resistances, ideality factor of diode and number of series and parallel connected solar cells used to assemble PV array. Conspicuous demonstration is executed to analyze effects of these specifications on the efficiency curve and power vs. voltage output characteristics of PV cell for specified models.展开更多
In this paper, we present an improved circuit model for single-photon avalanche diodes without any convergence problems. The device simulation is based on Orcad PSpice and all the employed components are available in ...In this paper, we present an improved circuit model for single-photon avalanche diodes without any convergence problems. The device simulation is based on Orcad PSpice and all the employed components are available in the standard library of the software. In particular, an intuitionistic and simple voltage-controlled current source is adopted to characterize the static behavior, which can better represent the voltage-current relationship than traditional model and reduce computational complexity of simulation. The derived can implement the self-sustaining, self-quenching and the recovery processes of the SPAD. And the simulation shows a reasonable result that the model can well emulate the avalanche process of SPAD.展开更多
The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence...The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence model,using the computational fluid dynamics(CFD)code FLUENT.The detailed velocity distribution was explored with a varying initial Froude number(Fr),with consideration of the steady subcritical flow conditions of an inland tsunami.In VDLV flows,the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged vegetation.An upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation,respectively.Overall,higher streamwise velocities were observed in the upper vegetation layer due to high porosity,with Pr=98%(sparse vegetation,where Pr is the porosity),as compared to those in the lower vegetation layer,which had comparatively low porosity,with Pr=91%(dense vegetation).A rising trend of velocities was found as the flow passed through the vegetation region,followed by a clear sawtooth distribution,as compared to the regions just upstream and downstream of vegetation where the flow was almost uniform.In VDLV flows,a rising trend in the flow resistance was observed with the increase in the initial Froude number,i.e.,Fr?0.67,0.70,and 0.73.However,the flow resistance in the case of SLV was relatively very low.The numerical results also show the flow structures within the vicinity of short and tall vegetation,which are difficult to attain through experimental measurements.展开更多
An accurate and complete circuit simulation model for single-photon avalanche diodes （SPADs） is presented. The derived model is not only able to simulate the static DC and dynamic AC behaviors of an SPAD operating i...An accurate and complete circuit simulation model for single-photon avalanche diodes （SPADs） is presented. The derived model is not only able to simulate the static DC and dynamic AC behaviors of an SPAD operating in Geiger-mode, but also can emulate the second breakdown and the forward bias behaviors. In particular, it considers important statistical effects, such as dark-counting and after-pulsing phenomena. The developed model is implemented using the Verilog-A description language and can be directly performed in commercial simulators such as Cadence Spectre. The Spectre simulation results give a very good agreement with the experimental results reported in the open literature. This model shows a high simulation accuracy and very fast simulation rate.展开更多
An analytical surface potential model for the single material double work function gate （SMDWG） MOSFET is developed based on the exact resultant solution of the two-dimensional Poisson equation. The model includes t...An analytical surface potential model for the single material double work function gate （SMDWG） MOSFET is developed based on the exact resultant solution of the two-dimensional Poisson equation. The model includes the effects of drain biases, gate oxide thickness, different combinations of S-gate and D-gate length and values of substrate doping concentration. More attention has been paid to seeking to explain the attributes of the SMDWG MOSFET, such as suppressing drain-induced barrier lowering （DIBL）, accelerating carrier drift velocity and device speed. The model is verified by comparison to the simulated results using the device simulator MEDICI. The accuracy of the results obtained using our analytical model is verified using numerical simulations. The model not only offers the physical insight into device physics but also provides the basic designing guideline for the device.展开更多
并网光伏系统通常以最大功率模式运行,无法全面响应电网调节需求,因此需要研究功率备用控制(power reserve control,PRC)。基于最大功率点估计(maximum power point estimation,MPPE)的PRC利用光伏等效模型,通过数据拟合实现MPPE,从而...并网光伏系统通常以最大功率模式运行,无法全面响应电网调节需求,因此需要研究功率备用控制(power reserve control,PRC)。基于最大功率点估计(maximum power point estimation,MPPE)的PRC利用光伏等效模型,通过数据拟合实现MPPE,从而实现光伏功率备用。然而,随着光伏组件老化,MPPE估计误差增大,可能影响系统安全稳定运行。文中提出考虑光伏组件老化时MPPE模型参数校准的光伏系统PRC。首先提出基于麻雀搜索算法的MPPE模型参数校准方法,然后根据光伏组件老化特性和MPPE误差演变趋势,提出MPPE模型校准的改进评价指标和校准周期整定原则,最后将其应用于基于MPPE的PRC中。仿真结果表明,该方法能够实现光伏组件老化后MPPE模型参数自动校准,并且显著提高了MPPE精度,增强了PRC在实际应用中的可靠性。展开更多
文摘This research appraises comparative analysis between single diode and double diode model of photovoltaic (PV) solar cells to enhance the conversion efficiency of power engendering PV solar systems. Single diode model is simple and easy to implement, whereas double diode model has better accuracy which acquiesces for more precise forecast of PV systems performance. Exploration is done on the basis of simulation results and MATLAB tool is used to serve this purpose. Simulations are performed by varying distinct model parameters such as solar irradiance, temperature, value of parasitic resistances, ideality factor of diode and number of series and parallel connected solar cells used to assemble PV array. Conspicuous demonstration is executed to analyze effects of these specifications on the efficiency curve and power vs. voltage output characteristics of PV cell for specified models.
文摘In this paper, we present an improved circuit model for single-photon avalanche diodes without any convergence problems. The device simulation is based on Orcad PSpice and all the employed components are available in the standard library of the software. In particular, an intuitionistic and simple voltage-controlled current source is adopted to characterize the static behavior, which can better represent the voltage-current relationship than traditional model and reduce computational complexity of simulation. The derived can implement the self-sustaining, self-quenching and the recovery processes of the SPAD. And the simulation shows a reasonable result that the model can well emulate the avalanche process of SPAD.
文摘The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence model,using the computational fluid dynamics(CFD)code FLUENT.The detailed velocity distribution was explored with a varying initial Froude number(Fr),with consideration of the steady subcritical flow conditions of an inland tsunami.In VDLV flows,the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged vegetation.An upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation,respectively.Overall,higher streamwise velocities were observed in the upper vegetation layer due to high porosity,with Pr=98%(sparse vegetation,where Pr is the porosity),as compared to those in the lower vegetation layer,which had comparatively low porosity,with Pr=91%(dense vegetation).A rising trend of velocities was found as the flow passed through the vegetation region,followed by a clear sawtooth distribution,as compared to the regions just upstream and downstream of vegetation where the flow was almost uniform.In VDLV flows,a rising trend in the flow resistance was observed with the increase in the initial Froude number,i.e.,Fr?0.67,0.70,and 0.73.However,the flow resistance in the case of SLV was relatively very low.The numerical results also show the flow structures within the vicinity of short and tall vegetation,which are difficult to attain through experimental measurements.
基金supported by the Natural Science Foundation of Jiangsu Province,China(No.BK20131379)
文摘An accurate and complete circuit simulation model for single-photon avalanche diodes （SPADs） is presented. The derived model is not only able to simulate the static DC and dynamic AC behaviors of an SPAD operating in Geiger-mode, but also can emulate the second breakdown and the forward bias behaviors. In particular, it considers important statistical effects, such as dark-counting and after-pulsing phenomena. The developed model is implemented using the Verilog-A description language and can be directly performed in commercial simulators such as Cadence Spectre. The Spectre simulation results give a very good agreement with the experimental results reported in the open literature. This model shows a high simulation accuracy and very fast simulation rate.
基金supported by the National Youth Science Foundation of China(No.61006064)the Natural Science Foundation of Education Office,Anhui Province(No.KJ2013A071)
文摘An analytical surface potential model for the single material double work function gate （SMDWG） MOSFET is developed based on the exact resultant solution of the two-dimensional Poisson equation. The model includes the effects of drain biases, gate oxide thickness, different combinations of S-gate and D-gate length and values of substrate doping concentration. More attention has been paid to seeking to explain the attributes of the SMDWG MOSFET, such as suppressing drain-induced barrier lowering （DIBL）, accelerating carrier drift velocity and device speed. The model is verified by comparison to the simulated results using the device simulator MEDICI. The accuracy of the results obtained using our analytical model is verified using numerical simulations. The model not only offers the physical insight into device physics but also provides the basic designing guideline for the device.
文摘并网光伏系统通常以最大功率模式运行,无法全面响应电网调节需求,因此需要研究功率备用控制(power reserve control,PRC)。基于最大功率点估计(maximum power point estimation,MPPE)的PRC利用光伏等效模型,通过数据拟合实现MPPE,从而实现光伏功率备用。然而,随着光伏组件老化,MPPE估计误差增大,可能影响系统安全稳定运行。文中提出考虑光伏组件老化时MPPE模型参数校准的光伏系统PRC。首先提出基于麻雀搜索算法的MPPE模型参数校准方法,然后根据光伏组件老化特性和MPPE误差演变趋势,提出MPPE模型校准的改进评价指标和校准周期整定原则,最后将其应用于基于MPPE的PRC中。仿真结果表明,该方法能够实现光伏组件老化后MPPE模型参数自动校准,并且显著提高了MPPE精度,增强了PRC在实际应用中的可靠性。
