With the introduction of the“dual carbon goals,”there has been a robust development of distributed photovoltaic power generation projects in the promotion of their construction.As part of this initiative,a comprehen...With the introduction of the“dual carbon goals,”there has been a robust development of distributed photovoltaic power generation projects in the promotion of their construction.As part of this initiative,a comprehensive and systematic analysis has been conducted to study the overall benefits of photovoltaic power generation projects.The evaluation process encompasses economic,technical,environmental,and social aspects,providing corresponding analysis methods and data references.Furthermore,targeted countermeasures and suggestions are proposed,signifying the research’s importance for the construction and development of subsequent distributed photovoltaic power generation projects.展开更多
This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a u...This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.展开更多
The analysis of the loss of distributed photovoltaic power generation systems involves the interests of energy users,energy-saving service companies,and power grid companies,so it has always been the focus of the indu...The analysis of the loss of distributed photovoltaic power generation systems involves the interests of energy users,energy-saving service companies,and power grid companies,so it has always been the focus of the industry and society in some manner or another.However,the related analysis for an actual case that considers different cooperative corporations’benefits is lacking in the presently available literature.This paper takes the distributed rooftop photovoltaic power generation project in an industrial park as the object,studies the analysis and calculation methods of line loss and transformer loss,analyzes the change of transformer loss under different temperatures and different load rates,and compares the data and trend of electricity consumption and power generation in industrial parks before and after the photovoltaic operation.This paper explores and practices the analysis method of the operating loss of distributed photovoltaic power generation and provides an essential reference for the benefit analysis and investment cost estimation of distributed photovoltaic power generation systems in industrial parks.The analyzed results reveal that the change loss is stable after the photovoltaic is connected,and there is no additional transformer loss.And before and after the photovoltaic system installation,there was no significant change in the total monthly data difference between the total meter and the sub-meter.展开更多
The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods ...The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods have been used and applied to determine the optimal allocation and sizing of the PV to be installed as DGs (ranging from 250 kW up to 3 MW). The first one is to determine the location according to the maximal power losses reduction over the feeder. The second one is by using the Harmony Search Algorithm which is claimed to be a powerful technique for optimal allocation of PV systems. The results of the two techniques were compared and found to be nearly closed. Furthermore, investigation on the effects on the feeder in terms of voltage levels, power factor readings, and short circuit current levels has been done. All calculations and simulations are conducted by using the MATLAB Simulation Program. Some field calculations and observations have been expended in order to substantiate the research findings and validation.展开更多
As the integration of distributed generations(DGs)transforms the traditional distribution network into the active distribution network,voltage stability assessments(VSA)of transmission grid and distribution grid are n...As the integration of distributed generations(DGs)transforms the traditional distribution network into the active distribution network,voltage stability assessments(VSA)of transmission grid and distribution grid are not suitable to be studied separately.This paper presents a distributed continuation power flow method for VSA of global transmission and distribution grid.Two different parameterization schemes are adopted to guarantee the coherence of load growth in transmission and distribution grids.In the correction step,the boundary bus voltage,load parameter and equivalent power are communicated between the transmission and distribution control centers to realize the distributed computation of load margin.The optimal multiplier technique is used to improve the convergence of the proposed method.The three-phase unbalanced characteristic of distribution networks and the reactive capability limits of DGs are considered.Simulation results on two integrated transmission and distribution test systems show that the proposed method is effective.展开更多
To solve the problem of permanent-shadow shading of photovoltaic buildings,a maximum power point tracking(MPPT)strategy to determine the search range by pre-delimiting area is proposed to improve MPPT efficiency.The s...To solve the problem of permanent-shadow shading of photovoltaic buildings,a maximum power point tracking(MPPT)strategy to determine the search range by pre-delimiting area is proposed to improve MPPT efficiency.The single correspondence between the solar-cell current-voltage(I-V)curve and the illumination conditions was proved by using the single-diode model of photovoltaic cells,thus proving that a change in the illumination conditions corresponds to a unique maximum power point(MPP)search area.According to the approximate relationship between MPP voltage,current and open-circuit voltage and short-circuit current of a photovoltaic module,the voltage region where the MPP is located is determined and the global maximum power point is determined using the power operating triangle strategy in this region.Simulation carried out in MATLAB proves the correctness and feasibility of the theoretical research.Simulation results show that the MPPT strategy proposed in this paper can improve the average efficiency by 1.125%when applied in series as building integrated photovoltaics.展开更多
基于上海一独立住宅光伏发电系统运行一年的数据,从发电量、光伏系统效率、光伏能源替代率、光伏系统效率影响因素等方面进行后评估。结果表明:过去一年度理论预测年发电量为5 738 k W·h,实际发电量为4 109 k W·h,全年度光伏...基于上海一独立住宅光伏发电系统运行一年的数据,从发电量、光伏系统效率、光伏能源替代率、光伏系统效率影响因素等方面进行后评估。结果表明:过去一年度理论预测年发电量为5 738 k W·h,实际发电量为4 109 k W·h,全年度光伏系统效率为73%。为研究光伏系统效率的影响因子,在系统运行期间未对光伏组件表面实施人工清洁维护,对此条件下的运行数据进行分析发现,光伏系统效率总体呈现逐渐降低的趋势。其中在近水平安装角度的情况下,组件光电转换效率最大降低达2.08%。在该住宅按照现行理想的设计条件运行(冬季连续采暖确保室内20℃、夏季连续空调确保室内26℃)的前提下,过去一年度的总用电量为12 054 k W·h,其中空调用电量为9 332 k W·h,占到总用电量的77.4%。全年光伏能源替代率为34%,过渡季节可实现光伏能源替代率最高达180%。独立住宅上存在较大的节能空间和光伏能源替代率提升空间。展开更多
文摘With the introduction of the“dual carbon goals,”there has been a robust development of distributed photovoltaic power generation projects in the promotion of their construction.As part of this initiative,a comprehensive and systematic analysis has been conducted to study the overall benefits of photovoltaic power generation projects.The evaluation process encompasses economic,technical,environmental,and social aspects,providing corresponding analysis methods and data references.Furthermore,targeted countermeasures and suggestions are proposed,signifying the research’s importance for the construction and development of subsequent distributed photovoltaic power generation projects.
文摘This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.
基金supported by the State Grid Corporation of China Science and Technology Project(5216AG21000 K).
文摘The analysis of the loss of distributed photovoltaic power generation systems involves the interests of energy users,energy-saving service companies,and power grid companies,so it has always been the focus of the industry and society in some manner or another.However,the related analysis for an actual case that considers different cooperative corporations’benefits is lacking in the presently available literature.This paper takes the distributed rooftop photovoltaic power generation project in an industrial park as the object,studies the analysis and calculation methods of line loss and transformer loss,analyzes the change of transformer loss under different temperatures and different load rates,and compares the data and trend of electricity consumption and power generation in industrial parks before and after the photovoltaic operation.This paper explores and practices the analysis method of the operating loss of distributed photovoltaic power generation and provides an essential reference for the benefit analysis and investment cost estimation of distributed photovoltaic power generation systems in industrial parks.The analyzed results reveal that the change loss is stable after the photovoltaic is connected,and there is no additional transformer loss.And before and after the photovoltaic system installation,there was no significant change in the total monthly data difference between the total meter and the sub-meter.
文摘The rapid spreading of the Photovoltaic (PV) Systems as Distributed Generation (DG) in medium and low voltage networks created many effects and changes on the existing power system networks. In this work, two methods have been used and applied to determine the optimal allocation and sizing of the PV to be installed as DGs (ranging from 250 kW up to 3 MW). The first one is to determine the location according to the maximal power losses reduction over the feeder. The second one is by using the Harmony Search Algorithm which is claimed to be a powerful technique for optimal allocation of PV systems. The results of the two techniques were compared and found to be nearly closed. Furthermore, investigation on the effects on the feeder in terms of voltage levels, power factor readings, and short circuit current levels has been done. All calculations and simulations are conducted by using the MATLAB Simulation Program. Some field calculations and observations have been expended in order to substantiate the research findings and validation.
基金This work is supported by National Natural Science Foundation of China(No.51077042,No.51577049)Special Foundation of The doctoral program of Higher Education(No.20120094110008).
文摘As the integration of distributed generations(DGs)transforms the traditional distribution network into the active distribution network,voltage stability assessments(VSA)of transmission grid and distribution grid are not suitable to be studied separately.This paper presents a distributed continuation power flow method for VSA of global transmission and distribution grid.Two different parameterization schemes are adopted to guarantee the coherence of load growth in transmission and distribution grids.In the correction step,the boundary bus voltage,load parameter and equivalent power are communicated between the transmission and distribution control centers to realize the distributed computation of load margin.The optimal multiplier technique is used to improve the convergence of the proposed method.The three-phase unbalanced characteristic of distribution networks and the reactive capability limits of DGs are considered.Simulation results on two integrated transmission and distribution test systems show that the proposed method is effective.
文摘To solve the problem of permanent-shadow shading of photovoltaic buildings,a maximum power point tracking(MPPT)strategy to determine the search range by pre-delimiting area is proposed to improve MPPT efficiency.The single correspondence between the solar-cell current-voltage(I-V)curve and the illumination conditions was proved by using the single-diode model of photovoltaic cells,thus proving that a change in the illumination conditions corresponds to a unique maximum power point(MPP)search area.According to the approximate relationship between MPP voltage,current and open-circuit voltage and short-circuit current of a photovoltaic module,the voltage region where the MPP is located is determined and the global maximum power point is determined using the power operating triangle strategy in this region.Simulation carried out in MATLAB proves the correctness and feasibility of the theoretical research.Simulation results show that the MPPT strategy proposed in this paper can improve the average efficiency by 1.125%when applied in series as building integrated photovoltaics.
文摘基于上海一独立住宅光伏发电系统运行一年的数据,从发电量、光伏系统效率、光伏能源替代率、光伏系统效率影响因素等方面进行后评估。结果表明:过去一年度理论预测年发电量为5 738 k W·h,实际发电量为4 109 k W·h,全年度光伏系统效率为73%。为研究光伏系统效率的影响因子,在系统运行期间未对光伏组件表面实施人工清洁维护,对此条件下的运行数据进行分析发现,光伏系统效率总体呈现逐渐降低的趋势。其中在近水平安装角度的情况下,组件光电转换效率最大降低达2.08%。在该住宅按照现行理想的设计条件运行(冬季连续采暖确保室内20℃、夏季连续空调确保室内26℃)的前提下,过去一年度的总用电量为12 054 k W·h,其中空调用电量为9 332 k W·h,占到总用电量的77.4%。全年光伏能源替代率为34%,过渡季节可实现光伏能源替代率最高达180%。独立住宅上存在较大的节能空间和光伏能源替代率提升空间。
