- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Assessing the effectiveness of Chinaa??s net-metering subsidies for household distributed photovoltaic systems
摘要： Consumer incentives play a vital role in promoting the adoption of renewable energy technology. In China, the government implemented a single, nation-wide net-metering subsidy to cultivate the distributed photovoltaic electricity generation market in 2013 and then had to reduce it twice due to the falling cost of photovoltaic modules and the large resultant financial gap. The aim of this study was to evaluate whether these subsidy adjustments were accurate, and also to identify the factors affecting the subsidy design. We applied a techno-economic evaluation to examine the actual market performance of China’s household distributed photovoltaic system in five typical cities with different levels of solar radiation and electricity consumption patterns, and then investigated the subsidy policy’s effectiveness through a cost-benefit analysis. The results show that a 3e7 kW photovoltaic capacity in different regions of solar radiation can meet the residential electricity demand. We found that the examination of net-metering effectiveness should consider both regional difference in solar radiation and the different levels of electricity demand. Additionally, the cost-benefit analysis also indicated that a reasonable, regionally differentiated metering subsidy should be in the range of 0.05e0.27 yuan/kWh.
关键词： Cost-benefit analysis,Distributed photovoltaic power generation,Techno-economic evaluation,Net-metering policy
更新于2025-09-23 15:19:57
-
Photovoltaic power forecast using empirical models and artificial intelligence approaches for water pumping systems
摘要： The solar water pumping system is one of the brightest applications of solar energy for its environmental and economic advantages. It consists of a photovoltaic panel which converts solar energy into electrical energy to operate a DC or AC motor and a battery bank. The photovoltaic power fluctuation can affect the water pumping system performances. Thus, the photovoltaic power prediction is very important to ensure a balance between the produced energy and the pump requirements. The prediction of the generated power depends on solar irradiation and ambient temperature forecasting. The purpose of this study was to evaluate various methodologies for weather data estimation namely: the empirical models, the feed forward neural network and the adaptive neuro-fuzzy inference system. The simulation results show that the ANFIS model can be successfully used to forecast the photovoltaic power. The predicted energy was used for the solar water pumping management algorithm.
关键词： water pumping system management,photovoltaic power,empirical models,forecast,artificial neural network,neuro fuzzy inference system
更新于2025-09-23 15:19:57
-
Performance Problem of Current Differential Protection of Lines Emanating from Photovoltaic Power Plants
摘要： The amplitude and phase angle of the fault current in photovoltaic power plants (PVPPs) are significantly influenced by the control system of the grid-connected inverters, unlike in a conventional synchronous source. Hence, PVPPs may adversely affect the performance of the current differential protection designed for synchronous sources-based power grids. In order to study the performance problem of current differential protection on AC transmission lines, an analytical expression of the fault current in the PVPPs was deduced, and the fault current characteristic was extensively analyzed. Based on this analysis, the ratio of differential current over restraint current was initially derived in this study; this ratio is observed to be affected by the control system parameters, power grid system parameters, fault resistance, and fault types. Moreover, the dynamic characteristics of this ratio can be clearly observed based on a three-dimensional diagram. Furthermore, the operating performance of the current differential protection was analyzed under different influencing factors. The mathematical analysis presents that the amplitude ratio of the fault current on both sides of the line is larger than nine and that current differential protection will operate reliably in any case. Meanwhile, the theoretical analysis and simulation results show that the current phase angle difference may become an obtuse angle in case of an ungrounded fault, which will cause inaccurate operation of the current differential protection. The results of this study will provide guidance for the engineering application of current differential protection in case the PVPPs are connected to a power grid.
关键词： performance problem,photovoltaic power plants,current differential protection,fault current behavior
更新于2025-09-23 15:19:57
-
Number of maximum power points in photovoltaic arrays during partial shading events by clouds
摘要： This article presents a study of the number of maximum power points (MPPs) of photovoltaic (PV) module arrays during partial shading events by clouds. Around 9000 shadow edges were identified in measured irradiance data, and the electrical characteristics of 250 to 500 PV module arrays with different configurations were studied during the irradiance changes. It was found that most of the partial shading events caused by clouds do not cause multiple MPPs for PV arrays, even for a moment. The number of MPPs was found to decrease with the increasing number of parallel-connected PV strings, but to increase strongly with the increasing length of the strings. According to the results, the use of a total-cross-tied electrical PV array configuration leads to worse system performance compared to a simple series-parallel configuration during partial shading events. Dark shadows with sharp edges moving parallel to the PV strings caused the largest MPP numbers, up to 20. The results show that energy losses due to operation at a local MPP instead of the global one during partial shading events by clouds have only a minor effect on the total energy production of PV arrays.
关键词： Maximum power point,Photovoltaic Array,Partial shading,Irradiance change,Photovoltaic power generation
更新于2025-09-19 17:13:59
-
P-Q capability chart analysis of multi-inverter photovoltaic power plant connected to medium voltage grid
摘要： This paper presents the proposal of the methodology for the development of realistic P-Q capability chart at point of common coupling of photovoltaic power plant, comprised of multiple inverter units and connected to medium voltage grid. Theoretical equations for the contribution to the total active and reactive power of the plant are derived for all plant components: inverters, low voltage cables, transformers, medium voltage cables and auxiliary consumption. It is concluded that equations for total active and reactive power are dependable on only two changing variables: voltage and momentary generation power of inverters. Equations for maximum and minimum values for total active and reactive power are further derived when known maximum and minimum values of changing variables are entered to equations, and these are presented on graph diagram as curves. Area in P-Q diagram within such calculated border curves is area of possible power plant operation points at the point of common coupling. Such representation model of this type of plant has not been proposed before. The proposed methodology has been applied to the case study plant and its operation P-Q diagram is constructed Measurements conducted on this case study plant are compared with calculated values for necessary corrections to the model.
关键词： Multi-inverter,Medium voltage grid,P-Q capability chart,Photovoltaic power plant,Reactive power
更新于2025-09-19 17:13:59
-
Frequency support from photovoltaic power plants using offline maximum power point tracking and variable droop control
摘要： With higher penetration of converter-connected renewable energy sources (RES) into power systems, the successful operation of the system is challenged by significant reductions in system inertia. Presently, given the dominant share of the conventional synchronous power plant, RES power plants are not demanded to provide ancillary services. However, as RES connections increase, RES power plants will play a major role in power system operation, contributing to frequency control. This study demonstrates that photovoltaic power plants (PVPPs) can provide effectively different types of frequency support based on a power reserve and an offline maximum power point tracking (MPPT) technique. An innovative method to de-load the PVPP without significantly increasing the MPPT complexity is proposed. Results from different PVPP frequency support methods, under varying levels of photovoltaic penetration, are presented which demonstrate their capability to provide inertia support comparable to that of synchronous generators. A new variable droop control method, which releases maximum power during the inertial response and returns to fixed droop gain value after a specified time is also presented. The results from using the variable droop show that the frequency nadir and the rate-of-change-of-frequency can be significantly reduced and some power reserve still maintained after a frequency event.
关键词： variable droop control,offline maximum power point tracking,photovoltaic power plants,system inertia,frequency support,renewable energy sources
更新于2025-09-19 17:13:59
-
[IEEE 2019 Chinese Automation Congress (CAC) - Hangzhou, China (2019.11.22-2019.11.24)] 2019 Chinese Automation Congress (CAC) - Research on Reactive Power Optimization Control Strategy of Distribution Network with Photovoltaic Generation
摘要： What the thesis studies is the active and reactive decoupling control method of photovoltaic grid-connected inverter, and then the reactive power of grid-connected inverter is optimized by genetic algorithm with the objective of minimizing network loss, So as to realize reactive power optimization control of the photovoltaic power generation system.An algorithm based on genetic algorithm for reactive power optimization of photovoltaic power generation and distribution network is proposed.A mathematical model for reactive power optimization of distribution network has been established. The mathematical model those of photovoltaic power generation system Considering the limits of not only minimum network loss but also node voltage, what is used to optimize the reactive power of photovoltaic power generation is genetic algorithm. The example simulation results indicate the designed optimization algorithm is effective and correct in reducing power loss and improving voltage quality.
关键词： Photovoltaic power generation,Grid-connected inverter,Genetic algorithm,Reactive power optimization
更新于2025-09-19 17:13:59
-
[IEEE 2019 IEEE 2nd International Conference on Automation, Electronics and Electrical Engineering (AUTEEE) - Shenyang, China (2019.11.22-2019.11.24)] 2019 IEEE 2nd International Conference on Automation, Electronics and Electrical Engineering (AUTEEE) - Voltage Influence Analysis of Photovoltaic Grid Connection under Ring Network Structure
摘要： Large-scale grid-connected photovoltaic power supply will impact the operation of the grid, resulting in voltage fluctuations, at the same time, harmonic injection will affect the distribution of harmonic voltage in the system. Based on the theoretical analysis and demonstration of the voltage deviation caused by the photovoltaic power supply connecting to the feeder of 10kV distribution network and the influence of the total harmonic distortion rate THDu.
关键词： photovoltaic power generation,voltage fluctuation,power flow reversal,distribution network,voltage jump
更新于2025-09-19 17:13:59
-
A Techno-economic Approach for Increasing the Connectivity of Photovoltaic Distributed Generators
摘要： High penetration of distributed generation (DG) results in technical problems as voltage rise, voltage unbalance, substation reverse power, and transformer overloading. These problems adversely affect the connectivity of DGs either in the planning stage by decreasing the number of connected DGs, or in the operation stage by applying DGs’ active power curtailment (APC). This paper presents a techno-economic approach for the enhancement of photovoltaic (PV) DGs connectivity. The proposed approach firstly employs a probabilistic economic technique for determining the non-curtailable portion of the PV DG power that ensures profitable DG investment. This portion is integrated, as an economic constraint, in the planning phase of the proposed approach that aims to maximize the number of PV DGs connected to the system. In the operation phase, the proposed approach utilizes the capabilities of the existing equipment on the system; i.e. regulators, capacitors, DGs reactive power, and DGs APC to mitigate all technical problems. The overall objective of this stage is to minimize the total DGs APC while fulfilling all technical and economic constraints. The proposed approach is tested on the modified IEEE 123-bus feeder. The results clarify the efficiency of the proposed techniques in increasing the connectivity of PV DGs while maintaining profitable DG project.
关键词： Distributed generators,voltage control,economic assessment,Photovoltaic,power curtailment
更新于2025-09-19 17:13:59
-
What is the future policy for photovoltaic power applications in China? Lessons from the past
摘要： Over the past decades, a series of policies and regulations have been formulated to encourage photovoltaic (PV) development in China. The phenomena of “subsidy deception” and “PV power curtailment and brownout” indicate the policies have encountered problems in implementation. A large gap between subsidies and renewable funds has compelled the Chinese government to gradually withdraw subsidy policy. As such, investors are focusing on assessing China’s future policies for PV application. To determine the reasons for the implementation problems and to seek solutions, this study summarized existing PV power application policies and established a two-dimensional framework to analyze these policies, using a content analysis. We found the government relies too much on the state’s macroeconomic control, and does not fully play the role of “invisible hand” in PV power applications. Supply-type and environment-type policies are widely used, making up almost 80% of the total. To fully enable the market’s role, it is necessary to reinforce demand-type policies and improve green certification transactions. These are forms of incentive policies instead of subsidies.
关键词： Content analysis,Photovoltaic power,Policy instrument,Project lifecycle
更新于2025-09-19 17:13:59