Photovoltaic Power Generation System Research Articles

Research on the adaptability of proton exchange membrane electrolysis in green hydrogen–electric coupling system under multi-operating conditions

The green hydrogen–electric coupling system can consume locally generated renewable energy, thereby improving energy utilization and enabling zero-carbon power supply within a certain range. This study focuses on a green hydrogen–electric coupling system that integrates photovoltaic, energy storage, and proton exchange membrane electrolysis (PEME). Firstly, the impact of operating temperature, power quality, and grid auxiliary services on the characteristics of the electrolysis cell is analyzed, and a voltage model and energy model for the cell are established. Secondly, a multi-operating conditions adaptability experiment for PEME grid-connected operation is designed. A test platform consisting of a grid simulator, simulated photovoltaic power generation system, lithium battery energy storage system, PEME, and measurement and acquisition device is then built. Finally, experiments are conducted to simulate multi-operating conditions such as temperature changes, voltage fluctuations, frequency offsets, harmonic pollution, and current adjustment speed. The energy efficiency and consumption is calculated based on the recorded data, and the results are helpful to guide the operation of the system.

Agricultural Grid Connected Photovoltaic System Design and Simulation in Egypt by using PVSYST Software

Agricultural Photovoltaic Systems are a key technology to achieve sustainable development goals by reducing competition between land for food and electricity. In addition, Agricultural Photovoltaic Systems are at the heart of the link between power generation, crop production and irrigation water conservation. The main ecophysiological constraint on crop production under photovoltaics is the reduction of light. It is difficult to recommend shade tolerance for some plant varieties due to insufficient information on shading conditions for most plants. The use of shading panels (photovoltaic panels) requires more crop-specific research to determine the optimal percentage of panels and their placement that will not reduce agricultural yields. Crop yield variation versus field shading and availability to maximize the system require extensive research. This study aims to develop a standard procedure for designing an agricultural grid-connected photovoltaic power generation system for solar power generation in an agricultural area in Bahteem, Egypt. The technical and annual performance of the grid-connected PV system was simulated using PV Syst software. The paper started with a pre-feasibility study of a grid-connected photovoltaic system using PV Syst. Software with an extensive database of meteorological data, including global daily horizontal solar irradiance, and a database of various renewable energy system components from different manufacturers. In this work, a comprehensive literature review of agricultural solar photovoltaic systems is conducted, with a particular focus on grid-connected systems, followed by a design procedure for grid-connected solar photovoltaic systems. The planned photovoltaic system will generate a total of 400 KWp of electricity. This generated electricity can drive down electricity prices by exporting excess electricity to the national grid. In addition, solar power systems are fuel-efficient and have a low environmental impact.

Study on the application of photovoltaic power generation systems in field observatories under the zero carbon goal

Emissions of greenhouse gases such as CO2 are rapidly increasing, causing the greenhouse effect, leading to global warming and serious impacts on the ecosystem, while photovoltaic power generation can reduce the large amount of pollutants and carbon emissions produced in the traditional power generation process. The article takes the photovoltaic power generation system of the national field observatory as the research object, and uses PVsyst software to design the system of two distributed photovoltaic power generation systems. After calculating and analysing the total power of the experimental equipment, the efficiency of photovoltaic power generation and the system cost of the field observatory, the scheme and scale of the photovoltaic power generation system are determined, and the construction of the photovoltaic power generation test system is completed. Finally, through the comparison and analysis of the one-year PV power generation data with the simulated data, the feasibility of the system design method is verified, which can meet the requirements of the field experimental station and create a zero-carbon field observatory to achieve green energy conservation and sustainable energy use, which is in line with the strategic development plan of carbon peaking and carbon neutrality promoted by the state and provides a design basis and useful reference for the construction of zero-carbon field experimental stations.

擬似ランダム信号を推定信号として用いた三相インバータによる純抵抗負荷の推定

In recent years, the introduction of photovoltaic power generation systems has been increasing from the perspective of global warming countermeasures. However, there is a problem that it becomes difficult to adjust the supply and demand balance of electric power. Therefore, in this research, the inverter by using estimation signal estimates the load of the consumer, then we aim to adjust the supply-demand balance at the demand side. By the verification of experimental, three-phase inverter, which is assumed to be an industrial photovoltaic power generation system, estimates the load by using pseudo random binary sequence signal and two proposed methods. The load estimation results show that the error rate of the estimated resistance of each phase is within a few percent by using the two proposed methods, and the load estimation is achieved.

Photovoltaic-based energy system coupled with energy storage for all-day stable PEM electrolytic hydrogen production

Photovoltaic (PV) power generation coupled with proton exchange membrane (PEM) water electrolysis favors improving the solar energy utilization and producing green hydrogen. But few systems proposed focus on achieving all-day stable hydrogen production, which is important for the future large-scale hydrogen utilization. Herein, a PV-Battery-PEM water electrolysis system for hydrogen production was constructed. An energy management strategy (EMS) was proposed to achieve the goal of all-day stable hydrogen production, improve energy utilization efficiency and reduce light discard rate. The PV power generation system, battery system and PEM electrolyzer for hydrogen production system were first established by Matlab/Simulink platform. Then, the overall PV-Battery-PEM electrolyzer system for hydrogen production was constructed, and the effectiveness of EMS was verified. The energy efficiency of the system under different working conditions with and without battery for energy storage was analyzed. The results show that the proposed energy management strategy can meet the purpose of all-day stable hydrogen production. Under the same working conditions, the energy efficiency of the system with battery for energy storage increases by 2–4% compared with the system without battery for energy storage, which indicates that the addition of energy storage can improve the energy utilization and reduce the light discarding.

Research on MPPT control strategy based on the Perturbation observation method

About traditional disturbance observation of larger changes in the external environment, the need for successive change step length, thus slow convergence speed of the shortcomings, based on traditional disturbance observation method, will be the main factors influencing the photovoltaic battery power curve (temperature, light intensity) is introduced into the control strategy of, when external conditions change dramatically, the method can directly reach the optimal duty ratio near, in this way, the slow convergence speed of the traditional perturbation observation method is effectively improved, and the dynamic tracking performance is optimized. In Matlab/Simulink, the improved control strategy model is built to verify that the improved control strategy can significantly improve the convergence speed and efficiency of the photovoltaic power generation system under the working condition of large changes in temperature and external illumination intensity.

Active Power Backflow Suppression Strategy of Cascaded PV Solid-State Transformer Under Interphase Short-Circuit Fault Condition

Currently, the grid-tied guidelines all require large and medium-sized photovoltaic (PV) power stations to stay connected to the grid during low-voltage ride through (LVRT). However, three-phase cascaded PV solid-state transformer (SST) has the inherent active power backflow problem during asymmetric voltage sags, causing that H-bridge dc-bus voltages are out of control and that the converter will be disconnected from the grid because of overvoltage fault. The existing control strategy is capable of avoiding active power backflow in theory by injecting appropriate zero-sequence voltage, but the overmodulation range is larger during interphase short-circuit fault, weakening active power backflow suppression effect. For this issue, this article proposes a combined control method of positive–negative-sequence maximum–minimum harmonic zero-sequence voltage injection strategy and adaptive zero-sequence voltage compensation strategy, which can shrink effectively active power backflow range of three-phase cascaded PV SST, increasing its adaptability to different output powers and different grid drop depths, and then improving LVRT capability of the PV power generation system. Finally, a low-voltage and low-power experimental prototype is made to verify the effectiveness and feasibility of the proposed control strategy.

필터링이 적용된 이미지 증대 기법을 통한 태양전지 결함 탐지 시스템

The need for renewable energy is increasing due to problems such as environmental pollution and resource depletion. Solar energy is the largest type of renewable energy and is increasing. However, when a micro-crack is formed in a solar cell, it greatly affects the photovoltaic power generation system. This degrades the performance of the solar power system and can be easily damaged. In this paper, solar cell defects were detected through Electroluminescent (EL) images. The Vision Transformer-Huge model was used to extract solar cell defect features. In addition, the CIFAR-10 augmentation policy and Imagenet augmentation policy included in Auto-augment were used to increase the performance of the model for the small dataset. When using the augmentation policy, the characteristics of the solar cell defect may disappear from the data, so filtering was performed with the model learned from the original data. For filtering, only images with a prediction probability of 70% or more of augmented images through the Soft-max function were used. When comparing the performance of the proposed methods and the method learned with the original data, it showed excellent performance. As a result, the proposed model showed a performance improvement of about 5% based on accuracy, and a recall value of about 93% was obtained.

태양광 연계 에너지저장장치 내부 환경 특성 분석

This paper analyzed internal environmental impact of energy storage device facilities connected to the photovoltaic power generation system. The use of energy storage system is increasing for demanding in new renewable energy (photovoltaic power, wind power, etc.) and adjusting frequency regulation(FR) in system operation.BRSince fires are concentrated in energy storage systems for connection with renewable energy, it is necessary to find the cause of the fire through analysis of the on-site installation environment and operation. This paper analyzes the internal environmental characteristics of energy storage systems connected to photovoltaic power generation and proposes a safety plan.

Portable Photovoltaic Power Generation System for Applications along the Railway and Its Improved Efficiency by Automatic Dust Removal by Foldable Solar Energy Collector

To meet the demands of power supply for applications along the railway in treacherous terrain, this article proposes a portable photovoltaic power generation system (PVPGS) based on a foldable mechanism for applications along the railway. First, the designed system mainly consists of a foldable solar energy collector (FSEC) and an energy conduit. Dust deposited on the photovoltaic panels is reduced while the FSEC is being folded or unfolded. Moreover, the characteristics of dust particles, effects of natural dust on photovoltaic glass transmittance, and power of portable PVPGS are investigated. In addition, the mechanism on improving the power generation efficiency of PVPGS is analyzed. The results demonstrate that the designed foldable mechanism can contain the dust deposition on photovoltaic power loss within 4%. Finally, Chengdu city and Sichuan–Tibet Railway are selected for an application prospect, and the results show that the average annual power generation of one portable PVPGS can reach up to 16.7 kWh, which is enough to power sensors and other applications along the railway. Simulations, theoretical analyses, and experiments confirm the feasibility of using the proposed portable PVPGS to power applications along the railway.

Automatic coordination control technology of interconnected medium voltage direct current (MVDC) distribution network based on frequency deviation

The automatic coordination control technology of interconnected medium voltage direct current (MVDC) distribution network based on frequency deviation is studied to improve the influence of frequency deviation on the operation of MVDC distribution network. Firstly, two regional interconnected MVDC distribution networks are built, and connected and operated in parallel with the AC power grid through the medium voltage single-phase AC port, to realize the interconnection of different regions of the distribution network according to the MVDC feeder. Through the mutual power support of each division of the distribution network, the frequency of each division of the distribution network is the same, and the frequency deviation of each division is reduced. According to the zoning frequency characteristics of the interconnected MVDC distribution network, the control strategy of the flexible interconnection device and the control strategy of the photovoltaic power generation system are combined to realize the automatic coordinated control of the frequency deviation of the interconnected MVDC distribution network. The experimental results show that this technology can improve the frequency deviation of the interconnected MVDC distribution network, realize the automatic coordinated control of the distribution network, and the fluctuation range of the tie line power deviation in each region decreases significantly.

Evolutionary Game of Digital-Driven Photovoltaic–Storage–Use Value Chain Collaboration: A Value Intelligence Creation Perspective

In the context of “carbon neutral”, distributed energy, including photovoltaic power generation and energy storage systems, is developing rapidly. Meanwhile, the new generation of information technology, such as “Cloud computing, Big data, the Internet of things, Mobile Internet, AI, Blockchain”, is driving the digital transformation of the energy industry. Under digital drive, how the agents in the photovoltaic–storage–use value chain collaborate and create value intelligently is a question worthy of deep consideration. Firstly, the value creation mechanism and collaborative process of the digital-driven photovoltaic–storage–use value chain are analyzed from a value intelligence creation perspective. Secondly, the tripartite evolutionary game model of photovoltaic power generator, energy storage provider and user is established. Finally, the influencing factors of digital- driven photovoltaic–storage–use value chain collaboration are explored through a numerical simulation, and management suggestions are put forward. The study finds the following: (1) The behavior choice of each agent in the value chain will affect the decision of other agents. In particular, the photovoltaic power generator has a great influence on the cooperative willingness of other agents. To promote value chain collaboration, the guiding role of the photovoltaic power generator should be fully realized. (2) Agents on the value chain can use a variety of digital technologies to improve enabling benefits, which is conducive to promoting value chain collaboration. (3) The driving costs and potential risks are obstacles for value chain collaboration. Cost reduction and risk prevention are effective ways to improve the willingness of collaboration. (4) Reasonable incentive compensation mechanisms and information asymmetry punishment measures are the keys to enhancing collective willingness. This research provides theoretical support for photovoltaic–storage–use value chain collaboration from a value intelligence creation perspective.

Intelligent Prediction of Photovoltaic Power Generation Considering Uncertainty Measurement

Background As a renewable energy, solar energy has the advantages of being non-polluting, clean, and renewable. With the variability of solar radiation, the complexity of meteorological factors, and other uncertain changes, how to measure its comprehensive uncertainty is very important. Objective The inherent regularity of the uncertainty behavior of photovoltaic power generation is revealed by the change process of photovoltaic power generation. Methods Using the empirical wavelet transform (EWT), the uncertainty measurement was studied from the perspective of social physics, and an optimized intelligent prediction model (PSOBOA-LSTM) was proposed based on the uncertainty. Results The intelligent prediction model (PSOBOA-LSTM) has a better prediction effect and higher accuracy than other models, and reveals the internal mechanism of the photovoltaic power generation system from the perspective of physics and sociology. Conclusion Using the PSOBOA-LSTM model can better facilitate the power dispatching department to reasonably arrange conventional power generation, coordinate operations and make maintenance arrangements based on the predicted photovoltaic power generation, and solve problems arising from the connection between grid dispatching and photovoltaic power generation forecasting.

Research on the joint optimal allocation of hydropower, wind energy and photovoltaic power generation in the basin

To improve the constancy of hydropower, wind energy and photovoltaic hybrid power generation systems for power furnish to the grid, the joint optimal allocation of hydropower, wind, and photovoltaic is studied. Firstly, the goal of the highest load-matching degree of hydropower, wind energy, and photovoltaic power is put forward. Considering the constraints such as the maximum total power generation ability of hydropower, wind energy, and photovoltaic power generation and the water balance of the reservoir, a joint optimal allocation model of hydropower, wind energy, and photovoltaic power generation in the basin is created, and solved by a progressive optimization algorithm. An example is given to illustrate the influence of source load matching degree on optimal allocation, and the validity of this approach is verified. The simulation results indicate that during grid-connected operation, hydropower, wind energy and photovoltaic complementary power generation can ensure high electricity furnish reliability and deliver more stable power to the grid.

The Effect of the Fast Frequency Response of the Solar Energy System on the Power System Dynamic Frequency Evolution

The existence of a large-scale photovoltaic power generation system without any rotational inertia can deteriorate the frequency stability of the power system. The solar energy storage system consisted of photovoltaic power generation and the energy storage device with fast charge and discharge can provide fast frequency responses to the grid through the power electronics controls, and therefore improve the dynamic frequency security of the low-inertia system. This paper discusses the modeling and fast frequency controls, namely virtual inertia and droop control. The modified WSCC 9-bus system with high photovoltaic power penetration and low inertia serves to show the effects of the solar energy storage system’s fast frequency responses on the frequency evolutions of the new power system. The results show that in the low inertia system with large-scale photovoltaic power generation, the active power droop control of the solar energy storage system can decrease the frequency deviations, but may introduce low-frequency oscillations during the frequency evolution following a contingency; the virtual inertia control can depress both the rate of change of frequency as well as the oscillations during the frequency evaluation.

A novel power balance control scheme for cascaded H-bridge multilevel converters with battery energy storage

Battery energy stored quasi-Z source cascaded H-bridge based photovoltaic power generation system combines advantages of quasi-z-source inverter, cascaded H-bridge, and battery energy storage system. However, the battery state of charge imbalance between the cascaded H-bridge inverter modules would reduce the system's performance and efficiency and potentially cause the system to fail. An integrated control technique of adaptive state of charge balancing based on gain scheduling and three-phase power balance of third harmonic injection based on fundamental frequency whole zero sequences is suggested for the quasi-Z source cascaded H-bridge battery storage system. Based on the mathematical relationship between the instantaneous state of charge of battery energy stored quasi-z-source cascaded H-bridge and the voltage reference value, this method updates the proportional controller gain in each sampling period. It combines the third harmonic injection method based on the fundamental frequency zero sequence to select the optimal modulation ratio Mn. Rapid state of charge balancing is accomplished without overmodulation while increasing the power balance range and decreasing DC link voltage swings. The simulation results validate the method's usefulness. The simulation results validate the proposed control method for ensuring power distribution between each phase and achieving a balanced state of charge of the battery energy stored quasi-Z source cascaded H-bridge photovoltaic system's battery energy storage.

RL 부하 연동 단상 태양광 발전 시스템의 부하 전류 센서리스 무효 전류 보상기법

The PV (photovoltaic) system can be used with RL loads on the grid side. However, when RL Load is connected, the phase of the grid current and voltage will not match due to the reactive current component. The reactive current generated at this time can be compensated by the inverter. In the case of such a single-phase PV system, a total of two current sensors are used to detect the inverter output current and the RL load current. This paper proposes a compensation technique using one current sensor without using two current sensors in a single-phase photovoltaic power generation system connected with an RL load.

Optimal topology control of monitoring sensor network based on physical layer security for smart photovoltaic power system

In order to realize the intelligent management of photovoltaic power generation system, wireless sensor network (WSN) is considered as a promised solution. However, the energy of sensor nodes in WSN is limited and the security is not guaranteed. In order to prolong the service life of WSN and to improve the security of monitoring, this paper comprehensively considers the factors those affect the security and efficiency of WSN, such as transmission power, sensor association and the choice of Cluster Head (CH). Therefore, this paper proposes a joint sensor secure rate and energy efficiency optimization algorithm to obtain the optimal topology and transmission power design. Then, an effective iterative algorithm based on Block Coordinate Descent (BCD) technology is proposed to obtain the optimal solution to minimize the energy consumption of WSN and maximize the secure rate of sensor networks, thus ensuring the security and reliability of monitoring. Sensor association is modeled as a 0–1 multi-knapsack optimization problem. Different complexity methods are implemented to solve this NP-hard problem, and their performance are compared with simulations.

Impact of large-scale photovoltaic-energy storage power generation system access on differential protection of main transformer under symmetrical faults

The low voltage ride-through (LVRT) requirements demand large-scale photovoltaic (PV) power generation system remain connected to the grid during faults. It results in considerable impact on the characteristics of fault current. This paper combines charge-discharge characteristics of the energy storage (ES) with PV generation system to enhance the LVRT capability. Based on the inverter control strategy and specific LVRT requirements, fault current characteristics of the PV-ES power generation system is discussed in this paper. In order to analyze the fault characteristic, the fault current expression as three-phase short-circuit faults occurs on both sides of the main transformer is calculated. Furthermore, taking the winding connection of the transformer into account, the ratio of differential current to braking current is further derived to find out the factors influencing the performance of the transformer differential protection. It is found that factors influencing the transformer differential protection include the rated capacity of the PV-ES generation system, fault severity, the length of transmission line and so on. And as the rated capacity of the PV-ES power generation system increase, the transformer differential protection would experience reduced sensitivity or even do not trip. The findings of this paper can lay a foundation for further improvement of the transformer differential protection. The elaborate performance evaluation of transformer differential protection, including the operation condition of the second harmonic braking element, is presented and verified by simulation using MATLAB/Simulink.

Tips for Buildings Energy Saving: Results of Some Research

Increasing global warming is largely attributable to human activities. International strategies have already been implemented to reduce emissions to zero, thus reducing energy consumption. Given the current world situation and the rising costs of raw materials (gas and oil), it is incumbent on us to find savings solutions that can also be implemented in our own small way; there are many solutions, especially in the domestic sphere. In this paper, the focus is on building energy savings that can be achieved using modern technologies and starting with the simplest solutions. In particular, this paper shows how the conscious use of natural lighting can lead to significant electricity savings. Moreover, it describes the effect of innovative building insulation materials and the effect due to the installation of a local photovoltaic power generation system; at the end, it illustrates the new horizons that are opening with the introduction of new building control techniques. Some studies are also reported where the extent of achievable savings can be understood.