Vigorously developing global renewable energy such as wind energy, solar energy, and hydropower and realizing global clean resource sharing are paramount driving forces for building the Global Energy Interconnection (GEI).With the help of a comparative analysis of renewable energy development and global renewable energy development scenarios, this paper expounds on the similarities between China1 and global renewable energy development.Based on the analysis of renewable energy development and the status of global renewable energy development in China, this paper summarizes the relevant experience and problems of renewable energy development in China.According to these problems, this paper also puts forward the corresponding solutions and measures, that is, to promote the healthy and steady development of renewable energy in China through the source-network-load-storage and market coordination.Finally, by analyzing the development requirements and current foundation of GEI, insights and suggestions are proposed for the future development of renewable energy for the GEI construction.

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There have been few studies on the hydropower exploitation plan for sections beyond the Inga hydropower project (HPP) in the lower reaches of the Congo River.Based on topographic and hydrological data of the basin, the exploitation plan for the lower reaches of the Congo River is herein studied.The preliminary proposal involves exploitation using threecascade hydropower stations.The Grand Inga HPP is the core of the mega hydropower base.The full supply level (FSL) of the reservoir, installed capacity, and regulation performance of the Grand Inga HPP are studied in detail.The main advantages and disadvantages of the high and low dam schemes of the Grand Inga Hydropower Project are compared, in addition to their effects on the overall development of the hydropower base.Moreover, the installed capacity is optimized based on the load characteristics.Based on simulation of cascade hydropower operation and comprehensive analysis, the project scale and implementation sequence is proposed.The influence of hydropower on socio-economic development, energy supply, and emission reduction is analyzed.Finally, the optimal exploitation scheme of the mega hydropower base for the lower reaches of the Congo River is proposed.

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Cross-border grid interconnection is a critical means to achieve wide-area share of hydro and other clean energy.Economic benefit assessment of cross-border grid interconnection projects should be carefully performed during early stage.In this paper, a method based on cost-benefit economic assessment for optimal planning of cross-border grid interconnection is proposed.An economic index for comprehensively assessing the cost of a transmission project and its resulting benefits of more usage of hydro energy is designed first.A chronological production cost simulation model considering hydro energy spillage due to transmission congestion and thermal operational limitation is then proposed to calculate the economic index.A case study is performed using the proposed method to determine the optimal capacity of a potential transmission link between Brazil and Argentina, which have rich and complementary hydro energy resources.

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The construction of intercontinental power grid interconnection projects is key to realizing the vision of Global Energy Interconnection, which is to solve global energy problems in a clean and sustainable manner.These projects may be influenced by a few factors that are neither technological nor economic, such as political, social, and international factors.This paper thus presents a multi-level model for recognizing which factor from a compiled list of 14 would impact a particular intercontinental interconnection project and for assessing the degree of the factor’s influence.In the first part of the model, the Analytic Hierarchy Process (AHP) method is used to recognize the project’s most significant impact factors.Using the recognition results, the second part of the model can assess the degree of the factor’s influence on the project based on ratings provided by experts.A comprehensive evaluation can thus be provided.As a case study, the proposed Saudi Arabia-Ethiopia power grid interconnection project connecting Asia and Africa was analyzed.Derived from a combination of multiple opinions from experts, evaluations from the model will be of direct benefit to decision-makers, investors, project implementers, and engineers, providing them with a deeper insight into the project.

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When a maintenance and operations ship is berthing, there is a chance the ship may collide into the wind turbine.When these ships collide into wind turbine structures, this can result in significant changes to the foundation and structure of the wind turbine.In this paper, the structural load of a 4 MW offshore wind turbine was analyzed during a collision with an operations and maintenance ship.The variations in the wind speeds on hub height, waves, and the sea currents were measured.The dynamic simulation of the wind turbine was carried out using the test data as the input parameters.As a result, the load condition of the turbine without a collision was obtained.Finally, the measured turbine load was compared with the simulation results.This study shows that the collision of the operation and the maintenance ship increases the bending moments at the tower’s bottom and the blade’s roots.

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Due to the characteristics of intermittent photovoltaic power generation and power fluctuations in distributed photovoltaic power generation, photovoltaic grid-connected systems are usually equipped with energy storage units.Most of the structures combined with energy storage are used as the DC side.At the same time, virtual synchronous generators have been widely used in distributed power generation due to their inertial damping and frequency and voltage regulation.For the PV-storage grid-connected system based on virtual synchronous generators, the existing control strategy has unclear function allocation, fluctuations in photovoltaic inverter output power, and high requirements for coordinated control of PV arrays, energy storage units, and photovoltaic inverters, which make the control strategy more complicated.In order to solve the above problems, a control strategy for PV-storage grid-connected system based on a virtual synchronous generator is proposed.In this strategy, the energy storage unit implements maximum power point tracking, and the photovoltaic inverter implements a virtual synchronous generator algorithm, so that the functions implemented by each part of the system are clear, which reduces the requirements for coordinated control.At the same time, the smooth power command is used to suppress the fluctuation of the output power of the photovoltaic inverter.The simulation validates the effectiveness of the proposed method from three aspects: grid-connected operating conditions, frequency-modulated operating conditions, and illumination sudden-drop operating condition.Compared with the existing control strategies, the proposed method simplifies the control strategies and stabilizes the photovoltaic inverter fluctuation in the output power of the inverter.

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Solar photovoltaic (PV) power represents one of the most promising future sources of energy in the world.Considered the cleanest form of energy, extensive research is being undertaken to widen its use.Notably, mega projects are being considered for installation in the Middle East and North Africa (MENA) region because of its high solar potential, with hopes of eventually feeding Europe from the PV electricity generated in this region and transported through high voltage direct current (DC) lines.However, current implementation of PV systems has shown that their reliability and efficiency depend upon surrounding environmental factors, such as the ambient temperature, wind, and rainfall, as well as soiling, pollution, and aging.The aim of this study was to investigate, through experimental tests, the effects of such factors on the power output of a grid connected PV station.The results showed that the output power and efficiency are deeply affected by various environmental factors, which are weather dependent.These findings may help us develop appropriate solutions to overcome these drawbacks.

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The amount of solar PV installed capacity has steadily increased to 44.5 GW at the end of FY2017, since the introduction of the Feed in Tariff (FiT) to Japan in 2012.On the other hand, since the first curtailment of solar PV was conducted on October 13th, 2018 in the Kyushu area, the curtailment has been frequently executed including wind power after that.In this study, cross-regional interconnector and pumped hydro energy storage (PHES) are focused on mitigating curtailment.

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In order to promote the development of the Internet of Things (IoT), there has been an increase in the coverage of the customer electric information acquisition system (CEIAS).The traditional fault location method for the distribution network only considers the information reported by the Feeder Terminal Unit (FTU) and the fault tolerance rate is low when the information is omitted or misreported.Therefore, this study considers the influence of the distributed generations (DGs) for the distribution network.This takes the CEIAS as a redundant information source and solves the model by applying a binary particle swarm optimization algorithm (BPSO).The improved Dempster/S-hafer evidence theory (D-S evidence theory) is used for evidence fusion to achieve the fault section location for the distribution network.An example is provided to verify that the proposed method can achieve single or multiple fault locations with a higher fault tolerance.

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As part of the ongoing information revolution, smart power grid technology has become a key focus area for research into power systems.Intelligent electrical appliances are now an important component of power systems, providing a smart power grid with increased control, stability, and safety.Based on the secure communication requirements of cloud energy storage systems, this paper presents the design and development of a node controller for a cloud energy storage network.The function division and system deployment processes were carried out to ensure the security of the communication network used for the cloud energy storage system.Safety protection measures were proposed according to the demands of the communication network, allowing the system to run safely and stably.Finally, the effectiveness of the system was verified through a client-side distributed energy storage demonstration project in Suzhou, China.The system was observed to operate safely and stably, demonstrating good peak-clipping and valley filling effects, and improving the system load characteristics.

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