This study analyzes the process of electric power system integration in various regions worldwide.This process is implemented by creating both interstate electric ties and power grids.The analysis is comprehensive and examines the system, spatial, technical, organizational, and market aspects of the integration.Various countries, including developed countries such as Europe and North America, as well as economically developing countries such as Central America and Africa, are involved in this process.However, the rates and scales of electric power integration differ across various regions worldwide.The analysis shows that the process of electric power integration, which has decades of history, is still ongoing,despite the growth of other trends, such as the development of distributed generation.Further electricity integration is expected to lead to the formation of a global power interconnection in the long term.

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The energy sector has an essential role in limiting the global average temperature increase to below 2 °C.Redirecting and advancing technological progress contribute to carbon-free transition solutions.Energy transition is currently one of the most debated issues in the world.This paper reviews and summarizes the current policy projections and their assumptions organized by some major countries in the energy sector, particularly in the coal sector, and provides a detailed discussion on specific and significant socio-technical pathways taken by countries to achieve zero-carbon targets.Their implementation involves restructuring the existing energy system and requires appropriate policy support and sufficient investment in infrastructure development and technological innovation.Some basic principles and countermeasures that have already been implemented by some major emitters, such as India and China, are also discussed, with different transformation pathways.Critical suggestions are also provided, such as implementing best practice policies at the national level, moving to more efficient transition strategies, national and regional cooperation, cross-border energy grid integration,and private sector involvement to reduce carbon emissions from coal-fired power plants, not only by reducing coal consumption but also by introducing various low carbon technologies.

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To achieve carbon neutrality by 2060, decarbonization in the energy sector is crucial.Hydrogen is expected to be vital for achieving the aim of carbon neutrality for two reasons: use of power-to-hydrogen (P2H) can avoid carbon emissions from hydrogen production, which is traditionally performed using fossil fuels; Hydrogen from P2H can be stored for long durations in large scales and then delivered as industrial raw material or fed back to the power system depending on the demand.In this study, we focus on the analysis and evaluation of hydrogen value in terms of improvement in the flexibility of the energy system, particularly that derived from hydrogen storage.An electricity–hydrogen coupled energy model is proposed to realize the hourly-level operation simulation and capacity planning optimization aiming at the lowest cost of energy.Based on this model and considering Northwest China as the region of study, the potential of improvement in the flexibility of hydrogen storage is determined through optimization calculations in a series of study cases with various hydrogen demand levels.The results of the quantitative calculations prove that effective hydrogen storage can improve the system flexibility by promoting the energy demand balance over a long term, contributing toward reducing the investment cost of both generators and battery storage and thus the total energy cost.This advantage can be further improved when the hydrogen demand rises.However, a cost reduction by 20% is required for hydrogen-related technologies to initiate hydrogen storage as long-term energy storage for power systems.This study provides a suggestion and reference for the advancement and planning of hydrogen storage development in regions with rich sources of renewable energy.

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With the release of the electricity sales side, large-scale small-capacity distributed power generation units are connected to the distribution side, forming multi-type market entities such as microgrids, integrated energy systems, and virtual power plants.With the large-scale integration of distributed energy, the energy market under the energy internet is different from a traditional transmission grid.It is currently developing in the direction of diversified entities and commodities,a flat structure, and a flexible and competitive multi-agent market mechanism.In this context, this study analyzes the value of combining blockchain and the electricity market presents the design of a blockchain trading framework for multi-agent cooperation and sharing of the energy internet.The nodes in market transactions are modeled through power system modeling in the physical layer and the transaction consensus strategy in the cyber layer; moreover, the nodes are verified in a modified IEEE 13 testing feeder of a distribution network.A transaction example is demonstrated using the multi-agent cooperation and sharing transaction platform based on the Ethereum private blockchain.

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China has set carbon emission goals for 2030 and 2060.Renewable energy sources, primarily wind and photovoltaic power, are being considered as the future of power generation.The major limitation to the development of new energies is the limited flexibility of regulations on power system resources, resulting in insufficient consumption capacity.Thus, the flexible resource costs for peak shaving as well as the reasonable coordinated development and operation optimization of regional renewable energy need to be considered.In this study, a renewable energy development layout configuration analysis method was established by considering the composite cost of a power system, comprehensively analyzing the potential of various flexibility regulation resources for the power system and its composite peak shaving cost,and combining renewable energy output characteristics, load forecasting, grid development, and other factors.For the optimization of various flexible resource utilization methods, a peak shaving cost estimation method from the perspective of the entire power system was established by combining the on-grid electricity prices and operating costs of different power sources.A collaborative optimization model of power system operation that aims at the lowest peak shaving cost and satisfies the constraints of operation, safety, and environmental protection was proposed.Finally, a certain area of Gansu Province was used as an example to perform detailed analysis and calculation, which demonstrated that the model has an optimal effect.This model can provide an analysis method for regional renewable energy development layout configurations and system optimization operations.

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Three-dimensional numerical simulations for a solar chimney power plant (SCPP) and wind supercharged solar chimney power plant (WSSCPP) based on the Spanish prototype using the solar ray-tracing algorithm were performed to study the shadow effect of the chimney.The area of the shadow region increases with an increase in the incident angle of the solar rays.A parametric study was performed by varying the incident angle from 0° to 30°.The temperature and velocity distributions at different incident angles were analyzed.In addition, we investigated the chimney shadow effect in several comprehensive SCPP systems.The findings show that the turbine shaft powers of the SCPP and WSSCPP were reduced by 22.4% and 13.7%, respectively, when the incident angle increased from 0° to 30°.In conclusion, it is important to consider the chimney shadow effect when estimating the performance in the design and cost analysis of SCPP systems.

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The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency and variability of power outputs from numerous distributed renewable generators could significantly jeopardize the secure operation of the distribution system.Therefore, it is necessary to assess the hosting capability for intermittent distributed generation by a distribution system considering operational constraints.This is the subject of this study.An assessment model considering the uncertainty of generation outputs from distributed generators is presented for this purpose.It involves different types of regulation or control functions using on-load tap-changers (OLTCs), reactive power compensation devices, energy storage systems, and the reactive power support of the distributed generators employed.A robust optimization model is then attained It is solved by Bertsimas robust counterpart through GUROBI solver.Finally, the feasibility and efficiency of the proposed method are demonstrated by a modified IEEE 33-bus distribution system.In addition, the effects of the aforementioned regulation or control functions on the enhancement of the hosting capability for intermittent distributed generation are examined.

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Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current (DC) power adjustment.Based on a converter steady-state model and a DC power model, the control angle constraints of a converter valve are relaxed for power regulation.In this paper, a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle, reactive power compensation, and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.

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Life-cycle cost (LCC) theory can be effectively applied to improve the efficiency and quality of power plant equipment and asset management.However, specific aspects of the LCC calculation and evaluation model require further research for practical application.This paper proposes an LCC assessment model for the management of electric power plant equipment during its service life.A membership function method based on fuzzy logic is used to improve the allocation of modernization and overhaul projects to multiple equipment assets.An LCC assessment model and evaluation system for power equipment are proposed and successfully applied to the equipment and project management of a Guangzhou power plant in the China Southern Power Grid, providing a decision-making mechanism that facilitates efficient operation and optimal utilization of power plant equipment and assets.

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