Freshwater resources and energy are the two material foundations of human survival and the two challenges for human sustainable development.China's huge population needs a large amount of freshwater for basic necessities.Desalination is an intelligent and promising technology for increasing water resources to realize a sustainable supply of freshwater.However,high levels of energy consumption and greenhouse gas emissions have restricted the development of desalination.Solar energy has the unique advantage that it can be harnessed in different forms.This paper discusses the water resources and solar energy utilization status in China and presents a comprehensive review on a possible solution:coupling desalination technologies with sustainable energy.China's desalination market is reviewed,and the energy consumption for several desalination processes is summarized to present a brief outlook of desalination techniques in China.Potential coupled methods for solar-powered desalination are compared.This study will facilitate understanding of the latent water crisis in China and help China's desalination market transition from conventional energy sources to choose an appropriate solar-powered desalination process.

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This paper describes the results of cost-profit analysis related to interconnectors for Japan-Russia and Japan-South Korea based on the Asia International Grid Connection Study Group 2nd report.The Group has been established in 2016 for conducting research on international electric power networks in Asia from the viewpoint of technology,investment and legal framework.2nd report of the Group was published in June 2018,examining the profitability of an interconnectors between Japan and neighboring countries.The Group has calculated expected profit from operation of these interconnectors.

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Environmental problems caused by traditional power production and the unbalanced distribution of energy resources and demand limit the development of sustainable societies.A feasible method to optimize the resource allocation has been proposed,and it involves cross-border and cross-regional electricity transactions.However,the uncertainty of renewable energy and the specific features of the cross-border electricity market are key issues which need to be considered in the trading mechanism design.Based on this,this paper sets up a long-term cross-border electricity trading model considering the uncertainty of renewable energy.First,annual transactions are matched according to the declared data of bidders with consideration of cross-border interconnection development benefits,potential benefit risks,and transmission costs.Second,for annual contract decomposition,the model uses the minimum generation cost function with a penalty item for power shortages to allocate electricity to each month.Additionally,the scenario reduction algorithm is combined with the unit commitment to construct a stochastic generation plan.Finally,a case study of the numerical results for the multinational electricity market in northeast Asia is used to show that the proposed trading model is feasible for cross-border electricity trading with high penetration of renewable energy.

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Because of the realization of HVDC connections parallel to the synchronous grid in Germany,operational concepts become more important in the context of system security aspects.In this article commonly known concepts are analyzed regarding their suitability for the German transmission system.Therefore,an approach for the analysis was developed and exemplary results are given using this approach.Under consideration of the overall system,the concepts of reducing losses in combination with minimizing (n-1)-warnings or -indications1 as well as the sole minimization of (n-1)-warnings and-indications are the most reasonable approaches.However,under grid security aspects best results can be achieved by reducing operational limits and therefore,by the minimization of (n-1)-warnings.

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This paper describes route designs and cost estimation for possible interconnections between Japan-Russia and between Japan-South Korea based on the Asia International Grid Connection Study Group 2nd report.The Group has conducted a desktop study to design several cable routes as possible options.To optimize the route,the group studied a wide range of open data,regarding sea depth,fishery zones,geographic condition,available transmission capacity in connecting points inside Japan and so on.

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This paper deals with power quality improvement using a three-phase active power filter (APF) connected to a PV power system.A direct power control (DPC) approach is proposed to eliminate harmonic current caused by any nonlinear loads and at the same time guarantees the delivery of a part of the load request from the same PV source.A boost converter is used for maximum power point (MPP) tracking purposes under various climate conditions through a fuzzy logic technique.The suggested study is tested under a MATLAB/Simulink environment.The obtained results depict the efficacy of the proposed procedures to meet the IEEE 519-1992 standard recommendation on harmonic levels.

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The demand for fast charging is increasing owing to the rapid expansion of the market for electric vehicles.In addition,the power generation technology for distributed photovoltaic has matured.This paper presents a design scheme for a fast charging station for electric vehicles equipped with distributed photovoltaic power generation system taking the area with certain conditions in Beijing as an example construction site.The technical indexes and equipment lectotype covering the general framework and subsystems of the charging station are determined by analyzing the charging service demand of fast charging stations.In this study,the layout of the station is developed and the operation benefits of the station is analyzed.The design scheme realizes the design objective of “rationalization,modularization and intelligentization”of the fast charging station and can be used as reference for the construction of a fast charging network in urban area.

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The development of electrical engineering and electronic,communications,smart power grid,and ultra-high voltage transmission technologies have driven the energy system revolution to the next generation:the energy internet.Progressive penetration of intermittent renewable energy sources into the energy system has led to unprecedented challenges to the currently wide use of coal-fired power generation technologies.Here,the applications and prospects of advanced coal-fired power generation technologies are analyzed.These technologies can be summarized into three categories:(1) large-scale and higher parameters coal-fired power generation technologies,including 620/650/700 °C ultra-supercritical thermal power and double reheat ultra-supercritical coal-fired power generation technologies; (2) system innovation and specific,highefficiency thermal cycles,which consist of renewable energy-aided coal-fired power generation technologies,a supercritical CO2 Brayton cycle for coal-fired power plants,large-scale air-cooling coal-fired power plant technologies,and innovative layouts for waste heat utilization and enhanced energy cascade utilization; (3) coal-fired power generation combined with poly-generation technologies,which are represented by integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) technologies.Concerning the existing coal-fired power units,which are responsible for peak shaving,possible strategies for enhancing flexibility and operational stability are discussed.Furthermore,future trends for coal-fired power plants coupled with cyber-physical system (CPS) technologies are introduced.The development of advanced,coal-fired power generation technologies demonstrates the progress of science and is suitable for the sustainable development of human society.

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Previous studies have proposed higher requirements for the transient characteristics of a DC transformer used in a flexible high-voltage direct current (HVDC) system to achieve faster sampling speed and meet wider bandwidth requirements of the control and protection signal,and to eventually suppress the large transient fault current.In this study,a transient characteristics verification method is proposed for transient characteristics verification of a DC transformer used in a flexible HVDC system based on resampling technology and LabVIEW measurement technology after analyzing the key technology for transient characteristics verification of a DC transformer.A laboratory experiment for the transient characteristics of a full-fiber electronic DC transformer is conducted,and experimental results show that such verification method can be employed for frequency response and step response verification of a DC transformer at 10% of the rated voltage and current,and can eventually improve the screening of a DC transformer.

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Heating by electricity rather than coal is considered one effective way to reduce environmental problems.Thus,the electric heating load is growing rapidly,which may cause undesired problems in distribution grids because of the randomness and dispersed integration of the load.However,the electric heating load may also function as an energy storage system with optimal operational control.Therefore,the optimal modeling of electric heating load characteristics,considering its randomness,is important for grid planning and construction.In this study,the heating loads of distributed residential users in a certain area are modeled based on the Fanger thermal comfort equation and the predicted mean vote thermal comfort index calculation method.Different temperatures are considered while modeling the users' heating loads.The heat load demand curve is estimated according to the time-varying equation of interior temperature.A multi-objective optimization model for the electric heating load with heat energy storage is then studied considering the demand response(DR),which optimizes economy and the comfort index.A fuzzy decision method is proposed,considering the factors influencing DR behavior.Finally,the validity of the proposed model is verified by simulations.The results show that the proposed model performs better than the traditional method.

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