2018, 42(4):2-10. DOI: 10.7500/AEPS20170927008
Abstract:Effective access to energy, energy conversion, control and use is the core of modern civilization. Energy Internet, as a new reform of the energy system, connects distributed energy storage, conversion devices, multiple loads and other energy networks, such as cooling, thermal, power and gas system, to achieve two-way complementary energy and integration optimization. The key technologies are selected from multi-energy complementarity in Energy Internet as the research object. Firstly, the recent researches of multi-energy complementarity and integration are summarized. Then, based on the hybrid energy model, key technologies and challenges are summarized as well, such as system planning, intelligent control, cooperative control and interaction technology, comprehensive evaluation, information security system communication and energy trading services. Finally, in order to provide some research ideas for multi-energy complementarity and integration optimization, the future energy system in the multi-energy complementarity is prospected.
2018, 42(4):11-24. DOI: 10.7500/AEPS20171002004
Abstract:Breaking down the pattern of mutual separation between different energy systems and realizing the integration and coordination of multi-energy system(MES)is an effective way to solve the problem of renewable energy accommodation. Firstly, the research framework of the MES theory and method towards renewable energy accommodation is put forward. On the basis of the research mentioned above, the existing researches are reviewed and corresponding thinking is proposed from the perspectives of basic modeling, operation optimization and system planning. Next, the existing researches are categorized into two typical research objects which are the electric-thermal coupling distract MES and the electric-gas coupling cross-regional MES. The related key points of the research on MES towards renewable energy accommodation are reviewed and commented. Finally, the key scientific problems towards the renewable energy accommodation are summarized and the future directions of the research on MES is prospected.
2017, 41(4):20-28. DOI: 10.7500/AEPS20160802010
Abstract:Owing to the situation that the interconnection among multiple distributed energy systems and interaction among electric, heating and cooling system are not given full consideration, the planning of Energy Internet at user side based on the energy router is studied. The schematic structure along with mathematical models of each unit is proposed first. Then, the location of energy router in each energy local area network(LAN)and scope of each LAN are determined by the intra/interclass distance ratio being minimum and Voronoi coupled with the alternative location and allocation(ALA)where minimum comprehensive load moment is presented. In addition, based on the chronological load of typical days and with the lowest annual cost of facilities, operating, fuel, power trading and carbon tax as the objective, a mixed-integer linear programming model is built to get synchronized configuration of the energy router and optimization of network among energy LANs. And multi-energy interaction and multi-energy router coordination are considered in the above model solved by commercial software Cplex. Finally, network optimization in each energy LAN is achieved based on the results of simple power flow calculation and relevant guide rules of planning. The simulation results show that the proposed partition and planning method applied to the Energy Internet is feasible and valid, multi-energy complementary and multi-energy router coordination more economical compared with traditional energy supply and can alleviate peak-valley time mismatch of different loads, while integrated planning of energy router and network is more economical than by stages. This work is supported by National Natural Science Foundation of China(No. 51377162).
2018, 42(4):165-173. DOI: 10.7500/AEPS20170903002
Abstract:With the development of Energy Internet and the deepening of energy interaction, the multi-energy coupling system makes higher demands of the energy supply reliability. Therefore, to quantify the coupling logic relationship among different energy sources, the comprehensive reliability evaluation method is urgent to be studied. Aiming at the problem that the traditional reliability evaluation method is difficult to effectively evaluate the energy supply reliability of the multi-energy coupling system, the multi-energy microgrid is taken as the research object firstly. The physical model of typical microgrid is constructed based on the energy hub model. Secondly, the state model of equipment components and the evaluation index of the reliability of multi-energy microgrid are established. The operation mechanism and the time sequence models of multi-energy microgrid are analyzed. The evaluation model of two kinds of typical operating mode which are grid-connected and electric-isolated are established by combining the Monte Carlo simulation with the failure mode and effect analysis method, respectively. The assessment process is also put forward. Finally, a practical example is given to evaluate the annual reliability indices of multi-energy microgrid and the reliability of the pre-arranged outage in the typical period of the typical scenario, and the availability and practicability of the proposed method are verified.
2017, 41(13):7-13. DOI: 10.7500/AEPS20161209002
Abstract:Improvement of renewable energy accommodation and energy utilization efficiency are both promising channels for sustainable development of electric and thermal energy systems. In view of the difference in the study subject and the analytic method, the constitutive relation between the basic components in the thermal system is revealed from the perspective of heat transport. By introducing the entransy theory and analogy between electricity and heat in transmission, an alternative model is developed from the angle of energy flow by considering the driving force and thermal resistance in heat transfer. Together with the topological structure, the energy flow model of the thermal system is developed to describe the law of integral heat transport. On this basis, the energy flow model of the electric-thermal integrated energy system in consideration of energy conservation and heat transfer irreversibility at the same time. This will unify the study perspective of electric and thermal energy in transmission while laying bare the law of integral energy transport. Finally, a simple integrated energy system is employed to minimize the total coal consumption by using the energy flow method and the dual-boundary method, respectively. The results show that the predicted wind power generation with the energy flow method is more accurate, which shows the feasibility and necessity.
2017, 41(1):18-24. DOI: 10.7500/AEPS20160513005
Abstract:With the integration of combined heat and power(CHP)units, central air-conditioners and gas boilers, power, gas, and heating systems are becoming tightly linked to each other in the integrated community energy system(ICES). An optimal hybrid power flow calculation method for ICES considering the electric distribution network reconfiguration is proposed to schedule the ICES effectively from the perspective of “source-grid-load”. Firstly, a power flow analysis model for the energy center(EC)is developed based on the energy hub model. Then, an optimal hybrid power flow calculation method considering the electric distribution network reconfiguration is proposed taking the constraints from unbalanced three-phase electric distribution network, the natural gas network, and the ECs into consideration. Numerical results indicate that the proposed method can integrate the reconfigurable topology of the electric distribution network into the optimal hybrid power flow as a flexible and dispatchable resource from the perspective of “source-grid-load”, further reducing the operation cost of the ICES.
2018, 42(4):113-120. DOI: 10.7500/AEPS20170512002
Abstract:Utilizing regional integrated energy system(RIES)to improve load side flexibility is an important technical means to increase the penetration level of renewable energy in the power system. The thermal and electrical energy storage system(ESS)in the RIES can be decoupled between the thermal and electric power to effectively reduce operation cost. The scenario-based analysis method is used to model the randomness of renewable energy output and review the impact of the renewable energy volatility on the operational optimization of RIES with combined cooling, heating and power(CCHP). Based on the characteristics of the equipment in RIES, a model for RIES including energy conversion equipment and ESS is established. Moreover, a simulation program in MATLAB using YALMIP toolbox and a software called CPLEX has been developed to obtain the optimal output of each unit in the system and the total operation cost in different dispatching modes. The result of the simulation program shows that a RIES with CCHP and ESS can effectively decouple its thermoelectric operation constraints with the help of energy storage equipment, bringing into full play the economic advantage received from the RIES operation backed by the Energy Internet.
2018, 42(4):158-164. DOI: 10.7500/AEPS20170915010
Abstract:The coordinated operation of multi-energy complementary power generation is gradually becoming the future development direction of power system, and it is also very important to accurately analyze the complementary characteristics of the power system. Based on the operation characteristics of multi-energy complementary power generation system, the evaluation of index characteristics analysis of hybrid wind-solar-hydro power generation system are constructed through the combination of sub-system evaluation index and complementary system evaluation index by the complementary coefficient. The index frame is constructed, which is suitable for the analysis of the complementary characteristics of hybrid wind-solar-hydro power generation system. Based on the framework, the characteristics of wind farms, photovoltaic power plants and hydroelectric power stations in Western China are analyzed. The results show that the active power output characteristics of hybrid wind-solar-hydro power generation system can keep the system load tracking well and have strong intraday complementarity.
2018, 42(4):104-112. DOI: 10.7500/AEPS20170527007
Abstract:The traditional dispatch mode of the power system cannot meet the requirement of multi-energy system dispatch in the background of development of Energy Internet and deep coupling among multi-energy networks. The high penetration of electric vehicles(EVs)is both opportunity and challenge for the multi-energy system to make flexible dispatch strategy. Based on the background, this paper develops a coordinated optimal dispatch model for electricity-gas-heat multi-energy system considering high penetration of EVs. The fuzzy optimization theory is adopted to deal with the total charge demand of EVs and the uncertainty of the wind power output. The model is proposed to minimize the total energy supply cost and the pollutant emission when the constraints of power flow, natural gas system, energy demand of energy hub and EV charge demand can be satisfied. The interior point method is chosen to solve the model. Finally, the typical 11-node multi-energy system is taken as an example, and the dispatch strategies and benefits under different EV charge/discharge modes and energy center structures are analyzed. The dispatch results under different EV numbers and confidence levels are compared, which shows that the proposed coordinated dispatch can improve the economic efficiency of the power system.
2018, 42(4):174-182. DOI: 10.7500/AEPS20170605005
Abstract:Regional integrated energy system(RIES)provides a platform for coupling utilization of multi-energy and makes various energy demands from clients possible. This paper starts with the analysis on the structure and advantages of RIES. When considering the coupling relationship between inner the power supplies within RIES, the situation how energy transforms, flows, distributes, and stores in the diverse processes is systematically described. The comprehensive evaluation index for RIES is constructed by extracting the general adaptive indicators from energy supply link, device link, power distribution link and the customer link. The evaluation index is designed based on taking the distribution system as a core and the multi-energy system coupling of distributed energy sources, natural gas, geothermal heat and public transportation. The analytic network process(ANP)of anti-entropy method is used to determine the index weight and the scoring function to solve the problem of the crossover and mutual influence between the indices caused by the inaccurate of weights calculation. The method can accurately assess the developmental level of domestic regional energy system, and its validity is proved by practical example calculation. Finally, the beneficial suggestions for the development of RIES in China are offered.
2018, 42(4):183-193. DOI: 10.7500/AEPS20170915012
Abstract:Multi-energy integration has put forward the new requirements for future market transactions within the energy industry. The blockchain can effectively support the innovative service pattern of new industries in the energy area as a new information technology. To extend the applications of multi-energy complementary control technology in the future, achieve the integration of multiple information resources and physical resources in the multi-energy system, and ensure the transaction information security in the integrated control process, this paper focuses on analyzing the applicability and the problem of data sharing in blockchain for multi-energy system, based on the transaction demand in the multi-energy system and current situation of the heterogeneous blockchain technique. The necessity and the method of constructing transaction system of multi-energy system based on heterogeneous blockchain technology are proposed. Finally, the key technologies of blockchain in the multi-energy system and the constraints on the follow-up business development are summarized. In addition, some technology schemes and relative suggestions are given to solve the problems of blockchain limitation and support the work of transaction between different heterogeneous blockchains in the future multi-energy system.