An Optimal Energy Management Method For Integrated Electrical And Natural Gas Networks With Multi-Energy Utilizations

With the development of the multi-energy system(MES)in recent years,more and more cross-sector multi-energy utilizations(MEU)come into being,which tightens the couplings among different energy sectors,and facilitates their mutual complementarity,thus significantly promotes the economy,flexibility and efficiency of the MES.Mutual complementarity is the nature of the MES,and also the means of realizing all the aforementioned merits.In order to fully realize these merits and improve the utilization of renewable energy sources through multi-energy mutual complementarity,energy management models of MEUs should be developed and integrated in the energy management model of the MES.Otherwise,MEUs may operate uncoordinatedly,which harms both the multi-energy mutual complementarity and the operation performance of the MES.Besides,studies on the energy management of MES tend to assume that natural gas demands of electric networks can be naturally fulfilled at all times,such as the sudden change in gas demands caused by the outputs change of gas turbines,which is hardly the fact.Owing to the far longer dispatch periods,sudden changes in gas demands caused by electric networks,for instance the outputs change of gas turbines and gas-driven MEUs,are accommodated by the linepack reserves in natural gas networks.Owing to this,the management of linepack reserves of natural gas networks should be considered when formulating energy management schemes.If not,not only the normal operation of the MEUs are harmed,gas turbines may not be able to ramp up and down,which will greatly damage the reserves adequacy and threaten the security of electric networks.Under these premises,the contribution of this dissertation can be summarized as follows:(1)Based on the energy efficiency matrix and energy dispatch factors,the energy management model of combined cooling,heat and power(CCHP)plants are developed,and based on which,the impacts of CCHP plants on both natural gas networks and electric networks are explored.Then,the potentials of CCHP plants,P2H/G2P plants and EV charging loads under demand management in promoting the operation performance of MES,especially its ability in accommodating RES are discussed with cases.(2)Combine the steady-state natural gas flow model and the pipeline linepack model,pipeline linepack reserve model is derived,based on which,the mechanism for accommodating sudden changes in natural gas demands caused by gas turbines and gas-driven MEUs is studied in depth.In order to measure the capacity of lincpack reserves in the natural gas network,the positive linepack reserve and negative linepack reserve are defined respectively.Combine the ramping capabilities of gas turbines and linepack reserve in the natural gas network,the capacity of the fast-response flexibility which gas turbines can provide is measured,based on which,the management model of linepack reserve in the integrated electrical and natural gas network(IEGN)is developed.(3)In order to promote the operation performance of the MES,especially its ability in accommodating RES,the mutual complementarity in the MES should be enhanced at first.It means that the relationship between energy sector and energy sector,energy sector and MEU,MEU and MEU should be optimally coordinated.In this way,based on the traditional power system economic dispatch model,this dissertation takes the energy management model of MEUs,including CCHP plants,P2H/G2P plants,and the demand management model of EV,and the energy management of natural gas networks,including the management model of linepack reserves into consideration,and proposes an optimal energy management method for IEGN with various MEUs.Finally,cases studies are conducted to prove its validity.The optimal energy management method proposed in this dissertation could serve the energy management of the MES,and hopefully further enrich the theoretical system and application framework in the area of MES operation.