| According to the statistics revealed by the United Nation Development Program in 2015,over one billion people in the world still have limited access to clean and stable energy supplies for cooking and electricity.Integrated multi-energy microgrid,as a new derivative form of conventional microgrid,optimally integrates a variety of distributed renewable energy,such as wind,solar,biomass energy,etc.,to reliably meet the diverse,clean energy needs for specific users in specific regions at a competitive cost.To build such multi-energy microgrids in these specific regions,it is necessary to coordinately utilize the traditional energy and the on-site abundant renewable energy resource,e.g.,wind,solar,geothermal,and biomass energy,to meet the multiple energy needs and accommodating renewable energy by op timizing and allocating the microgrid's structure.In this thesis,the energy supply shortage in remote areas,such as rural areas,mountainous areas and offshore islands that are far away from the power grid or the natural gas network because of relativel y insufficient and expensive energy supply infrastructure,is specially addressed.Based on the biomass energy that is usually abundant in those areas,the proposed multi-energy microgrid integrates biomass energy with other clean energy sources by utilizing their complementarity with the proposed mechanism of accommodating renewable energy.residential-level and region-level multi-energy microgrids are proposed in this thesis respectively,finally formulating comprehensive research on the planning and disp atch optimization for integrated energy micro-grids.The main work of this thesis is summarized as follows:1.An energy trading framework based on the mechanism of LBP's accommodating renewable energy is proposed for increasing the on-site renewable energy accommodating capacity.First,based on the temperature-sensitive characteristics of biogas fermentation,a thermodynamic model of microbial fermentation in biogas digesters is proposed to establish a dynamic balance between biogas production and temperature;Further,as the biogas production increase driven by the solar-assisted heating source inside LBP,the energy conversion of electricitychemical energy(biogas)-electricity enables the LBP to exhibit the battery-like characteristic.By utilizing this characteristic,it absorbs the volatility of renewable energy and realizes the load shift,which has been analyzed in chapter 2.In this way,a bilevel energy trading model that considers the PV,LBP,and DRA that providing the system-level service is proposed for simultaneously optimizing the DRA's profit and social ware.This model utilizes the KKT conditions and strong duality theory,transforms the original problem into a single-level equilibrium constrained mathematical programming problem to solve.The results showed that the influences of LBP on the profits of DSO and DRA as well as the system dispatch when the system is operated at different PV penetration levels.The propo sed battery-like characteristic of LBP will help improve the reliable operati on of the renewable-energy-based microgrid in remote areas where abundant biomass resources exist,and enhance the onsite accommodation capacity of renewable energy.2.Based on the LBP's mechanism of accom modating renewable energy,a planning model of the off-grid residential solar-biogas multi-energy microgrid is proposed based on the complementarity between solar and biogas.First,it formulate s the energy conversion matrix of the proposed solar-biogas multi-energy microgrid based on the principle of EH,mapping the energy flow from the inputs of solar and biomass energy to the outputs of heat,electricity,and biogas.Furthermore,based on the basic structure of the EH,the planning model is formulated as a two-stage problem for determining the optimal capacity of each system component to minimize the total system investment cost while meeting the residential heating,electricity,and biogas demands.Considering the computation burden brought by the involvement of the large number of scenario.This model is iteratively solved by the scenario-based Benders decomposition method that divides the original problem into master-and sub-problems.Finally,the simulation results are demonstrated by analyzing the influence of the complementarity of solar and biogas on the system dispatch and LCOE.Compared with the existing generation technologies,the proposed the off-grid residential solar-biogas multi-energy microgrid has economic merit,which provides an affordable solution to the energy supply shortage in remote areas.3.According to the fact that the biogas production in a CBP highly depends on the stable supply of the local-sourced biomass feedstock,a multi-stage coordinated expansion planning of the power distribution system and the bioga s delivery system considering the biomass supply network is proposed.First,it proposes the coupling relationship of the power distribution system,biogas delivery system and the biogas supply network by analyzing their corresponding physical characterist ics.Model the biomass supply network and analyze the influence of the distribution of the biomass feedstock on the planning results;This model aims to determine the allocating and sizing of CBP and DGs,the expansion scheme of the power distribution syst em and the design of the local biogas delivery system within the planning horizon.Considering the uncertainty of the ever-varying load demands and the biomass availability,the nonanticipativity constraint is especially considered to make this model form ulated as a multi-stage model that can adjust its decisions along with the uncertainty realiz ation process.The proposed multi-stage expansion planning model fully considers the biomass supply network and provides a more reasonable solution to the regional electricity and biogas supplies while reaching the tradeoff between the regional biomass availability and the local energy demands.4.Based on the research on the proposed planning method of the biogas-electricity coordinated network,a comparative study and assessment of the multiple biogaselectricity coordinated networks considering the mixed biomass flow is proposed.First,according to the differences between the mono-digestion and the co-digestion,the optimal biomass flow mixture is defined and inc orporated in the modeling of the biomass supply network.Given the topology of the regional power distribution system,a novel model-based optimization is presented.Considering the regional availability of different geographically dispersed feedstock,it allocates multiple biogas plants of mono-digestion or co-digestion systems and designs the corresponding local biogas delivery networks The optimization results in cases of various numbers of biogas plants are installed are demonstrated by real power system.Their corresponding economic and ecological impacts are compared.This proposed method can help the LBP-based enterprises evaluate the economic and ecological performance when determining the investment of the regional energy supply system. |
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