Multi-energy Complementarity And Integrated Optimal Allocation For Hybrid Renewable Energy System

Energy is the basis of human society and economic development,while energy problem is a worldwide problem.At present,fossil fuels are the main kinds of energy sources.Since the industrial revolution in the 1870 s,the consumption of fossil fuels has skyrocketed,and more than 90 percent of energy needed by world economic activity comes from fossil fuels.The massive use of fossil fuels has caused serious environmental pollution,contributing to a series of environmental issues,such as global warming.Confronted with the energy crisis,many countries pay great attention to the development policy of energy.New energy sources,such as wind energy,solar energy,tidal energy and geothermal energy,have been developing rapidly.Because of the intermittency and uncertainty of new energy,large scale access of wind power and solar power to power system will seriously affect the power quality and stable operation of the main power grid,and create problems like abandoning wind power,abandoning photovoltaic power and even breaking away from the grid,which restrict the large-scale utilization and development of new energy.In order to increase the permeability of new energy,micro-grid has been developed and promoted in many countries.In micro energy network,two problems remain to be solved: how to build a multi-energy complementary system based on characteristics of each energy source,and how to increase the permeability and utilization ratio of new energy.Aiming at problems above,this paper conducts the following researches:To make up the lack of normative mathematical abstraction for multi-energy complementary analysis,the complementary expression paradigm of multiple energy resources is explored,and a comprehensive,general and normative complementarity description is given.From a mathematical point of view,the complementarity between different energy sources means that the multi-energy comprehensive optimization performance is stronger than the use of individual energy,and the optimization depth can be used to quantify the degree of complementarity.Therefore,the complementary expression paradigm of different energy sources includes many kinds of energy sources and their scales,performance indicators and the degree of complementarity.On the basis of the complementary expression paradigm,on the one hand,the complementarities between different energy sources in terms of stability,storage capacity and scheduling ability are further discovered;on the other hand,the comprehensive complementarity mechanism between various energy sources is revealed,and the general description of multiple energy sources and complementarities is established.In this paper,the complementarity between different energy sources is abstracted into a general complementarity of mathematical description of multiple energy sources from the case analysis between two or three sources of energy,providing a new focus for the improvement of comprehensive energy power system optimization.In view of the characteristics of the remote mountainous areas,the idea of constructing independent microgrids which are integrated with the use of biogas and other renewable energy in remote mountainous and rural areas,where the electric power facilities are relatively backward,has been put forward.In order to reduce the cost of construction,operation and maintenance of the microgrid,and to make full use of the local natural resources and improve the efficiency of comprehensive utilization of energy and finally,to realize the selfbalance of energy supply and demand,we should make full use of the complementarity between different energy sources to reduce dependence on energy storage,or even get rid of the energy storage devices.Based on solar-biogas micro energy network in mountain areas,the current rural basic energy consumption structure is introduced and analyzed,and the load forecast model for heat load and electric load is established.Complete solar-biogas complementary microgrid structure is formed by building a solar-biogas micro-energy network in mountain,defining output variables and input variables of microgrid,and analyzing the task and mode of heating system and power supply system.In order to achieve the mountain microgrid independent energy balance,the basic components of the microgrid is configured on a scale by establishing the load model of electricity,heat and gas,and using the deviation between supply and demand as the objective function.Finally,feasibility and scale configuration of microgrid is verified using an example of the typical household load of the power grid.In this paper,for the new energy power generation access to the shipboard power grid,on the basis of ordinary shipboard energy system,the photovoltaic system and the energy storage system are added to form a PV-diesel-storage mixed energy shipboard.Using a variety of energy complementarity,energy efficiency is improved,and energy storage system charge and discharge is reasonably managed,so as to achieve the minimum operating cost of the ship.Firstly,the structure of the shipboard energy system is analyzed in detail.Then,according to the characteristics of the shipboard load and the operating conditions,the output model of different power supply is established.The ship power supply is optimized based on cost and mobility.Finally,using medium-sized yacht as an example,by comparing the multi-energy power supply emergency power model,the conventional energy storage model and a single energy fuel unit power supply,the advantages of PV-diesel-storage mixed energy shipboard on mobility and cost are verified.Further study on the fluctuation of power grid caused by new energy resources is conducted.In the multi-energy complementary application,volatility is the most important factor affecting the safe and stable operation of power system.Therefore,it is necessary to evaluate the impact of volatility,and use the volatility constraint to optimize the controlable energy resources and renewable energy output.In this paper,the biggest short-term load fluctuation is defined,and a prediction method based on the MAO curve is put forward.Then,considering the influence of load fluctuation,probability interval prediction method is introduced to further improve the prediction accuracy of maximum fluctuations,finally,the paper verifies the prediction method through practical cases.On the basis of maximum load fluctuation,we further analyzes the relationship between the power reserve and the ramp ability reserve,and further studies the maximum fluctuation of load using the prediction error distribution,Finally,the paper proposes the optimal goal of minimum climbing ability reserve with maximum fluctuation,and its effectiveness is verified by cases.From two-way complementary expression to multi-energy complementary universal expression paradigm,we can expand to individual energy source and combinations of various energy sources,and build a hybrid multi-energy complementary index system.In order to reveal the value and function of multi-energy complementarity in hybrid multi-energy system,we analyzed the multi-energy complementary expression paradigm,and designed solar-biogas complementary energy systems for mountainous areas and islands,and designed solar-diesel-energy storage systems and energy volatility complementation based on mobile complementarity for ships.The feasibility of the hybrid multi-energy system and the effectiveness of the integrated optimization method are validated by simulating two cases of mountainous and island PV-marsh system and shipboard integrated energy system.The results provide a strong support for the widespread use of hybrid multi-energy microgrids.