Research On The Planning And Operation Of Hybrid Renewable Energy System Considering Energy Storage

The transformation process of global energy system structure has been accelerating.With the efforts of the international community to copy with climate change and the consensus on low-carbon energy,increasing countries have actively reformulated relevant policies to drive the development of renewable energy(such as photovoltaic and wind power)in a positive direction.China also announced that it will strive to attain the peak of CO₂ emissions by 2030 and realize carbon neutrality by 2060.The regions rich in renewable energy are often located in remote mountainous areas,which have weak connection with the main power grid or is in offgrid operation mode.Owing to the planning,management,technology and other reasons,the problem of renewable energy curtailment is very prominent.How to provide stable,reliable,clean and economic power supply to these remote areas is an urgent global development challenge.Meanwhile,there are many uncertain factors in the hybrid renewable energy system.This leads to severe challenges to the further improvement of the ultilization level of renewable energy.With the support and help of the National key R&D Program project“Research and application demonstration of distributed PV and cascade small hydropower complementary combined generation technology”(2018YFB0905200),this dissertation has carried out the planning and operation research of hybrid renewable energy system with considering energy storage system.It is important in the development model of clean energy system structure,optimizing the allocation of renewable energy resources,improving the power supply reliability of renewable energy system and improving the consumption level of renewable energy.For the development mode of clean energy system structure,optimizing the allocation,improving the power supply reliability and the ulitizaiton level of renewable energy will play an important role.The main research contents are as follows:(1)The multi-objective optimization model of an off-grid photovoltaic-wind-hydropower station with pumped-storage installation hybrid renewable energy system is established.A multi-objective optimization problem of the hybrid renewable energy system is constructed with considering various factors of reliability and economy.It is solved based on multi-objective particle swarm optimization algorithm.Afterwards,a set of Pareto optimal solutions are obtained.For considering policy requirements,this dissertation proposes a three-objective optimization model considering the photovoltaic/wind power curtailment rate,and analyzes the relationship between the curtailment rate and the techno-economy objective.The proposed model and method can provide a theoretical basis for the actual system construction.(2)An off-grid electricity/hydrogen hybrid renewable energy system based on photovoltaic power generation is proposed.A mixed integer linear programming model for the system operation optimization is developed.Because of the uncertain factors(photovoltaic power generation,electric load demand and hydrogen load demand)in the system,the operation strategy of proposed system is introduced based on the scenario based stochastic optimization method to maximize the system revenue.Conditional value at risk method is employed to evaluate the financial risk of the system in the uncertain environment.The system proposed in this dissertation can promote the development of new energy vehicles,reduce environmental pollution,and solve the influence of uncertain factors in the operation of the system.(3)For off-grid gas supply system,a natural gas supply-demand balance model based on chance constraint is proposed.An operation optimization model for minimizing the system total operation cost is established.An ambiguity set based on the historical data of wind power generation is proposed to copy with the uncertain wind power output.The distributionally robust optimization method is applied to address the chance-constrained natural gas supply and demand balance model.This method can reformulate the operational optimization model into a mixed integer linear optimization problem.The proposed method can reduce the conservatism of traditional robust optimization methods.(4)Owing to the importance of the state of charge of the energy storage system,an operation problem of an energy hub is introduced to minimize its total operation cost.The operation strategy of the energy hub based on the look-ahead risk-constrained method for two consecutive days is proposed.Considering the operation strategy of the second day,the state of charge at the end of the first day is optimized.Multiple scenarios are applied to depict uncertain variables.The demand response program is used to reduce the system total operation cost and improve the system flexibility.The proposed method can effectively reduce the total operation cost of the energy hub.Overall,this dissertation provides a practical solution for improving the ultilization level of renewable energy.The proposed methods for uncertain optimization problems can effectively characterize the uncertainty in hybrid renewable energy system.The planning and operation models of hybrid renewable energy system are constructed from different perspectives.It gives scientific planning methods,decision-making schemes and guiding suggestions for the planning and operation of hybrid renewable energy system in a complex and uncertain environment.This dissertation is conducive to promoting the development of renewable energy and the structural transformation of energy system.