| Nowdays,the energy development in China is facing serious problems of resource scarcity and environmental pollution.Presiedent Xi put forward the goal of “building global energy Internet and realizing green and low-carbon development” at the first International Cooperation Summit Forum of “Belt and Road” and pointed out the strategic direction for countries to build "Belt and Road" and promote energy transitation.Integrated energy system(IES),as the main carrier of energy Internet,is jointly participated by various energy forms such as electricity,heat,gas and cold.Different energy systems can achieve complementary support through coupling links to improve the overall energy supply security of IES.However,IES faces many uncertainties such as strong randomness of renewable energy output,large differences in the fluctuation pattern of multi-energy loads and large scope of cross-system failure(CSF),which bring new challenges for its safe operation.In this regard,this thesis develops static safety analysis approach for regional integrated energy systems(RIES)from two perspectives: probabilistic multi-energy flow and risk assessment.The main work includes:1.A decomposed multi-energy flow calculation method for RIES is proposed,and the operation modes of multiple coupling equipment are considered.At first,the operating characteristics and mathematical models of coupling equipment including gas turbine units and combined heat and power units are introduced.Then,based on the steady-state models of power distribution system(PDS),district heating system(DHS)and natural gas system(NGS),four sequences for solving multi-energy flow can be developed according to the operation mode of these coupling equipment.Finally,A test case with 101 nodes is used to verify the effectiveness of the proposed solution and the difference of results between grid connected mode and island mode in IES is analyzed.2.A probabilistic multi-energy flow calculation method considering multiple uuncertainties in RIES is proposed based on the decomposed multi-energy flow solution.First,three types of CSF are defined according to the location of component failure and their impact patterns on different energy systems,and the corresponding criteria and analysis methods are given.Subsequently,the topology can be mapped to a directed adjacency matrix,and the set of forced shutdown components affected by the initial failure can be obtained through a failure screening method based on the classified CSF,which realizes the fault state consequence analysis considering the energy coupling interaction.Finally,taking into account at the uncertain factors such as source load fluctuation and component failure,a probabilistic multi-energy flow calculation method based on Monte Carlo simulation(MCS)is proposed to solve the probability distribution of energy flow parameters.The impact of CSF on the energy flow probability distribution of RIES is investigated from different perspectives by studying a 101-node test system and a 119-node practical system in Tianjin.3.A risk assessment and alleviation method for RIES is proposed.Firstly,the traditional risk indices like line overload,voltage magnitude violation and load loss in PDS can be extended to DHS and NGS,which can build risk indices suitable for RIES.Then,a quantitative risk assessment for RIES is proposed using MCS with a large sample of sourceload fluctuations and component failures.And the assessment results can be used to locate root cause and weak points in RIES,providing a basis for the precise formulation of risk alleviation schemes.Finally,the impact of multiple types of uncertainties on the operational risk of RIES is analyzed through a 101-node test system,and various risk alleviation schemes are set up to verify the effectiveness of the proposed method. |
