Reliability Evaluation Of Integrated Electrical And Natural-Gas System With Power-to-Gas

With the utilization of gas-fired generators have been increased and the power-to-gas technology is become mature.The coupling relationship between electrical and natural-gas is becoming stronger.The integrated electrical and natural-gas system with power-to-gas own larger scale,more types of components and stronger uncertainties,and energy is transferred and tightly coupled among each energy sub-systems compared to energy sub-systems for electricity and gas,which makes great contributions to complexity for the reliability evaluation.In the current application scenario,P2 G can effectively mitigate the phenomenon of abandoned wind power,and the running state of P2 G is closely related to the stochastic factors(such as system load level and wind speed).Against the feature of power-to-gas devices,current reliability evaluation methods have different defects in the calculation of energy flow,load curtailments and reliability evaluation indices.Therefore,this paper deals with these problems in the following three aspects:(1)An energy flow calculation method of integrated electrical and natural-gas system is proposed.Considering that running state of power-to-gas devices are influenced by load level,wind speed and other factors,based on a relationship between the net load and the sum of generator output,this paper proposes the model of power-to-gas devices considering the opening condition.Then,combining the model of gas-fired CHP plants and gas-fired generators,and the network model of natural-gas subsystem and electricity subsystem,an energy flow model and its solving method of integrated electrical and natural-gas system is presented.Finally,the simulation energy flow results of IEEE14-NGS10 integrated electrical and natural-gas system verify the effectiveness of the proposed model and method.(2)A load curtailments calculation method of integrated electrical and natural-gas system is proposed.Based on a relationship between the operation strategy of power-to-gas devices and the wind curtailment,as well as,the relationship between power output and heat output of gas-fired CHP plants,and heat load curtailment,this paper proposes the model of power-to-gas devices and gas-fired CHP plants considering remedial actions.Furthermore,with the objective of integrated minimum wind and load curtailments,and minimum the conversion loss of power-to-gas devices,considering network constraint of subsystem,operation constraint of coupling components,and adjustment constraint of remedial actions,an optimal load curtailment model of integrated electrical and natural-gas system is constructed.Meanwhile,according to the discrete characteristics of the optimization model,a two-stage algorithm is proposed.Finally,the simulation load curtailment results of IEEE14-NGS10 integrated electrical and natural-gas system verify the effectiveness of the proposed model and method.(3)A reliability evaluation indices calculation method of integrated electrical and natural-gas system is proposed.In order to improvement the reliability evaluation indices,this paper establishes reliability indices such as expected electric/gas/heat demand not supplied,expected wind power abandoned,power-to-gas device capacity utilization and contribution of power-to-gas devices.Then,considering the random factors of the integrated electrical and natural-gas system,this paper presents the probability model of electric/gas/heat load and wind power,as well as the reliability model of component failure.Furthermore,based on the energy flow model and the optimal load curtailment model as well as the reliability indices,a reliability evaluation method and a calculation step of reliability indices are proposed.Finally,the simulation reliability evaluation results of IEEE14-NGS10 integrated electrical and natural-gas system verify the effectiveness of the proposed model,indices and method.