| Coal resources are increasingly depleted.The development of renewable energy technologies is not yet mature enough to replace large-scale coal.As a clean fossil energy source,natural gas has become the first choice for energy substitution.In the integrated power-gas system,with the increase in the proportion of gas-fired power generation,the influence of various uncertainties such as pipeline corrosion damage,gas leakage and “gas shortage” on the reliability of the power system cannot be ignored anymore.Therefore,this paper studies the influence of the natural gas network failures on the reliability of power systems and the identification of weak parts in the integrated powergas system.In order to evaluate the effect of natural gas network failures on the reliability of power systems,reliability models are established for natural gas sources,natural gas pipelines,and natural gas compressors in the natural gas network,and then a multi-state gas turbine model that took into account natural gas network failures is established.The Ford-Fulkerson method is used to obtain the amount of natural gas supply at each natural gas load under various failure conditions.Through the coupling of gas turbines,a multistate model for gas turbines considering natural gas network failures is established to quantify the adequacy of natural gas network.A case study is conducted on the modified Belgium natural gas network,which has 3 natural gas sources and 20 nodes.Monte Carlo simulation method is used to analyze the adequacy of the natural gas network,and the multi-state capacity outage probability table of the gas turbine was obtained.A composite power system reliability evaluation method considering natural gas network failures is proposed by coupling gas turbines.The method based on the multistate model of the gas turbine and the reliability model of conventional power components established an adequacy model of the composite power system;By using a non-sequential Monte Carlo simulation method,composite power system reliability evaluation indexes can be obtained based on a load shedding model based on the optimal power flow.Computation programs for the proposed models are coded by the software MATLAB and CPLEX.Adequacy evaluation is conducted on the IEEE RTS-79 bulk power system,which including the modified Belgium natural gas network The influence of natural gas network failures on the adequacy of the composite system was explored.The influence analysis of the degree of natural gas network components failure,gas turbine permeability and load multiple of composite power system on the adequacy of composite power system are also performed.Traditional power system reliability tracing only considers the internal components of the power system,and the external systems or components associated with the power system are not in the category,which makes the traditional power system reliability tracing method not applicable to the integrated power-gas system.Based on the traditional power system reliability tracing criteria and principles,the integrated power-gas system reliability tracing and secondary distribution of natural gas network reliability indexes method is proposed.The natural gas network is the equivalent component of power system and are traced the unreliability with all the power system components in the method.,and the reliability index of the equivalent component is distributed a second time in the natural gas network according to the power system reliability tracing principle and criteria.Weak parts identification of the integrated power-gas system also performed.Case studies of the IEEE RTS79 system including natural gas network was performed to identify weak parts in the system such as generators,transmission lines,and gas pipelines.At the same time,the reliability improvement measures of the system were analyzed based on the reliability tracing results.Analysis shows that improvements on these weak parts can effectively enhance the reliability of the system. |
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