MILP-Based Combined Power and Natural Gas System Risk Assessment in Energy Internet

In this paper, a generalized combined power and natural gas network risk assessment model is proposed for quantifying its risk level considering dangerous factors such as generation outages, transmission line contingencies, natural gas pipeline contingencies, compressor failures and gas source and load fluctuation. This evaluation model statistics the specific electricity and gas load loss in reliance on a state-based non-sequential Monte Carlo method, it aims at minimizing the Cost of Lost Load (COLL) of the combined system based on the security-constrained steady-state analysis. Usually, the model is non-linear and non-convex, to overcome the problem's non-convexity, an increment based mix integral linear programing (IMILP) is employed to effectively and accurately solve the COLL minimization optimization model. Besides, a specific customized reliability indexes are developed to comprehensively assess the risk from cost, gas and electricity loss three dimensions. At last, the evaluation model is verified by a one combined 6-node electricity network and 14-node gas network test case. The results show that the proposed model can quantitatively assess the effect of those uncertainties on the combined system risk level.