| In the context of energy transition,natural gas-fired power generation is widely used in scenarios such as smoothing out renewable energy fluctuations due to its fast and flexible regulation characteristic and low carbon emissions,and is one of the important components to facilitate energy carbon peaking and build a clean,low-carbon,safe and efficient energy system.The massive application of gas-fired generators will lead to a progressive deepening of the coupling between power system and natural gas system,promoting the complementary synergistic optimization of the pan-energy system..At the same time,due to the deepening of the coupling,disturbances in power system or natural gas system may interact with each other through the coupling equipment such as the gas turbine,which will cause serious cross-system failures under extreme conditions.Therefore,it is important to investigate the mutual coupling influence and safe and stable operation of the integrated electric-gas energy system(IEGES).This thesis is focused on the small-signal stability region and its practical analysis model for a regional integrated electric-gas energy system(RIEGES)with multiple microturbines(MTs)connected,taking into account the slow dynamic characteristic of the natural gas pipeline network system and the control characteristic of MT,and the main works are as follows:(1)Based on the dynamic characteristic equations of the gas distribution pipeline,a discretization model of the gas distribution pipeline is derived;based on the conventional Rowen MT dynamic model,a modified MT dynamic model with the variation of the inlet gas characteristics of the MT is established by introducing the improved fuel supply component,which lays the foundation for the stability analysis of the dynamic interaction process between the MT and the gas distribution system.(2)The definition of the small-signal stability region of RIEGES in the space of PI control parameters of the fuel supply component of MT is given,as well as the method of constructing the small-signal stability boundary.In terms of the small-signal stability boundary search method,the small-signal stability analysis model of the RIEGES based on the eigenvalue analysis method is proposed.Considering the correlation of each part,the model is built based on the space discretization model of gas distribution pipeline and the improved dynamic model of MT,which can effectively take into account the interaction effects of the slow dynamic characteristic of the natural gas pipeline system and the regulation characteristic of the MT.(3)Based on typical cases,firstly,the small-signal instability phenomenon of RIEGES with multiple MTs is demonstrated,and the disturbance propagation mechanism and stability characteristic are revealed;secondly,the small-signal stability region in the PI parameter space of the fuel supply component of MT is established,its characteristics are initially explored,and the effects of PI control parameters,power generation control commands and gas distribution pipeline parameters on the smallsignal stability region are analyzed;finally,the effects of the discrete grid space step size of the gas distribution system on the small-signal stability analysis results are analyzed. |
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