Design-oriented transient stability analysis and enhancement method for fully VSG-controlled flexible interconnected distribution system

Le résumé fourni par la source

• The large signal model is established by taking the output reference angular frequency of DC voltage controller as a dynamic variable, which can directly reflect the influence of DC voltage variation on transient stability and avoid numerical calculation errors. • The effect of the proportional and integral coefficients of the DC voltage controller on transient stability is consistent, that is, the smaller the parameters are, the better the transient stability is, and the transient stability is more sensitive to changes in the integral coefficient. • DC capacitance and short-circuit ratio have the same effect on transient stability of FIDS, that is, the greater the two, the more favorable it is to improve the transient stability of FIDS. • The proposed method can effectively suppress fault current and enhance transient stability simultaneously. When severe short-circuit fault occurs in distribution network, just like single virtual synchronous generator (VSG) grid-connected system, distribution system flexibly interconnected by soft open points (SOP) with full VSG control will also cause transient stability problem, accompanied by fault overcurrent problem. However, the existing research has paid little attention to it. In order to fill this gap, this paper taking three-port SOP as an example. Firstly, the large-signal model of flexible interconnected distribution system (FIDS) is established by analyzing the characteristics of DC voltage controller and regarding its output reference angular frequency as a dynamic variable. Secondly, the influence of DC voltage controller parameters, DC capacitance and short-circuit ratio (SCR) on transient stability of FIDS is quantitatively analyzed, and their influence laws on transient stability and parameter design principles are drawn. Then, through the relevant circuit equivalent model, a method for improving the transient stability of FIDS that considers fault current limiting is proposed. Finally, simulations and experiments validate the correctness of the model construction and the parameter impact analysis, and the effectiveness of the proposed method. © 2017 Elsevier Inc. All rights reserved.

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