| One of the major threats of large-scale interconnected power grid is lowfrequency oscillation.Especially when renewable energy injected,the uncertainty of power makes low frequency oscillation(LFO)become more complex,so how to analyze and control the LFO becomes extremely important.Although the research of this field has made great progress,it is still unsolved problem that physical nature of small signal stability affected by local network.In this paper,combining the energy function with the concept of small signal mode,using the modal energy to study small signal stability quantitative analysis method based on local information of network from the perspective of energy decomposition.And it explore application of method in the evaluation of power oscillation,identification of main oscillation path,damping control,and to reveal the mechanism of LFO effectively.It can effectively identify weak links in the network and realize the evaluation of oscillation degree.It provides practical and feasible new way of thinking to solve small signal stability analysis(SSSA)and power oscillation suppression.So to sum up,the main work accomplished in this paper has the following several aspects:(1)Modal potential energy function based on network branch is established.Therefore,potential energy of each branch under different modes in the network can be calculated.The structure of modal potential energy is studied.It provides conditions for the small signal stability analysis based on local information.(2)The characteristics of each branch distribution of modal potential energy in the network is studied.This paper expounds transformation relations between branch potential energy distribution in the network and kinetic energy of generat ors.The relationship on branch modal potential energy distribution and the small signal stability of the system is analyzed.The accumulation characteristic of modal potential energy in the network distribution and its corresponding relationship with moda l oscillation center of system is studied.The power oscillation mechanism of the system is explained from the perspective of network modal potential.(3)In further analysis characteristic of branch modal potential energy,power oscillation criterion of system based on branch information is established.It proposed branch modal potential energy analysis method that it only depends on branch information.To use this method can quantitative analyze small signal stability of system,and evaluate the influence of small signal stability of system come from branch in the network and cut set,so as to find the weak links in the network.Modal potential energy entropy evaluation index is proposed,which it can get energy decomposition analysis from the view point of network.To evaluation damping of system under different modes.(4)Based on branch modal potential energy analysis method,to construct widearea measurement potential energy based on the network.And energy modes decomposition of power oscillation for interconnected power grid is carried out.Mode shape of power oscillation can be obtained.At the same time,through the establishment of indicators can quickly discriminate mode shape,generator's participation,and identify dominant oscillation system path.(5)To construct modal kinetic energy,modal potential energy and total modal energy function of interconnected power grid including wind farm,and then using total modal energy dissipation principle combining sliding mode variable struc ture control theory,a novel robust sliding mode control and H?(SMCH)method based on energy is used to design wide-area damping controller of doubly-fed induction generation in order to improve damping and application of potential branch modal potential energy analysis in wide-area damping control is studied. |
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