Discrimination method of delay dependent robust stability of power system

Abstract

The invention belongs to the technical field of power systems and relates to an improved discrimination method of Lyapunov robust stability of a power system containing uncertain delay links, which is characterized by solving the Lyapunov functional of a delay system based on the Krasovskii theory, then expressing the derived function of a system trajectory from the functional by a group of linear matrix inequalities (LMI), reducing the conservation of the criterion by introducing a few necessary loose terms in the process of deducing functional derivatives and then transforming the disturbance terms containing uncertainties by utilizing the Schur complement, thereby obtaining the stability criterion. The method of the invention has the advantages of less conservation and high operation efficiency.

Description

technical field [0001] The invention belongs to the technical field of electric power systems, and relates to a method for judging stability with uncertain time lag. Background technique [0002] In nature, the future development trend of the system depends on both the current state and the past state. This kind of phenomenon is called time lag [1-2] . The time-delay phenomenon widely exists in all links of the power system, and it is an important cause of control equipment failure, system deterioration and instability. important practical significance [2-4] . [0003] Studies on the stability of time-delay systems have been carried out earlier [1] , as early as the 1950s, O.J.Smith proposed the complete theory of Smith predictor [5] , when the time-delay variation law of the system is known, the known fixed time-delay in the transfer function can be completely eliminated through it, so that it can be simplified as a general system for consideration; in addition, in the...

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Problems solved by technology

In addition, based on the stability criterion of Lyapunov theory, only the sufficient conditions for the stability of the time-delay system are given, and the method itself has a certain degree of conservatism. Therefore, research in recent years has mostly focused on how to reduce the conservatism of the Lyapunov time-delay stability criterion. [9-15]

[13] added loose items in the derivation process of the single-delay stability criterion to reduce the conservatism of the method, and received good results. On this basis, a time-delay-dependent robust stability criterion was derived. Literature [13] 14] Extend this method to multi-delay systems, forming the so-called Free Weighting Matrix (Free Weighting Matrix) method, but the introduction of a large number of loose items greatly affects the computational efficiency of the method

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