Analysis method for influence of wind farm access on fault limit cut-off time of multi-machine system

Abstract

The invention relates to an analysis method for the influence of wind farm access on a fault limit cut-off time of a multi-machine system. Based on a transient energy function theory, starting from anoriginal multi-machine system, a first integral method is used to construct a transient state energy function of the multi-machine system including a wind farm. On the basis, a relationship between acritical energy value of the system and the transient output power of the wind farm is derived, the change of a critical energy borne by the system brought by the change generated by a network topology structure due to the access of a DFIG is quantitatively analyzed, and the influence of the wind farm access on system stability margin is reflected from the perspective of critical energy. According to the influence of the DFIG on the equivalent electromagnetic power of the system during a fault period, the change of a system state variable and an energy accumulation process are analyzed, and the influence mode of the wind farm access system on the speed of the system transient energy accumulation is given. The fault limit cut-off time is calculated by the accumulation time from the transient energy to the system critical energy.

Description

technical field [0001] The field of the present invention is the analysis of the impact of new energy access on the transient stability of the power system, especially for the power multi-machine system including wind farms, analyzing the impact of wind farm access on the power multi-machine system fault limit removal from the transient energy function The impact of time reflects the impact on the transient stability of the power multi-machine system. Background technique [0002] The continuous expansion of clean energy demand and the increasing maturity of wind power generation technology have made wind power generation vigorously developed and applied all over the world. However, while the access of large-scale wind farms provides more energy supply to the grid, it also brings many unfavorable factors. For example, the connection of a large proportion of wind power often changes the power flow distribution and topology of the system, thereby affecting the overall toleran...

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Problems solved by technology

[0004] At present, the research related to this invention is mainly aimed at single-machine infinite system or equivalent double-machine system [2-3] , seldom analyze the impact of wind farm connection on system power angle transient stability directly from the actual power multi-machine system, and it is difficult to consider the influence of wind farm connection in multi-machine system on system transient stability ; Many related studies have given general laws through simulation analysis [5-7] , the conclusion is not convincing due to the lack of theoretical support

Currently in research [2,9-10] , most of them fail to comprehensively consider the mechanism of wind farm access to system critical energy and energy accumulation process to comprehensively affect the transient power angle stability of power system, and only analyze its impact from a single perspective, and the conclusion is one-sided; in addition, some studies believe that After the wind farm is connected to the power multi-machine system, the change of the energy margin of the whole system is to increase the energy limit that the wind turbines can withstand in the transient process on the basis of the energy margin of the original system [4] , without considering the impact of wind turbine access on the network topology, the conclusion has limitations

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