Stability analysis method and device for direct-driven wind power plant grid-connected system

Abstract

The invention discloses a stability analysis method and device for a direct-driven wind power plant grid-connected system, and relates to the technical field of stability analysis of a power system. The method comprises the following steps: acquiring a state equation and an algebraic equation of a grid-connected system, and carrying out simultaneous merging by taking grid-side voltage as a carrier; representing a phase-locked loop and a network side control link in the form of equivalent impedance and an equivalent voltage source to obtain an equivalent circuit and equivalent impedance of the direct-driven wind power plant; combining the equivalent impedance to obtain a stability margin expression of the grid-connected system; obtaining the normalized sensitivity of different parameters in the grid-connected system to the stability margin of the system according to the stability margin expression; and quantifying the influence degree of different parameters on the normalized sensitivity of the system stability margin, and screening out dominant influence factors. According to the method, the analytical expression of the equivalent impedance of the direct-driven fan is constructed, and the Nyquist stability criterion is adopted, so that the stability margin of the grid-connected system of the direct-driven wind power plant can be deduced, and the influence degree of different parameters on the stability of the system can be quantified.

Description

technical field [0001] The invention relates to the technical field of power system stability analysis, in particular to a stability analysis method for a grid-connected system of a direct drive wind farm. Background technique [0002] With the vigorous development of renewable energy such as wind power, wind power has broad development prospects, but the increase in wind turbine capacity has made the trend of power electronics in the power system more and more significant, which has brought new challenges to the stable operation of the power system. As one of the mainstream types of wind turbines, direct-drive wind turbines are prone to oscillation and instability problems when connected to the power grid. For example, in 2015, subsynchronous oscillations occurred in the Hami area of ​​Xinjiang. [0003] Around how to solve the phenomenon of oscillation instability, some scholars have achieved certain results. The methods used in existing studies, such as eigenvalue analys...

AI Technical Summary

Problems solved by technology

The methods used in existing studies, such as eigenvalue analysis, impedance analysis and time-domain simulation, can only judge whether the system is stable or not after calculating the eigenvalue or impedance or simulation, which fail to directly reflect the impact of different parameters. Stability of grid-connected system of direct drive wind farm

In addition, the existing research has not yet reached a consensus on the dominant influencing factors of direct drive fans

Images