System and method for detecting amplitude-phase of voltage dip of grid-connected bus of wind power generation system

Abstract

The invention provides a system and method for detecting the amplitude-phase of voltage dip of a grid-connected bus of a wind power generation system. The system comprises a voltage measurement module, an alpha-beta-0 coordinate transformation module, a first derivation and equation solving module, a positive sequence and negative sequence reference voltage generating module, a p-q-r coordinate transformation module and a voltage amplitude and phase computation module. The method comprises the following steps of: obtaining ualpha, ubeta and u0 from the three-phase grid voltage measured by the voltage measurement module via the alpha-beta-0 coordinate transformation module; realizing decoupling of the positive sequence components and the negative sequence components of ualpha and ubeta by adopting the first derivation and equation solving module; obtaining the reference voltages ualphaREF and ubetaREF respectively after carrying out normalization and lowpass filtering on ualpha and ubeta; realizing decoupling of the p axis positive sequence component and negative sequence component and q axis positive sequence component and negative sequence component of the voltage in the p-q-r coordinate transformation module; and computing the amplitudes U<+> and U<-> and phases phi<+> and phi<-> of the fundamental positive sequence component and negative sequence component of the voltage by adopting the voltage amplitude and phase computation module.

Description

technical field [0001] The invention relates to the electrical control technology of wind power generation connected to the grid. Background technique [0002] The grid-connected operation of wind power and the existing power system can effectively reduce power peak loads, alleviate voltage sags, eliminate overload and congestion, increase transmission margins, and improve power supply reliability. Due to technical limitations, some wind turbines did not have low-voltage ride-through capability during the initial development period of wind power, which has also led to frequent accidents of wind turbines going off-grid in some wind power bases recently. [0003] On February 24, 2011, the Jiuquan Wind Power Base of Northwest Power Grid, due to the three-phase short-circuit fault of the 35 kV cable feeder cable head of Qiaoxi No. 10,000 kilowatts, accounting for 54.4% of the wind power output in Jiuquan area before the accident. On April 17, a cable head on the high-voltage s...

AI Technical Summary

Problems solved by technology

However, the main problem faced by the three-phase software phase-locked loop is: affected by the negative sequence components and harmonic components of the power grid, the cut-off frequency of the loop filter must be reduced in order to obtain a good steady-state accuracy for the phase-locked system, which greatly Affect the dynamic response performance of the system

However, although the least squares method has a high dynamic response speed, the system harmonics have a great influence on the steady-state accuracy of the algorithm; the Chirp-Z transform method can obtain better frequency domain analysis results than the discrete Fourier transform (DFT) , but its steady-state performance of tracking the frequency of the power grid is inferior to that of the improved software phase-locked loop; the minimum root mean square algorithm with variable step size uses a large number of iterative processes, and the amount of calculation is large

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