Wind turbine control reference signal detection method for unsymmetrical failure of electric grid

Abstract

The invention discloses a method for detecting a reference signal controlled by a wind-powered electricity generation set in case of asymmetrical failure of an electric grid. The method separates a positive-sequence component and a negative-sequence component from the acquired three-phase asymmetrical voltage of a stator of a wind-driven generator by a'T/16 delay' separation method, and realizes rapid detection on the positive-sequence component amplitude, the phase and the frequency of fundamental voltage. The method can rapidly separate the positive-sequence component and the negative-sequence component from the voltage in the electric grid with failure, has the advantages of high detection accuracy and good real-time property, and provides basis for the operation control of the wind-powered electricity generation set under various circumstances of failures in the electric grid.

Description

technical field [0001] The invention relates to the wind power generator control technology in the field of energy, in particular to the detection technology of the reference signal used for wind power generator operation control under the condition of asymmetric power grid failure. Background technique [0002] Modern large-scale wind power generation systems mainly include double-fed asynchronous generators (DFIG) and permanent magnet synchronous generators. In order to improve power generation efficiency, variable-speed constant-frequency power generation operations are implemented, and the DFIG system is the current mainstream model. At present, my country's wind power technology mostly stays in the operation control under ideal grid conditions. Since the actual grid often has various symmetrical and asymmetrical faults, it is necessary to carry out research on operation control under grid faults and propose corresponding control technologies. In recent years, internatio...

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Problems solved by technology

[0009] figure 1 The method shown generally uses a software phase-locked loop (PLL) 8 to detect and track the frequency and phase of the grid voltage, but the traditional software PLL cannot eliminate the influence of the negative sequence component in the unbalanced voltage, that is, when the voltage is unbalanced, the PLL Unable to obtain accurate voltage frequency and phase signals

In addition, an important feature of grid voltage faults is voltage phase jumps, which occur instantaneously, but the method of integrating voltage and frequency used by traditional PLLs cannot capture voltage phase jumps, resulting in a long period of time after the fault occurs. There is a large error in the voltage phase detection within a period of time, which directly affects the accuracy of the stator voltage, current and rotor current rotation coordinate transformation, and then affects the dynamic performance and stability of the entire control system

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