Grid-connected synchronous phase-lock method based on improved series signal delay cancellation algorithm

Abstract

The invention discloses a grid-connected synchronous phase-lock method based on an improved series signal delay cancellation algorithm. According to a mathematic model of a single-phase distorted grid voltage, a fundamental component signal of one-phase of voltage is extracted and an orthogonal signal is constructed by using a static coordinate frame phase-locked loop method; a liapunov function is constructed based on the fundamental component signal of one-phase of voltage and the orthogonal signal, and an adaptive orthogonal generator and a frequency-locked loop are obtained because the derivative of the liapunov function is less than zero, which means the global system is in a stable and convergent state; and on the basis of the frequency output quantities of the adaptive orthogonal generator and the frequency-locked loop, feedback to a delay cancellation operator is carried out and thus the grid fundamental period T participates in real-time calculation of a delay operator valpha beta (t-T / n), so that tracking and extraction of the grid fundamental positive-sequence component is still carried out by a cascade stage delay cancellation method in a frequency fluctuation state and thus accurate phase locking of the grid fundamental positive-sequence signal is realized.

Description

technical field [0001] The invention relates to a grid-connected synchronous phase-locking method based on an improved serial signal delay cancellation algorithm. Background technique [0002] Affected by the energy crisis and environmental pollution, people pay more and more attention to renewable energy, and its proportion in the power system is also increasing. Due to the strong randomness and intermittent nature of wind power generation and photovoltaic power generation, as well as the uncertainty of load changes, there are often voltage drops, harmonic distortion, and grid frequency, phase, and amplitude fluctuations in weak grids or grid faults. mutation. In order to ensure the reliable and safe operation of grid-connected inverters, its control system must be able to quickly detect changes in grid parameters and provide accurate information to ensure that the system works in accordance with grid standards. The phase-locked loop can quickly track the phase and freque...

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Problems solved by technology

The multiple second-order integral method (MSOGI) in the literature uses the frequency-locked loop to track the frequency of the fundamental wave in real time, and decouples the harmonic components in the three-phase voltage through multi-loop parallel feedback decoupling, and then uses the symmetrical component analysis method to extract the positive wave of the fundamental wave. Sequential component phase-locking, this method is based on the stationary coordinate system, omitting the control loop, but the design of its quadrature generator needs to make a compromise between steady-state and dynamic performance

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