Intelligent integrated low-voltage reactive module high-precision phase-locking method

Abstract

Disclosed is a high-precision phase locking method for an intelligent integrated low-pressure reactive power module, the method comprising a multiplicative phase discrimination link (1), a variable frequency period integration link (2), a variable parameter integration separation speed change PI regulation link (3), an angular frequency integration link (4), a frequency estimation link (5), remainder (6), sine (7) and cosine (8). An improved PI regulator uses a variable parameter integration separation speed change PI regulator for regulation, so that the phase locking precision is improved and the static deviation is eliminated under the premise that the rapidity of phase locking can be ensured. An improved loop filter can eliminate the influence of harmonic wave and frequency changes on the output precision of a phase-locked loop when in a steady state.

Description

technical field [0001] The invention relates to a phase-locking method, in particular to a high-precision phase-locking method for an intelligent integrated low-voltage reactive power module. Background technique [0002] In the field of low-voltage power distribution, no matter the instrumentation or reactive power compensation module, it is necessary to synchronize the phase of the grid for accurate calculation and control to achieve the effect of compensation and optimization. Rolling mills, intermediate frequency furnaces and other unbalanced and impactful industrial electrical equipment are increasing, resulting in many power quality problems such as low power factor, voltage fluctuation and flicker, and three-phase voltage and current imbalance. Therefore, when performing reactive power compensation for this type of impact load, it is necessary to use instantaneous reactive power for fast compensation, and the key to calculating instantaneous reactive power lies in the...

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Problems solved by technology

For occasions where the harmonic distortion of the grid voltage is serious, this method may cause multiple level jumps near the voltage zero point, and the synchronization will fail.

The second method: the fundamental wave Fourier transform calculation phase method, this method can only be used in the occasion of fixed frequency, and the amount of calculation is large

The third type: phase-locking technology based on dq algorithm, this method can be divided into three-phase and single-phase phase-locking, three-phase phase-locking is only suitable for voltage balance and voltage distortion is not serious occasions, sensitive to grid voltage, phase-locking error is relatively large Large; single-phase needs to generate quadrature signals, one adopts a lagging 90° method, and the other adopts a generalized integral method. The former cannot achieve an accurate 90° lagging signal due to fluctuations in grid frequency, and inaccurate frequency tracking leads to phase-locking failure. , the latter is sensitive to the power grid, due to the influence of frequency fluctuations and harmonics, the quadrature signal obtained by the generalized integral method will contain harmonic components, resulting in phase-locking distortion

[0004] The traditional loop filter is directly composed of PI regulators. This kind of loop filter has poor steady-state accuracy and cannot completely eliminate the influence of harmonics and frequency changes on the output accuracy of the phase-locked loop. Due to the traditional phase-locked loop PI regulator , if the adjustment coefficient is selected too large, the phase-locking speed will be fast, but the output fluctuation will be large, and the result will be inaccurate. If the adjustment coefficient is selected to be small, although the fluctuation will reduce the fluctuation, the phase-locking speed will be greatly reduced

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