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Software phase locking method applicable to single-phase and three-phase power systems

A three-phase power, single-phase technology, applied to the components of electrical measuring instruments, measuring electricity, measuring electrical variables, etc.

Inactive Publication Date: 2018-06-29
CHINA UNIV OF MINING & TECH (BEIJING)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Aiming at the problems existing in the existing phase-locking methods, the invention discloses a software phase-locking method suitable for single-phase and three-phase power systems. It can still accurately track the frequency and phase angle of the grid voltage even when it is distorted

Method used

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  • Software phase locking method applicable to single-phase and three-phase power systems
  • Software phase locking method applicable to single-phase and three-phase power systems
  • Software phase locking method applicable to single-phase and three-phase power systems

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Embodiment

[0074] Embodiment: simulation result analysis

[0075] In the electromagnetic transient simulation software PSCAD / EMTDC, use Fortran language to realize the software phase-locked loop. Simulation model parameters: the three-phase grid voltage is 1kV, the grid frequency is 50Hz, and the sampling frequency is 10kHz. Phase C voltage contains 10% of the third harmonic and 10% of the fifth harmonic, and a phase A ground fault occurs at 0.5s, and the duration is 0.3s. The simulation results under grid voltage asymmetry and distortion are as follows: Figure 5 shown.

[0076] Figure 5 Contains four subgraphs, Figure 5 (a)- Figure 5 (d) are three-phase grid voltage, u q , The frequency and phase angle locked by the phase-locked loop. Depend on Figure 5 As shown in (a), the grid voltage is in a distorted state and a phase A ground fault occurs at 0.5s, and the duration is 0.3s. Depend on Figure 5 As shown in (b), under grid voltage asymmetry and distortion u q Always re...

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Abstract

The invention discloses a software phase locking method applicable to single-phase and three-phase power systems and belongs to the technical field of grid synchronization. The design thought mainly comprises the following steps: determining a single-phase or three-phase phase-locked loop mode by virtue of a state of a control switch K, and enabling a single-phase voltage to generate two paths oforthogonal signals such as u alpha and u beta by virtue of a phase-shifting algorithm or enabling a three-phase voltage to generate the u alpha and u beta by adopting Clark coordinate transformation;enabling the u alpha and u beta to pass through a positive-sequence component extraction link and a complex band-pass filter so as to obtain a network voltage fundamental positive-sequence component;performing Park transformation to obtain u d and u q, feeding the difference of the u q and 0 into a PI controller to be regulated, adding the output quantity of the PI controller and a rated angularfrequency omega f of the power grid so as to obtain a starting phase angle by using an integrator, and obtaining the final phase angle from the starting phase angle by using a comparator and a selector. The phase locking method provided by the invention can be applicable to the single-phase and three-phase power systems, and the frequency and phase angle of the network voltage can be accurately tracked under asymmetric distorted network voltages.

Description

technical field [0001] The invention belongs to the technical field of grid synchronization, and in particular relates to a software phase-locking method suitable for single-phase and three-phase power systems. Background technique [0002] With the continuous advancement of power electronics technology, the proportion of power electronic grid-connected devices such as new energy grid-connected inverters based on power electronic power switches, high-voltage direct current transmission converters, and active filters in the power system is gradually increasing. The modern power system presents the trend of power electronics. The phase-locked loop is an important link in the control system of the power electronic grid-connected device. The performance of the phase-locked loop will directly affect the control performance of the power electronic grid-connected device and even affect its stability. Due to the extensive application of power electronic grid-connected devices in th...

Claims

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Application Information

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IPC IPC(8): G01R1/30G01R23/02G01R25/00
CPCG01R1/30G01R23/02G01R25/00
Inventor 梁营玉许冠军王聪
Owner CHINA UNIV OF MINING & TECH (BEIJING)
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