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Output phase-locked loop system of grid-connected converter and control method

An output control and converter technology, applied in AC network circuits, parallel feeding arrangement of single network, reduction of multiphase network asymmetry, etc., can solve the amplitude and phase error of current feedback amount, poor system dynamic performance, etc. It can reduce the amplitude and phase error, improve the adaptability, and have the effect of strong anti-interference.

Active Publication Date: 2017-10-17
STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The invention aims to solve the problem that the delay caused by the separation of the positive and negative sequence components of the output of the grid-connected converter causes amplitude and phase errors in the current feedback, resulting in poor dynamic performance of the entire system

Method used

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  • Output phase-locked loop system of grid-connected converter and control method
  • Output phase-locked loop system of grid-connected converter and control method
  • Output phase-locked loop system of grid-connected converter and control method

Examples

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Embodiment 1

[0028] figure 1 is a schematic structural diagram of the grid-connected converter output phase-locked loop system of this embodiment, and the grid-connected converter output phase-locked loop system includes a Clark transformation module 11, a delay elimination module 12, a Park transformation module 13, and a PI adjustment module device 14, integration module 15, amplification module 16 and superposition module 17.

[0029] Specifically, the Clark transformation module 11 is used for the three-phase voltage signal v output by the grid-connected converter a , v b and v c Perform Clark transformation to obtain the two-phase voltage v in the αβ coordinate system α and v β , that is, the three-phase voltage signal v output by the grid-connected converter a , v b and v c Transform from the abc coordinate system to the αβ coordinate system. Those skilled in the art know the specific implementation method of the Clark transform, which will not be repeated here.

[0030] The...

Embodiment 2

[0055] According to the output phase-locked loop system of the grid-connected converter provided in Embodiment 1, this embodiment provides a method for controlling the output of the grid-connected converter under the condition of unbalanced power grid. When the three-phase power grid is unbalanced, the negative sequence component of the voltage will cause the output instantaneous power of the grid-connected converter to fluctuate at twice the frequency, and then cause the fluctuation of the DC bus voltage. If the fluctuation is too large, the DC overvoltage / undervoltage protection of the converter will be triggered. In order to avoid the above phenomenon, it is necessary to control the output negative sequence current of the grid-connected converter.

[0056] According to the instantaneous power theory, the output active power of the grid-connected converter is calculated as:

[0057] P c =P c0+ +P c0- +P 1 cos(2ω 0 t)+P 2 sin(2ω 0 t) Formula (10)

[0058] In the form...

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Abstract

The invention discloses an output phase-locked loop system of a grid-connected converter and a control method. The system comprises a Clark transform module for Clark transform of a three-phase voltage signal outputted by a grid-connected converter, a delay elimination module for carrying out delay elimination on two phases of voltages in an alpha-beta coordinate system, a Park transform module for Park transform of the two phases of voltages in the alpha-beta coordinate system after delay elimination according to an initial output phase, a PI regulator for PI adjustment on a q-axis signal, an integration module for integration processing on a grid voltage estimation value to obtain an initial output phase, an amplification module for amplification of a frequency adjustment error to obtain a phase compensation value, and a superimposition module for superimposition of the initial output phase and the phase compensation value to obtain a final output phase. With the output phase-locked loop system and the control method, the fundamental frequency and phase information of the output voltage of the grid-connected converter can be obtained accurately when the system voltage is not balanced or distorts.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a grid-connected converter output phase-locked loop system and a control method. Background technique [0002] With the development of AC-DC hybrid systems such as new energy power generation, micro-grid, and high-voltage DC transmission, power electronic converters as power exchange interfaces are increasingly used in power systems. As an important class of power electronic devices, grid-connected converters mainly include wind power grid-connected inverters for fundamental wave applications, photovoltaic grid-connected inverters, static var generators, and grid-connected inverters for grid harmonic control. Parallel power active filter. [0003] The power grid voltage is three-phase symmetrical in an ideal state, but in the actual power grid, the three-phase unbalance of the power grid voltage often occurs, including normal small value unbalance and fault transient a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/26H02J3/01
CPCH02J3/01H02J3/26H02J3/382H02J2203/20Y02E40/40Y02E40/50
Inventor 徐琳林瑞星杨华
Owner STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST
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