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AFD islanding detection method of three-phase grid-connected inverter

An island detection and inverter technology, which is applied in the direction of instruments, measuring electronics, measuring devices, etc., can solve the problems of small detection blind area, large detection blind area, and reduced quality of network current waveform, so as to reduce the distortion rate and distortion degree, the effect of high DC voltage utilization

Inactive Publication Date: 2018-01-30
郭琳
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Problems solved by technology

It is easy to implement and the cost is low, but there is a large detection blind spot
The active island detection method can quickly detect islands when the power grid is powered off by applying disturbance components to relevant parameters, and the detection blind zone is small. When the power grid is normal, due to the existence of disturbance components, the grid current will be reduced Waveform quality

Method used

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  • AFD islanding detection method of three-phase grid-connected inverter
  • AFD islanding detection method of three-phase grid-connected inverter
  • AFD islanding detection method of three-phase grid-connected inverter

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Embodiment Construction

[0014] specific implementation plan

[0015] figure 1 In SVPWM control, its voltage reference rotation vector U ref Output from active and reactive current loops and It is obtained by Parker's inverse transformation. According to the principle of coordinate transformation, the phase angle θ is calculated by the grid voltage phase-locked loop (PLL), and θ also determines the U ref The frequency of θ affects the frequency of the incoming current. Therefore, the essence of disturbing θ is the disturbance of the incoming current frequency. The phase-locked angle θ′ after the disturbance participates in the Parker transformation of the current feedback value on the AC side and and Parker's inverse transformation, the calculation result participates in the SVPWM operation and obtains the driving waveform.

[0016] The phase angle at which the dead zone occurs is related to the amount of frequency disturbance, the switching period, and the number of times of averaging. In...

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Abstract

The present invention discloses an AFD (Active Frequency Drift) islanding detection method of a three-phase grid-connected inverter. The AFD islanding detection method comprises three parts consistingof an AFD algorithm based on a phase-locking angle disturbance, blind spot detection analysis and semi-decoupling disturbance control. A three-phase grid-connected inverter play an important part infields of a new energy generation system, an electric car and the like, and islanding detection is very necessary for ensuing safe and stable operation of a system. The AFD islanding detection methodfor controlling a three-phase grid-connected inverter based on space vector pulse width modulation (SVPWM) is provided to apply disturbance to a phase-locking angle calculated by a phase-locked loop (PLL). Causes of formation of an islanding detection blind area are analyzed and possibility of the blind area is eliminated, three-phase currents is subjected to harmonic wave analysis after the disturbance is applied, and an improved semi-decoupling control algorithm for harmonic wave inhibition is provided.

Description

Technical field [0001] The invention relates to an island detection method, in particular to an AFD island detection method for a three-phase grid-connected inverter. Background technique [0002] When the grid power supply is interrupted, due to the existence of local loads, the grid-connected power generation system at the user end fails to detect grid failures in time and continues to supply power to the loads, thus forming an island of power supply, resulting in confusion of AC voltage frequency, phase and amplitude, which seriously It will damage the electrical equipment connected to the isolated island and cause harm to personal safety. Therefore, it is of great significance to detect the islanding phenomenon and cut off the grid-connected power generation system from the mains in time when the islanding is detected. Islanding detection was initially applied to photovoltaic grid connection. With the development of power electronics technology, its application in new e...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00H02J3/38
Inventor 郭琳
Owner 郭琳
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