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Islanding detection method for low-frequency sinusoidal phase disturbance

A technology of phase disturbance and island detection, applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve the problems of speeding up the detection speed, high island recognition rate, and not eliminating the detection blind area.

Inactive Publication Date: 2017-01-18
XI'AN POLYTECHNIC UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The sliding mode frequency offset method is an efficient detection method, which is simple to implement, does not need to add additional hardware, and has a high island recognition rate and has little impact on power quality; however, there are detection blind spots under certain conditions
[0007] The active frequency offset method with positive feedback is an improvement to the active frequency offset method, which reduces the detection blind area and speeds up the detection speed, but does not eliminate the detection blind area

Method used

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  • Islanding detection method for low-frequency sinusoidal phase disturbance
  • Islanding detection method for low-frequency sinusoidal phase disturbance
  • Islanding detection method for low-frequency sinusoidal phase disturbance

Examples

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Embodiment

[0166] take f 2 =5Hz, θ m =π / 15, the local load parameters are taken as R=20Ω, L=25.478mH, C=398.089μF, at this time, the local load quality factor Q=2.5, assuming that the grid-connected voltage peak value is 311V, under the condition of active power matching, the grid will be disconnected When the amplitude of the front and rear load voltage remains unchanged, the amplitude of the inverter output current I m =311V / 20Ω=15.55A;

[0167] According to the command expression of the inverter output current, the grid-connected current command at this time is obtained as:

[0168] i s ( t ) = 15.55 · s i n ( 100 π t + π 15 s i n 10 π t ) ;

[0169] The basis for judging the occurrence of the island effect i...

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Abstract

The invention discloses an island detection method adopting low-frequency sinusoidal phase perturbation. The island detection method comprises the following specific steps: 1, determining a grid-connected inverter output current instruction; 2, determining the island detection judging rule according to the grid-connected inverter output current instruction in the step 1 and the value of the quality factor Q of a local load; 3, computing the voltage frequency f at the common connection point between a photovoltaic grid-connected system and a power network in a real-time manner; 4, carrying out island effect determination according to the frequency f obtained in the step 3 and the island detection judging rule obtained in the step 2. The island detection method has the characteristics that no detection blind zone exists; the distortion of grid-connected current is low.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverter control methods, and relates to an island detection method for low-frequency sinusoidal phase disturbances. Background technique [0002] With the rapid development of distributed power generation, more and more solar energy is converted into electrical energy and transmitted to the grid through grid-connected inverters, which poses challenges to the safe and stable operation of the grid, and must be solved accordingly The biggest problem is the islanding detection of grid-connected inverters. [0003] The island effect in the photovoltaic grid-connected power generation system means that when the grid stops supplying power, the photovoltaic power station fails to detect the change of the grid status in time and fails to cut itself off from the grid, forming an isolated power supply area with the surrounding loads that the grid cannot control . Islanding effect may cause serious ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/00
Inventor 陈增禄王宁孟新新王晓俊田苗苗
Owner XI'AN POLYTECHNIC UNIVERSITY
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