Random sequence-dependent photovoltaic island state detection method and device

A technology of random sequence and detection method, applied in the direction of measurement device, emergency protection circuit device, measurement power, etc., to achieve the effect of no blind spot detection and reduce the injection of power grid harmonics

Active Publication Date: 2013-08-14
WUHAN UNIV
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Problems solved by technology

However, there are obvious deficiencies in the detection of these photovoltaic

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  • Random sequence-dependent photovoltaic island state detection method and device
  • Random sequence-dependent photovoltaic island state detection method and device
  • Random sequence-dependent photovoltaic island state detection method and device

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Embodiment Construction

[0050] The technical solution of the present invention will be described in detail below in conjunction with the drawings and embodiments.

[0051] please see figure 1 , the technical scheme adopted in the present invention is: a detection method of a random sequence correlation photovoltaic island state, comprising the following steps:

[0052] Step 1: Select a random sequence with strong autocorrelation of appropriate length; the period of the random sequence T=L*△T; where T is the total period of the random sequence to detect the photovoltaic island state, L is the length of the random sequence, and △T is the Dither period for current matching.

[0053] Step 2: Perform periodic matching disturbance on the output current amplitude of the photovoltaic inverter according to the distribution of random sequence symbols; its specific implementation includes the following sub-steps:

[0054] Step 2.1: Determine the pulse signal of the photovoltaic inverter output control current...

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Abstract

The invention discloses a random sequence-dependent photovoltaic island state detection method and a random sequence-dependent photovoltaic island state detection device. According to the technical scheme, the method comprises the following steps of: detecting current output by a photovoltaic inverter and the variation of load voltage to obtain a dependency coefficient; comparing the dependency coefficient with a threshold value to obtain a logic value of the dependency coefficient; calculating the absolute value distribution of a difference between two adjacent code elements; performing not exclusive or calculation on the logic value of the dependency coefficient and an absolute value of the difference between the code elements, and adding 1 to the variable if the logic value is real; and counting the ratio of 1 according to a not exclusive or calculation result, and judging whether the photovoltaic inverter is in an island state or not. The device comprises a photovoltaic cell, a pulse signal generator, a power module, a filtering inductor, a current sensor, a voltage sensor, a current signal acquirer, a voltage signal acquirer, a random sequence-dependent island detector, a first circuit breaker, a power grid and a second circuit breaker. According to the method and the device, the photovoltaic island state can be detected without any dead zone, and the injection of power grid harmonics is effectively reduced.

Description

technical field [0001] The invention relates to the technical field of new energy control, in particular to a detection method and device for a random sequence correlation photovoltaic island state. Background technique [0002] Recently, scientists are faced with the challenge of how to obtain clean, efficient, and environmentally friendly energy. Photovoltaic cells, as an emerging green energy source, have received more and more attention. Therefore, research on photovoltaic power generation devices is of great significance. It is of great significance to effectively detect the islanding state in the control method of photovoltaic inverter. [0003] The islanding phenomenon of grid-connected inverters means that when the power grid is interrupted for some reason, the inverter still transmits power to the grid, and forms a self-sufficient power supply island that cannot be controlled by the public grid system with the local load. The occurrence of this phenomenon will thre...

Claims

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Application Information

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IPC IPC(8): G01R31/00H02H7/26
Inventor 李德识李磊陈健
Owner WUHAN UNIV
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