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Method for modeling large-scale photovoltaic grid-connected system with multiple parallel-connected grid-connected inverters through considering dead zone

A system modeling and inverter technology, applied in the direction of photovoltaic power generation, AC network circuit, single network parallel feeding arrangement, etc., can solve the problems of non-linear factor processing without dead zone effect, no dead zone establishment, etc.

Active Publication Date: 2016-08-31
CHONGQING UNIV
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Problems solved by technology

Some have reflected the influence of the dead zone effect in the impedance model established for the single-phase photovoltaic grid-connected system, but have not dealt with the nonlinear factors introduced by the dead zone effect, and have not really built the dead zone into the impedance model.
Some consider the influence of high-order harmonics generated by PWM modulation and low-order harmonics introduced by the dead zone effect on the output voltage of the inverter, but the equivalent error voltage formed by the dead zone effect is regarded as a component of the power supply , not reflected in the impedance model

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  • Method for modeling large-scale photovoltaic grid-connected system with multiple parallel-connected grid-connected inverters through considering dead zone
  • Method for modeling large-scale photovoltaic grid-connected system with multiple parallel-connected grid-connected inverters through considering dead zone
  • Method for modeling large-scale photovoltaic grid-connected system with multiple parallel-connected grid-connected inverters through considering dead zone

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Embodiment Construction

[0035] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings; it should be understood that the preferred embodiments are only for illustrating the present invention, rather than limiting the protection scope of the present invention.

[0036] For the normal operation of the inverter circuit, it is generally necessary to add a certain dead time to the control signal of the switching device to prevent the straight-through phenomenon of the upper and lower bridge arms of the inverter. Although the added dead time is very short, the low-order The harmonic accumulation effect will affect the power quality, especially in large-scale photovoltaic grid-connected systems, which will seriously distort the grid-connected current waveform and affect the stable operation of the system.

[0037] Such as figure 1 As shown, for the convenience of analysis, the DC side of the inverter is equivalent to a series connect...

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Abstract

The invention discloses a method for modeling a large-scale photovoltaic grid-connected system with multiple parallel-connected grid-connected inverters through considering a dead zone. The method comprises the following steps: S1, during modeling, considering the influence of the dead zone, and obtaining a relation between each voltage component of dead zone distortion voltages of the inverters and ideal fundamental wave voltages output by the inverters; S2, through Laplace transformation, adding fundamental waves of the dead zone distortion voltages and introduced low-subharmonic components into an impedance model of the grid-connected system so as to obtain an impedance model of a single-inverter grid-connected system; and S3, according to the impedance model of the single-inverter grid-connected system, obtaining a Norton equivalent circuit of the large-scale photovoltaic grid-connected system with the multiple parallel-connected grid-connected inverters and obtaining output impedance at a photovoltaic power station side. According to the invention, a reference is provided for analysis of stability of the large-scale photovoltaic grid-connected system during power grid impedance change and analysis and treatment of electric energy quality.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a modeling method for a large-scale photovoltaic grid-connected system in which multiple grid-connected inverters are connected in parallel in consideration of dead zones. Background technique [0002] With the energy shortage and environmental pollution caused by the continuous consumption of traditional energy, clean and renewable energy such as solar energy has been greatly developed. According to the 13th Five-Year Plan of the National Energy Administration, by the end of 2020, the installed capacity of solar power will reach 160 million kilowatts, the annual power generation will reach 170 billion kilowatt-hours, and the total annual investment will be about 200 billion yuan. It is worth noting that among them, the total installed capacity of photovoltaic power generation will reach 150 million kilowatts. Photovoltaic power stations will also gradually...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCH02J3/383H02J2203/20Y02E10/56
Inventor 周林张前进郭珂李海啸郑堃谢星宇
Owner CHONGQING UNIV
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