Improved VSG control strategy for dealing with grid harmonics

A control strategy, harmonic technology, applied in AC network to reduce harmonics/ripple, harmonic reduction devices, etc., can solve problems such as slow response time, and achieve the effect of reducing and eliminating harmonic components.

Active Publication Date: 2019-07-12
CHINA UNIV OF MINING & TECH
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Problems solved by technology

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides an improved VSG control strategy for grid harmonics, solving the problem that traditional VSG harmonic suppression methods only target Specific sub-harmonics or problems that require differential operations tend to introduce additional harmonic components and slow down response time

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  • Improved VSG control strategy for dealing with grid harmonics
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  • Improved VSG control strategy for dealing with grid harmonics

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Embodiment Construction

[0033] like figure 1 The VSG control block diagram shown, by P ref , Q ref The amplitude and phase angle of the reference voltage are obtained through the VSG control algorithm, and the voltage reference command is output. For grid-connected inverters based on LCL filters, the system model under VSG control is available figure 2 Equivalent, where u 0 , u C , u PCC , u g are the output voltage of the grid-connected inverter, capacitor voltage, grid-connected point voltage and grid voltage; i L and i g are the output current on the grid-connected inverter side and the output current on the grid side, respectively; L 1 , L 2 , R 1 , R 2 , C are LCL filter inductance, filter inductance internal resistance and capacitance; Z G is the grid impedance; Z VSG is the equivalent output impedance of the virtual synchronous generator.

[0034] image 3 in, u gc and i Lc are the grid voltage measurement value and the inverter side current measurement value, respectively. ...

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Abstract

The invention relates to an improved VSG control strategy for dealing with grid harmonics, and belongs to the technical field of power quality of VSG to effectively suppress the harmonic content of the VSG grid-connected point current when the grid contains harmonics. The improved VSG control strategy comprises steps of firstly, establishing a VSG equivalent model, and providing an inductive current reference value algorithm based on improved biquadratic generalized integral based on the analysis of the influence of grid harmonics on the grid current; replacing the differential operation in the full feedforward control of the grid voltage by an inertia integral link; and analyzing the corresponding current regulator mechanism so as to select a corresponding current regulator to achieve current tracking and harmonic suppression.

Description

technical field [0001] The invention relates to an improved VSG control strategy for dealing with power grid harmonics, and belongs to the technical field of VSG power quality. Background technique [0002] With the increase of the installed capacity of distributed inverters in the power system, the proportion of the installed capacity of traditional synchronous generators has gradually decreased. Because distributed generation systems interfaced with power electronic converters lack the inertia and damping of traditional synchronous generators, power systems are more susceptible to power fluctuations and system failures. VSG enables the distributed power supply based on grid-connected inverter to simulate or partially simulate the frequency and voltage control characteristics of the synchronous generator from the external characteristics, which can provide certain inertia and damping for the grid, thereby improving the stability of the distributed system. [0003] However,...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/01
CPCH02J3/01Y02E40/40
Inventor 韩丽王书欢陈锴史丽萍金荣泽卢俊结
Owner CHINA UNIV OF MINING & TECH
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