Star-connected STATCOM multiple overload control method under unbalanced power grid condition

A technology for grid imbalance and overload control, applied in the direction of single-grid parallel feeding arrangement, multi-phase network asymmetry reduction, multi-phase network elimination/reduction of asymmetry, etc., can solve problems such as STATCOM overmodulation, and improve stability. , the effect of solving the overmodulation problem

CN113364003APending Publication Date: 2021-09-07RONGXIN HUIKO ELECTRIC TECH CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2021-09-07

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Abstract

The invention provides a star-connected STATCOM multiple overload control method under an unbalanced power grid condition. The star-connected STATCOM multiple overload control method comprises a power grid voltage PLL link, a reactive current reference instruction distribution link, a zero-sequence voltage injection and capacitor voltage balance control link and a current inner loop control link. The positive-sequence active phases and the positive-sequence reactive phases of the three-phase power grid are obtained through the power grid voltage phase locking link and are input to the reactive current reference instruction distribution link; a three-phase reactive current alternating current reference instruction is obtained through the reactive current reference instruction distribution link, and is input to the zero-sequence voltage injection and capacitor voltage balance control link and the current inner loop control link to obtain a three-phase current AC reference instruction and a zero-sequence voltage; and the three-phase current AC reference instruction and the zero sequence voltage are input into the current inner loop control link to obtain a three-phase voltage modulation wave. According to the present invention, the stability of the capacitor voltage at the direct current side of an interphase branch of the STATCOM is improved, and the problem of over-modulation of the star-connected STATCOM in an asymmetric transient fault is solved.
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Description

technical field

[0001] The invention relates to the technical field of flexible power transmission and power electronics application, in particular to a star-connected STATCOM multiple overload control method under the condition of unbalanced power grid. Background technique

[0002] Static synchronous compensator (STATCOM), as a new type of power electronic equipment, has excellent dynamic reactive power compensation performance, and is widely used in various fields of flexible power transmission systems, such as wind farms, photovoltaic grid-connected, battery energy storage, electric arc furnaces Flicker suppression, subsynchronous oscillation, and more.

[0003] When the grid voltage of the star-connected STATCOM is unbalanced and needs to output multiple overload currents, the power unit is prone to over-modulation, and the DC side voltage is difficult to stabilize, resulting in the continuous and stable operation of the equipment. In order to solve this problem, the p...

Examples

Embodiment Construction

[0029] The specific embodiments provided by the present invention will be described in detail below in conjunction with the accompanying drawings.

[0030] figure 1 It is the connection topology diagram of the star-connected STATCOM system in the prior art. The method of the invention is based on this star-connected STATCOM system connection topology.

[0031] Such as Figure 2-5 As shown, a star-connected STATCOM multiple overload control method in the case of unbalanced power grid divides the entire STATCOM control system into four control links: grid voltage phase-locked PLL link, reactive current reference command distribution link, zero-sequence voltage Injection and capacitor voltage balance control link, current inner loop control link.

[0032] 1. Grid voltage phase-locked PLL link

[0033] Uan, Ubn, Ucn three-phase grid voltage instantaneous value through the phase-locked loop Get the respective positive sequence active phase cosθ of A, B, and C three-phase grid...