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MMC alternating current side fault energy balance control method based on feedforward control

A technology of AC side fault and feedforward control, which is applied in the direction of power transmission AC network, AC power input conversion to DC power output, output power conversion device, etc., can solve problems such as fault protection and immature control strategy, and achieve improvement The effect of responsiveness

Inactive Publication Date: 2020-03-31
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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Problems solved by technology

[0002] The high-voltage flexible DC transmission technology based on Modular Multilevel Converter (MMC) is a new generation of DC transmission technology with the core of the voltage source converter. As an emerging technology, its related fault protection and Control strategies are immature

Method used

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  • MMC alternating current side fault energy balance control method based on feedforward control
  • MMC alternating current side fault energy balance control method based on feedforward control
  • MMC alternating current side fault energy balance control method based on feedforward control

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Embodiment Construction

[0015] The present invention will be further described below in conjunction with accompanying drawings and examples.

[0016] like figure 1 The schematic diagram of the MMC structure is shown, which consists of three phases and each phase has two upper and lower bridge arms. Each bridge arm has N sub-modules and a reactor L connected in series at the same time. 0 , the port voltage of the upper and lower bridge arms of the converter is The current of the upper and lower bridge arms of the converter is Represents the AC measured voltage and current, V DC , V l DC are the high-voltage DC side voltage and the upper and lower pole voltages, where k=a, b, c.

[0017] According to Kirchhoff's voltage law:

[0018]

[0019]

[0020] In the above formula: L 0 is the bridge arm inductance, They are the upper and lower bridge arm voltages of phase K (K=a,b,c), is the upper and lower bridge arm current of K phase, u dc is the DC side voltage, the physical relationsh...

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Abstract

The invention discloses an MMC alternating current side fault energy balance control method based on feedforward control. A feedforward control strategy is provided so that voltage balance of amodular multilevel converter under an unbalanced power grid condition is improved. The method comprises the following steps of analyzing the coupling relationship between the bridge arm energy and each electrical signal and establishing a bridge arm energy mathematical model under a coordinate system. Due to the addition of the feedforward compensation, the anti-interference capability of the alternating current power grid on asymmetric faults and sudden voltage imbalance is improved; flexible and rapid control of bridge arm energy is realized through an internal current signal of the converter. Abridge arm zero-sequence current suppression link is added, finally, static-error-free tracking control over an alternating-current-side direct-current-side current signal is achieved through a PIR controller, double-frequency components in circulating current and direct-current-side current are filtered out through a PR controller, and the alternating-current-side fault ride-through capacity is greatly improved.

Description

[0001] The invention discloses a feedforward control-based MMC AC side fault energy equalization control method, which is applied to the field of flexible direct current transmission. Background technique [0002] The high-voltage flexible DC transmission technology based on Modular Multilevel Converter (MMC) is a new generation of DC transmission technology with the core of the voltage source converter. As an emerging technology, its related fault protection and Control strategies are immature. Therefore, it is of great significance to study the protection and ride-through capability of the flexible HVDC system during faults. [0003] The MMC converter control system includes DC side, AC side and circulating current control. The most challenging part is the balance control of sub-module capacitor voltage, which aims to achieve the balance of energy flow inside the converter, including the total energy of all bridge arms. control, phase-to-phase energy balance control, and en...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M7/5387H02J3/24H02J3/36
CPCH02J3/24H02J3/36H02M7/483H02M7/53871Y02B70/10Y02E60/60
Inventor 夏向阳刘远徐雷
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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