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Doubly-fed fan based on unified power quality conditioner and application method thereof

A double-fed fan, power quality technology, applied in the usage of superconductor elements, flexible AC transmission system, reducing/preventing power oscillation, etc., can solve the problems of inability to negative sequence voltage, current control, weak current and power oscillation suppression effect, etc. , to achieve the effect of improving reliability, solving output power instability, and improving acceptability

Active Publication Date: 2020-03-31
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing UPQC generally cannot control the negative sequence voltage and current, but can only perform overall regulation, and the suppression effect on current and power oscillations caused by asymmetrical faults is very weak

Method used

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  • Doubly-fed fan based on unified power quality conditioner and application method thereof
  • Doubly-fed fan based on unified power quality conditioner and application method thereof
  • Doubly-fed fan based on unified power quality conditioner and application method thereof

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Embodiment Construction

[0041] The present invention is described in detail below in conjunction with accompanying drawing:

[0042] 1. Analysis of DFIG oscillation mechanism under unbalanced fault

[0043] The complex power output by DFIG can be expressed in the stator dq rotating coordinate system as:

[0044]

[0045]Among them, the first subscript d represents DFIG, and the second subscript dq represents the d-axis and q-axis components in the stator dq rotating coordinate system respectively. In formula (1), the part and imaginary part of the complex power are active and reactive power, respectively. Then active and reactive power can be expressed as:

[0046]

[0047]

[0048] Among them, the subscripts d0, dcos2 and dsin2 represent the DC component and double frequency oscillation in the active and reactive power respectively. Under normal conditions and symmetrical faults, P dcos2 ,P dsin2 ,Q dcos2 ,Q dsin2 are all 0; under asymmetrical faults, P dcos2 ,P dsin2 ,Q dcos2 , Q...

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Abstract

The invention discloses a doubly-fed fan based on a unified power quality regulator. An energy storage type unified power quality regulator is connected between the doubly-fed fan and a power grid. The regulator comprises a series inverter SSC and a parallel inverter PSC, a direct-current branch is arranged between the two inverters, and a direct-current capacitor and a DC-DC chopper are connectedto the direct-current branch in parallel. The chopper is connected with a superconducting magnetic energy storage part in parallel; wherein the series inverter SSC is mounted on one side close to thedoubly-fed fan, and the parallel inverter PSC is mounted on one side close to a power grid; the series inverter SSC is connected with the power transmission line in series through the LC filter and the isolation transformer, the parallel inverter PSC is connected to the power transmission line on the double-fed fan side in parallel through the filter inductor, the negative sequence regulator is adopted to control the negative sequence current, and double-frequency oscillation can be obviously restrained.

Description

technical field [0001] The invention relates to the technical field of doubly-fed fan equipment, in particular to a doubly-fed fan protection method based on a unified power quality regulator. Background technique [0002] As one of the most promising renewable energy power generation methods, wind power is considered to be an important means to solve global warming and energy depletion. With the increasing scale and capacity of wind farms, the problems exposed by the most popular type of wind turbines - doubly-fed induction generator (DFIG) are becoming more and more obvious. The two problems of unstable output power due to unstable wind speed and weak low-voltage ride-through capability need to be solved urgently. When the power grid fails, the voltage and current on the rotor side of DFIG are affected by the transient induced electromotive force on the stator side, the stator and rotor currents will increase sharply, and the electromagnetic torque will also oscillate sev...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/28H02J3/24H02J3/46
CPCH02J3/28H02J3/24H02J3/46Y02E40/10
Inventor 金建勋杨若奂
Owner TIANJIN UNIV