A wind turbine grid-connected system based on hybrid direct current transmission

A hybrid DC power transmission and DC reactor technology, which is applied in AC network circuits, power transmission AC networks, wind power generation, etc., can solve problems such as LCC commutation failure and large DC current, and achieve DC current growth suppression and commutation The effect of reducing the probability of failure and reducing the cost and loss

CN105790300BActive Publication Date: 2018-07-24STATE GRID ZHEJIANG ELECTRIC POWER COMPANY ECONOMIC TECHN INST +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2018-07-24

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Abstract

The invention discloses a hybrid DC transmission-based fan grid-connected system. In the operation process of an existing hybrid direct-current system, fluctuation of an inverter side DC voltage is caused by fluctuation of a network voltage, so that fluctuation of a DC is caused and a commutation failure of an LCC is easily caused. The hybrid DC transmission-based fan grid-connected system comprises a rectifier station, an inverter station, a DC line and a wind turbine generator, wherein the rectifier station comprises a modular multilevel converter MMC, a rectifier side DC reactor and a rectifier side transformer; the inverter station comprises the line commutation converter LCC, an inverter side DC reactor and an inverter side transformer; the hybrid DC transmission-based fan grid-connected system is characterized in that the modular multilevel converter MMC is controlled by a stator module capacitor voltage and a constant DC at a DC side; and a permanent magnet direct-drive fan is controlled by a low voltage drop power. According to the hybrid DC transmission-based fan grid-connected system, a DC increase is suppressed by virtue of a constant DC control of the MMC and low voltage drop power control of the fan; and the probability of the commutation failure of the hybrid DC is reduced.
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Description

technical field

[0001] The invention relates to a wind power grid-connected system, in particular to a wind power grid-connected system based on hybrid direct current transmission. Background technique

[0002] Wind power is an important renewable energy source. Large-scale installed wind farms are often located far away from the load center, and DC transmission is an important technology for long-distance transmission of wind power. Existing DC transmission converters mainly include a grid commutation converter LCC and a voltage source converter VSC. Domestic voltage source converter VSC mainly adopts modular multilevel converter MMC topology. LCC has the advantages of low loss, low cost, and mature technology. However, the operation of LCC requires the commutation voltage provided by the AC grid, so it cannot be directly connected to the AC system of the wind farm. MMC can be directly connected to passive systems of wind farms, but it has problems such as high cost comp...

Examples

Embodiment Construction

[0023] In order to describe the present invention more specifically, the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] Such as figure 1 As shown, the present invention is composed of a rectification station, an inverter station, a DC line and a wind turbine; the rectification station is composed of a modular multilevel converter MMC, a rectification-side DC reactor and a rectification-side transformer; the inverter The station is composed of the commutation converter LCC of the grid, the DC reactor of the inverter side and the transformer of the inverter side; the wind turbine adopts a permanent magnet direct drive fan.

[0025] The MMC adopts stator module capacitor voltage and constant DC current control on the DC side, and the formula used for the stator module capacitor voltage control is:

[0026]

[0027] Among them, I dcref is the DC current reference va...