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Current control method and device of flexible DC power transmission current transformer

A flexible direct current transmission and current control technology, which is applied in wind power generation, single-network parallel feeding arrangement, etc., can solve the problems that the direct current control method is difficult to apply directly, so as to reduce the amount of calculation and storage space, improve efficiency, and control quickly Effect

Inactive Publication Date: 2008-10-29
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

Therefore, these two types of direct current control methods are difficult to apply directly.

Method used

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  • Current control method and device of flexible DC power transmission current transformer
  • Current control method and device of flexible DC power transmission current transformer
  • Current control method and device of flexible DC power transmission current transformer

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[0075] Such as Figure 5 Shown is a schematic diagram of the hysteresis loop width estimation circuit in the device of the present invention, which uses a monostable oscillator and the switching frequency f s Control the pulse period of its output as T s , Fixed clock frequency f r Control the width of its output pulse T r . Considering T r >T s When the pulse width control cannot be realized, the detection gain 1 / K of the hysteresis width h is introduced (where Ks , The pulse width is KT r s . The pulse signal is used to control an analog switch, through the duty cycle KT r / T s To adjust the estimated value of hysteresis width h r . The filter in the figure uses a low-pass filter to filter out the estimated value of the hysteresis width h r High frequency disturbance improves system stability. The estimated value of hysteresis width h r Feed back to the hysteresis comparator to form a period of closed loop control, so that the period of the switching signal output by the hysteres...

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Abstract

The invention relates to a current control method for a flexible DC transmission convertor and a device thereof, which pertains to the technical field of power transmission in wind power generation. The current control of the invention adopts a hysteresis loop comparator with the adjustable width of a hysteresis loop; the current bias is compared with the width of the hysteresis loop; when the current bias exceeds the width of the hysteresis loop, the hysteresis loop comparator outputs switching signals to change the switching tube state of the bridge circuit of the convertor and reduce the current bias so as to achieve the purpose of current tracing control; meanwhile, the closed loop control of switching signal frequency is brought in by the hysteresis loop comparator; the phase and the period of the switching signal are controlled to be equal to the phase and the period of a fixed clock signal by the dynamic regulation to the width of the hysteresis loop, thus causing the frequency of the switching signal to be a fixed value. The method and the device promote the dynamic response speed and precision of the current tracing control of the flexible wind power DC transmission convertor on the sea, meanwhile, the switching frequency of the power tube of the convertor is kept to be fixed, switching stress and switching lose are reduced and the transmission efficiency is improved.

Description

Technical field [0001] The invention relates to a current control method and device in the technical field of power transmission, in particular to a current control method and device of a flexible direct current transmission converter for offshore wind power generation power transmission. Background technique [0002] With the increasing scale of offshore wind farms, wind farms are getting farther and farther from the coast, and their capacity has increased to tens or even millions of kilowatts. Flexible DC transmission is a new type of power transmission technology based on voltage source converter (VSC), insulated gate bipolar transistor (IGBT) and pulse width modulation (PWM) technology. This technology has the ability to supply power to passive networks, and It realizes the independent control of active power and reactive power of the transmission system, and does not require additional reactive power compensation equipment. It meets the requirements of long-distance transmis...

Claims

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Application Information

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IPC IPC(8): H02J3/38
CPCY02E10/763Y02E10/76
Inventor 李响王志新
Owner SHANGHAI JIAO TONG UNIV
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