Control method of UHVDC connected to isolated doubly-fed wind farm
A UHV DC and control method technology, applied in the direction of power transmission AC network, etc., can solve the problem that the UHV DC external transmission mode cannot operate normally and stably, and achieve the effect of eliminating unbalanced power
Active Publication Date: 2018-07-17
XJ ELECTRIC +2
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[0005] The purpose of the present invention is to provide a control method for connecting UHV DC to an isolated doubly-fed wind farm, so as to solve the problem that the UHV DC external transmission mode of an isolated doubly-fed wind farm cannot operate normally and stably
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[0018] The present invention will be described in further detail below in conjunction with the accompanying drawings.
[0019] like figure 2 , 3 Shown is the UHV DC external transmission system of an isolated doubly-fed wind farm with a transient unbalanced power controller added.
[0020] The primary system of transient unbalanced power controller such as figure 2 Shown in dashed box. Including VSC (Voltage Source Converter), C dc (DC capacitor), Bi-DC / DC (cascaded bidirectional DC / DC converter) and SC (super capacitor). The VSC adopts a three-phase full-bridge structure (multi-level structure can also be used), and the AC side is connected to the UHV DC sending-end AC bus B1 through a rectifier transformer. VSC, C dc , Bi-DC / DC constitute PCS (Power Conditioning System).
[0021] The principle structure of the control system of the transient unbalance controller is as follows: image 3 Shown in the dotted line.
[0022] The capacitor voltage and the UHV DC sending...
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The invention relates to a method for controlling an extra-high-voltage direct current to be accessed to an isolated doubly-fed wind power station. The method is characterized by, according to the current voltage of a super capacitor and a given voltage reference value of the super capacitor as well as a system frequency reference value, calculating current system frequency and outputting a new system frequency reference value; calculating an amplitude correction value of a current three-phase modulation signal according to the current voltage of a DC sending-end AC bus (B1) and a given voltage reference value of the bus (B1); and calculating the three-phase sine modulation signal meeting the system frequency reference value and the modulation signal amplitude correction value, and furthermore, obtaining a trigger pulse to control the operation of a VSC. According to an unbalanced power characteristic quantity extraction mechanism, a transient unbalanced power controller for controlling the extra-high-voltage direct current to be accessed to the isolated doubly-fed wind power station is prepared, and coordination control between the controller and extra-high-voltage direct current regulation is established, so that stable operation of an extra-high-voltage DC externally-sending system of the isolated doubly-fed wind power station is realized.
Description
technical field [0001] The invention relates to a control method for an ultra-high voltage direct current connected to an isolated doubly-fed wind farm, which is suitable for transient unbalanced operation. Background technique [0002] UHV DC connected to isolated doubly-fed wind farm refers to the cooperation of wind farm alone with DC transmission system to realize the long-distance transmission of wind power. The UHV DC external transmission system of an isolated doubly-fed wind farm is as follows: figure 1 As shown, this article is aimed at this type of system. [0003] At present, there are no successful engineering cases in the world for connecting UHV DC to isolated doubly-fed wind farms. For UHV DC connected to isolated doubly-fed wind farms, since the UHV DC transmission system adopts constant power control or constant current control, for the AC busbar at the DC sending end, the entire DC transmission system connected to the busbar is equivalent to A constant p...
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IPC IPC(8): H02J3/36
CPCY02E60/60
Inventor 李少华张爱玲苏匀李泰彭忠王柏恒张望郝正航李生福陈卓
Owner XJ ELECTRIC