Control Method of Three-phase Grid-connected Converter Using DC Capacitor to Realize Self-Synchronization Dynamically
A technology of DC capacitance and control method, which is applied in the direction of AC network circuits, wind power generation, electrical components, etc., can solve the problems that the weak grid cannot support the grid frequency, and the three-phase converter is not suitable, so as to improve the frequency support ability and improve the Dynamic performance, the effect of improving adaptability
Active Publication Date: 2019-08-16
ZHEJIANG UNIV
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[0004] In order to solve the problem that the three-phase converter controlled by phase-locked loop in the prior art is not suitable for weak grid operation and cannot support the grid frequency, the present invention proposes a three-phase grid-connected converter that uses DC capacitors to dynamically realize self-synchronization device control method
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[0056] The embodiment incorporates the infinite system (such as figure 2 shown) as an example, the single-machine infinite system is simulated, and the converter adopts the control method proposed by the present invention, such as figure 1 shown, it can be seen figure 1 The control structure does not contain traditional phase-locked loops. When the system is processed per unit, the reference value of the converter capacity is 50KVA, the reference value of the AC line voltage is 380V, the reference value of the AC frequency is 50Hz, and the reference value of the DC bus voltage is 700V. when figure 2 The active power output of the power source on the DC bus from P S = 0 step to P S = 0.6p.u. (where p.u. represents per unit value) and equivalent reactance X = 0.2p.u., the virtual power angle trajectory of the converter is as follows Figure 4 (a) shown. It can be seen that the converter reaches the stable equilibrium point on the virtual power angle curve after the trans...
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The invention discloses a method for realizing self-synchronizing three-phase grid-connected converter control dynamically with a direct-current capacitor. A park transformation angular frequency of the output of a direct-current capacitor voltage controller inside a three-phase grid-connected converter is used as an actual angular frequency value of the converter to realize dynamic coupling of the direct-current capacitor voltage and the converter output angular frequency, thereby achieving an objective of realizing grid-connected self synchronization of the converter based on a direct-current capacitor dynamically. According to the method disclosed by the invention, phase-locked-loop-free self-synchronous grid connection of a three-phase converter is realized and thus the converter can adapt to a low-short-circuit-ratio weak current grid; and with energy storage of the direct-current capacitor, participation in frequency adjustment of the grid by the three-phase converter is realized, so that the frequency support capability of the grid by the converter is enhanced.
Description
technical field [0001] The invention belongs to the field of electrical engineering, and in particular relates to a control method for a three-phase grid-connected converter that utilizes a DC capacitor to dynamically realize self-synchronization. Background technique [0002] In recent years, with the development of renewable energy technologies such as wind power and photovoltaics, the penetration rate of three-phase converters in the power grid has gradually increased. In the future power grid dominated by converters, the characteristics of the converter determine the characteristics of the grid and are of great significance to the safe and stable operation of the grid. Therefore, the control method of the converter has received extensive attention. [0003] At present, the control of three-phase converters mainly adopts vector control based on phase-locked loops, but this control method cannot make the converters participate in the frequency regulation of the power grid,...
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IPC IPC(8): H02J3/42H02J3/38
CPCH02J3/383H02J3/386H02J3/42Y02E10/56Y02E10/76
Inventor 黄林彬辛焕海
Owner ZHEJIANG UNIV