A STATCOM that suppresses internal circulation in delta-junctions

Abstract

The invention discloses a static synchronous compensator (STATCOM) capable of suppressing delta-type connection internal circulation. A plurality of linkage units are connected in a serial mode to form a linkage string to be in serial connection with an inductance coil. Three linkage strings and the inductance coil are connected in the serial mode to constitute a main circuit of the STATCOM in a delta-type structure. Three inductance coils are wound on a shared open iron core so that exciting magnetomotive force among three windings is increased through coupling, inductance value of the coils is greatly increased, and therefore a three-phase electric reactor of the shared iron core is constituted. When the STATCOM in delta-type connection carries out non-symmetrical compensation on a power grid, zero sequence current and harmonic current of multiples of three are generated in the delta-type connection. The STATCOM can effectively suppress the zero sequence current and harmonic current of the multiples of three in delta internal circulation. Besides, positive sequence current and negative sequence current do not generate the exciting magnetomotive force in inductance, and the size and the weight of the electric reactor can be greatly reduced.

Description

technical field [0001] The invention relates to the technical field of power electronics, and more specifically relates to a STATCOM capable of suppressing the internal circulation of a △-type connection, which is suitable for harmonic suppression and reactive power compensation of an asymmetric power grid. Background technique [0002] With the rapid development of modern industry, nonlinear loads such as high-power power electronic devices and electric arc furnaces have been widely used. At the same time, it has brought more and more serious reactive power problems and harmonic pollution to the power grid. In addition, unbalanced loads And asymmetrical short-circuit faults will make the three-phase grid unbalanced. The above factors will cause the voltage fluctuation of the power grid, the distortion of the current waveform, the degradation of the power quality and the threat to the safety of the power grid. And STATCOM (STATicsynchronous COMPensator) can continuously and...

AI Technical Summary

Problems solved by technology

However, the Y-connected STATCOM is not easy to implement phase-separated asymmetry compensation due to the condition that the vector sum of the three-phase currents is equal to zero.

[0005] When using STATCOM to implement asymmetric compensation for the power grid, a circulating current, namely zero-sequence current and three-fold harmonic current will be generated in the △-type connection of the STATCOM. This current circulates in △. If it is not effectively suppressed, it will affect the poses a threat to the safety of power switching devices in

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