Active power filter (APF) device based on double vehicle stability control (VSC) interactive parallelly-connected harmonic compensation open loop and closed loop combination

Abstract

The invention discloses an active power filter (APF) device based on double vehicle stability control (VSC) interactive parallelly-connected harmonic compensation open loop and closed loop combination. The APF device comprises a main controller and a plurality of parallelly-connected double VSC interactive parallelly-connected power units, wherein the double VSC interactive parallelly-connected power units adopt double VSC interactive parallelly-connected structures and comprise frontward parts (open loop compensation), shared direct current parts and backward parts (closed loop compensation), the shared direct current parts share the capacitors, the frontward parts and the backward parts are respectively and sequentially connected with a grid-tied inductance and a common-mode inductance in serial mode, converge through a frontward group busbar and a backward group busbar respectively, are combined to a grid through a grid-side compensation point and a load-side compensation point, and load current signals between the grid-side compensation point and the load-side compensation point are transmitted to respective double VSC interactive parallelly-connected power units. The APF device effectively maximums output and simultaneously minimizes total output ripples of the whole machine, and effectively restrains zero sequence circulating current between double VSCs, and the whole machine has the dynamic fast response characteristics of open loop compensation and steady-state high accuracy characteristics of closed loop compensation.

Description

technical field [0001] The present invention relates to a multi-machine fractional APF (Active Power Filter, active power filter) device, in particular to a dual VSC (Voltage Source Converter, voltage source converter) interactive parallel harmonic compensation open-closed loop combination The multi-machine fractional APF device is used for the treatment of large-capacity and high-performance fully active harmonics in low-voltage power grids. Background technique [0002] With the widespread use of nonlinear loads such as power electronic devices in the low-voltage power grid, the harmonic content of the low-voltage power grid is increasing, which seriously affects the power quality of the power grid. The use of APF devices for fully active harmonic control is currently recognized as the best harmonic control method, but the current large-capacity and high-performance harmonic control requirements make APF technical difficulties. If the stand-alone APF is to achieve large-c...

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Problems solved by technology

[0004] (1) Hybrid harmonic control of APF multi-machine parallel connection + passive filter group, in which APF compensates the sub-low current harmonics in the high-frequency segment, and the passive filter group compensates the sub-large current harmonics in the low-frequency segment. The disadvantages of this method are: Low-voltage and high-current harmonic compensation is mainly the output of passive filtering, which does not fully have the advantages of active harmonic control. Although the large capacity of harmonic control has been realized, the high-performance requirements of harmonic control have not been realized.

[0005] (2) Fully active harmonic control with full compensation of APF multi-machines, in which the parallel unit modules are the same, all parallel units are fully compensated and have the same output, and the operating mode is the same (open loop or closed loop). The disadvantage of this method is : The full compensation of a single machine requires a high switching frequency, which limits the output capacity of a single machine, so that large-capacity output requires too many parallel units, which greatly increases the cost; each parallel unit operates in open-loop or closed-loop compensation mode, and the whole machine cannot have both The dynamic fast response characteristics of open-loop compensation and the steady-state high-precision characteristics of closed-loop compensation; when the compensation current is small, the multi-machine unit needs the main controller to participate in the control to achieve redundant mode operation, and cannot automatically redundant operation

[0006] (3) Completely active harmonic control of APF multi-machine interactive parallel connection, in which all parallel units share the DC side capacitor, and the output of each AC side is connected to the grid through a multi-winding transformer. The disadvantage of this method is that although it effectively reduces the However, in order to suppress the circulation between multiple machines, the output of the AC side must be isolated by a multi-winding transformer and then connected to the grid. In this way, when the whole machine outputs a large capacity, the compensation current needs to pass through the transformer and then be connected to the grid, resulting in harmonic Wave can compensate for the reduction of the frequency band and the deterioration of the compensation effect. Moreover, this kind of large-capacity transformer is difficult to manufacture, the volume is huge, and it will generate serious heat during operation, which will cause excessive loss of the whole machine.

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