Unit H-bridge module bypass circuit of chain type static synchronous compensator (STATCOM)

Abstract

The invention discloses a unit H-bridge module bypass circuit of a chain type static synchronous compensator (STATCOM). The bypass circuit comprises a direct current power supply, an H-bridge module, a current transformer and a bypass switch, wherein the direct current power supply is connected with the H-bridge module and is inverted into an alternating current power supply through the H-bridge module; the current transformer is connected with one end of the alternating current power supply; and the bypass switch comprises an anti-parallel thyristor circuit, a resistor-capacitor (RC) absorbing circuit and a thyristor gate pole electronic circuit board. The unit H-bridge module bypass circuit adopts a mode of taking energy for voltage and current at the same time, can still provide a direct current power supply for the bypass switch under the condition that an insulated gate bipolar transistor (IGBT) in the H-bridge module is damaged, breaks through the tradition that the conventional bypass switch takes energy from a direct current side of a unit H-bridge module, and ensures that the bypass switch can act stably and reliably.

Description

technical field [0001] The invention relates to a unit H-bridge module bypass circuit of a chained STATCOM. Background technique [0002] With the development of power electronics technology, static synchronous compensators (SVG or STATCOM) based on turn-off devices (IGBT, IGCT) are gradually applied. STATCOM uses a self-commutated converter, which regards the converter circuit as a It is an AC voltage source that generates fundamental and harmonic voltages. Controlling the magnitude and phase of the fundamental voltage of the compensator can change the magnitude and phase of the fundamental reactive current, or directly control the current on the AC side, so that the circuit can absorb or Send out reactive power that meets the requirements, realize the integration of dynamic compensation of inductive reactive power and capacitive reactive power, and the maximum compensation capacity of the device is not affected by the grid voltage. [0003] The main circuit structure of S...

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Problems solved by technology

[0005] The invention patent with the application number 201010624231.1 provides a chain-type STATCOM link unit bypass structure using a mechanical switch. A specially designed mechanical switch K is used instead of a power electronic device as the bypass circuit of the link unit. The circuit structure is simple. The number of selected components is small, and the installation and operation are convenient. It provides reliable protection for the entire H-bridge chain link unit, realizes the redundant function of the H-bridge module, and avoids the frequent exit of the chain STATCOM device due to module failure; solves the problem of large-capacity switching devices It is difficult to select the type and the control power supply is not easy to obtain. However, when the bypass switch is started randomly, the pulse of the entire chain STATCOM device needs to be blocked, which is equivalent to stopping the entire device, which will affect the stability and stability of the power system. Safety; at the same time, the contactor power is obtained from the DC side. If the IGBT module fails, the DC voltage may rise abnormally or drop to zero. At this time, the energy-taking power supply will fail, and the bypass switch will fail, resulting in bypass switch If it fails, the device must be out of operation, which greatly reduces the reliability of the chained STATCOM device, and frequent switching also brings major safety hazards to the power system

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