Novel four-bridge-arm topology power distribution network integrated arc extinguishing device and method

Abstract

The invention relates to a novel four-bridge-arm topology power distribution network integrated arc extinction device and method. The integrated arc extinction device adopts a four-bridge-arm H-bridge converter, wherein three bridge arms are in star connection and are hung on each phase line through a connecting inductor, and a fourth bridge arm is connected between the neutral point of the three bridge arms and the ground. The integrated arc extinguishing method comprises the following steps: when the system is in normal operation, the integrated arc extinguishing device dynamically tracks and compensates reactive power, active power and three-phase unbalanced load of the power distribution network and inhibits three-phase grounding parameter unbalanced voltage; and when a grounding fault occurs, the three-phase grounding parameter unbalanced voltage suppression is switched to flexible arc extinction, and the grounding fault current is compensated to zero. The device is high in response speed, capable of rapidly and effectively inhibiting the grounding fault arc, rich in function and high in equipment utilization rate.

Description

technical field [0001] The invention relates to the field of arc suppression for single-phase grounding faults in power grids, in particular to an integrated arc suppression device and method for a distribution network with a novel four-bridge-arm topology. Background technique [0002] With the expansion of the distribution network scale, the ground fault capacitive current increases, the arc suppression coil cannot compensate the harmonic and active components, and the residual current of the ground fault is large, so that the ground fault arc cannot be extinguished by itself, causing fire and phase-to-phase short circuit fault. And it is easy to develop into intermittent arc grounding faults, which will generate arc overvoltage and cause breakdown damage to power grid equipment. The flexible arc suppression method has become a research hotspot because it can compensate the reactive power, active power and harmonic components in the ground fault current. [0003] The exis...

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Problems solved by technology

[0003] The existing flexible arc suppression devices mainly include: one is the master-slave arc suppression device, the arc suppression coil is the main arc suppression device, which compensates most of the capacitive current in the ground fault current; From the inverter device, the remaining harmonic current and active current of the ground fault current are compensated, but limited by the number of inverter levels, the output harmonic characteristics are poor; the second is the three-phase cascaded H-bridge arc suppression device, which uses three The phase cascaded H-bridge converter is an arc suppression device, the three phases are directly connected to the busbar, and the neutral point is directly grounded or grounded through a switch, but more H-bridge units are required, and the input cost is higher

[0004] In addition, the current flexible arc suppression device only plays a role during the ground fault period, and is idle during normal operation, but the duration of the ground fault is short, and the utilization rate of the power electronic modules in the flexible arc suppression device is low, resulting in waste of resources

The existing multi-functional arc suppression device grounds the neutral point of the SVG through the arc suppression coil. The SVG single-phase withstand voltage only needs half of the line voltage, and the input of H-bridge units is less, but the response speed is slow due to the influence of the arc suppression coil. ; and the active and harmonic components in the ground fault current are not compensated, and the arc suppression effect is limited; in addition, it only has two functions of reactive power compensation and arc suppression, and the utilization rate of the device still needs to be improved

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