Frequency converter low-voltage ride-through (LVRT) supporting apparatus based on super capacitor

Abstract

The invention discloses a frequency converter LVRT supporting apparatus based on a super capacitor. Currently relatively severe voltage sags caused by certain power grid faults lead to the shutdown of a factory frequency converter. The apparatus is characterized in that a super capacitor energy-storage unit is connected with a frequency converter direct current link through a non-return diode; a frequency converter rectifying unit is prevented for bearing extra super capacitor charging currents by using the unidirectional conduction of the diode; the energy stored by the super capacitor is guaranteed to be only transmitted to a main circuit during a voltage drop period; the input side of a super capacitor charging unit is connected with an AC power supply; the output side of the super capacitor charging unit is connected with the super capacitor energy-storage unit; and a super capacitor voltage-sharing unit is connected with the super capacitor energy-storage unit. The apparatus which makes a common frequency converter have LVRT capabilities can satisfy frequency converter LVRT supporting demands in each industrial field.

Description

technical field [0001] The invention relates to inverter low-voltage ride-through support equipment, in particular to an inverter low-voltage ride-through support device based on a supercapacitor, which can ensure that the inverter does not stop when the grid voltage sags, and ensures that the entire system related to it The production system works continuously. Background technique [0002] In the actual power grid, UHV AC and DC line faults, low-frequency oscillation of the power grid, startup of large motors, and short-circuit faults of the power grid will cause large voltage sags. This kind of power grid voltage sag often leads to the shutdown of the factory inverter. If the shutdown occurs on some key equipment, the entire production system will stop working, causing serious economic losses to the enterprise and society. There are two aspects to solve the problem of low voltage ride-through of this type of inverter. On the one hand, the operation ability of the inverte...

AI Technical Summary

Problems solved by technology

This kind of power grid voltage sag often leads to the shutdown of the factory inverter. If the shutdown occurs on some key equipment, the entire production system will stop working, causing serious economic losses to the enterprise and society.

There are two aspects to solve the problem of low voltage ride-through of this type of inverter. On the one hand, the operation ability of the inverter itself under the condition of low voltage is excavated. Generally, the inverter itself can maintain the control circuit at a voltage as low as 65% of the rated voltage. Continue to work, but often due to the limitation of power margin, it still trips due to over-current

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