Fault current determination method for droop control inverter

Abstract

The invention discloses a fault current determination method for a droop control inverter. The method comprises the steps of pre-establishing a grid-connected system equivalent model comprising a droop control inverter under an asymmetric fault type, obtaining a fault current total current relational expression of the droop control inverter under the asymmetric fault type based on the grid-connected system equivalent model; when the fault current is calculated subsequently, adopting a fault current iteration algorithm in combination with a fault current total current relational expression to eliminate strong coupling between power and voltage; and obtaining fault current full current in full-scale time; in this way, the characteristics (including transient characteristics) of the fault current of the droop control inverter at any time under the asymmetric fault type can be obtained; guidance is provided for a fault ride-through strategy of the droop control inverter, guidance is also provided for micro-grid relay protection setting containing the droop control inverter, and the safety and reliability of the droop control inverter in a grid-connected system are improved.

Description

technical field [0001] The invention relates to the technical field of fault analysis, in particular to a method for determining a fault current of a droop control inverter. Background technique [0002] In recent years, based on the technological progress of power electronic systems, the concept of microgrid has emerged as the times require. As an autonomous system that can realize self-control and management, the microgrid can effectively absorb the output of intermittent and distributed renewable energy generation while improving the reliability of power supply for users. Usually, power electronic devices such as inverters are used as the interface of distributed energy in microgrids. For these microgrids with high penetration of renewable energy, the dynamic characteristics of the grid-connected system are mainly determined by the control scheme adopted by the microsource itself and the inverter. Among the control schemes adopted by inverters, the droop control strateg...

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Problems solved by technology

Therefore, in order to improve the reliability of the protection system and ensure the safety and reliability of the power electronic equipment in the droop control inverter, it is necessary to study and analyze its asymmetric fault characteristics. However, there is no one in the prior art A scheme for the transient characteristics of the fault current of droop-controlled inverters under asymmetrical fault types, which reduces the safety and reliability of droop-controlled inverters in grid-connected systems

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