New energy grid-connected system voltage support strength evaluation method and system

Abstract

The invention discloses a new energy grid-connected system voltage support strength evaluation method and system. The method comprises the steps of determining a first short-circuit ratio index of the new energy grid-connected system based on short-circuit capacity provided for a grid-connected point by an alternating current system in the new energy grid-connected system and equivalent grid-connected capacity of new energy at the grid-connected point; determining a second short-circuit ratio index of the new energy grid-connected system based on the voltage variation at the new energy access grid-connected point; determining a critical short-circuit ratio of the new energy grid-connected system based on parameters of the alternating current system and the equivalent maximum transmission power transmitted to the alternating current system by the new energy; and based on the first short-circuit ratio index, the second short-circuit ratio index and the critical short-circuit ratio, determining the voltage support strength provided by the new energy grid-connected system at the grid-connected point by using a preset voltage support strength evaluation rule.

Description

technical field [0001] The present invention relates to the technical field of renewable energy grid-connected stability analysis, and more specifically, to a method and system for evaluating voltage support strength of a new energy grid-connected system. Background technique [0002] my country's large-scale new energy development is concentrated in the west and north. Wind power and photovoltaic units have low voltage regulation capabilities. When connected to a weak power grid, they are easily disconnected due to voltage fluctuations, and the system needs to provide voltage support. The short circuit ratio is an important index to measure the voltage support strength of the system. The critical short circuit ratio is the short circuit ratio corresponding to the critical stable state of the system. By comparing the current short-circuit ratio of the system with its critical short-circuit ratio, the operating state of the system can be judged, and the voltage support stren...

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Problems solved by technology

[0003] At present, the short-circuit ratio is an important indicator for evaluating the voltage support strength of the new energy grid-connected system. There is a contradiction between its accuracy and practicability, and the calculation of the critical short-circuit ratio is not uniform due to the numerous construction methods. Support strength assessment provides accurate, fast, intuitive, and practical methods

[0004] Aiming at the above-mentioned technical problems existing in the prior art that it is difficult to provide an accurate, fast, intuitive and practical method for evaluating the voltage support strength of the new energy grid-connected system, no effective solution has been proposed yet

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