Method and device for evaluating strength of flexible direct-current receiving-end power grid and storage medium

Abstract

The invention discloses a method and device for evaluating the strength of a flexible DC receiving end power grid, and a storage medium, and the method comprises the steps: obtaining an AC / DC system,and enabling a flexible DC to work in a control mode of fixed active power and reactive power; measuring the active power and the reactive power of the flexible direct-current feed-in alternating-current power grid and the voltage amplitude of an accessed alternating-current bus, and obtaining the equivalent impedance of a receiving-end alternating-current power grid; calculating according to theactive power, the reactive power, the voltage amplitude and the equivalent impedance to obtain a short-circuit ratio of the AC-DC system; comparing the short-circuit ratio with a preset critical short-circuit ratio; if the short-circuit ratio is greater than the critical short-circuit ratio, determining that the AC-DC system can operate stably; and if the short-circuit ratio is smaller than the critical short-circuit ratio, determining that the AC-DC system cannot operate stably. According to the method, the short-circuit ratio of the system is calculated by utilizing the system parameters which are easy to measure, and the critical short-circuit ratio is kept unchanged, so that the evaluation of the strength of the flexible direct-current receiving-end power grid in actual engineering becomes more convenient.

Description

technical field [0001] The invention relates to the technical field of grid planning and operation of a power system, in particular to a method, device and storage medium for evaluating the strength of a flexible direct current receiving end grid. Background technique [0002] my country's energy resources and load demand are reversely distributed, and long-distance transmission of electric energy is inevitable. The voltage source converter type HVDC transmission (flexible DC) has the advantages of not relying on grid commutation, the output active and reactive power can be decoupled and controlled, and can provide dynamic reactive power support when the traditional DC commutation fails. With rapid development, it is widely used in long-distance power transmission, new energy consumption, and asynchronous interconnection of power grids. However, in the case of flexible DC connected to the power grid, if the power grid at the receiving end is too weak and the voltage support...

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Problems solved by technology

[0003] At present, there are few studies on the accurate evaluation of the strength of the receiving end power grid in this field. Some scholars use the reciprocal of the impedance to define the short-circuit ratio of the system after the flexible DC is fed into the power grid. The critical short-circuit ratio of the power calculation system is used to judge the strength of the receiving end grid of the flexible DC through the short-circuit ratio and the critical short-circuit ratio. However, the electromotive force of the AC grid in this method is not an actual physical quantity, which is difficult to obtain directly by measurement. The calculated critical short-circuit ratio will vary with the operating state of the flexible DC and the electromotive force of the AC grid, and is not a definite value, which makes it inconvenient to apply this method in actual engineering

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