Sag domain identification method considering load sensitivity uncertainty

Abstract

The invention discloses a sag domain identification method considering load sensitivity uncertainty. The method comprises the following steps of carrying out power flow calculation to obtain a systemnode voltage amplitude before failure; calculating each sequence impedance; calculating a residual voltage of each bus fault; obtaining upper and lower limits of a uncertainty interval of a sensitiveload according to an existing voltage tolerance curve and forming a discriminant matrix; calculate a line critical point according to the discriminant matrix and a lower limit and an upper limit of the uncertainty interval of the sensitive load; and traversing all lines and all uncertain spaces, and outputting two sag domain identification results corresponding to the upper and lower limits of theuncertainty interval of the sensitive load. In the invention, the uncertainty interval of load sensitivity is considered, a sag domain which is close to an actual project is described, and disadvantages that an existing sag domain identification method does not consider different tolerance capacities of the sensitive load to a voltage sag, the sag domain is fixed by a clear boundary, and all sagdomain critical points can not be considered are overcome.

Description

technical field [0001] The present invention relates to the technical field of voltage sag domain identification in electric power systems, and more particularly, relates to a sag domain identification method considering the uncertainty of load sensitivity. Background technique [0002] Load sensitivity refers to the sensitivity of the load to power quality problems such as voltage quality. When the power quality supplied to the load is poor, the load can withstand interference and still work normally. The lower the capacity, the higher the sensitivity. In the actual power system During operation, the load sensitivity is uncertain; the sag domain refers to that when a short-circuit fault occurs in the power system, the fault causes the voltage amplitude of the sensitive point to drop below a certain voltage tolerance threshold, which makes the sensitive load unable to work normally. The set of fault points, in order to reduce the adverse impact of voltage sag on sensitive lo...

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Problems solved by technology

[0004] At present, a variety of methods for dip region identification have been proposed at home and abroad, mainly including fault point method, critical distance method, analytical method and other methods. The above methods all have more or less defects in the calculation of dip region identification. For example, Chen Tiemin , Yang Honggeng mentioned in "Voltage Sag Evaluation Based on Improved Fault Point Method" published in "Electric Power Automation Equipment" (2008, 28 (6)) that the accuracy of the fault point method is difficult to guarantee when identifying and calculating the sag domain, requiring a large number of Fault point information can improve the calculation accuracy; moreover, the current calculation methods for dip domains are all based on traditional short-circuit calculations, and the algorithm considers few influencing factors, resulting in a large difference between the pre-evaluation results of dip domains and the actual results. On the other hand, the current There are methods to calculate the exact boundary of the sag domain. The range of the sag domain is mainly determined by the voltage sag tolerance of the equipment. Generally, although the voltage sag tolerance of sensitive loads is considered to be a specific However, due to the different operating modes and load conditions of the equipment, the withstand capacity of the sensitive equipment may be different. In this case, the voltage sag withstand characteristic of the sensitive load cannot be described by a fixed voltage sag withstand curve. The position of the voltage sag withstand curve is uncertain, and the corresponding voltage critical point cannot be fully considered. Therefore, the fixed sag domain boundary will have certain limitations at this time

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