Optimization method of impedance values of three-winding transformer of substation

Abstract

The invention relates to an optimization method of impedance values of a three-winding transformer of a substation. The method comprises the steps of: (1) setting constraint limit values of short-circuit current of various voltage class sides of the substation and upper and lower limit constraint values of three side impedance percents Uk12%, Uk13% and Uk23% of the transformer; (2) setting short-circuit impedance percent calculation step length segments NUk12%, NUk13% and NUk23% by combining the engineering actual situation to divide calculation point numerical matrixes of the three side impedance percents Uk12%, Uk13% and Uk23%; (3) calculating and judging whether each impedance value meets a manufacturing constraint, a short-circuit current constraint and the like or not on each impedance value calculation point; and (4) taking the maximum single-unit capacity upper limit value, of a reactive power compensation device of the substation, stored in the step (3) as the preferred value. The optimization method has the beneficial effects that a specific and reasonable optimization design of the impedance values of the three-winding transformer is carried out aiming at various substations; the adaptability is high; and the application range is wide.

Description

technical field [0001] The invention relates to the field of electric transmission and distribution, in particular to a method for optimizing the impedance value of a three-winding transformer in a substation. Background technique [0002] The design of short-circuit impedance parameters of power transformers is an important link in the engineering design of power plants and substations. At present, most substations with three voltage levels use three-winding transformers. The selection of the impedance value of the three-winding transformer directly affects the short-circuit current level of the three-side voltage level, and the size of the short-circuit capacity indirectly affects the unit of low reactive power compensation equipment in the substation. Group capacity and group number are closely related to the economic benefits of project construction. [0003] Such as figure 1 Shown is a schematic diagram of short-circuit current calculation for a typical 220kV substati...

AI Technical Summary

Problems solved by technology

For substations in different regions, their positions and positions in the power system are different, especially for terminal substations with low grid coupling, due to the relatively high impedance of the system, if the general impedance value (standard impedance value) with a relatively high impedance value is still used ), will limit the short-circuit current to an extremely low level, and the excessive reduction of the short-circuit capacity of the low-voltage side will cause voltage fluctuations caused by switching of reactive power compensation equipment: after the short-circuit capacity is reduced, if a single group of reactive power compensation equipment If the capacity is large, the voltage fluctuation of the system during switching will not meet the power quality requirements. At this time, the problem of voltage fluctuation can only be compensated by reducing the single-group capacity of the reactive power compensation device and increasing the number of groups of reactive power compensation equipment. Taking this measure will greatly increase equipment investment and substation area, thereby increasing the cost of engineering construction: At present, 220kV substations in Jiangsu generally use general-purpose impedance transformers with relatively high impedance values, and at the same time use 6000kvar with a small capacity. Capacitors are used as reactive power compensation, occupying a large area and high one-time investment costs

This method is accidental, the designer may be able to find a relatively reasonable parameter range through a few trial calculations, or may not be able to find a reasonable impedance value after many attempts, and even if this method is used to find a relatively reasonable value, there is no guarantee The scope of optimization covers the whole world

[0010] In summary, the current design and optimization method for the impedance value of a three-winding transformer in a substation has no theoretical support, complicated manual calculations (requires multiple trial calculations, irregularities), and poor efficiency of design parameters (unable to achieve optimization, high construction costs, and poor economic benefits)

Images