Method for selecting the inductance value of the reactor in the variable impedance transformer

Abstract

A method for selecting the inductance value of a reactor in a variable impedance transformer can quickly obtain the impedance value of a current limiting reactor by using the impedance value of the variable impedance transformer in the factory parameters of the variable impedance transformer, so that the inductance value of the current limiting reactor in the variable impedance transformer can be quickly and accurately obtained to effectively ensure the safe and stable operation of the transformer.

Description

Technical Field

[0001] The invention relates to the technical field of transformers, and in particular to a method for selecting the inductance value of a reactor in a variable impedance transformer. Background Art

[0002] As the scale of power grids continues to increase, short-circuit currents are increasingly affecting the safe and stable operation of power systems. For this reason, people have adopted various types of short-circuit current limiting measures, and various short-circuit current limiting technical solutions have been widely used in different occasions. In recent years, with the rapid progress of advanced control technology, circuit breaker breaking technology, and advanced manufacturing technology, the design and application of variable impedance transformers have become possible. However, there is currently little discussion on the selection of the inductance value of the current limiting reactor in the variable impedance transformer. That is to say, if a variable impedance transformer is used to limit the short-circuit current of the power system, how to select the inductance value of the reactor is a problem that the designer has to face. Summary of the invention

[0003] In order to solve the technical problems existing in the above-mentioned technology, it is necessary to provide a method for selecting the inductance value of the reactor in the variable impedance transformer.

[0004] A method for selecting the inductance value of a reactor in a variable impedance transformer comprises the following steps:

[0005] Get the impedance value X of the variable impedance transformer y , impedance value of variable impedance transformer X y It can be directly obtained from the factory parameters of the variable impedance transformer.

[0006] Assume the system voltage is U N The impedance value of the current limiting reactor in the variable impedance transformer is X x Before the current-limiting reactor is connected in series with the variable impedance transformer, the short-circuit current is expressed as I1. After the current-limiting reactor is connected in series, the short-circuit current is expressed as I2.

[0007]

[0008]

[0009] The current limiting ratio R is defined as the ratio of the short-circuit current after the current limiting reactor is connected in series to the short-circuit current before the current limiting reactor is not connected in series, where:

[0010]

[0011] Define the current limiting depth as K, where:

[0012] K = 1-R (4);

[0013] According to the above-defined formulas (1), (2), (3), and (4), the calculation formula for the current limiting depth K can be obtained as follows:

[0014]

[0015] Definition of impedance ratio Z R , which represents the ratio of the impedance value of the current limiting reactor to the impedance value of the variable impedance transformer, where:

[0016]

[0017] According to the above defined formulas (5) and (6), the current limiting depth K and impedance ratio Z are obtained. R The relationship between

[0018]

[0019] Given the value of the current limiting ratio R, the following formula can be calculated from the above defined formulas (4) and (5):

[0020]

[0021] According to the above-defined formulas (8) and (6), Z can be calculated R The relationship with R is as follows:

[0022]

[0023] According to the formula (9) defined above, the calculation formula for the reactance value of the reactor in the variable impedance transformer is as follows:

[0024]

[0025] It can be concluded that when the current limiting ratio R value is given, the reactance value of the current limiting reactor in the variable impedance transformer is the impedance value of the variable impedance transformer. times, the impedance value of the current limiting reactor can be quickly obtained;

[0026] According to the above-defined formula (10), the calculation formula for the inductance value of the current limiting reactor in the variable impedance transformer can be obtained as follows:

[0027]

[0028] Where f represents frequency.

[0029] It can be seen from the above technical scheme that the method for selecting the inductance value of the reactor in the variable impedance transformer provided by the present invention can quickly and easily design the inductance value of the reactor in the variable impedance transformer, providing a simple design method for practical application in engineering, and also providing a design basis for the selection of simulation parameters of the reactor in the simulation system containing the variable impedance transformer, and providing a reference for the device parameter selection problem in the research field of application devices to solve the short-circuit current problem of the power system. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner", "lower" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0032] A method for selecting the inductance value of a reactor in a variable impedance transformer comprises the following steps:

[0033] Get the impedance value X of the variable impedance transformer y , impedance value of variable impedance transformer X y It can be directly obtained from the factory parameters of the variable impedance transformer.

[0034] Assume the system voltage is U N The impedance value of the current limiting reactor in the variable impedance transformer is X x Before the current-limiting reactor is connected in series with the variable impedance transformer, the short-circuit current is expressed as I1. After the current-limiting reactor is connected in series, the short-circuit current is expressed as I2.

[0035]

[0036]

[0037] The current limiting ratio R is defined as the ratio of the short-circuit current after the current limiting reactor is connected in series to the short-circuit current before the current limiting reactor is not connected in series, where:

[0038]

[0039] Define the current limiting depth as K, where:

[0040] K = 1-R (4);

[0041] According to the above-defined formulas (1), (2), (3), and (4), the calculation formula for the current limiting depth K can be obtained as follows:

[0042]

[0043] Definition of impedance ratio Z R , which represents the ratio of the impedance value of the current limiting reactor to the impedance value of the variable impedance transformer, where:

[0044]

[0045] According to the above defined formulas (5) and (6), the current limiting humidity K and the impedance ratio Z are obtained. R The relationship between

[0046]

[0047] Given the value of the current limiting ratio R, the following formula can be calculated from the above defined formulas (4) and (5):

[0048]

[0049] According to the above-defined formulas (8) and (6), Z can be calculated R The relationship with R is as follows:

[0050]

[0051] According to the formula (9) defined above, the calculation formula for the reactance value of the reactor in the variable impedance transformer is as follows:

[0052]

[0053] It can be concluded that when the current limiting ratio R value is given, the reactance value of the current limiting reactor in the variable impedance transformer is the impedance value of the variable impedance transformer. times, the impedance value of the current limiting reactor can be quickly obtained;

[0054] According to the above-defined formula (10), the calculation formula for the inductance value of the current limiting reactor in the variable impedance transformer can be obtained as follows:

[0055]

[0056] Where f represents frequency.

[0057] Example 1

[0058] If the current limiting ratio R is set to 50%, the reactance value of the current limiting reactor in the variable impedance transformer is the impedance value of the variable impedance transformer. times, the impedance value X of the current limiting reactor can be quickly obtained x =X y , according to the formula The inductance value of the current limiting reactor can be obtained Among them, the impedance value of the variable impedance transformer is X y It can be directly obtained from the factory parameters of the variable impedance transformer.

[0059] Example 2

[0060] If the current limiting ratio R is set to 20%, the reactance value of the current limiting reactor in the variable impedance transformer is the impedance value of the variable impedance transformer. times, the impedance value X of the current limiting reactor can be quickly obtained x =4X y , according to the formula The inductance value of the current limiting reactor can be obtained Among them, the impedance value of the variable impedance transformer is X y It can be directly obtained from the factory parameters of the variable impedance transformer.

[0061] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for selecting the inductance value of a reactor in a variable impedance transformer, characterized in that: The following steps are included: Get the impedance value X of the variable impedance transformer y , impedance value of variable impedance transformer X y It can be directly obtained from the factory parameters of the variable impedance transformer. Assume the system voltage is U N The impedance value of the current limiting reactor in the variable impedance transformer is X x Before the current-limiting reactor is connected in series with the variable impedance transformer, the short-circuit current is expressed as I1. After the current-limiting reactor is connected in series, the short-circuit current is expressed as I2. The current limiting ratio R is defined as the ratio of the short-circuit current after the current limiting reactor is connected in series to the short-circuit current before the current limiting reactor is not connected in series, where: Define the current limiting depth as K, where: K = 1-R (4); According to the above-defined formulas (1), (2), (3), and (4), the calculation formula for the current limiting depth K can be obtained as follows: Definition of impedance ratio Z R , which represents the ratio of the impedance value of the current limiting reactor to the impedance value of the variable impedance transformer, where: According to the above defined formulas (5) and (6), the current limiting humidity K and the impedance ratio Z are obtained. R The relationship between Given the value of the current limiting ratio R, the following formula can be calculated from the above defined formulas (4) and (5): According to the above-defined formulas (8) and (6), Z can be calculated R The relationship with R is as follows: According to the formula (9) defined above, the calculation formula for the reactance value of the reactor in the variable impedance transformer is as follows: It can be concluded that when the current limiting ratio R value is given, the reactance value of the current limiting reactor in the variable impedance transformer is the impedance value of the variable impedance transformer. times, the impedance value X of the current limiting reactor can be quickly obtained x , According to the above-defined formula (10), the calculation formula for the inductance value of the current limiting reactor in the variable impedance transformer can be obtained as follows: Where f represents the power system operating frequency.

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