阅读说明：本技术 一种汽轮发电机低励限制曲线获取方法 (Method for acquiring low excitation limit curve of steam turbine generator ) 是由 张明江 穆兴华 崔佳鹏 董尔佳 董一凡 陈晓光 师广志 荣爽 关万琳 刘志鹏 谷 于 2019-10-31 设计创作，主要内容包括：一种汽轮发电机低励限制曲线获取方法,属于汽轮发电机励磁调节器低励限制曲线整定领域。解决了现有的低励限制曲线获取过程复杂及精度低的问题。首先,根据汽轮发电机静态稳定状态下的数据信息,在阻抗坐标系下,获得汽轮发电机静稳阻抗圆的圆心坐标(0,a)和半径r；再根据圆心坐标(0,a)、半径r和K<Sub>k</Sub>,在阻抗坐标系下,绘制汽轮发电机静稳裕度阻抗圆；最后,根据汽轮发电机静稳裕度阻抗圆,绘制汽轮发电机静稳裕度阻抗圆的外切正六边形,从而获得外切正六边形曲线方程,该外切正六边形曲线方程为汽轮发电机低励限制曲线方程,从而完成对汽轮发电机低励限制曲线方程的获取。主要用于汽轮发电机领域。(A method for acquiring a low excitation limit curve of a steam turbine generator belongs to the field of setting of the low excitation limit curve of an excitation regulator of the steam turbine generator. The problems of complex acquisition process and low precision of the existing low excitation limiting curve are solved. Firstly, according to data information of a steam turbine generator in a static stable state, obtaining the center coordinates (0, a) and the radius r of a static stable impedance circle of the steam turbine generator in an impedance coordinate system; then according to the coordinate (0, a) of the circle center, the radius r and K k Drawing a static stability margin impedance circle of the steam turbine generator under an impedance coordinate system; finally, drawing the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator according to the static stability margin impedance circle of the steam turbine generator so as to obtain a circumscribed regular hexagon curve equation, wherein the circumscribed regular hexagon curve equation is a low excitation limit curve equation of the steam turbine generator, and thus, the steam turbine generator is completedAnd obtaining a motor low excitation limit curve equation. The method is mainly used in the field of turbonators.)

1. A method for acquiring a low excitation limit curve of a steam turbine generator is characterized by comprising the following steps:

acquiring the center coordinates (0, a) and the radius r of a statically stable impedance circle of the turbonator in an impedance coordinate system according to data information of the turbonator in a statically stable state; wherein the abscissa of the impedance coordinate system represents resistance and the ordinate represents reactance; a is the longitudinal coordinate of the circle center of the static stable impedance circle of the turbonator;

step two, according to the coordinates (0, a) of the circle center, the radius r and the radius K_kDrawing a turbine generator static stability margin impedance circle under an impedance coordinate system, wherein the turbine generator static stability impedance circle and the turbine generator static stability margin impedance circle are concentric circles;

K_krepresenting the coefficients;

and step three, drawing an externally tangent regular hexagon of the static stability margin impedance circle of the steam turbine generator according to the static stability margin impedance circle of the steam turbine generator so as to obtain an externally tangent regular hexagon curve equation, wherein the externally tangent regular hexagon curve equation is a low excitation limit curve equation of the steam turbine generator, and thus the low excitation limit curve equation of the steam turbine generator is obtained.

2. The method for obtaining the low excitation limit curve of the steam turbine generator as claimed in claim 1, wherein in the step one, according to the data information of the steam turbine generator in the static stable state, the specific process of obtaining the center coordinates (0, a) and the radius r of the static stable impedance circle of the steam turbine generator in the impedance coordinate system is as follows:

the method comprises the steps of acquiring data information of the turbonator in a static stable state, wherein the data information comprises X_con、X_d、U_N、S_N、n_aAnd n_v(ii) a Wherein the content of the first and second substances,

X_conthe equivalent reactance between the generator and the system;

X_dis a generator synchronous reactance;

U_Nrated voltage for the generator;

S_Nrated apparent power for the generator;

n_athe transformation ratio of a current transformer at the generator terminal is set;

n_vthe transformation ratio of a generator terminal voltage transformer is obtained;

step two, under an impedance coordinate system, according to X_con、X_d、U_N、S_N、n_aAnd n_vObtaining a and a radius r, thereby obtaining the circle center coordinates (0, a) and the radius r of the turbine generator steady impedance circle; wherein the content of the first and second substances,

3. the method for obtaining the low excitation limit curve of the steam turbine generator as claimed in claim 1, wherein in the second step, the center coordinates (0, a), the radius r and the radius K are used as the reference_kUnder an impedance coordinate system, the specific process of drawing the turbine generator static stability margin impedance circle is as follows:

step two, a, because the turbine generator static stability impedance circle and the turbine generator static stability margin impedance circle are concentric circles_YuA, so as to obtain the center coordinates (0, a) of the turbine generator static margin impedance circle_Yu)；

Wherein, a_YuThe vertical coordinate of the circle center of the turbine generator static stability margin impedance circle;

step two, enabling the radius r of the turbine generator static stability margin impedance circle_Yu＝K_kR, from the center coordinates (0, a)_Yu) And radius r_YuAnd drawing the turbine generator static stability margin impedance circle under the impedance coordinate system, thereby completing the drawing of the turbine generator static stability margin impedance circle.

4. Low excitation of steam turbine generator as claimed in claim 3The method for obtaining the limit curve is characterized in that K is more than or equal to 1.05_k≤1.2。

5. The method for obtaining the low excitation limit curve of the steam turbine generator as claimed in claim 1, wherein in the third step, the concrete process of drawing the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator according to the static stability margin impedance circle of the steam turbine generator so as to obtain the circumscribed regular hexagon curve equation is as follows:

step three, enabling two tangent points O of the turbine generator static stability margin impedance circle₁And O₅Respectively are (0, K)_k·r-r+X_c) And (0, - (K)_k·r-r)+X_b)；

Wherein, X_cAnd X_bAre all intermediate variables, and

X_conthe equivalent reactance between the generator and the system;

X_dis a generator synchronous reactance;

U_Nrated voltage for the generator;

S_Nrated apparent power for the generator;

n_athe transformation ratio of a current transformer at the generator terminal is set;

n_vthe transformation ratio of a generator terminal voltage transformer is obtained;

step three and two, according to two tangent points O₁And O₅And radius r of a turbine generator static margin impedance circle_Yu＝K_kR, six vertexes O of circumscribed regular hexagon for obtaining turbine generator static stability margin impedance circle₂、O₃、O₄、O₆、O₇、O₈According to O, according to₁To O₈Drawing the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator by the coordinates of the resistance circle, thereby obtaining a circumscribed regular hexagon curve equation;

vertex O₂Has the coordinates of (K)_k·r·tan30°，K_k·r-r+X_c)；

Vertex O₃Has the coordinates of (K)_k·r/cos30°，a)；

Vertex O₄Has the coordinates of (K)_k·r·tan30°，-(K_k·r-r)+X_b)；

Vertex O₆Has the coordinate of (-K)_k·r·tan30°，-(K_k·r-r)+X_b)；

Vertex O₇Has the coordinate of (-K)_k·r/cos30°，a)；

Vertex O₈Has the coordinate of (-K)_k·r·tan30°，K_k·r-r+X_c)。

Technical Field

The invention belongs to the field of setting of a low excitation limit curve of an excitation regulator of a steam turbine generator, and particularly relates to a method for acquiring the low excitation limit curve of the steam turbine generator based on a statically stable impedance circle circumscribed regular hexagon.

Background

When the steam turbine generator is in phase-in operation, the low excitation limit curve under the impedance coordinate system changes due to the change of random terminal voltage, active power and reactive power, the phase-in depth is often difficult to control, the setting of the low excitation limit curve is complex, the problem of mismatching of the demagnetization protection and the low excitation limit curve is easy to occur, and the demagnetization and misoperation halt are caused, so that a setting method of the low excitation limit curve of the steam turbine generator, which has a simple acquisition process and high precision, is necessary to be provided.

Disclosure of Invention

The invention provides a method for acquiring a low excitation limit curve of a steam turbine generator, aiming at solving the problems of complex acquisition process and low precision of the existing low excitation limit curve.

A method for acquiring a low excitation limit curve of a steam turbine generator comprises the following steps:

acquiring the center coordinates (0, a) and the radius r of a statically stable impedance circle of the turbonator in an impedance coordinate system according to data information of the turbonator in a statically stable state; wherein the abscissa of the impedance coordinate system represents resistance and the ordinate represents reactance; a is the longitudinal coordinate of the circle center of the static stable impedance circle of the turbonator;

step two, according to the coordinates (0, a) of the circle center, the radius r and the radius K_kDrawing a turbine generator static stability margin impedance circle under an impedance coordinate system, wherein the turbine generator static stability impedance circle and the turbine generator static stability margin impedance circle are concentric circles;

K_krepresenting the coefficients;

and step three, drawing an externally tangent regular hexagon of the static stability margin impedance circle of the steam turbine generator according to the static stability margin impedance circle of the steam turbine generator so as to obtain an externally tangent regular hexagon curve equation, wherein the externally tangent regular hexagon curve equation is a low excitation limit curve equation of the steam turbine generator, and thus the low excitation limit curve equation of the steam turbine generator is obtained.

Preferably, in the step one, the specific process of obtaining the circle center coordinates (0, a) and the radius r of the turbine generator statically stable impedance circle in the impedance coordinate system according to the data information of the turbine generator statically stable state is as follows:

the method comprises the steps of acquiring data information of the turbonator in a static stable state, wherein the data information comprises X_con、X_d、U_N、S_N、n_aAnd n_v(ii) a Wherein the content of the first and second substances,

X_conthe equivalent reactance between the generator and the system;

X_dis a generator synchronous reactance;

U_Nrated voltage for the generator;

S_Nrated apparent power for the generator;

n_athe transformation ratio of a current transformer at the generator terminal is set;

n_vthe transformation ratio of a generator terminal voltage transformer is obtained;

step two, under an impedance coordinate system, according to X_con、X_d、U_N、S_N、n_aAnd n_vObtaining a and a radius r, thereby obtaining the circle center coordinates (0, a) and the radius r of the turbine generator steady impedance circle; wherein the content of the first and second substances,

preferably, in step two, the radius r and the radius K are determined according to the coordinates (0, a) of the center of the circle_kUnder an impedance coordinate system, the specific process of drawing the turbine generator static stability margin impedance circle is as follows:

step two, a, because the turbine generator static stability impedance circle and the turbine generator static stability margin impedance circle are concentric circles_YuA, so as to obtain the center coordinates (0, a) of the turbine generator static margin impedance circle_Yu)；

Wherein, a_YuThe vertical coordinate of the circle center of the turbine generator static stability margin impedance circle;

step two, enabling the radius r of the turbine generator static stability margin impedance circle_Yu＝K_kR, from the center coordinates (0, a)_Yu) And radius r_YuAnd drawing the turbine generator static stability margin impedance circle under the impedance coordinate system, thereby completing the drawing of the turbine generator static stability margin impedance circle.

Preferably, 1.05. ltoreq. K_k≤1.2。

Preferably, in the third step, drawing the circumscribed regular hexagon of the turbine generator static stability margin impedance circle according to the turbine generator static stability margin impedance circle, so as to obtain the circumscribed regular hexagon curve equation, the specific process is as follows:

step three, enabling two tangent points O of the turbine generator static stability margin impedance circle₁And O₅Respectively are (0, K)_k·r-r+X_c) And (0, - (K)_k·r-r)+X_b)；

Wherein, X_cAnd X_bAre all intermediate variables, and

X_conthe equivalent reactance between the generator and the system;

X_dis a generator synchronous reactance;

U_Nrated voltage for the generator;

S_Nrated apparent power for the generator;

n_athe transformation ratio of a current transformer at the generator terminal is set;

n_vthe transformation ratio of a generator terminal voltage transformer is obtained;

step three and two, according to two tangent points O₁And O₅And radius r of a turbine generator static margin impedance circle_Yu＝K_kR, six vertexes O of circumscribed regular hexagon for obtaining turbine generator static stability margin impedance circle₂、O₃、O₄、O₆、O₇、O₈According to O, according to₁To O₈Drawing the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator by the coordinates of the resistance circle, thereby obtaining a circumscribed regular hexagon curve equation;

vertex O₂Has the coordinates of (K)_k·r·tan30°，K_k·r-r+X_c)；

Vertex O₃Has the coordinates of (K)_k·r/cos30°，a)；

Vertex O₄Has the coordinates of (K)_k·r·tan30°，-(K_k·r-r)+X_b)；

Vertex O₆Has the coordinate of (-K)_k·r·tan30°，-(K_k·r-r)+X_b)；

Vertex O₇Has the coordinate of (-K)_k·r/cos30°，a)；

Vertex O₈Has the coordinate of (-K)_k·r·tan30°，K_k·r-r+X_c)。

The invention has the advantages that the defect of the low excitation limit curve of the traditional turbonator is made up, and the phase advancing capability of the turbonator can be exerted to a greater extent; the low excitation limiting curve determined by the method is more accurate, the method is visual and clear, the setting is simple, and the loss of excitation protection can be effectively prevented from being prior to the low excitation limiting action.

When the static stability impedance circle is used as a judgment basis, the low excitation limiting action is carried out when the static stability impedance circle is externally tangent to the regular hexagon, and the action of demagnetization protection caused by too deep phase advance depth is avoided. . The method is visual and clear, setting is simple, and demagnetization protection can be effectively prevented from being preceded by low excitation limiting action.

Drawings

FIG. 1 is a diagram showing a relative relationship between a turbine generator static stability impedance circle, a turbine generator static stability margin impedance circle and a circumscribed regular hexagon in an impedance coordinate system; wherein the abscissa R is resistance and the ordinate X is reactance.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.

The method for acquiring the low excitation limit curve of the steam turbine generator in the embodiment comprises the following steps:

acquiring the center coordinates (0, a) and the radius r of a statically stable impedance circle of the turbonator in an impedance coordinate system according to data information of the turbonator in a statically stable state; wherein the abscissa of the impedance coordinate system represents resistance and the ordinate represents reactance; a is the longitudinal coordinate of the circle center of the static stable impedance circle of the turbonator;

step two, according to the coordinates (0, a) of the circle center, the radius r and the radius K_kDrawing a turbine generator static stability margin impedance circle under an impedance coordinate system, wherein the turbine generator static stability impedance circle and the turbine generator static stability margin impedance circle are concentric circles;

K_krepresenting the coefficients;

and step three, drawing an externally tangent regular hexagon of the static stability margin impedance circle of the steam turbine generator according to the static stability margin impedance circle of the steam turbine generator so as to obtain an externally tangent regular hexagon curve equation, wherein the externally tangent regular hexagon curve equation is a low excitation limit curve equation of the steam turbine generator, and thus the low excitation limit curve equation of the steam turbine generator is obtained.

In the invention, the static stability impedance circle of the steam turbine generator, the static stability margin impedance circle of the steam turbine generator and the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator are concentric, the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator wraps the static stability impedance circle of the steam turbine generator and the static stability margin impedance circle of the steam turbine generator at the outermost layer, and the distance between the static stability impedance circle and the circumscribed regular hexagon of the static stability margin impedance circle passes through K_kAnd (5) controlling.

The method has the advantages of simple process for obtaining the low excitation limiting curve of the turbonator, intuition and clarity, and capability of effectively preventing the loss of excitation protection from being prior to the low excitation limiting action. In the specific application process, the terminal measured impedance is calculated by detecting the terminal voltage and current of the steam turbine generator, whether the terminal measured impedance enters the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator is used as a judgment basis, when the terminal measured impedance enters the circumscribed regular hexagon, the low excitation limiting action is performed, the increase of the phase advance depth is prevented, and the problem of mismatching of the demagnetization protection and the low excitation limiting curve is avoided, so that the demagnetization is caused and the machine is stopped.

Further, in the first step, according to the data information of the steam turbine generator in the static stable state, in the impedance coordinate system, the specific process of obtaining the circle center coordinates (0, a) and the radius r of the static stable impedance circle of the steam turbine generator is as follows:

the method comprises the steps of acquiring data information of the turbonator in a static stable state, wherein the data information comprises X_con、X_d、U_N、S_N、n_aAnd n_v(ii) a Wherein the content of the first and second substances,

X_conthe equivalent reactance between the generator and the system;

X_dis a generator synchronous reactance;

U_Nrated voltage for the generator;

S_Nrated apparent power for the generator;

n_athe transformation ratio of a current transformer at the generator terminal is set;

n_vthe transformation ratio of a generator terminal voltage transformer is obtained;

step two, under an impedance coordinate system, according to X_con、X_d、U_N、S_N、n_aAnd n_vObtaining a and a radius r, thereby obtaining the circle center coordinates (0, a) and the radius r of the turbine generator steady impedance circle; wherein the content of the first and second substances,

further, in the second step, according to the coordinates (0, a) of the circle center, the radius r and the radius K_kUnder an impedance coordinate system, the specific process of drawing the turbine generator static stability margin impedance circle is as follows:

step two, a, because the turbine generator static stability impedance circle and the turbine generator static stability margin impedance circle are concentric circles_YuA fromAnd obtaining the center coordinates (0, a) of the static stability margin impedance circle of the turbonator_Yu)；

Wherein, a_YuThe vertical coordinate of the circle center of the turbine generator static stability margin impedance circle;

step two, enabling the radius r of the turbine generator static stability margin impedance circle_Yu＝K_kR, from the center coordinates (0, a)_Yu) And radius r_YuAnd drawing the turbine generator static stability margin impedance circle under the impedance coordinate system, thereby completing the drawing of the turbine generator static stability margin impedance circle.

Further, K is not less than 1.05_k≤1.2。

Further, in the third step, drawing the circumscribed regular hexagon of the turbine generator static stability margin impedance circle according to the turbine generator static stability margin impedance circle, so that the concrete process of obtaining the circumscribed regular hexagon curve equation is as follows:

step three, enabling two tangent points O of the turbine generator static stability margin impedance circle₁And O₅Respectively are (0, K)_k·r-r+X_c) And (0, - (K)_k·r-r)+X_b)；

Wherein, X_cAnd X_bAre all intermediate variables, and

X_conthe equivalent reactance between the generator and the system;

X_dis a generator synchronous reactance;

U_Nrated voltage for the generator;

S_Nrated apparent power for the generator;

n_athe transformation ratio of a current transformer at the generator terminal is set;

n_vthe transformation ratio of a generator terminal voltage transformer is obtained;

step three and two, according to two tangent points O₁And O₅And radius r of a turbine generator static margin impedance circle_Yu＝K_kR, six vertexes O of circumscribed regular hexagon for obtaining turbine generator static stability margin impedance circle₂、O₃、O₄、O₆、O₇、O₈According to O, according to₁To O₈Drawing the circumscribed regular hexagon of the static stability margin impedance circle of the steam turbine generator by the coordinates of the resistance circle, thereby obtaining a circumscribed regular hexagon curve equation;

vertex O₂Has the coordinates of (K)_k·r·tan30°，K_k·r-r+X_c)；

Vertex O₃Has the coordinates of (K)_k·r/cos30°，a)；

Vertex O₄Has the coordinates of (K)_k·r·tan30°，-(K_k·r-r)+X_b)；

Vertex O₆Has the coordinate of (-K)_k·r·tan30°，-(K_k·r-r)+X_b)；

Vertex O₇Has the coordinate of (-K)_k·r/cos30°，a)；

Vertex O₈Has the coordinate of (-K)_k·r·tan30°，K_k·r-r+X_c)。

Wherein the side length of the circumscribed regular hexagon is K_k·r/cos30°。

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that features described in different dependent claims and herein may be combined in ways different from those described in the original claims. It is also to be understood that features described in connection with individual embodiments may be used in other described embodiments.