CN110927572A

CN110927572A - Generator low excitation limit fixed value determination method based on mapping method

Info

Publication number: CN110927572A
Application number: CN201911171831.4A
Authority: CN
Inventors: 窦骞; 张炜; 卢广陵; 张翌晖; 丘浩
Original assignee: Electric Power Research Institute of Guangxi Power Grid Co Ltd
Current assignee: Electric Power Research Institute of Guangxi Power Grid Co Ltd
Priority date: 2019-11-26
Filing date: 2019-11-26
Publication date: 2020-03-27

Abstract

The invention discloses a generator low excitation limit fixed value determining method based on a mapping method, relates to the technical field of power distribution, and solves the problem of determining the generator low excitation limit fixed value. The method uses a mapping method, data obtained by a phase advance test is mapped into a phase advance capacity map, the mapping method comprises the steps of determining a rectangular coordinate map with an abscissa as reactive power Q and an ordinate as active power P, marking points of the phase advance test data in the corresponding position in the map, connecting straight lines between two adjacent points, extending a line segment of the connecting line of the two points close to the abscissa and intersecting the line segment at one point, wherein the formed broken line is the maximum phase advance operation capacity map of the generator set, and then finding out the corresponding reactive power value, so that the accurate low excitation limit fixed value can be obtained.

Description

Generator low excitation limit fixed value determination method based on mapping method

Technical Field

The invention relates to the technical field of power distribution, in particular to a generator low excitation limit fixed value determining method based on a mapping method.

Background

In order to ensure the voltage stability of the power grid, the power grid requires that each generator set should have a certain phase-advancing capability. However, when the phase advance depth exceeds the static stability limit depth of the generator, the generator may be unstable, and therefore, the generator set needs to perform a phase advance test to determine the maximum phase advance capacity. After the phase advance capacity is determined, in order to ensure that the situation that the reactive power is lower than the maximum phase advance depth due to misoperation and other reasons when the unit operates in a phase advance mode is avoided, low excitation limiting curves are arranged in excitation regulators of the generator set, and as long as the reactive power is lower than a set low excitation limiting fixed value, the excitation regulators cannot continue to reduce the magnetic field, so that the voltage is kept stable, the low excitation limiting fixed value needs to be accurately determined, and the situation that the reactive power is lower than the maximum phase advance depth is avoided.

Disclosure of Invention

In order to overcome the defects, the invention provides a generator low excitation limit fixed value determining method based on a mapping method, and solves the problem of determining the generator low excitation limit fixed value.

In order to achieve the purpose, the invention adopts the following technical scheme:

a generator low excitation limit fixed value determining method based on a mapping method comprises the following steps of 1, drawing a coordinate graph: determining a rectangular coordinate graph with an abscissa as reactive power Q and an ordinate axis as active power P, linearly connecting a plurality of phase advance test data at corresponding local index points in the graph, and extending a line segment of a connecting line of the two points close to the abscissa axis and intersecting the line segment at one point to form a broken line which is the maximum phase advance operation capacity graph of the generator set; step 2, reading the maximum phase-advancing reactive power value: determining the number of maximum phase-advancing reactive power values to be read and the value of the corresponding active power P, and respectively reading the maximum phase-advancing reactive power values corresponding to the active power P of the generator through a maximum phase-advancing running capacity diagram, wherein the maximum phase-advancing reactive power values are low excitation limit fixed values of the generator.

Further, step 3 is included, a generator low excitation limit fixed value table is drawn: and drawing a generator low excitation limit set value table according to the data converted and read from the maximum phase-advancing running capacity diagram, wherein the generator low excitation limit set value table comprises an apparent power per unit value, an active power MW, a reactive power MVAR and a reactive power per unit value.

Further, at least two items of the entry test data are arranged.

Further, the maximum phase advance reactive power value in the step 2 is a per-unit value obtained through conversion.

Compared with the prior art, the invention has the beneficial effects that:

the obtained phase advance test data are marked in a right-angle coordinate graph and are connected in parallel to form a phase advance operation capacity graph, corresponding reactive power values are directly read through the graph, the phase advance test data of the generator can be conveniently converted into a low excitation limit fixed value of the generator, and the converted low excitation limit fixed value is effective and accurate.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.

Fig. 1 is a diagram of the capacity of the generator in phase operation according to the embodiment of the invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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.

A generator low excitation limit fixed value determining method based on a mapping method comprises the following steps of 1, drawing a coordinate graph: determining a rectangular coordinate graph with an abscissa as reactive power Q and an ordinate axis as active power P, linearly connecting adjacent two points at corresponding local standard points of the phase advance test data in the graph, extending a line segment of a connecting line of the two points close to the abscissa axis and intersecting the line segment at one point, and forming a broken line which is the maximum phase advance operation capacity graph of the generator set; step 2, reading the maximum phase-advancing reactive power value: respectively reading out the maximum phase advance reactive power values corresponding to the active power P =0%, 25%, 50%, 75% and 100% of the generator through a graph, and obtaining a low excitation limit fixed value of the generator; step 3, drawing a generator low excitation limit fixed value table: and drawing a generator low excitation limit set value table according to the maximum phase advance operation capacity graph and the read data, wherein the generator low excitation limit set value table comprises a sequence number, an apparent power normalized value, an active power MW, a reactive power MVAR and a reactive power normalized value.

Due to the fact that the phase advance test time is long, too many points cannot be made in the phase advance test due to the fact that the phase advance test time is long, the phase advance test cannot be made in a low-load region of a thermal power generating unit and a vibration region of a hydroelectric generating unit, the phase advance test is basically made in China at present under three different active power working conditions, and the maximum phase advance compatible quantity curve of the generator is determined by three points. However, the low excitation limit fixed value of the existing imported or domestic excitation regulator is generally determined by 5 points, three phase advance test data of a certain thermal power plant are shown in table 1, and as can be seen from the table, the phase advance test data cannot be directly used as the fixed value of the low excitation limit, and conversion is needed in the middle.

Table 1: phase-entering test data of #1 generator of certain thermal power plant

As shown in fig. 1, the abscissa in the figure is the reactive power Q of the generator, the ordinate is the active power P of the generator, wherein D, E, F three points are the phase advance test data in table 1, AB is the maximum excitation current limit curve of the generator, then D, E, F three points are connected together by straight lines respectively, and a line segment EF is extended to the abscissa to intersect at point G, a broken line DEFG is the maximum phase advance operation capacity map of the generator set, the right side of the ordinate in the figure is the late phase portion, the left side is the phase advance portion, and for low excitation limit, the left phase advance portion is mainly focused. In the figure, the maximum phase advance reactive power values corresponding to the active power P =0%, 25%, 50%, 75% and 100% of the generator are respectively read, and then a generator low excitation limit fixed value table is obtained through drawing, that is, the data in table 2, the maximum phase advance reactive power value is a normalized value, the normalized value is a low excitation limit fixed value of the generator, and the normalized values of the active power and the reactive power are both based on the rated apparent power SN.

Table 2: low excitation limit fixed value table for #1 generator of certain thermal power plant

The graph can be automatically calculated by using software of a generator phase-advancing test system V1.0, and a fixed value is read, wherein the precision of the graph meets the requirement. The generator phase advance test system V1.0 has acquired software copyright, has a registration number of 2019SR1003303, only needs to input relevant parameters in software, then selects 'actual phase advance', presses a 'confirm' button, and then inputs phase advance test data in a popped small window to automatically draw, if the phase advance test data is less than 5 points, sets other 2 points to be the same data as the last point, and greatly improves the accuracy of the read numerical value through software drawing.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention, and therefore, the scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A generator low excitation limit fixed value determination method based on a mapping method is characterized by comprising the following steps: comprises the following steps of (a) carrying out,

step 1, drawing a coordinate graph: determining a rectangular coordinate system with an abscissa as reactive power Q and an ordinate axis as active power P, linearly connecting a plurality of phase advance test data at corresponding local index points in the graph, and extending a line segment of a connecting line of the two points close to the abscissa axis and intersecting the line segment at one point to form a broken line which is the maximum phase advance operation capacity graph of the generator set;

step 2, reading the maximum phase-advancing reactive power value: determining the number of maximum phase-advancing reactive power values to be read and the value of the corresponding active power P, and respectively reading the maximum phase-advancing reactive power values corresponding to the active power P of the generator through a maximum phase-advancing running capacity diagram, wherein the maximum phase-advancing reactive power values are low excitation limit fixed values of the generator.

2. The mapping-based generator low excitation limit fixed value determination method according to claim 1, characterized in that: the method further comprises a step 3 of drawing a generator low excitation limit fixed value table: and drawing a generator low excitation limit set value table according to data read and converted from the maximum phase-advancing running capacity diagram, wherein the generator low excitation limit set value table comprises an apparent power per unit value, an active power MW, a reactive power MVAR and a reactive power per unit value.

3. The mapping-based generator low excitation limit fixed value determination method according to claim 1, characterized in that: at least two items of entry test data are set.

4. The mapping-based generator low excitation limit fixed value determination method according to claim 1, characterized in that: and 2, converting the maximum phase advancing reactive power value into a per-unit value.