CN112653130A - Method and system for determining frequency supporting capacity of power grid based on inertia ratio - Google Patents

Method and system for determining frequency supporting capacity of power grid based on inertia ratio Download PDF

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CN112653130A
CN112653130A CN202011431163.7A CN202011431163A CN112653130A CN 112653130 A CN112653130 A CN 112653130A CN 202011431163 A CN202011431163 A CN 202011431163A CN 112653130 A CN112653130 A CN 112653130A
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power grid
direct current
frequency
evaluation index
inertia ratio
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CN112653130B (en
Inventor
张璐路
吕颖
贾海波
史东宇
张伟
万雄
常乃超
陶洪铸
王宝财
杨超
于之虹
魏亚威
马晶
李琨
高强
鲁广明
王兵
陆俊
戴红阳
侯金秀
解梅
石琛
贾育培
严剑峰
李亚楼
田芳
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

Abstract

The invention discloses a method and a system for determining the frequency supporting capability of a power grid based on an inertia ratio, wherein the method comprises the following steps: determining a system inertia ratio of the power grid; determining an evaluation index according to the type of the power grid, and calculating an evaluation index value of the evaluation index according to the system inertia ratio; and determining the frequency supporting capacity of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index. Also disclosed are a method and a system for determining the frequency support capability of a power grid based on an inertia ratio, comprising: determining a system inertia ratio of the power grid; calculating a system inertia ratio threshold value of the power grid according to the type of the power grid; and determining the frequency supporting capacity of the power grid according to the system inertia ratio and a system inertia ratio threshold value. The method can realize the quick judgment of the frequency supporting capacity of the synchronous power grid, and can lay a foundation for improving the new energy consumption level on the basis of the safety of the power grid.

Description

Method and system for determining frequency supporting capacity of power grid based on inertia ratio
Technical Field
The invention relates to the technical field of online safety and stability calculation and analysis of power systems, in particular to a method and a system for determining frequency supporting capacity of a power grid based on an inertia ratio.
Background
With the rapid development of new energy and the promotion of clean energy substitution, the output ratio of the new energy in the operation of a power grid is continuously improved, the starting mode of a conventional unit is continuously reduced, the rotational inertia of the system is continuously reduced, the disturbance resistance is reduced, and the frequency stability risk is gradually increased.
Inertia is a degree of impedance that describes a change in the state of motion of an object, and in an electrical system, represents the amount of rotational kinetic energy stored on the shaft of a generator. The inertia determines the dynamic change condition of the power grid when disturbed, and directly reflects the disturbance resistance of the system.
Therefore, a method for determining the frequency supporting capability of the grid based on the inertia ratio is needed.
Disclosure of Invention
The invention provides a method and a system for determining the frequency supporting capacity of a power grid based on an inertia ratio, and aims to solve the problem of determining the frequency supporting capacity of the power grid.
In order to solve the above problem, according to an aspect of the present invention, there is provided a method of determining a frequency supporting capability of a power grid based on an inertia ratio, the method including:
determining a system inertia ratio of the power grid;
determining an evaluation index according to the type of the power grid, and calculating an evaluation index value of the evaluation index according to the system inertia ratio;
and determining the frequency supporting capacity of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index.
Preferably, when the type of the power grid is a direct current transmission end power grid, the evaluation index is the maximum frequency change rate or the transient state maximum frequency;
and when the type of the power grid is a direct current receiving end power grid, the evaluation index is the maximum frequency change rate or the lowest transient frequency.
Preferably, the calculating an evaluation index value of the evaluation index according to the system inertia ratio includes:
when the evaluation index is the maximum frequency change rate, calculating an evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000021
wherein ,
Figure BDA0002820687250000022
is the maximum frequency rate of change value; k is a radical offIs a frequency rate of change proportionality coefficient; the IR is a system inertia ratio, and when the type of the power grid is a direct current transmission end power grid, the IR is SIR; when the type of the power grid is a direct current receiving end power grid, IR is RIR;
when the evaluation index is the transient highest frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000023
wherein ,ΔfmIs the transient highest frequency value; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid; the SIR is a system inertia ratio corresponding to a direct current transmission end power grid;
when the evaluation index is the lowest transient frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000024
wherein ,ΔfmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
Preferably, the determining the frequency support capability of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index comprises:
if the evaluation index value is less than or equal to the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid meets the requirement, and if the evaluation index value is smaller, indicating that the frequency support capability of the power grid is stronger;
and if the evaluation index value is larger than the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid does not meet the requirement.
According to another aspect of the present invention, there is provided a method of determining a frequency supporting capability of a power grid based on an inertia ratio, the method comprising:
determining a system inertia ratio of the power grid;
calculating a system inertia ratio threshold value of the power grid according to the type of the power grid;
and determining the frequency supporting capacity of the power grid according to the system inertia ratio and a system inertia ratio threshold value.
Preferably, the calculating the system inertia ratio threshold of the power grid according to the type of the power grid includes:
when the type of the power grid is a direct current transmission end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000031
wherein ,SIRminA system inertia ratio threshold value corresponding to a direct current sending end power grid; the STRD is a transient frequency change rate limit value of a direct current transmission end power grid; k is a radical ofsfThe frequency change rate proportionality coefficient is corresponding to a direct current transmission end power grid; STMD is the frequency deviation limit value of the direct current transmitting end power grid; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid;
when the type of the power grid is a direct current receiving end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000032
wherein ,RIRminA system inertia ratio threshold value corresponding to the direct current receiving end power grid; RTRD is transient frequency change rate limit value of the direct current receiving end power grid; k is a radical ofrfThe frequency change rate proportionality coefficient is corresponding to a direct current receiving end power grid; Δ fmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
Preferably, the determining the frequency supporting capability of the power grid according to the system inertia ratio and a system inertia ratio threshold value comprises:
if the system inertia ratio is larger than or equal to the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid meets the requirement, and if the system inertia ratio is larger, indicating that the frequency supporting capacity of the power grid is stronger;
and if the system inertia ratio is smaller than the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid does not meet the requirement.
Preferably, wherein the determining the system inertia ratio of the power grid comprises:
Figure BDA0002820687250000041
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
According to yet another aspect of the present invention, there is provided a system for determining a frequency supporting capability of a power grid based on an inertia ratio, the system comprising:
the system inertia ratio determining unit is used for determining the system inertia ratio of the power grid;
the evaluation index value determination unit is used for determining an evaluation index according to the type of the power grid and calculating the evaluation index value of the evaluation index according to the system inertia ratio;
and the frequency support capacity determining unit is used for determining the frequency support capacity of the power grid according to the evaluation index value and an evaluation index threshold value corresponding to the evaluation index.
Preferably, when the type of the power grid is a direct current transmission end power grid, the evaluation index is the maximum frequency change rate or the transient state maximum frequency;
and when the type of the power grid is a direct current receiving end power grid, the evaluation index is the maximum frequency change rate or the lowest transient frequency.
Preferably, the evaluation index value determination unit, which calculates the evaluation index value of the evaluation index according to the system inertia ratio, includes:
when the evaluation index is the maximum frequency change rate, calculating an evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000051
wherein ,
Figure BDA0002820687250000052
is the maximum frequency rate of change value; k is a radical offIs a frequency rate of change proportionality coefficient; the IR is a system inertia ratio, and when the type of the power grid is a direct current transmission end power grid, the IR is SIR; when the type of the power grid is a direct current receiving end power grid, IR is RIR;
when the evaluation index is the transient highest frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000053
wherein ,ΔfmIs the transient highest frequency value; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid; the SIR is a system inertia ratio corresponding to a direct current transmission end power grid; (ii) a
When the evaluation index is the lowest transient frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000054
wherein ,ΔfmIs the transient lowest frequency value; kLIs a DC receiving endLoad frequency modulation factor of the network; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
Preferably, the frequency support capability determining unit, which determines the frequency support capability of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index, includes:
if the evaluation index value is less than or equal to the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid meets the requirement, and if the evaluation index value is smaller, indicating that the frequency support capability of the power grid is stronger;
and if the evaluation index value is larger than the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid does not meet the requirement.
According to yet another aspect of the present invention, there is provided a system for determining a frequency supporting capability of a power grid based on an inertia ratio, the system comprising:
the system inertia ratio determining unit is used for determining the system inertia ratio of the power grid;
the system inertia ratio threshold value determining unit is used for calculating a system inertia ratio threshold value of the power grid according to the type of the power grid;
and the frequency supporting capacity determining unit is used for determining the frequency supporting capacity of the power grid according to the system inertia ratio and a system inertia ratio threshold value.
Preferably, the system inertia ratio threshold determination unit, which calculates the system inertia ratio threshold of the power grid according to the type of the power grid, includes:
when the type of the power grid is a direct current transmission end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000061
wherein ,SIRminA system inertia ratio threshold value corresponding to a direct current sending end power grid; the STRD is a transient frequency change rate limit value of a direct current transmission end power grid; k is a radical ofsfThe frequency change rate proportionality coefficient is corresponding to a direct current transmission end power grid; STMD is the frequency deviation limit value of the direct current transmitting end power grid; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid;
when the type of the power grid is a direct current receiving end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000062
wherein ,RIRminA system inertia ratio threshold value corresponding to the direct current receiving end power grid; RTRD is transient frequency change rate limit value of the direct current receiving end power grid; k is a radical ofrfThe frequency change rate proportionality coefficient is corresponding to a direct current receiving end power grid; Δ fmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
Preferably, the determining unit of the frequency support capability determines the frequency support capability of the power grid according to the system inertia ratio and a system inertia ratio threshold, and includes:
if the system inertia ratio is larger than or equal to the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid meets the requirement, and if the system inertia ratio is larger, indicating that the frequency supporting capacity of the power grid is stronger;
and if the system inertia ratio is smaller than the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid does not meet the requirement.
Preferably, the determining unit of the system inertia ratio determines the system inertia ratio of the power grid, and includes:
Figure BDA0002820687250000071
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
The invention provides a method and a system for determining the frequency supporting capacity of a power grid based on an inertia ratio, wherein on the basis of determining the inertia ratio of the system, the frequency supporting capacity of the power grid is evaluated through an evaluation index value and a system inertia ratio threshold value, so that the frequency supporting capacity of the synchronous power grid can be rapidly judged, and a foundation can be laid for improving the new energy consumption level on the basis of the safety of the power grid.
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A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
FIG. 1 is a flow diagram of a method 100 of determining a frequency support capability of a power grid based on an inertia ratio, according to an embodiment of the present invention;
FIG. 2 is a flow diagram of a method 200 of determining a frequency support capability of a power grid based on an inertia ratio, according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a system 300 for determining a frequency support capability of a power grid based on an inertia ratio, according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a system 400 for determining a frequency supporting capability of a power grid based on an inertia ratio according to an embodiment of the invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The invention provides a method and a system for determining the frequency supporting capacity of a power grid based on an inertia ratio, wherein on the basis of determining the inertia ratio of the system, the frequency supporting capacity of the power grid is evaluated through an evaluation index value and a system inertia ratio threshold value, so that the frequency supporting capacity of the synchronous power grid can be rapidly judged, and a foundation can be laid for improving the new energy consumption level on the basis of the safety of the power grid.
Fig. 1 is a flow diagram of a method 100 of determining a frequency support capability of a power grid based on an inertia ratio, according to an embodiment of the invention. As shown in fig. 1, a method 100 for determining a frequency supporting capability of a power grid based on an inertia ratio is provided, which starts with step 101, and determines a system inertia ratio of the power grid in step 101.
Preferably, wherein the determining the system inertia ratio of the power grid comprises:
Figure BDA0002820687250000091
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
In the invention, the system inertia ratio is defined as the ratio of the system rotational inertia to the disturbance power, namely:
Figure BDA0002820687250000092
where IR represents the system inertia ratio, J represents the system moment of inertia, and Δ P represents the disturbance power.
For a power grid subarea mainly using direct current transmission, when calculating the inertia ratio of a direct current transmitting end power grid under the condition of expected fault disturbance, a generator list GenSet is formed by searching generators contained in the subarea, and each unit is subjected to unit operation state RiRated capacity Sn of unitiAnd the inertia time constant T of the unitjiCalculating the total sum to obtain the system moment of inertia under the subarea; considering disturbance power delta P when the expected fault of the direct current transmitting end power grid occurs, the system inertia ratio SIR of the direct current transmitting end power grid and the system inertia ratio RIR of the direct current receiving end power grid under the condition of the expected fault disturbance are respectively as follows:
Figure BDA0002820687250000093
Figure BDA0002820687250000094
wherein, for the unit i, R when the unit is put into operationiWhen the unit is out of service R1i0. Based on the characteristic that the power angle and the electrical angular speed of the generator rotor cannot generate sudden change in the electromechanical transient process, omega0The electrical angular velocity can be calculated before the unit fault occurs.
In step 102, an evaluation index is determined according to the type of the power grid, and an evaluation index value of the evaluation index is calculated according to the system inertia ratio.
Preferably, when the type of the power grid is a direct current transmission end power grid, the evaluation index is the maximum frequency change rate or the transient state maximum frequency;
and when the type of the power grid is a direct current receiving end power grid, the evaluation index is the maximum frequency change rate or the lowest transient frequency.
Preferably, the calculating an evaluation index value of the evaluation index according to the system inertia ratio includes:
when the evaluation index is the maximum frequency change rate, calculating an evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000101
wherein ,
Figure BDA0002820687250000102
is the maximum frequency rate of change value; k is a radical offIs a frequency rate of change proportionality coefficient; the IR is a system inertia ratio, and when the type of the power grid is a direct current transmission end power grid, the IR is SIR; when the type of the power grid is a direct current receiving end power grid, IR is RIR;
when the evaluation index is the transient highest frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000103
wherein ,ΔfmIs the transient highest frequency value; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid; the SIR is a system inertia ratio corresponding to a direct current transmission end power grid; (ii) a
When the evaluation index is the lowest transient frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000104
wherein ,ΔfmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
In the embodiment of the invention, for the direct current sending end power grid, the frequency supporting capability of the direct current sending end power grid is evaluated by estimating the system frequency change rate when disturbance occurs and simultaneously according to the transient frequency change rate limit value STRD of the direct current sending end power grid. When the evaluation index is the maximum frequency change rate, considering that the disturbance power when the fault is expected to occur is delta P, the disturbance power born by each commissioning unit is delta P when the fault is instantly distributediExistence of
Figure BDA0002820687250000111
Frequency change rate at instant of unit i fault
Figure BDA0002820687250000112
Comprises the following steps:
Figure BDA0002820687250000113
the maximum frequency change rate of the unit in the subarea can be determined according to the system inertia ratio SIR of the direct current transmission end power grid
Figure BDA0002820687250000114
Comprises the following steps:
Figure BDA0002820687250000115
wherein, the most effective isComparing the large frequency change rate with a preset transient frequency change rate limit value STRD of the direct current transmission end power grid, and determining the frequency supporting capacity of the synchronous power grid to which the unit belongs; according to the analysis experience, the transient frequency change rate limit value STRD of the direct current transmission end power grid is generally 2Hz/s, ksfGenerally, the amount of the catalyst is 2 to 3.
In the embodiment of the invention, for the direct current transmission end power grid, the system frequency change rate when disturbance occurs can be estimated, and the frequency supporting capability of the direct current transmission end power grid is estimated according to the transient frequency change rate limit value STRD of the direct current transmission end power grid. When the evaluation index is the transient state highest rate, considering that the direct current sending end power grid is provided with a safety control device, after the safety control device acts, the system frequency can be recovered to be normal in a short time, before the safety control device acts, main factors influencing the transient state frequency change of the direct current sending end power grid are the system rotational inertia and the load frequency modulation characteristic, and the transient state frequency change formula of the direct current sending end power grid after disturbance occurs is as follows:
Figure BDA0002820687250000116
wherein D is the load frequency modulation factor of the direct current transmission end power grid, H is the equivalent generator inertia constant of the direct current transmission end power grid,
Figure BDA0002820687250000117
t is the time at which the disturbance occurs. Estimating transient frequency variation of the direct current sending end power grid after disturbance occurs according to a system inertia ratio SIR of the direct current sending end power grid, wherein the transient frequency variation is as follows:
Figure BDA0002820687250000118
wherein ,SGZGenerating capacity for a direct current sending end power grid; and comparing the transient state maximum frequency with the transient state frequency deviation limit STMD of the direct current transmission end power grid, and evaluating the frequency supporting capability of the synchronous power grid to which the unit belongs. According to the experience of the actual power grid operation mode, the transient frequency deviation limit STMD of the direct current transmission end power grid is generally 0.6Hz,t is the security control action time, which is generally 300ms, and the corresponding frequency deviation value is the maximum at this time.
In the embodiment of the invention, for the direct current receiving end power grid, when the evaluation index is the maximum frequency change rate, the method for determining the evaluation index value has the same principle as that of the direct current transmitting end power grid, the system frequency change rate when disturbance occurs is estimated, and the frequency supporting capability of the direct current receiving end power grid is estimated according to the transient frequency change rate limit RTRD of the direct current receiving end power grid. Specifically, the maximum frequency change rate is calculated using the following formula, including:
Figure BDA0002820687250000121
Figure BDA0002820687250000122
Figure BDA0002820687250000123
Figure BDA0002820687250000124
by comparing the maximum frequency change rate with a preset transient frequency change rate limit RTRD of the direct current receiving end power grid, the frequency supporting capability of the synchronous power grid to which the unit belongs can be determined. According to the analysis experience, the transient frequency change rate limit RTRD of the direct current receiving end power grid is generally 4.8Hz/s, krfIs as follows. . . K is a number ofrfGenerally, 4-5 is taken.
In the embodiment of the invention, for the direct current receiving end power grid, the system transient lowest frequency after the disturbance is generated is estimated according to the transient frequency change formula of the direct current receiving end power grid, and the frequency supporting capability of the direct current receiving end power grid is estimated according to the transient frequency deviation limit RTMD of the direct current receiving end power grid. When the evaluation index is the lowest transient frequency, the transient frequency change formula of the direct current receiving end power grid after the disturbance occurs is as follows:
Figure BDA0002820687250000125
Figure BDA0002820687250000126
Figure BDA0002820687250000127
Figure BDA0002820687250000131
Figure BDA0002820687250000132
Figure BDA0002820687250000133
the transient frequency change formula of the direct current receiving end power grid is derived, and the time t corresponding to the lowest transient frequency is obtainedmThe calculation formula is as follows:
Figure BDA0002820687250000134
tmthe transient lowest frequency calculation formula corresponding to the moment is as follows:
Figure BDA0002820687250000135
wherein ,KLFor the load frequency-modulation factor, K, of the DC receiving-end networkGFrequency modulation factor, K, of a unit for a direct current receiving networkmIs a DC receiving endMechanical power gain coefficient of net, TRIs the reheating time constant of the direct current receiving end power grid, H is the unit equivalent inertia constant of the direct current receiving end power grid, FHThe high-pressure turbine is a high-pressure turbine of a direct current receiving end power grid.
Estimating the lowest transient frequency of the direct current receiving end power grid after disturbance occurs according to the inertia ratio of the direct current receiving end power grid as follows:
Figure BDA0002820687250000136
by applying the lowest frequency of the transient Δ fmAnd comparing the frequency with a transient frequency deviation limit RTMD of the direct current receiving end power grid, and evaluating the frequency supporting capability of the synchronous power grid to which the unit belongs. According to an actual power grid empirical operation mode, a transient frequency deviation limit RTMD of a direct current receiving end power grid is generally 0.75 Hz.
In step 103, the frequency supporting capability of the power grid is determined according to the evaluation index value and an evaluation index threshold value corresponding to the evaluation index.
Preferably, the determining the frequency support capability of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index comprises:
if the evaluation index value is less than or equal to the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid meets the requirement, and if the evaluation index value is smaller, indicating that the frequency support capability of the power grid is stronger;
and if the evaluation index value is larger than the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid does not meet the requirement.
In the invention, for the direct current transmission end power grid, when the evaluation index is the maximum frequency change rate, the evaluation index is compared
Figure BDA0002820687250000141
And size of STRD, if
Figure BDA0002820687250000142
STR or lessD, determining that the frequency supporting capability of the power grid meets the requirement, and
Figure BDA0002820687250000143
the smaller the frequency, the stronger the frequency supporting capability of the synchronous grid.
For the direct-current transmission end power grid, when the evaluation index is the transient highest frequency, comparing the magnitude of delta f with the magnitude of STMD, if the delta f of the delta f is smaller than or equal to the magnitude of the STMD, determining that the frequency supporting capability of the power grid meets the requirement, and if the delta f is smaller, indicating that the frequency supporting capability of the synchronous power grid is stronger.
For the direct current receiving end power grid, when the evaluation index is the maximum frequency change rate, comparison is carried out
Figure BDA0002820687250000144
And the magnitude of, if
Figure BDA0002820687250000145
If the frequency support capacity is less than or equal to RTRD, determining that the frequency support capacity of the power grid meets the requirement, and
Figure BDA0002820687250000146
the smaller the size, the stronger the frequency supporting capability of the synchronous grid.
For the direct current receiving end power grid, when the evaluation index is the lowest transient frequency, comparing delta fmWith the size of RTMD, if Δ fmIf the frequency support capacity is less than or equal to RTMD, determining that the frequency support capacity of the power grid meets the requirement, and delta fmThe smaller the size, the stronger the frequency supporting capability of the synchronous grid.
Fig. 2 is a flow diagram of a method 200 of determining a frequency support capability of a power grid based on an inertia ratio, according to an embodiment of the invention. As shown in fig. 2, a method 200 for determining a frequency supporting capability of a power grid based on an inertia ratio is provided in an embodiment of the present invention, starting at step 201, and determining a system inertia ratio of the power grid at step 201.
Preferably, wherein the determining the system inertia ratio of the power grid comprises:
Figure BDA0002820687250000147
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
In the present invention, the method for determining the system inertia ratio is the same as the method for determining the system inertia ratio in step 101 of the method 100, and is not described herein again.
In step 202, a system inertia ratio threshold of the power grid is calculated according to the type of the power grid.
Preferably, the calculating the system inertia ratio threshold of the power grid according to the type of the power grid includes:
when the type of the power grid is a direct current transmission end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000151
wherein ,SIRminA system inertia ratio threshold value corresponding to a direct current sending end power grid; the STRD is a transient frequency change rate limit value of a direct current transmission end power grid; k is a radical ofsfThe frequency change rate proportionality coefficient is corresponding to a direct current transmission end power grid; STMD is the frequency deviation limit value of the direct current transmitting end power grid; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid;
when the type of the power grid is a direct current receiving end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000152
wherein ,RIRminA system inertia ratio threshold value corresponding to the direct current receiving end power grid; RTRD is transient frequency change rate limit value of the direct current receiving end power grid; k is a radical ofrfThe frequency change rate proportionality coefficient is corresponding to a direct current receiving end power grid; Δ fmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
In an embodiment of the present invention, calculating a first inertia ratio threshold value of a dc-link power grid according to a frequency change rate limit STRD when a dc-link power grid disturbance occurs includes:
Figure BDA0002820687250000153
wherein, the transient frequency change rate limits STRD and k of the DC transmission end power gridsfThe values of (A) are obtained empirically from the analysis. The transient frequency change rate limit value STRD of the direct current transmission end power grid is generally 2Hz/s, ksfGenerally, the amount of the catalyst is 2 to 3. For example, the first inertia ratio threshold of the dc-side grid is calculated to be 50.
Calculating a second inertia ratio threshold of the direct current sending end power grid according to the transient frequency deviation limit STMD after the disturbance of the direct current sending end power grid occurs, wherein the second inertia ratio threshold comprises the following steps:
Figure BDA0002820687250000161
wherein, transient frequency deviation limit STMD, t of DC transmitting end electric networkc and SGZThe value of (A) is obtained according to the experience of the actual power grid operation mode. The transient frequency deviation limit STMD of the direct current transmission end power grid is generally 0.6Hz, t is generally 300ms, and SGZGenerally greater than 40000 MVA. For example, calculating a second inertia of the DC-side gridThe quantity ratio threshold is 20.
And (4) selecting the larger frequency based on the frequency change rate when the disturbance of the direct current sending end power grid occurs and the highest transient frequency after the disturbance occurs, and obtaining that the inertia ratio threshold of the direct current sending end power grid is 50.
In an embodiment of the present invention, calculating a third inertia ratio threshold of the dc-receiving grid according to a frequency change rate limit RTRD when the dc-receiving grid disturbance occurs includes:
Figure BDA0002820687250000162
wherein, the transient frequency change rate limit RTRD and k of the DC receiving end power gridrfThe value of (a) is taken according to analytical experience. The transient frequency change rate limit RTRD of the direct current receiving end power grid is generally 4.8Hz/s, krfGenerally, the amount is 4 to 5. For example, a first inertia ratio threshold of the dc receiving grid is calculated as 42.
Calculating a fourth inertia ratio threshold of the direct current receiving end power grid according to the transient frequency deviation limit RTMD after the disturbance of the direct current receiving end power grid occurs, wherein the fourth inertia ratio threshold comprises the following steps:
Figure BDA0002820687250000163
wherein, the transient frequency deviation limit RTMD and K of the DC receiving end power gridm、KL、KG、TR、FHAnd H is obtained according to the experience of the actual power grid operation mode. The transient frequency deviation limit RTMD of the direct current receiving end power grid is generally 0.75Hz and KmGenerally 0.95, KLHas a value range of 1-2, KGHas a value range of 10-20, TRHas a value range of 6-12, H has a value range of 3-6, FHThe value range of (A) is 0.2-0.6. For example, the second inertia ratio threshold of the dc receiving grid is calculated to be 70.
And selecting the larger frequency based on the frequency change rate when the disturbance of the direct current receiving end power grid occurs and the lowest transient frequency after the disturbance occurs, so as to obtain the inertia ratio threshold value of the direct current receiving end power grid as 70.
In step 203, the frequency supporting capacity of the power grid is determined according to the system inertia ratio and a system inertia ratio threshold value.
Preferably, the determining the frequency supporting capability of the power grid according to the system inertia ratio and a system inertia ratio threshold value comprises:
if the system inertia ratio is larger than or equal to the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid meets the requirement, and if the system inertia ratio is larger, indicating that the frequency supporting capacity of the power grid is stronger;
and if the system inertia ratio is smaller than the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid does not meet the requirement.
The method can realize the rapid judgment of the frequency supporting capability of the power grid, and lays a foundation for improving the consumption level of new energy on the basis of the safety of the power grid; according to the unit running state, the unit rated capacity and the unit inertia time constant of each partition in the power grid, the inertia ratio of the synchronous power grid can be quickly calculated, and the system frequency change rate when the expected fault disturbance occurs and the system transient extreme value frequency after the disturbance occurs can be estimated; the frequency supporting capability of the synchronous power grid is rapidly evaluated, and the larger the inertia ratio value is, the stronger the frequency supporting capability is; and meanwhile, monitoring and early warning the frequency supporting capacity of the power grid according to an inertia ratio threshold value obtained by analysis experience.
Fig. 3 is a schematic diagram of a system 300 for determining a frequency supporting capability of a power grid based on an inertia ratio according to an embodiment of the invention. As shown in fig. 3, a system 300 for determining a frequency supporting capability of a power grid based on an inertia ratio according to an embodiment of the present invention includes: a system inertia ratio determination unit 301, an evaluation index value determination unit 302, and a frequency support ability determination unit 303.
Preferably, the system inertia ratio determining unit 301 is configured to determine a system inertia ratio of the power grid.
Preferably, the determining unit 301 for the system inertia ratio determines the system inertia ratio of the power grid, and includes:
Figure BDA0002820687250000171
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
Preferably, the evaluation index value determination unit 302 is configured to determine an evaluation index according to a type of a power grid, and calculate an evaluation index value of the evaluation index according to the system inertia ratio.
Preferably, when the type of the power grid is a direct current transmission end power grid, the evaluation index is the maximum frequency change rate or the transient state maximum frequency;
and when the type of the power grid is a direct current receiving end power grid, the evaluation index is the maximum frequency change rate or the lowest transient frequency.
Preferably, the evaluation index value determination unit 302, which calculates the evaluation index value of the evaluation index according to the system inertia ratio, includes:
when the evaluation index is the maximum frequency change rate, calculating an evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000181
wherein ,
Figure BDA0002820687250000182
is the maximum frequency rate of change value; k is a radical offIs a frequency rate of change proportionality coefficient; the IR is a system inertia ratio, and when the type of the power grid is a direct current transmission end power grid, the IR is SIR; when the type of the power grid is a direct current receiving end power grid, IR is RIR;
when the evaluation index is the transient highest frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000183
wherein ,ΔfmIs the transient highest frequency value; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid; the SIR is a system inertia ratio corresponding to a direct current transmission end power grid; (ii) a
When the evaluation index is the lowest transient frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure BDA0002820687250000184
wherein ,ΔfmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
Preferably, the frequency support capability determining unit 303 is configured to determine the frequency support capability of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index.
Preferably, the determining unit 303 for frequency supporting capability determines the frequency supporting capability of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index, and includes:
if the evaluation index value is less than or equal to the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid meets the requirement, and if the evaluation index value is smaller, indicating that the frequency support capability of the power grid is stronger;
and if the evaluation index value is larger than the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid does not meet the requirement.
The system 300 for determining the frequency supporting capability of the power grid based on the inertia ratio according to the embodiment of the present invention corresponds to the method 100 for determining the frequency supporting capability of the power grid based on the inertia ratio according to another embodiment of the present invention, and is not described herein again.
Fig. 4 is a schematic diagram of a system 400 for determining a frequency supporting capability of a power grid based on an inertia ratio according to an embodiment of the invention. As shown in fig. 4, a system 400 for determining a frequency supporting capability of a power grid based on an inertia ratio according to an embodiment of the present invention includes: a system inertia ratio determination unit 401, a system inertia ratio threshold determination unit 402, and a frequency support capability determination unit 403.
Preferably, the system inertia ratio determining unit 401 is configured to determine a system inertia ratio of the power grid.
Preferably, the determining unit 401 for the system inertia ratio of the power grid, which determines the system inertia ratio of the power grid, includes:
Figure BDA0002820687250000191
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
Preferably, the system inertia ratio threshold determination unit 402 is configured to calculate a system inertia ratio threshold of the power grid according to the type of the power grid.
Preferably, the calculating the system inertia ratio threshold of the power grid according to the type of the power grid by the system inertia ratio threshold determining unit 402 includes:
when the type of the power grid is a direct current transmission end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000201
wherein ,SIRminA system inertia ratio threshold value corresponding to a direct current sending end power grid; the STRD is a transient frequency change rate limit value of a direct current transmission end power grid; k is a radical ofsfThe frequency change rate proportionality coefficient is corresponding to a direct current transmission end power grid; STMD is the frequency deviation limit value of the direct current transmitting end power grid; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid; when the type of the power grid is a direct current receiving end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure BDA0002820687250000202
wherein ,RIRminA system inertia ratio threshold value corresponding to the direct current receiving end power grid; RTRD is transient frequency change rate limit value of the direct current receiving end power grid; k is a radical ofrfThe frequency change rate proportionality coefficient is corresponding to a direct current receiving end power grid; Δ fmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
Preferably, the frequency support capability determining unit 403 is configured to determine the frequency support capability of the power grid according to the system inertia ratio and a system inertia ratio threshold.
Preferably, the determining unit 403 for frequency supporting capability of the power grid according to the system inertia ratio and a system inertia ratio threshold includes:
if the system inertia ratio is larger than or equal to the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid meets the requirement, and if the system inertia ratio is larger, indicating that the frequency supporting capacity of the power grid is stronger;
and if the system inertia ratio is smaller than the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid does not meet the requirement.
The system 400 for determining the frequency supporting capability of the power grid based on the inertia ratio according to the embodiment of the present invention corresponds to the method 200 for determining the frequency supporting capability of the power grid based on the inertia ratio according to another embodiment of the present invention, and is not described herein again.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

Claims (16)

1. A method of determining a frequency support capability of a power grid based on an inertia ratio, the method comprising:
determining a system inertia ratio of the power grid;
determining an evaluation index according to the type of the power grid, and calculating an evaluation index value of the evaluation index according to the system inertia ratio;
and determining the frequency supporting capacity of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index.
2. The method according to claim 1, wherein when the type of the power grid is a direct current transmission end power grid, the evaluation index is a maximum frequency change rate or a transient state maximum frequency;
and when the type of the power grid is a direct current receiving end power grid, the evaluation index is the maximum frequency change rate or the lowest transient frequency.
3. The method according to claim 2, wherein the calculating an evaluation index value of the evaluation index according to the system inertia ratio includes:
when the evaluation index is the maximum frequency change rate, calculating an evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure FDA0002820687240000011
wherein ,
Figure FDA0002820687240000012
is the maximum frequency rate of change value; k is a radical offIs a frequency rate of change proportionality coefficient; the IR is a system inertia ratio, and when the type of the power grid is a direct current transmission end power grid, the IR is SIR; when the type of the power grid is a direct current receiving end power grid, IR is RIR;
when the evaluation index is the transient highest frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure FDA0002820687240000013
wherein ,ΔfmIs the transient highest frequency value; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid; the SIR is a system inertia ratio corresponding to a direct current transmission end power grid;
when the evaluation index is the lowest transient frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure FDA0002820687240000021
wherein ,ΔfmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
4. The method according to claim 1, wherein the determining the frequency support capability of the power grid according to the evaluation index value and an evaluation index threshold corresponding to the evaluation index comprises:
if the evaluation index value is less than or equal to the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid meets the requirement, and if the evaluation index value is smaller, indicating that the frequency support capability of the power grid is stronger;
and if the evaluation index value is larger than the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid does not meet the requirement.
5. A method of determining a frequency support capability of a power grid based on an inertia ratio, the method comprising:
determining a system inertia ratio of the power grid;
calculating a system inertia ratio threshold value of the power grid according to the type of the power grid;
and determining the frequency supporting capacity of the power grid according to the system inertia ratio and a system inertia ratio threshold value.
6. The method of claim 5, wherein calculating the system inertia ratio threshold for the power grid based on the type of power grid comprises:
when the type of the power grid is a direct current transmission end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure FDA0002820687240000031
wherein ,SIRminA system inertia ratio threshold value corresponding to a direct current sending end power grid; the STRD is a transient frequency change rate limit value of a direct current transmission end power grid; k is a radical ofsfThe frequency change rate proportionality coefficient is corresponding to a direct current transmission end power grid; STMD is the frequency deviation limit value of the direct current transmitting end power grid; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid;
when the type of the power grid is a direct current receiving end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure FDA0002820687240000032
wherein ,RIRminA system inertia ratio threshold value corresponding to the direct current receiving end power grid; RTRD is transient frequency change rate limit value of the direct current receiving end power grid; k is a radical ofrfThe frequency change rate proportionality coefficient is corresponding to a direct current receiving end power grid; Δ fmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHFor dc receiving end electric networkHigh pressure turbine ratio of (a); and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
7. The method of claim 5, wherein determining the frequency support capability of the power grid as a function of the system inertia ratio and a system inertia ratio threshold comprises:
if the system inertia ratio is larger than or equal to the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid meets the requirement, and if the system inertia ratio is larger, indicating that the frequency supporting capacity of the power grid is stronger;
and if the system inertia ratio is smaller than the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid does not meet the requirement.
8. The method of claim 1 or 5, wherein the determining a system inertia ratio of the power grid comprises:
Figure FDA0002820687240000041
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
9. A system for determining a frequency supporting capability of a power grid based on an inertia ratio, the system comprising:
the system inertia ratio determining unit is used for determining the system inertia ratio of the power grid;
the evaluation index value determination unit is used for determining an evaluation index according to the type of the power grid and calculating the evaluation index value of the evaluation index according to the system inertia ratio;
and the frequency support capacity determining unit is used for determining the frequency support capacity of the power grid according to the evaluation index value and an evaluation index threshold value corresponding to the evaluation index.
10. The system according to claim 9, wherein when the type of the power grid is a dc transmission side power grid, the evaluation index is a maximum frequency change rate or a transient state maximum frequency;
and when the type of the power grid is a direct current receiving end power grid, the evaluation index is the maximum frequency change rate or the lowest transient frequency.
11. The system according to claim 10, wherein the evaluation index value determination unit calculates the evaluation index value of the evaluation index from the system inertia ratio, and includes:
when the evaluation index is the maximum frequency change rate, calculating an evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure FDA0002820687240000042
wherein ,
Figure FDA0002820687240000043
is the maximum frequency rate of change value; k is a radical offIs a frequency rate of change proportionality coefficient; the IR is a system inertia ratio, and when the type of the power grid is a direct current transmission end power grid, the IR is SIR; when the type of the power grid is a direct current receiving end power grid, IR is RIR;
when the evaluation index is the transient highest frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure FDA0002820687240000051
wherein ,ΔfmIs the transient highest frequency value; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid;the SIR is a system inertia ratio corresponding to a direct current transmission end power grid;
when the evaluation index is the lowest transient frequency, calculating the evaluation index value by using the following formula, wherein the calculation comprises the following steps:
Figure FDA0002820687240000052
wherein ,ΔfmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is the unit equivalent inertia constant of the direct current receiving end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
12. The system according to claim 9, wherein the frequency support capability determination unit determines the frequency support capability of the grid based on the evaluation index value and an evaluation index threshold corresponding to the evaluation index, and includes:
if the evaluation index value is less than or equal to the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid meets the requirement, and if the evaluation index value is smaller, indicating that the frequency support capability of the power grid is stronger;
and if the evaluation index value is larger than the evaluation index threshold value corresponding to the evaluation index, determining that the frequency support capability of the power grid does not meet the requirement.
13. A system for determining a frequency supporting capability of a power grid based on an inertia ratio, the system comprising:
the system inertia ratio determining unit is used for determining the system inertia ratio of the power grid;
the system inertia ratio threshold value determining unit is used for calculating a system inertia ratio threshold value of the power grid according to the type of the power grid;
and the frequency supporting capacity determining unit is used for determining the frequency supporting capacity of the power grid according to the system inertia ratio and a system inertia ratio threshold value.
14. The system of claim 13, wherein the system inertia ratio threshold determination unit calculates the system inertia ratio threshold of the power grid according to the type of the power grid, comprising:
when the type of the power grid is a direct current transmission end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure FDA0002820687240000061
wherein ,SIRminA system inertia ratio threshold value corresponding to a direct current sending end power grid; the STRD is a transient frequency change rate limit value of a direct current transmission end power grid; k is a radical ofsfThe frequency change rate proportionality coefficient is corresponding to a direct current transmission end power grid; STMD is the frequency deviation limit value of the direct current transmitting end power grid; t is tcThe safety control action time; sGZGenerating capacity for a direct current sending end power grid;
when the type of the power grid is a direct current receiving end power grid, calculating the system inertia ratio threshold value by using the following formula, wherein the formula comprises the following steps:
Figure FDA0002820687240000062
wherein ,RIRminA system inertia ratio threshold value corresponding to the direct current receiving end power grid; RTRD is transient frequency change rate limit value of the direct current receiving end power grid; k is a radical ofrfThe frequency change rate proportionality coefficient is corresponding to a direct current receiving end power grid; Δ fmIs the transient lowest frequency value; kLThe load frequency modulation factor is the load frequency modulation factor of the direct current receiving end power grid; kGThe frequency modulation factor is a unit frequency modulation factor of a direct current receiving end power grid; kmThe coefficient is the mechanical power gain coefficient of the direct current receiving end power grid; t isRThe reheating time constant is the reheating time constant of the direct current receiving end power grid; h is direct currentThe unit equivalent inertia constant of the receiving-end power grid; fHThe high-pressure turbine is a direct-current receiving end power grid; and RIR is the system inertia ratio corresponding to the direct current receiving end power grid.
15. The system of claim 13, wherein the frequency support capability determination unit determines the frequency support capability of the power grid based on the system inertia ratio and a system inertia ratio threshold, comprising:
if the system inertia ratio is larger than or equal to the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid meets the requirement, and if the system inertia ratio is larger, indicating that the frequency supporting capacity of the power grid is stronger;
and if the system inertia ratio is smaller than the system inertia ratio threshold value, determining that the frequency supporting capacity of the power grid does not meet the requirement.
16. The system according to claim 9 or 13, wherein the system inertia ratio determination unit determines a system inertia ratio of the power grid, including:
Figure FDA0002820687240000071
wherein, IR is the system inertia ratio; j represents the system moment of inertia; Δ P represents the disturbance power; riIs the unit running state of the unit i, and R when the unit is put into operationiWhen the unit is out of service R1i＝0；SniThe rated capacity of the unit i is set; t isjiThe unit inertia time constant of the unit i is obtained; omega0The electric angular velocity before the unit fault occurs.
CN202011431163.7A 2020-12-07 2020-12-07 Method and system for determining frequency supporting capacity of power grid based on inertia ratio Active CN112653130B (en)

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CN113471972A (en) * 2021-09-03 2021-10-01 中国电力科学研究院有限公司 Method and system for monitoring inertia of power system
CN115630875A (en) * 2022-12-05 2023-01-20 中国电力科学研究院有限公司 Rotational inertia evaluation method and system of synchronous power grid

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CN111276973A (en) * 2020-03-09 2020-06-12 国网江苏省电力有限公司 Method for evaluating inertia requirement of power system considering wind power fluctuation
CN111725847A (en) * 2020-06-29 2020-09-29 南通大学 Frequency control method considering double-fed fan kinetic energy throughput capacity

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CN111276973A (en) * 2020-03-09 2020-06-12 国网江苏省电力有限公司 Method for evaluating inertia requirement of power system considering wind power fluctuation
CN111725847A (en) * 2020-06-29 2020-09-29 南通大学 Frequency control method considering double-fed fan kinetic energy throughput capacity

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Publication number Priority date Publication date Assignee Title
CN113471972A (en) * 2021-09-03 2021-10-01 中国电力科学研究院有限公司 Method and system for monitoring inertia of power system
CN115630875A (en) * 2022-12-05 2023-01-20 中国电力科学研究院有限公司 Rotational inertia evaluation method and system of synchronous power grid
CN115630875B (en) * 2022-12-05 2023-03-07 中国电力科学研究院有限公司 Rotational inertia evaluation method and system of synchronous power grid

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