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CN109921439B - On-line tuning method and device for low-frequency load shedding of power system based on frequency trajectory - Google Patents

On-line tuning method and device for low-frequency load shedding of power system based on frequency trajectory Download PDF

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CN109921439B
CN109921439B CN201910315866.4A CN201910315866A CN109921439B CN 109921439 B CN109921439 B CN 109921439B CN 201910315866 A CN201910315866 A CN 201910315866A CN 109921439 B CN109921439 B CN 109921439B
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power shortage
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CN109921439A (en
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刘克天
郝思鹏
李军
蒋春容
王书征
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Nanjing Institute of Technology
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    • Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

本发明提供了基于频率轨迹的电力系统低频减载在线整定方法及装置，通过实时测量安装母线的就地频率，计算就地频率偏移值及计算频率变化率；计算母线就地频率轨迹偏移面积，建立频率轨迹偏移面积与系统功率缺额之间的关系式，计算系统功率缺额；根据系统功率缺额占系统总容量的比例大小，确定不同的低频减载方案；选定与方案相应的负荷，执行低频减载方案；设定功率缺额计算程序的启动机制，根据频率变化率值决定低频减载功率缺额计算算法的启动。本发明利用就地频率轨迹偏移面积计算系统功率缺额，计算结果更准确；基于系统功率缺额计算结果，在线制定适用不同大小系统功率缺额的低频减载整定方案，低频减载方案更具有针对性。

Figure 201910315866

The invention provides an on-line tuning method and device for low-frequency load shedding of a power system based on a frequency trajectory. By measuring the on-site frequency of the installed bus in real time, the on-site frequency offset value and the frequency change rate are calculated; area, establish the relationship between the frequency trajectory offset area and the system power shortage, and calculate the system power shortage; according to the ratio of the system power shortage to the total system capacity, determine different low-frequency load shedding schemes; select the load corresponding to the scheme , implement the low-frequency load shedding plan; set the starting mechanism of the power shortage calculation program, and determine the start of the low-frequency load shedding power shortage calculation algorithm according to the frequency change rate value. The present invention uses the local frequency track offset area to calculate the system power shortage, and the calculation result is more accurate; based on the calculation result of the system power shortage, the low-frequency load shedding setting scheme suitable for the power shortage of the system of different sizes is formulated online, and the low-frequency load shedding scheme is more targeted. .

Figure 201910315866

Description

Power system low-frequency load shedding online setting method and device based on frequency track
Technical Field
The invention belongs to the technical field of power systems, and particularly relates to a low-frequency load shedding online setting method and device of a power system based on a frequency track.
Background
The frequency is an important index of the stable operation and the power quality of the power system. The frequency of the power system is mainly determined by the balance condition between the active power output and the load of the power system. Frequency stabilization, power angle stabilization and voltage stabilization are defined as three major stabilities of the current power system. The power system mostly adopts the long-distance and large-capacity alternating current and direct current transmission technology, and once a large-capacity transmission channel exits from operation, the problem of frequency stability is caused in a receiving end system. If effective control measures are not taken, system frequency collapse can be caused, and a large-area power failure event occurs in a power system.
Currently, the frequency stability control mode of the power system mainly includes automatic load shedding and low-frequency load shedding. Depending on the mechanism of action and the control principle, auto load shedding is an open-loop control measure driven by events, while low-frequency load shedding is a closed-loop control measure driven by frequency variations. The automatic load shedding and the low-frequency load shedding belong to the second and third defense lines of the safety and stability control of the power system respectively, and the automatic load shedding is mainly used for the power angle stability control of the power system in most occasions. The low-frequency load shedding as the last line of defense is an indispensable control measure for the frequency stability control of the power system. Whether the low-frequency load shedding scheme is reasonable or not is set, and the stability of the frequency of the power system is directly related.
The main content of the low-frequency load shedding setting is the setting of the total load and the number of turns of the basic wheel cutting. The low-frequency load shedding setting method mainly comprises a traditional method, a semi-adaptive method and an adaptive method. The existing low-frequency load shedding setting method mainly has two defects: firstly, no matter the traditional method, the semi-adaptive method and the adaptive method are adopted, the power shortage of the current system cannot be accurately calculated, and the low-frequency load shedding load is inaccurate; secondly, once the load shedding round and the load shedding amount are set, the actual power shortage event of the system cannot be changed, for the event with large power shortage, the low-frequency load shedding action is slow, the system frequency recovery is slow, for the practice with small power shortage, the first round load shedding amount is large, and the rotation standby of the system cannot be fully utilized.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a low-frequency deloading online setting method for a power system based on a frequency track, which uses local frequency track data of a disturbed low-frequency deloading installation bus to calculate the frequency track offset area, calculates the power shortage of the system online and carries out low-frequency deloading setting and comprises the following steps:
s1 measures frequency trajectory: measuring the local frequency of the installed bus in real time, calculating a local frequency deviation value and a frequency change rate, and setting a frequency change rate threshold;
s2 calculates the power deficit: setting a starting mechanism of a power shortage calculation program, and determining the starting of a low-frequency load shedding power shortage calculation algorithm according to a frequency change rate value; when the absolute value of the frequency change rate obtained in the step S1 exceeds the absolute value of the set threshold, starting to calculate the local frequency trajectory offset area of the bus, establishing a relational expression between the local frequency trajectory offset area and the system power shortage, and calculating the system power shortage;
s3, determining a low-frequency load shedding setting scheme: determining a corresponding low-frequency load shedding scheme according to the proportion of the system power shortage to the total system capacity calculated in the step S2;
s4 performs low frequency deloading: and determining the starting of low-frequency load shedding according to the local frequency deviation value, selecting the load corresponding to the setting scheme, and executing the low-frequency load shedding scheme.
In order to optimize the technical scheme, the specific measures adopted further comprise:
in a step S2, it is included,
1) the precondition for the system power shortage calculation is as follows:
after the system has an active power disturbance event, the frequency of each bus in the system fluctuates up and down around the system inertia center frequency, and the areas enclosed by each bus frequency curve and the inertia center frequency curve in the system, the time axis and the real-time frequency axis are approximately equal, as shown in the following formula (1):
Figure BDA0002031730450000021
in the formula: Δ ωCOIFor the system inertial center frequency offset, Δ ωiFor each bus frequency offset value, SCOIIs the area of the orbit of the system inertia center frequency, namely the system inertia center frequency curve and the time axis and the real-time frequency axis are at t1The area enclosed by the time; siFor each bus frequency trace offset area, i.e. each bus frequency offset curve is at t1The area enclosed by the time; t is t1The time is the time corresponding to the low-frequency load shedding first-wheel action frequency;
determining the frequency track offset area of the inertia center of the system by calculating the frequency track offset area of each bus of the system; establishing a relation between the system inertia center frequency track offset area and the system power shortage, and calculating the power shortage of the system on line;
2) the calculation algorithm of the power shortage of the power system is as follows:
after the active power shortage event occurs in the system, the generator rotor motion equation (2) is as follows:
Figure BDA0002031730450000022
in the formula: deltaiIs the power angle of the generator i; omegaiIs the frequency of generator i; t is t*Is t isB＝1/ωBAs a reference time per unit value, ωBRated frequency for the generator;
Figure BDA0002031730450000023
is t isBThe inertia constant of the generator i as a reference; t ismi、TeiMechanical torque and electromagnetic torque on the generator rotor; d is the mechanical damping coefficient of the generator rotor;
neglecting the influence of the mechanical damping of the generator, taking the time reference value as 1s, and converting the expression (2) into the expression (3):
Figure BDA0002031730450000031
in the formula: mi、Pmi、PeGiThe inertia time constant of the generator i, the mechanical power and the electromagnetic power on the rotor are respectively;
the system inertial center frequency is defined as equation (4):
Figure BDA0002031730450000032
in the formula: omegaCOIIs the system inertial center frequency; mTIs the total inertia constant of the system(ii) a m is the number of generator nodes;
further, a dynamic expression (5) for the system inertia center frequency is derived as follows:
Figure BDA0002031730450000033
0 second time the system suffers from a size of PdOf sustained active power disturbance, Pd> 0 represents increasing load, Pd< 0 represents a reduction in load; the system load adopts a constant power model, and an offset value expression (6) of the system inertia center frequency after active disturbance occurs is as follows:
Figure BDA0002031730450000034
in the formula: delta PmTThe total of the mechanical power changes of all generators in the system; pdThe continuous active disturbance suffered by the system, namely the active power shortage of the system;
laplace transform the above formula to obtain expression (7):
Figure BDA0002031730450000035
in the formula: s is the laplace operator.
Assuming that the occurrence time after disturbance is 0 second, the initial value delta omega of the offset value of the system inertia center frequencyCOI0Zero, the above formula can be further simplified to expression (8):
Figure BDA0002031730450000036
after disturbance, a single-machine equivalent model is used to describe the relationship between the total mechanical power output of the system and the inertia center frequency of the system, and the power-frequency characteristic of the system is shown as the following formula (9):
Figure BDA0002031730450000041
in the formula: r is the total active-frequency difference adjustment coefficient of the system; t is1、T2、T3The active-frequency regulation characteristic of the system described by the above formula is obtained by simulating the system, and performing single-machine equivalence;
and (8) and (9) simultaneous expression, wherein the calculated system inertia center frequency deviation value after disturbance is as the expression (10):
Figure BDA0002031730450000042
the above formula analysis gives an expression of the system inertia center frequency deviation value after the power shortage event occurs; the characteristic root of the system inertia center frequency deviation value expression consists of a zero root and three non-zero roots, and the time domain expression (11) of the system inertia center frequency deviation value after disturbance is as follows:
Figure BDA0002031730450000043
in the formula: r is1、r2、r3Three non-zero characteristic roots of formula (10); c. C1、c2、c3、c4The coefficients of the time domain expression corresponding to the three nonzero characteristic roots and the zero root are obtained;
the moment of active disturbance is 0 second, and the moment when the bus frequency reaches the low-frequency load shedding first-wheel action frequency is t1Integrating equation (11) to obtain equation (12):
Figure BDA0002031730450000044
in the formula: s is the bus line local frequency trajectory offset area, Δ ω (t) represents the bus line local frequency offset value at time t, and the parameter r1、r2、r3、c1、c2、c3、c4C-channelAfter the system is analyzed and obtained through calculation,
Figure BDA0002031730450000045
from equation (12), the relationship (13) between the frequency trajectory offset area and the system power deficit is as follows:
Figure BDA0002031730450000046
the power deficit of the system is quickly calculated using equation (13).
The starting mechanism of the power shortage calculation routine in step S2 is as follows:
the starting power shortage calculation of each low-frequency load shedding device needs to meet the following starting condition, as shown in formula (14):
Figure BDA0002031730450000051
in the formula: alpha is the initial frequency reduction rate caused by the minimum power shortage event which can be borne by the system when no low-frequency load reduction and other load shedding control measures exist, and is the set threshold;
Figure BDA0002031730450000052
the local frequency change rate of each bus is obtained;
the maximum allowable frequency reduction coefficient α is calculated by equation (15):
Figure BDA0002031730450000053
in the formula: pdmThe maximum allowable power shortage which can be borne by the system when no frequency stability control measures are taken; t is 0+Representing the moment after the active disturbance occurs;
obtaining maximum allowable power shortage P by performing single machine equivalence or simulation on the systemdmAnd should be such that the lowest value of the system frequency, Δ ωmWith steady-state value Δ ω∞Two conditions of the following formula (16) are satisfied simultaneously:
Δωm≥βm
Δω∞≥β∞
in the formula: beta is am、β∞The lowest frequency and steady-state frequency offset value that the system can bear without frequency stability control measures.
In step S3, the low frequency shedding scheme includes,
the low-frequency load shedding basic wheel is set to adopt 5 turns, the action frequency difference value among the turns is 0.25Hz, the load shedding proportion of each basic wheel does not adopt a fixed value, but adopts different load shedding schemes according to the proportion of the system power shortage to the total capacity of the system:
when the proportion of the system power shortage in the total system capacity is not less than 25%, the first round load shedding proportion is 50%, and the other round load shedding proportions are 12.5%;
when the proportion of the system power shortage in the total system capacity is 15-25%, the first turn load shedding proportion is 40%, and the other turn load shedding proportions are 15%;
when the proportion of the system power shortage in the total system capacity is less than 15%, the first-round load shedding proportion is 30%, and the other-round load shedding proportions are 17.5%.
In step S4, it is determined whether the low frequency load shedding load is activated or not based on the local frequency offset value:
setting a low-frequency deloading first wheel action frequency deviation value and a low-frequency deloading first wheel action frequency track deviation area value; when the calculated local frequency deviation value is lower than the low-frequency deloading first-wheel action frequency deviation value, or the calculated bus local frequency trajectory deviation area is smaller than the low-frequency deloading first-wheel action frequency trajectory deviation area, starting first-wheel load shedding by low-frequency deloading;
that is, the low-frequency load shedding first-wheel load shedding starting condition is shown by the following formula (17):
Δωi≤Δω1
or
Si≤Ss
Wherein, Δ ω1A low-frequency deloading first-wheel action frequency deviation value; ssThe local frequency track deviation area value corresponding to the low-frequency load shedding first-wheel action; Δ ωiAn in-situ frequency offset value for low frequency load shedding measurements; siThe area values are shifted for the local frequency trajectory.
The invention also provides a low-frequency load shedding online setting device of the power system based on the frequency track, which is characterized by comprising a frequency track measuring module, a power shortage calculating module, a low-frequency load shedding setting module and a low-frequency load shedding executing module,
a frequency trajectory measurement module: the system is used for measuring the local frequency of the installed bus in real time, calculating a local frequency deviation value and calculating a frequency change rate;
a power deficit calculation module: determining the starting of a low-frequency load shedding power deficit calculation algorithm according to the frequency change rate value, and calculating the local frequency locus offset area of the bus when the absolute value of the frequency change rate obtained by a frequency locus measurement module exceeds the absolute value of a set threshold, establishing the relation between the local frequency locus offset area and the system power deficit, and calculating the system power deficit;
a low-frequency load shedding setting module: determining a corresponding low-frequency load shedding scheme according to the proportion of the system power shortage to the total system capacity calculated by the power shortage calculation module;
low-frequency load shedding execution model: and determining the starting of the low-frequency load shedding according to the local frequency deviation value, selecting the load corresponding to the scheme, and executing the low-frequency load shedding setting scheme.
The invention has the beneficial effects that: the invention provides a system power shortage calculation method based on frequency track offset area and a low-frequency load shedding setting method based on power shortage of different sizes, the system power shortage is calculated by using local frequency track offset area, and the calculation result is more accurate; based on the calculation result of the system power shortage, different low-frequency load shedding setting schemes are made on line, when the system power shortage is small, the system can be fully used for rotation standby, when the system power shortage is large, the system frequency can be quickly recovered, and the low-frequency load shedding schemes are more targeted.
Drawings
FIG. 1 is a flow chart of a method provided by the present invention.
FIG. 2 is a schematic diagram of an online tuning device provided by the present invention.
FIG. 3 is a graph of bus frequency and center frequency of inertia for an IEEE3 machine 9 bus system in accordance with an embodiment of the present invention.
FIG. 4 is a graph illustrating simulation plots of bus frequencies of an IEEE3 machine 9 bus system in accordance with an embodiment of the present invention.
FIG. 5 is a diagram of a simulation result of system inertia center frequency curves of different output low-frequency load shedding setting methods under the condition of 900MW power shortage in the embodiment of the present invention.
FIG. 6 is a diagram of a simulation result of system inertia center frequency curves of different output low-frequency load shedding setting methods under 1500Mw power shortage in the embodiment of the present invention.
FIG. 7 is a diagram of a simulation result of system inertia center frequency curves of different output low-frequency load shedding setting methods under the condition of 2000MW power shortage in the embodiment of the present invention.
Table 1 is one embodiment of the low frequency load shedding scheme provided by the present invention.
Table 2 is a table of the results of the calculation of the system power deficit using the local frequency data of each bus in the embodiment of the present invention.
Table 3 shows the low frequency deloading mounted bus and the corresponding maximum cuttable load meter according to the embodiment of the present invention.
Table 4 is a comparison table of the basic wheel setting schemes of the method, the traditional method and the self-adaptive method.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings.
Referring to fig. 1-4, the invention provides a low-frequency load shedding online setting method for a power system based on a frequency track, which comprises the steps of using local frequency track data of a disturbed low-frequency load shedding installation bus, establishing a relation between a frequency track offset area and system power shortage, calculating the system power shortage online by calculating the frequency track offset area, and performing low-frequency load shedding online setting according to the power shortage with different sizes.
The invention comprises the following steps:
s1 measures frequency trajectory: measuring the local frequency of the installed bus in real time, calculating the local frequency deviation value of the bus and the frequency change rate, and setting a frequency change rate threshold;
s2 calculates the power deficit: setting a starting mechanism of a power shortage calculation program, and determining the starting of a low-frequency load shedding power shortage calculation algorithm according to a frequency change rate value; when the absolute value of the frequency change rate obtained in the step S1 exceeds the absolute value of the set threshold, calculating the bus local frequency trajectory offset area, and calculating the system power shortage;
1) the precondition for the system power shortage calculation is as follows:
the system is provided with a plurality of installation buses, when the system has an active power disturbance event, the frequency of each bus in the system fluctuates up and down around the inertia center frequency of the system, the area enclosed by the frequency curve of each bus in the system, the time axis and the real-time frequency axis is approximately equal to the area enclosed by the inertia center frequency curve, the time axis and the real-time frequency axis, and the area is as follows (1):
Figure BDA0002031730450000071
in the formula: Δ ωCOIFor the system inertial center frequency offset, Δ ωiFor each bus frequency offset value, SCOIIs the area of the orbit of the system inertia center frequency, namely the system inertia center frequency curve and the time axis and the real-time frequency axis are at t1The area enclosed by the time; siFor each bus frequency trace offset area, i.e. each bus frequency trace offset curve is at t1The area enclosed by the time; t is t1The time is the time corresponding to the low-frequency deloading first-wheel action frequency, and the ordinate in the figure 3 is the frequency.
In summary, the frequency locus offset area of the inertia center of the system can be determined by calculating the frequency locus offset area of each bus of the system. By establishing the relation between the system inertia center frequency track offset area and the system power shortage, the power shortage of the system can be calculated on line by calculating the offset area of each bus frequency track.
2) The calculation algorithm of the power shortage of the power system is as follows:
after the active power shortage event occurs in the system, the generator rotor motion equation (2) is as follows:
Figure BDA0002031730450000081
in the formula: deltaiIs the power angle of the generator i; omegaiIs the frequency of generator i; t is t*Is t isB＝1/ωBAs a reference time per unit value, ωBRated frequency for the generator;
Figure BDA0002031730450000085
is t isBThe inertia constant of the generator i as a reference; t ismi、TeiMechanical torque and electromagnetic torque on the generator rotor; d is the mechanical damping coefficient of the generator rotor.
Neglecting the influence of the mechanical damping of the generator, taking the time reference value as 1s, and converting the expression (2) into the expression (3):
Figure BDA0002031730450000082
in the formula: mi、Pmi、PeGiThe inertia time constant of the generator i, the mechanical power and the electromagnetic power on the rotor are respectively;
the system inertial center frequency is defined as equation (4):
Figure BDA0002031730450000083
in the formula: omegaCOIIs the system inertial center frequency; mTIs the system total inertia constant; m is the number of generator nodes;
further, a dynamic expression (5) for the system inertia center frequency is derived as follows:
Figure BDA0002031730450000084
0 second time the system suffers from a size of PdOf sustained active power disturbance, Pd> 0 represents increasing load, Pd< 0 represents a reduction in load; the system load adopts a constant power model, and an offset value expression (6) of the system inertia center frequency after active disturbance occurs is as follows:
Figure BDA0002031730450000091
in the formula: delta PmTThe total of the mechanical power changes of all generators in the system; pdIs the sustained active disturbance to which the system is subjected, i.e. the active power deficit of the system.
Laplace transform the above formula to obtain expression (7):
Figure BDA0002031730450000092
in the formula: s is the laplace operator.
Assuming that the occurrence time after disturbance is 0 second, the initial value delta omega of the offset value of the system inertia center frequencyCOI0Zero, the above formula (7) can be further simplified to expression (8):
Figure BDA0002031730450000093
after disturbance, a single-machine equivalent model is used to describe the relationship between the total mechanical power output of the system and the inertia center frequency of the system, and the power-frequency characteristic of the system is shown as the following formula (9):
Figure BDA0002031730450000094
in the formula: r is the total active-frequency difference adjustment coefficient of the system; t is1、T2、T3For the time constant, the active-frequency regulation characteristic of the system described by the above formula is obtained by simulating the system, and performing single machine equivalence.
And (8) and (9) simultaneous expression, wherein the calculated system inertia center frequency deviation value after disturbance is as the expression (10):
Figure BDA0002031730450000095
the above formula analysis gives an expression of the system inertia center frequency deviation value after the power shortage event occurs; the characteristic root of the system inertia center frequency deviation value expression consists of a zero root and three non-zero roots, and the time domain expression (11) of the system inertia center frequency deviation value after disturbance is as follows:
Figure BDA0002031730450000096
in the formula: r is1、r2、r3Three non-zero characteristic roots of formula (10); c. C1、c2、c3、c4The coefficients of the time domain expression corresponding to the three non-zero characteristic roots and the zero root are obtained.
The moment of active disturbance is 0 second, and the moment when the bus frequency reaches the low-frequency load shedding first-wheel action frequency is t1Integrating equation (11) to obtain equation (12):
Figure BDA0002031730450000101
in the formula: s is the bus bar local frequency trajectory offset area, Δ ω (t) represents the bus bar local frequency offset value at time t,
Figure BDA0002031730450000102
from equation (12), the relationship (13) between the bus bar local frequency trajectory offset area and the system power deficit is as follows:
Figure BDA0002031730450000103
the active-frequency regulation characteristic of the system described by the formula (9) can be obtained by simulating the system, and performing single machine equivalence. The parameter r in the formula (13)1、r2、r3、c1、c2、c3、c4C can be obtained in advance by analyzing and calculating the system. The low frequency load shedding device can quickly calculate the power shortage of the system by using the formula (13) by only measuring the local frequency and the frequency track offset area S.
3) The starting mechanism of the system power shortage calculation program is as follows:
in the invention, the power shortage of the system is calculated by calculating the offset area of the low-frequency deloading local frequency track, and in order to prevent the low-frequency deloading device from initiating action when the system frequency runs for a long time at a frequency slightly lower than the rated frequency (such as 59.9Hz), a set of mechanism is required to be designed to start the power shortage calculation program in the low-frequency deloading device.
A plurality of low-frequency load shedding devices are arranged in the system, and the starting power shortage calculation program of each low-frequency load shedding device needs to meet the following starting conditions, as shown in a formula (14):
Figure BDA0002031730450000104
in the formula: alpha is the initial frequency reduction rate caused by the minimum power shortage event which can be borne by the system when no low-frequency load reduction and other load shedding control measures exist, and is the set threshold; Δ ωiLocal frequency offset values for each low frequency load shedding bus;
Figure BDA0002031730450000105
the local frequency change rate of each bus is obtained;
the maximum allowable frequency reduction coefficient α is calculated by equation (15):
Figure BDA0002031730450000106
in the formula: pdmThe maximum allowable power shortage which can be borne by the system when no frequency stability control measures are taken; t is 0+Representing the moment after the active disturbance occurs;
obtaining maximum allowable power shortage P by performing single machine equivalence or simulation on the systemdmAnd should be such that the lowest value of the system frequency, Δ ωmWith steady-state value Δ ω∞Two conditions of the following formula (16) are satisfied simultaneously:
Δωm≥βm
Δω∞≥β∞
in the formula: beta is am、β∞The lowest frequency and steady-state frequency offset value that the system can bear without frequency stability control measures.
S3, determining a low-frequency load shedding setting scheme: determining a corresponding low-frequency load shedding scheme according to the proportion of the system power shortage to the total system capacity calculated in the step S2;
s4 performs low frequency deloading: and determining the starting of the low-frequency load shedding load according to the local frequency deviation value, selecting the load corresponding to the low-frequency load shedding setting scheme, and executing the low-frequency load shedding scheme.
The low-frequency load shedding setting scheme based on different power deficit is designed as follows:
in the existing low-frequency load shedding setting scheme, the first-wheel action frequency and the load shedding proportion of each round are not changed once being set, and the same setting scheme is adopted for power shortage events with different sizes. In the invention, the first-wheel action frequency and the load shedding proportion of each low-frequency load shedding wheel are determined by the magnitude of the power shortage. For a large power shortage event, each low-frequency load shedding round should act as early as possible and cut off a large load, and the system frequency is restored as soon as possible; for smaller power shortage, each low-frequency load shedding action is not suitable to be too early, the load cutting amount is not suitable to be too large, and the rotation of the system is fully utilized for standby on the basis of ensuring the frequency stability of the system.
In the invention, the low-frequency load shedding first-wheel action moment is determined by the low-frequency load shedding local frequency and the frequency offset curve area. As long as the low-frequency deloading local frequency deviation value is lower than the set initial wheel action frequency deviation value or the bus local frequency trajectory deviation area (negative value) calculated by the low-frequency deloading device is smaller than the low-frequency deloading initial wheel action frequency trajectory deviation area, the low-frequency deloading starts initial wheel load shedding (generally, when the low-frequency deloading local frequency deviation value is lower than the set initial wheel action frequency deviation value or the bus local frequency trajectory deviation area (negative value) calculated by the low-frequency deloading device is smaller than the low-frequency deloading initial wheel action frequency trajectory deviation area for a period of time, the initial wheel load shedding action is started again, the period of time is generally 0-0.1s), and the low-frequency deloading initial wheel action:
Δωi≤Δω1
or
Si≤Ss
Wherein, Δ ω1A low-frequency deloading first-wheel action frequency deviation value; ssThe local frequency track deviation area value corresponding to the low-frequency load shedding first-wheel action; Δ ωiA bus in-place frequency offset value for low frequency load shedding measurement; siThe area values are shifted for the local frequency trajectory.
The invention proposes that the low-frequency load-shedding basic wheel adopts 5 turns, and the action frequency difference value between every two turns is 0.25 Hz. The load shedding proportion of each basic wheel is not fixed any more, but different load shedding schemes are adopted according to the proportion of the power shortage of the calculated system to the total capacity, and system personnel can design corresponding number of turns, action frequency difference of each turn and power shortage of different sizes by themselves when applying the invention. An example of the scheme adopted by the low frequency load shedding device of the present invention is shown in table 1:
when the proportion of the system power shortage in the total system capacity is not less than 25%, the first round load shedding proportion is 50%, and the other round load shedding proportions are 12.5%;
when the proportion of the system power shortage in the total system capacity is 15-25%, the first turn load shedding proportion is 40%, and the other turn load shedding proportions are 15%;
when the proportion of the system power shortage in the total system capacity is less than 15%, the first-round load shedding proportion is 30%, and the other-round load shedding proportions are 17.5%.
Table 1 low frequency load shedding scheme of the invention
Figure BDA0002031730450000121
Wherein P isdFor a calculated power deficit, PTIs the total system capacity.
The invention also provides a low-frequency load shedding online setting device of the power system based on the frequency track, which comprises a frequency track measuring module, a power shortage calculating module, a low-frequency load shedding setting module and a low-frequency load shedding executing module, wherein the functions of the modules are as follows:
a frequency trajectory measurement module: the low-frequency load shedding device is used for measuring the local frequency of the installed bus in real time, calculating a local frequency deviation value and calculating the frequency change rate;
a power deficit calculation module: the method comprises the following steps of determining the starting of a low-frequency load shedding power deficit calculation algorithm according to a frequency change rate value, wherein a power deficit calculation module is used for calculating the local frequency locus offset area of a bus when the absolute value of the frequency change rate obtained by a frequency locus measurement module exceeds the absolute value of a set threshold, establishing the relation between the local frequency locus offset area of the bus and the system power deficit, and calculating the system power deficit;
a low-frequency load shedding setting module: determining a corresponding low-frequency load shedding scheme according to the proportion of the system power shortage to the total system capacity calculated by the power shortage calculation module;
low-frequency load shedding execution model: and determining the starting of the low-frequency load shedding according to the local frequency deviation value, selecting the load corresponding to the scheme, and executing the low-frequency load shedding setting scheme.
The preferred embodiment provided by the present invention is as follows:
hair brushThe IEEE10 machine 39 bus system is taken as a test system, and the system power shortage algorithm and the low-frequency load shedding setting method are verified. In the original data, the total installed capacity of the bus system of the IEEE10 machine 39 is 7961.2MW, and the total active load is 6150.1 MW. To construct a large power shortage event, an infinite capacity generator is added at the bus 4. In the system, each generator is provided with a TGOV1 type speed regulator, the difference regulating coefficient of each generator speed regulator is 5% according to the respective volume, and the time constant T of the speed regulator1、T2、T3Take 0.5s, 1.5s, 5.0s, respectively.
1) System power deficit calculation
And (3) simulation process: the generator at bus 4 injects active power 1500MW into the system. At 0s, the generator at bus 4 is out of operation, thus resulting in an active power shortage of 1500MW for the system. All bus frequencies are output in a simulation mode, and each bus frequency curve of the system is output in a simulation mode, and the frequency curve is shown in figure 4.
Taking the bus frequency reaching 59Hz as an example, the local frequency data of each bus is used to calculate the system power shortage, and the calculation results are shown in table 2.
TABLE 2 System Power deficit calculation results (59Hz)
Figure BDA0002031730450000131
And (4) analyzing a calculation result: as can be seen from Table 2, the power shortage of the system can be calculated better by measuring the frequency track deviation area of each bus, wherein the minimum error is the calculation result of the No. 12 bus, the error is-12.4 MW, and the error percentage is 0.83%; the maximum error is the calculation result of the No. 36 bus, the error is-76.61 MW, and the error percentage is 5.1%; the average error for all bus calculations was-33.25 MW with an average error percentage of 2.2%.
2) Low frequency load shedding scheme implementation
The low-frequency load shedding model is established by using the commercial simulation software custom function of the power system, and the effectiveness of the low-frequency load shedding scheme is verified. The low-frequency load shedding scheme adopts the scheme in table 1, and according to the size of the bus load, the installation place and the maximum load shedding amount of the low-frequency load shedding device are shown in table 3:
TABLE 3 Low frequency relief mounting bus and cuttable load
Figure BDA0002031730450000141
The effectiveness of low-frequency load shedding in the invention is verified when different power is in shortage, and the system power shortage P is simulated respectively by changing the active power injected by the generator at the bus 4d≥25％、25％≥Pd≥15％、15％≥PdThe corresponding power deficit is 2000MW, 1500MW, 900MW, respectively. And (3) comparing the effects of the low-frequency load shedding online setting method based on the frequency track, the low-frequency load shedding traditional setting method and the self-adaptive method provided by the invention through simulation. The first-wheel operation frequency was set to 59.2Hz, the step difference was 0.2Hz, and the operation delay was 0.1 s. The traditional method adopts the maximum power shortage event which can occur in the system, namely 39 bus generators are out of operation, and the power shortage is 1500 MW. The adaptive method uses the system inertial center frequency to calculate the power deficit. The basic round setting scheme of the three methods is shown in table 4. The action frequency of the special wheel is 59Hz, the delay time is 10s, and the cutting load amount is 20% of the maximum power deficit.
TABLE 4 Low-frequency load shedding setting scheme
Figure BDA0002031730450000142
Under the condition of three kinds of power shortage, system inertia center frequency curves of different low-frequency load shedding setting methods are respectively output, and simulation results are shown in fig. 5-7.
And (3) simulation result analysis: when the power shortage of the system is 900MW, the power shortage is smaller at the moment, and the three low-frequency load shedding and setting schemes are all operated in one turn, so that the load shedding amount is minimum, and the rotary standby release is facilitated; when the power shortage of the system is 1500MW, the power is larger at the moment, one low-frequency load shedding action is performed, and two actions are performed by a traditional method and a self-adaptive method, so that the first round of the scheme is large in load shedding amount and the system frequency can be recovered more quickly compared with the traditional method and the self-adaptive method; when the power shortage of the system is 2000MW, the power shortage is very serious, the scheme of the invention and the self-adaptive low-frequency load shedding act for 2 rounds, and the traditional method acts for 3 rounds. Compared with the self-adaptive method, the method has the advantages of accurate power shortage calculation and quick system frequency recovery. Compared with the traditional method, the invention has the advantages of large first round load cutting amount and few action rounds, and is more beneficial to the quick recovery of the system frequency.
According to simulation results, the system power shortage calculation method based on the frequency track offset area and the low-frequency load shedding setting method based on the power shortage with different sizes, which are provided by the invention, make up two defects of the current low-frequency load shedding method: firstly, an online accurate calculation method of system power shortage is provided; secondly, according to the calculation result of the power shortage, different low-frequency load shedding schemes can be set on line aiming at the power shortage with different sizes, so that the low-frequency load shedding schemes are more targeted.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.

Claims (5)

1.基于频率轨迹的电力系统低频减载在线整定方法，其特征在于，包括以下步骤：1. An on-line tuning method for low-frequency load shedding of a power system based on a frequency trajectory, characterized in that it comprises the following steps: S1测量频率轨迹：实时测量安装母线的就地频率，计算就地频率偏移值及计算频率变化率，设定频率变化率阈值；S1 measurement frequency trajectory: measure the local frequency of the installed bus in real time, calculate the local frequency offset value and calculate the frequency change rate, and set the frequency change rate threshold; S2计算功率缺额：设定功率缺额计算程序的启动机制，根据频率变化率值决定低频减载功率缺额计算算法的启动；当步骤S1中所得到的频率变化率的绝对值超过设定的阈值的绝对值时，则启动计算母线就地频率轨迹偏移面积，建立频率轨迹偏移面积与系统功率缺额之间的关系式，计算系统功率缺额；S2 Calculate power shortage: set the startup mechanism of the power shortage calculation program, and determine the start of the low-frequency load shedding power shortage calculation algorithm according to the frequency change rate value; when the absolute value of the frequency change rate obtained in step S1 exceeds the set threshold value When the absolute value is set, the calculation of the local frequency track offset area of the bus is started, and the relationship between the frequency track offset area and the system power shortage is established to calculate the system power shortage; S3确定低频减载整定方案：根据步骤S2计算的系统功率缺额占系统总容量的比例大小，确定相应的低频减载方案；S3: Determine the low-frequency load shedding setting scheme: determine the corresponding low-frequency load shedding scheme according to the ratio of the system power shortage to the total system capacity calculated in step S2; S4执行低频减载：根据就地频率偏移值决定低频减载的启动，选定与整定方案相应的负荷，执行低频减载方案；S4 Execute low-frequency load shedding: determine the start of low-frequency load shedding according to the local frequency offset value, select the load corresponding to the tuning plan, and execute the low-frequency load shedding plan; 设定低频减载首轮动作频率偏移值与低频减载首轮动作频率轨迹偏移面积值；当计算得到的就地频率偏移值低于低频减载首轮动作频率偏移值，或者所计算的母线就地频率轨迹偏移面积小于低频减载首轮动作频率轨迹偏移面积时，低频减载启动首轮切负荷；Set the frequency offset value of the first-round action of low-frequency load shedding and the track offset area value of the first-round action of low-frequency load shedding; when the calculated local frequency offset value is lower than the first-round action frequency offset value of low-frequency load shedding, or When the calculated busbar local frequency track offset area is smaller than the first-round action frequency track offset area of low-frequency load shedding, the low-frequency load shedding starts the first-round load shedding; 即低频减载首轮切负荷启动条件如下式所示：That is, the starting conditions of the first round of load shedding for low-frequency load shedding are as follows: Δωi≤Δω1 Δω i ≤Δω 1 或or Si≤Ss S i ≤ S s 其中，Δω1为低频减载首轮动作频率偏移值；Ss为低频减载首轮动作所对应的就地频率轨迹偏移面积值；Δωi计算得到的就地频率偏移值；Si为计算的母线就地频率轨迹偏移面积值。Among them, Δω 1 is the frequency offset value of the first-round action of low-frequency load shedding; S s is the local frequency track offset area value corresponding to the first-round action of low-frequency load shedding; the local frequency offset value calculated by Δω i ; S i is the calculated bus local frequency track offset area value. 2.根据权利要求1所述的在线整定方法，其特征在于，步骤S2中包括，2. online tuning method according to claim 1, is characterized in that, in step S2, comprises, 1)系统功率缺额计算的前提条件如下：1) The prerequisites for the calculation of system power shortage are as follows: 系统发生有功功率扰动事件后，系统中各母线的频率围绕着系统惯性中心频率上下波动，系统中各母线频率曲线与时间轴及实时频率轴所围成的面积，与惯性中心频率曲线与时间轴及实时频率轴所围成的面积近似相等，如下式(1)：After the active power disturbance event occurs in the system, the frequency of each busbar in the system fluctuates up and down around the inertial center frequency of the system. and the area enclosed by the real-time frequency axis are approximately equal, as shown in the following formula (1):
Figure FDA0003019896630000011
Figure FDA0003019896630000011
 式中：ΔωCOI为系统惯性中心频率偏移值，Δωi为各母线频率偏移值，SCOI为系统惯性中心频率轨迹面积、Si为各母线频率轨迹偏移面积，t1为时间，指低频减载首轮动作频率所对应的时间；In the formula: Δω COI is the frequency offset value of the system inertia center, Δω i is the frequency offset value of each bus, S COI is the frequency track area of the system inertia center, S i is the frequency track offset area of each bus, t 1 is the time, Refers to the time corresponding to the first-round action frequency of low-frequency load shedding; 通过计算出系统各母线频率轨迹偏移面积，确定系统惯性中心频率轨迹偏移面积；建立系统惯性中心频率轨迹偏移面积与系统功率缺额之间的关系，在线计算系统的功率缺额；By calculating the frequency trajectory offset area of each bus of the system, determine the system inertia center frequency trajectory offset area; establish the relationship between the system inertia center frequency trajectory offset area and the system power deficit, and calculate the system power deficit online; 2)电力系统功率缺额的计算算法如下：2) The calculation algorithm of the power shortage of the power system is as follows: 系统发生有功缺额事件后，发电机转子运动方程(2)为：After the active power deficit event occurs in the system, the generator rotor motion equation (2) is:
Figure FDA0003019896630000021
Figure FDA0003019896630000021
 式中：δi为发电机i的功角；ωi为发电机i的频率；t*是以tB＝1/ωB为基准的时间标幺值，ωB为发电机额定频率；
Figure FDA0003019896630000024
是以tB为基准的发电机i的惯性常量；Tmi、Tei为发电机转子上的机械转矩和电磁转矩；D为发电机转子的机械阻尼系数；In the formula: δ i is the power angle of generator i; ω i is the frequency of generator i; t * is the time per unit value based on t B =1/ω B , and ω B is the rated frequency of the generator;
Figure FDA0003019896630000024
is the inertia constant of generator i based on t B ; T mi and T ei are the mechanical torque and electromagnetic torque on the generator rotor; D is the mechanical damping coefficient of the generator rotor; 忽略发电机机械阻尼的影响，时间基准值取1s，(2)式转变为式(3)：Ignoring the influence of generator mechanical damping, the time reference value is 1s, and equation (2) is transformed into equation (3):
Figure FDA0003019896630000022
Figure FDA0003019896630000022
 式中：Mi、Pmi、PeGi分别为发电机i的惯性时间常数、转子上的机械功率和电磁功率；where Mi , Pmi , and PeGi are the inertia time constant of generator i, the mechanical power and the electromagnetic power on the rotor, respectively; 系统惯性中心频率定义为式(4)：The inertia center frequency of the system is defined as equation (4):
Figure FDA0003019896630000023
Figure FDA0003019896630000023
 式中：ωCOI为系统惯性中心频率；MT为系统总惯性常量；m为发电机节点数量；Where: ω COI is the center frequency of inertia of the system; M T is the total inertia constant of the system; m is the number of generator nodes; 进一步，推导系统惯性中心频率的动态表达式(5)为：Further, the dynamic expression (5) for deriving the inertial center frequency of the system is:
Figure FDA0003019896630000031
Figure FDA0003019896630000031
 0秒时刻系统遭受大小为Pd的持续有功功率扰动，Pd＞0代表增加负荷，Pd＜0代表削减负荷；系统负荷采用恒功率模型，有功扰动发生后系统惯性中心频率的偏移值表达式(6)为：At 0 seconds, the system suffers a continuous active power disturbance of the magnitude of P d . P d > 0 means increasing the load, and P d < 0 means reducing the load; the system load adopts a constant power model, and the offset value of the inertia center frequency of the system after the active disturbance occurs Expression (6) is:
Figure FDA0003019896630000032
Figure FDA0003019896630000032
 式中：ΔPmT为系统所有发电机机械功率变化的总和；Pd为系统所遭受的持续有功扰动，也即系统的有功功率缺额；In the formula: ΔP mT is the sum of the mechanical power changes of all generators in the system; P d is the continuous active power disturbance suffered by the system, that is, the active power deficit of the system; 对上式进行拉普拉斯变换，得表达式(7)：Laplace transform is performed on the above formula, and the expression (7) is obtained:
Figure FDA0003019896630000033
Figure FDA0003019896630000033
 式中：s为拉普拉斯算子；In the formula: s is the Laplace operator; 假设扰动后发生时刻为0秒，系统惯性中心频率偏移值的初始值ΔωCOI0为零，则上式可进一步化简为表达式(8)：Assuming that the time after the disturbance is 0 seconds, and the initial value Δω COI0 of the system inertia center frequency offset value is zero, the above formula can be further simplified to expression (8):
Figure FDA0003019896630000034
Figure FDA0003019896630000034
 扰动后，使用单机等值模型来描述系统总的机械功率出力与系统惯性中心频率之间的关系，则系统功率-频率特性如下式(9)所示：After the disturbance, the single-machine equivalent model is used to describe the relationship between the total mechanical power output of the system and the inertia center frequency of the system, the system power-frequency characteristic is shown in the following formula (9):
Figure FDA0003019896630000035
Figure FDA0003019896630000035
 式中：R为系统总的有功-频率调差系数；T1、T2、T3为时间常数，上式所描述的系统功率-频率调节特性通过对系统进行仿真、单机等值方式获取；In the formula: R is the total active power-frequency adjustment coefficient of the system; T 1 , T 2 , and T 3 are the time constants, and the system power-frequency adjustment characteristics described by the above formula are obtained by simulating the system and obtaining the equivalent value of a single machine; 联立(8)(9)两式，计算扰动后系统惯性中心频率偏移值如式(10)：Combine the two equations (8) and (9), and calculate the frequency offset value of the inertial center of the system after the disturbance as in equation (10):
Figure FDA0003019896630000036
Figure FDA0003019896630000036
 上式解析给出了发生功率缺额事件后系统惯性中心频率偏移值的表达式；系统惯性中心频率偏移值表达式的特征根由一个零根和三个非零根组成，则扰动后系统惯性中心频率偏移值的时域表达式(11)为：The above formula analytically gives the expression of the frequency offset value of the system inertia center after the occurrence of a power shortage event; the characteristic root of the expression of the system inertia center frequency offset value consists of a zero root and three non-zero roots, then the system inertia after disturbance The time domain expression (11) of the center frequency offset value is:
Figure FDA0003019896630000047
Figure FDA0003019896630000047
 式中：r1、r2、r3为式(10)的三个非零特征根；c1、c2、c3、c4为三个非零特征根与零根所对应时域表达式的系数；In the formula: r 1 , r 2 , r 3 are the three non-zero eigenvalues of formula (10); c 1 , c 2 , c 3 , and c 4 are the time domain expressions corresponding to the three non-zero eigenvalues and the zero roots coefficients of the formula; 有功扰动时刻为0秒，母线频率达到低频减载首轮动作频率时刻为t1，对式(11)进行积分，得到式(12)：The time of active power disturbance is 0 seconds, and the moment when the busbar frequency reaches the first-round action frequency of low-frequency load shedding is t 1 . Integrate equation (11) to obtain equation (12):
Figure FDA0003019896630000041
Figure FDA0003019896630000041
 式中：S是母线就地频率轨迹偏移面积，Δω(t)表示在t时刻的母线就地频率偏移值，参数r1、r2、r3、c1、c2、c3、c4、C通过对系统进行分析和计算获取，
Figure FDA0003019896630000042
In the formula: S is the bus on-site frequency track offset area, Δω(t) represents the bus on-site frequency offset value at time t, and the parameters r 1 , r 2 , r 3 , c 1 , c 2 , c 3 , c 4 , C is obtained by analyzing and calculating the system,
Figure FDA0003019896630000042
 由式(12)可得，频率轨迹偏移面积与系统功率缺额之间的关系式(13)如下：From equation (12), the relationship between the frequency track offset area and the system power deficit (13) is as follows:
Figure FDA0003019896630000043
Figure FDA0003019896630000043
 利用式(13)快速计算系统的功率缺额。Use equation (13) to quickly calculate the power deficit of the system. 3.根据权利要求2所述的在线整定方法，其特征在于，步骤S2中功率缺额计算程序的启动机制如下：3. online setting method according to claim 2, is characterized in that, in step S2, the startup mechanism of power shortage calculation program is as follows: 各低频减载装置启动功率缺额计算需满足如下启动条件，如式(14)：The calculation of the starting power shortage of each low-frequency load shedding device must meet the following starting conditions, such as formula (14):
Figure FDA0003019896630000044
Figure FDA0003019896630000044
 式中：α为无低频减载及其它切负荷控制措施时系统所能承受的最小功率缺额事件所引起的初始频率下降率，即为设定的阈值；
Figure FDA0003019896630000045
为各母线就地频率变化率；In the formula: α is the initial frequency drop rate caused by the minimum power shortage event that the system can withstand without low-frequency load shedding and other load shedding control measures, which is the set threshold;
Figure FDA0003019896630000045
is the local frequency change rate of each bus; 最大允许频率下降系数α的计算公式(15)为：The calculation formula (15) of the maximum allowable frequency reduction coefficient α is:
Figure FDA0003019896630000046
Figure FDA0003019896630000046
 式中：Pdm为无频率稳定控制措施时系统所能承受的最大允许功率缺额；t＝0+表示有功扰动发生后的瞬间；In the formula: P dm is the maximum allowable power deficit that the system can withstand without frequency stabilization control measures; t = 0 + represents the instant after the active power disturbance occurs; 通过对系统进行单机等值或者仿真得到最大允许功率缺额Pdm，并且应使系统频率的最低值Δωm与稳态值Δω∞同时满足下式(16)两个条件：The maximum allowable power shortfall P dm is obtained by performing the stand-alone equivalent or simulation of the system, and the minimum value Δω m of the system frequency and the steady-state value Δω ∞ should satisfy the following two conditions at the same time (16): Δωm≥βm Δω m ≥β m Δω∞≥β∞ Δω ∞ ≥β ∞ 式中：βm、β∞为无频率稳定控制措施时，系统所能承受的最低频率和稳态频率偏移值。In the formula: β m , β ∞ are the minimum frequency and steady-state frequency offset that the system can bear when there is no frequency stabilization control measure. 4.根据权利要求1所述的在线整定方法，其特征在于，步骤S3中，低频减载方案包括，4. The online tuning method according to claim 1, wherein in step S3, the low-frequency load shedding scheme comprises: 设置低频减载基本轮采用5轮次，各轮次之间动作频率差值为0.25Hz，各基本轮所切除负荷比例不采取固定值，而是根据系统功率缺额占系统总容量的比例大小，采取不同的切负荷方案：The low-frequency load shedding basic wheel is set to use 5 rounds, and the difference between the operating frequencies between each round is 0.25Hz. The proportion of the load removed by each basic wheel does not take a fixed value, but is based on the proportion of the system power shortage to the total system capacity. Take different load shedding scenarios: 当系统功率缺额占系统总容量的比例不小于25％时，首轮切负荷比例为50％，其他轮次切负荷比例均为12.5％；When the ratio of the system power shortage to the total system capacity is not less than 25%, the load shedding ratio of the first round is 50%, and the load shedding ratio of other rounds is 12.5%; 当系统功率缺额占系统总容量的比例为15％-25％之间时，首轮切负荷比例为40％，其他轮次切负荷比例均为15％；When the ratio of the system power shortage to the total system capacity is between 15% and 25%, the load shedding ratio of the first round is 40%, and the load shedding ratio of other rounds is 15%; 当系统功率缺额占系统总容量的比例小于15％时，首轮切负荷比例为30％，其他轮次切负荷比例均为17.5％。When the ratio of the system power shortage to the total system capacity is less than 15%, the load shedding ratio of the first round is 30%, and the load shedding ratio of other rounds is 17.5%. 5.根据权利要求1所述的在线整定方法，其特征在于，使用该方法的电力系统低频减载装置包括频率轨迹测量模块、功率缺额计算模块、低频减载整定模块以及低频减载执行模块，5 . The online tuning method according to claim 1 , wherein the low-frequency load shedding device of the power system using the method comprises a frequency trajectory measurement module, a power shortage calculation module, a low-frequency load shedding setting module and a low-frequency load shedding execution module, 6 . 频率轨迹测量模块：用于实时测量安装母线的就地频率，计算就地频率偏移值及计算频率变化率；Frequency track measurement module: used to measure the local frequency of the installed bus in real time, calculate the local frequency offset value and calculate the frequency change rate; 功率缺额计算模块：根据频率变化率值决定低频减载功率缺额计算算法的启动，用于当频率轨迹测量模块得到的频率变化率的绝对值超过设定的阈值的绝对值时，计算母线就地频率轨迹偏移面积，建立频率轨迹偏移面积与系统功率缺额之间的关系，计算系统功率缺额；Power shortage calculation module: determine the start of the low-frequency load shedding power shortage calculation algorithm according to the frequency change rate value. When the absolute value of the frequency change rate obtained by the frequency trace measurement module exceeds the absolute value of the set threshold, the bus is calculated on the spot. Frequency trajectory offset area, establish the relationship between the frequency trajectory offset area and the system power deficit, and calculate the system power deficit; 低频减载整定模块：根据功率缺额计算模块所计算的系统功率缺额占系统总容量的比例大小，确定相应的低频减载方案；Low-frequency load shedding setting module: Determine the corresponding low-frequency load shedding scheme according to the ratio of the system power deficit to the total system capacity calculated by the power deficit calculation module; 低频减载执行模型：根据就地频率偏移值决定低频减载切负荷的启动，选定与方案相应的负荷，执行低频减载整定方案。Low-frequency load shedding execution model: The start of low-frequency load shedding load shedding is determined according to the local frequency offset value, the load corresponding to the scheme is selected, and the low-frequency load shedding tuning scheme is executed.
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