CN107658894B - Load substation voltage instability judgment method and device - Google Patents

Load substation voltage instability judgment method and device Download PDF

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CN107658894B
CN107658894B CN201710806125.7A CN201710806125A CN107658894B CN 107658894 B CN107658894 B CN 107658894B CN 201710806125 A CN201710806125 A CN 201710806125A CN 107658894 B CN107658894 B CN 107658894B
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load
voltage
substation
direct current
bus
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CN107658894A (en
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陈湘
凌卫家
宋云亭
邓晖
华文
楼伯良
孙维真
马世英
张鑫
郑超
唐晓骏
李惠玲
罗红梅
张恺
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • 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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H02J2003/365—Reducing harmonics or oscillations in HVDC
    • 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]
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The invention provides a method and a device for judging voltage instability of a load transformer substation. According to the technical scheme provided by the invention, simulation calculation is not required to be carried out on various fault conditions which may occur to all direct current systems, and the fault and load transformer substation with hidden danger in voltage stability is obtained based on the power transfer voltage drop coefficient and the occupation ratio of different loads in the load transformer substation, so that the checking and simulation are carried out in a targeted manner, guidance is provided for safe and stable operation of a power grid, and the workload of safe and stable checking of an alternating current-direct current hybrid power grid is reduced.

Description

Load substation voltage instability judgment method and device
Technical Field
The invention relates to the technical field of safety and stability of power systems, in particular to a method and a device for judging voltage instability of a load transformer substation.
Background
The area of China is wide, the energy distribution and the load demand are asymmetric, the southwest area has abundant hydraulic resources, the northwest area has sufficient resources such as coal, wind energy, solar energy and the like, the load demand is mainly distributed in economically developed areas in the east coast, and long-distance and large-capacity power transmission is necessary due to the distribution characteristics of the energy and the load.
The extra-high voltage direct current is a main mode for carrying out long-distance and large-capacity power transmission, but when a locking fault occurs in a direct current system, a receiving-end power grid has power shortage, tide is transferred to each load point in a large scale, and if the voltage stability of the load point is poor, a voltage instability accident can be caused, so that voltage stability analysis is required. At present, when the safety and stability of the operation of a power grid are analyzed, for the influence of direct-current power transfer in an alternating-current and direct-current hybrid system on the operation of a receiving-end system, simulation calculation needs to be performed on various fault conditions which may occur to all direct-current systems, faults which may cause the instability of the power grid are found out according to calculation results, and countermeasures are made.
Practical operation experience of a power grid shows that the static voltage stability level is high, the main grid voltage distribution is reasonable, the basis and the premise of system voltage stability are provided, and the improvement of the dynamic reactive power reserve of the system is a basic measure for improving the voltage stability level. The power grid with higher static voltage level has stronger resistance to major accident disturbance, so that the power transmission capability of the power transmission line can be improved by improving the static voltage stability level of the receiving end system.
The current mature voltage stability analysis method is a static voltage stability analysis method which mainly evaluates the voltage stability level of a system through various voltage stability safety indexes of a computing system and identifies a weak load bus and a relatively weak area which are sensitive to voltage stability through a modal analysis method or other sensitivity analysis methods. The following describes the static voltage stability analysis method in detail:
the static voltage stability analysis method generally performs comprehensive evaluation on the voltage stability of the system by calculating various voltage stability safety indexes, and can determine the relative weak link of the system.
The nature of voltage collapse is that as power is continually transferred into a bounded region, the envelope of the regional voltage waveform becomes lower until the voltage collapses at a critical point. The PV curve analysis method reproduces the voltage change situation in the system during slow load increase or section flow change, and the nonlinear limiting factors during the transition process can also be approximately simulated. By combining the PV curve analysis under the normal operation mode and the operation mode after the accident, the method can help to determine reasonable measures for inhibiting voltage instability and understand the development process of voltage collapse.
The load model in the PV curve analysis method may be expressed in the form of a static load model, i.e., a combination of constant power, constant current, and constant impedance, wherein the constant power method most easily causes voltage collapse, and the constant power type load approximately takes into account the voltage regulation characteristics of the power distribution network, and thus the constant power load model is recommended in the PV curve analysis method. If a more detailed load model is further considered, the transformer on the low voltage load side needs to be modeled.
The P-V diagram of the ac busbar is shown in fig. 1 and can be generated by two methods, one of which is by increasing the load and the external power of the area under study; the other is by increasing the current through a given profile.
Although the static voltage stability analysis method can predict potential voltage collapse accidents affecting voltage stability and safety in a complex system, the method can only reflect the voltage instability phenomenon caused by slow increase of load, cannot determine a specific fault form which can cause the voltage instability, and cannot make a targeted countermeasure. And the static voltage stability analysis method can only judge the voltage stability margin of each alternating current bus in a normal mode, and can not distinguish the voltage stability margin change conditions of different alternating current buses in different fault modes.
Disclosure of Invention
In order to overcome the defects that a static voltage stability analysis method in the prior art cannot determine a specific fault form which may cause voltage instability and cannot distinguish the voltage stability margin change conditions of different alternating current buses under different fault forms, the invention provides a method and a device for judging the voltage instability of a load substation.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
the invention provides a method for judging voltage instability of a load transformer substation, which comprises the following steps:
calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
judging the voltage stability of the load transformer substation according to a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
and judging whether voltage stability verification needs to be carried out on the load transformer substation according to the voltage stability of the load transformer substation, if so, simulating by using power system simulation software to obtain a simulation result, and judging whether voltage instability occurs in the load transformer substation according to the simulation result.
The power transfer voltage drop coefficient between the converter bus of the direct current system and the high-voltage side bus of the load substation is calculated according to the following formula:
Figure BDA0001402743050000031
wherein alpha isijIs a power transfer voltage drop coefficient, U, between a converter bus i of a direct current system and a high-voltage side bus j of a load substationj0The voltage of a high-voltage side bus j of a load substation under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000032
is composed of
Figure BDA0001402743050000033
The real part of (a) is,
Figure BDA0001402743050000034
is the equivalent impedance of a converter bus i of a direct current system to a high-voltage side bus j of a load substation,
Figure BDA0001402743050000035
calculated as follows:
Figure BDA0001402743050000036
wherein, Ui0Is the voltage, U, of a current conversion bus i of a direct current system in the normal running state of a receiving-end power gridi1Current conversion bus of direct current system after power transmission change for direct current systemi voltage, Uj1Voltage, I, of a high-voltage side bus j of a load substation after a change in the power delivered to the DC systemi0Injecting current of alternating current power grid into current conversion bus I of direct current system under normal operation state of receiving end power gridi1Injecting current I of alternating current network into current converting bus I of direct current system after power transmission of direct current system is changedi0Calculated as follows:
Figure BDA0001402743050000037
wherein, Pi0、Qi0Respectively the active power and the reactive power absorbed by a converter bus i of the direct current system under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000039
is Ui0The conjugate complex number of (a);
Ii1calculated as follows:
Figure BDA0001402743050000038
wherein, Pi1、Qi1Respectively transmitting active power and reactive power absorbed by a current conversion bus i of the direct current system after the power of the direct current system is changed,
Figure BDA00014027430500000310
is Ui1The complex conjugate of (a).
The judging the voltage stability of the load transformer substation according to the power transfer voltage drop coefficient between the converter bus of the direct current system and the high-voltage side bus of the load transformer substation comprises the following steps:
when alpha isij<When the voltage is 0.1 hour, the voltage stability of the load transformer substation is good;
when 0.1<αij<When 0.2 hour, the voltage stability of the load transformer substation is general;
when 0.2<αijIn time, the voltage stability of the load substation is poor.
The step of judging whether the voltage stability check of the load transformer substation is needed or not according to the voltage stability of the load transformer substation comprises the following steps:
for a load substation with good voltage stability, if the motor load in the load components of the load substation is 70%, voltage stability verification needs to be performed on the load substation;
for a load substation with general voltage stability, if the motor load proportion in the load components of the load substation reaches 40%, voltage stability verification needs to be performed on the load substation;
and for the load transformer substation with poor voltage stability, directly carrying out voltage stability verification on the load transformer substation.
The step of judging whether the voltage instability of the load transformer substation occurs according to the simulation result comprises the following steps:
in the transient process after the direct current system has a blocking fault, if the voltage of the high-voltage side bus j of the load substation cannot be recovered to 80% or more of the reference voltage within 10 seconds, the voltage of the load substation is unstable.
The invention also provides a device for judging voltage instability of a load transformer substation, which comprises:
the calculation module is used for calculating a power transfer voltage reduction coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
the first judgment module is used for judging the voltage stability of the load transformer substation according to a power transfer voltage reduction coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
and the second judgment module is used for judging whether voltage stability verification needs to be carried out on the load transformer substation according to the voltage stability of the load transformer substation, if so, simulating by using power system simulation software to obtain a simulation result, and judging whether voltage instability occurs in the load transformer substation according to the simulation result.
The calculation module is used for calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load substation according to the following formula:
Figure BDA0001402743050000041
wherein alpha isijIs a power transfer voltage drop coefficient, U, between a converter bus i of a direct current system and a high-voltage side bus j of a load substationj0The voltage of a high-voltage side bus j of a load substation under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000042
is composed of
Figure BDA0001402743050000043
The real part of (a) is,
Figure BDA0001402743050000044
is the equivalent impedance of a converter bus i of a direct current system to a high-voltage side bus j of a load substation,
Figure BDA0001402743050000045
calculated as follows:
Figure BDA0001402743050000046
wherein, Ui0Is the voltage, U, of a current conversion bus i of a direct current system in the normal running state of a receiving-end power gridi1Voltage, U, of a commutation bus i of a direct current system after a change in the power delivered to the direct current systemj1Voltage, I, of a high-voltage side bus j of a load substation after a change in the power delivered to the DC systemi0Injecting current of alternating current power grid into current conversion bus I of direct current system under normal operation state of receiving end power gridi1Injecting current I of alternating current network into current converting bus I of direct current system after power transmission of direct current system is changedi0Calculated as follows:
Figure BDA0001402743050000051
wherein, Pi0、Qi0Respectively as normal for receiving end power gridThe active power and the reactive power absorbed by a converter bus i of the direct current system in the running state,
Figure BDA0001402743050000053
is Ui0The conjugate complex number of (a);
Ii1calculated as follows:
Figure BDA0001402743050000052
wherein, Pi1、Qi1Respectively transmitting active power and reactive power absorbed by a current conversion bus i of the direct current system after the power of the direct current system is changed,
Figure BDA0001402743050000054
is Ui1The complex conjugate of (a).
The first judging module is specifically configured to:
when alpha isij<When the voltage is 0.1 hour, the voltage stability of the load transformer substation is good;
when 0.1<αij<When 0.2 hour, the voltage stability of the load transformer substation is general;
when 0.2<αijIn time, the voltage stability of the load substation is poor.
The second judging module includes a first judging unit, and the first judging unit is specifically configured to:
for a load substation with good voltage stability, if the motor load in the load components of the load substation is 70%, voltage stability verification needs to be performed on the load substation;
for a load substation with general voltage stability, if the motor load proportion in the load components of the load substation reaches 40%, voltage stability verification needs to be performed on the load substation;
and for the load transformer substation with poor voltage stability, directly carrying out voltage stability verification on the load transformer substation.
The second determining module further includes a second determining unit, and the second determining unit is specifically configured to:
in the transient process after the direct current system has a blocking fault, if the voltage of the high-voltage side bus j of the load substation cannot be recovered to 80% or more of the reference voltage within 10 seconds, the voltage of the load substation is unstable.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
the technical scheme provided by the invention preliminarily judges the voltage stability of the load transformer substation based on the power transfer voltage drop coefficient between the converter buses of different direct current systems and the high-voltage side bus of the load transformer substation, combines whether the voltage stability of the load transformer substation needs to be checked or not according to the proportion of different loads in the load transformer substation, simulates through power system simulation software, and further judges whether the voltage instability of the load transformer substation occurs or not according to the simulation result;
according to the technical scheme provided by the invention, simulation calculation is not required to be carried out on various fault conditions which may occur to all direct current systems, and the fault and load transformer substation with hidden danger in voltage stability is obtained based on the power transfer voltage drop coefficient and the occupation ratio of different loads in the load transformer substation, so that the checking and simulation are carried out in a targeted manner, guidance is provided for safe and stable operation of a power grid, and the workload of safe and stable checking of an alternating current-direct current hybrid power grid is reduced.
Drawings
FIG. 1 is a P-V plot of an AC bus of the prior art;
fig. 2 is a flowchart of a method for determining voltage instability of a load substation according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention provides a method for judging voltage instability of a load transformer substation, which has the specific process as shown in figure 2 and comprises the following steps:
s101: calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
s102: judging the voltage stability of the load transformer substation according to the power transfer voltage drop coefficient between the converter bus of the direct current system and the high-voltage side bus of the load transformer substation, which is obtained by calculation in the step S101;
s103: and judging whether voltage stability verification needs to be carried out on the load transformer substation according to the voltage stability of the load transformer substation obtained in the step S102, if so, simulating by using power system simulation software to obtain a simulation result, and judging whether voltage instability occurs in the load transformer substation according to the simulation result.
In S101, a total of n DC systems are provided, each of which is designated as DC1，DC2，…，DCnSince one direct current system corresponds to one commutation bus, n commutation buses are available, that is, i is 1, …, n; the load transformer substation is determined according to the flow direction of active power of a transformer, the active power flowing from a high-voltage side bus to a low-voltage side bus is the load transformer substation, and the high-voltage side buses of the m load transformer substations are respectively named as AC (alternating current) if m load transformer substations are provided in total1，AC2，ACj，…，ACmSince one load substation corresponds to one high-voltage side bus, j is 1, 2, …, m;
then, the power transfer voltage drop coefficient between the converter bus of the dc system and the high-voltage side bus of the load substation is calculated according to the following formula:
Figure BDA0001402743050000071
wherein alpha isijIs a power transfer voltage drop coefficient, U, between a converter bus i of a direct current system and a high-voltage side bus j of a load substationj0The voltage of a high-voltage side bus j of a load substation under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000072
is composed of
Figure BDA0001402743050000073
The real part of (a) is,
Figure BDA0001402743050000074
is the equivalent impedance of a converter bus i of a direct current system to a high-voltage side bus j of a load substation,
Figure BDA0001402743050000075
and Uj0The per-unit value is taken as the value,
Figure BDA0001402743050000076
calculated as follows:
Figure BDA0001402743050000077
wherein, Ui0Is the voltage, U, of a current conversion bus i of a direct current system in the normal running state of a receiving-end power gridi1Voltage, U, of a commutation bus i of a direct current system after a change in the power delivered to the direct current systemj1Voltage, I, of a high-voltage side bus j of a load substation after a change in the power delivered to the DC systemi0Injecting current of alternating current power grid into current conversion bus I of direct current system under normal operation state of receiving end power gridi1Injecting current I of alternating current network into current converting bus I of direct current system after power transmission of direct current system is changedi0Calculated as follows:
Figure BDA0001402743050000078
wherein, Pi0、Qi0Respectively the active power and the reactive power absorbed by a converter bus i of the direct current system under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000079
is Ui0The conjugate complex number of (a);
Ii1calculated as follows:
Figure BDA00014027430500000710
wherein, Pi1、Qi1Respectively transmitting active power and reactive power absorbed by a current conversion bus i of the direct current system after the power of the direct current system is changed,
Figure BDA00014027430500000711
is Ui1The complex conjugate of (a).
In the above step S102, the voltage stability of the load substation is determined according to the power transfer voltage drop coefficient between the converter bus of the dc system and the high-voltage side bus of the load substation, which is specifically divided into the following three cases:
(1) when alpha isij<When the voltage is 0.1 hour, the voltage stability of the load transformer substation is good;
(2) when 0.1<αij<When 0.2 hour, the voltage stability of the load transformer substation is general;
(3) when 0.2<αijIn time, the voltage stability of the load substation is poor.
In the current electric power system analysis, a load model comprises a motor load and a static load, and as long as the load composition of each load transformer substation is known, the higher the motor load proportion is, the worse the voltage stability is. In S103, whether voltage stability verification needs to be performed on the load substation is determined according to the voltage stability of the load substation, which is divided into the following three cases:
(1) for a load substation with good voltage stability, if the motor load in the load components of the load substation is 70%, voltage stability verification needs to be performed on the load substation;
(2) for a load substation with general voltage stability, if the motor load proportion in the load components of the load substation reaches 40%, voltage stability verification needs to be performed on the load substation;
(3) and for the load transformer substation with poor voltage stability, directly carrying out voltage stability verification on the load transformer substation.
In the above step S103, the specific process of determining whether the voltage instability occurs in the load substation according to the simulation result is as follows:
in the transient process after the direct current system has a blocking fault, if the voltage of the high-voltage side bus j of the load substation cannot be recovered to 80% or more of the reference voltage within 10 seconds, the voltage of the load substation is unstable.
Based on the same inventive concept, the embodiment of the invention also provides a device for judging the voltage instability of the load transformer substation, the principle of solving the problems of the devices is similar to the method for judging the voltage instability of the load transformer substation, the device for judging the voltage instability of the load transformer substation mainly comprises a calculation module, a first judgment module and a second judgment module, and the specific functions of the three modules are described as follows:
the calculating module is mainly used for calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load substation;
the first judgment module is mainly used for judging the voltage stability of the load transformer substation according to a power transfer voltage reduction coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
the second judgment module is mainly used for judging whether voltage stability verification needs to be carried out on the load transformer substation according to the voltage stability of the load transformer substation, if so, simulating by using power system simulation software to obtain a simulation result, and judging whether voltage instability occurs in the load transformer substation according to the simulation result.
The calculating module is used for calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load substation according to the following formula:
Figure BDA0001402743050000081
wherein alpha isijIs a power transfer voltage drop coefficient, U, between a converter bus i of a direct current system and a high-voltage side bus j of a load substationj0The voltage of a high-voltage side bus j of a load substation under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000091
is composed of
Figure BDA0001402743050000092
The real part of (a) is,
Figure BDA0001402743050000093
is the equivalent impedance of a converter bus i of a direct current system to a high-voltage side bus j of a load substation,
Figure BDA0001402743050000094
calculated as follows:
Figure BDA0001402743050000095
wherein, Ui0Is the voltage, U, of a current conversion bus i of a direct current system in the normal running state of a receiving-end power gridi1Voltage, U, of a commutation bus i of a direct current system after a change in the power delivered to the direct current systemj1Voltage, I, of a high-voltage side bus j of a load substation after a change in the power delivered to the DC systemi0Injecting current of alternating current power grid into current conversion bus I of direct current system under normal operation state of receiving end power gridi1Injecting current I of alternating current network into current converting bus I of direct current system after power transmission of direct current system is changedi0Calculated as follows:
Figure BDA0001402743050000096
wherein, Pi0、Qi0Respectively the active power and the reactive power absorbed by a converter bus i of the direct current system under the normal operation state of a receiving-end power grid,
Figure BDA0001402743050000097
is Ui0The conjugate complex number of (a);
Ii1calculated as follows:
Figure BDA0001402743050000098
wherein, Pi1、Qi1Respectively transmitting active power and reactive power absorbed by a current conversion bus i of the direct current system after the power of the direct current system is changed,
Figure BDA0001402743050000099
is Ui1The complex conjugate of (a).
The specific process of judging the voltage stability of the load transformer substation by the first judging module according to the power transfer voltage reduction coefficient between the converter bus of the direct current system and the high-voltage side bus of the load transformer substation is as follows:
when alpha isij<When the voltage is 0.1 hour, the voltage stability of the load transformer substation is good;
when 0.1<αij<When 0.2 hour, the voltage stability of the load transformer substation is general;
when 0.2<αijIn time, the voltage stability of the load substation is poor.
The second judging module comprises a first judging unit, and the first judging unit judges whether the voltage stability of the load transformer substation needs to be checked according to the voltage stability of the load transformer substation as follows:
for a load substation with good voltage stability, if the motor load in the load components of the load substation is 70%, voltage stability verification needs to be performed on the load substation;
for a load substation with general voltage stability, if the motor load proportion in the load components of the load substation reaches 40%, voltage stability verification needs to be performed on the load substation;
and for the load transformer substation with poor voltage stability, directly carrying out voltage stability verification on the load transformer substation.
The second judging module further comprises a second judging unit, and the specific process of judging whether the voltage instability of the load transformer substation occurs according to the simulation result is as follows:
in the transient process after the direct current system has a blocking fault, if the voltage of the high-voltage side bus j of the load substation cannot be recovered to 80% or more of the reference voltage within 10 seconds, the voltage of the load substation is unstable.
For convenience of description, each part of the above-described apparatus is separately described as being functionally divided into various modules or units. Of course, the functionality of the various modules or units may be implemented in the same one or more pieces of software or hardware when implementing the present application.
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 intended to illustrate the technical solution of the present invention and not to limit the same, and a person of ordinary skill in the art can make modifications or equivalents to the specific embodiments of the present invention with reference to the above embodiments, and such modifications or equivalents without departing from the spirit and scope of the present invention are within the scope of the claims of the present invention as set forth in the claims.

Claims (2)

1. A method for judging voltage instability of a load transformer substation is characterized by comprising the following steps:
calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
judging the voltage stability of the load transformer substation according to a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
judging whether voltage stability verification needs to be carried out on the load transformer substation according to the voltage stability of the load transformer substation, if so, simulating by using power system simulation software to obtain a simulation result, and judging whether voltage instability occurs in the load transformer substation according to the simulation result;
the power transfer voltage drop coefficient between the converter bus of the direct current system and the high-voltage side bus of the load substation is calculated according to the following formula:
Figure FDA0002914069350000011
wherein alpha isijIs a power transfer voltage drop coefficient, U, between a converter bus i of a direct current system and a high-voltage side bus j of a load substationj0For the normal operation of the receiving-end power gridThe voltage of the high-side bus j of the load substation in this state,
Figure FDA0002914069350000012
is composed of
Figure FDA0002914069350000013
The real part of (a) is,
Figure FDA0002914069350000014
is the equivalent impedance of a converter bus i of a direct current system to a high-voltage side bus j of a load substation,
Figure FDA0002914069350000015
calculated as follows:
Figure FDA0002914069350000016
wherein, Ui0Is the voltage, U, of a current conversion bus i of a direct current system in the normal running state of a receiving-end power gridi1Voltage, U, of a commutation bus i of a direct current system after a change in the power delivered to the direct current systemj1Voltage, I, of a high-voltage side bus j of a load substation after a change in the power delivered to the DC systemi0Injecting current of alternating current power grid into current conversion bus I of direct current system under normal operation state of receiving end power gridi1Injecting current I of alternating current network into current converting bus I of direct current system after power transmission of direct current system is changedi0Calculated as follows:
Figure FDA0002914069350000017
wherein, Pi0、Qi0Respectively the active power and the reactive power absorbed by a converter bus i of the direct current system under the normal operation state of a receiving-end power grid,
Figure FDA0002914069350000018
is Ui0The conjugate complex number of (a);
Ii1calculated as follows:
Figure FDA0002914069350000021
wherein, Pi1、Qi1Respectively transmitting active power and reactive power absorbed by a current conversion bus i of the direct current system after the power of the direct current system is changed,
Figure FDA0002914069350000022
is Ui1The conjugate complex number of (a);
the judging the voltage stability of the load transformer substation according to the power transfer voltage drop coefficient between the converter bus of the direct current system and the high-voltage side bus of the load transformer substation comprises the following steps:
when alpha isij<When the voltage is 0.1 hour, the voltage stability of the load transformer substation is good;
when 0.1<αij<When 0.2 hour, the voltage stability of the load transformer substation is general;
when 0.2<αijIn time, the voltage stability of the load substation is poor;
the step of judging whether the voltage stability check of the load transformer substation is needed or not according to the voltage stability of the load transformer substation comprises the following steps:
for a load substation with good voltage stability, if the motor load in the load components of the load substation is 70%, voltage stability verification needs to be performed on the load substation;
for a load substation with general voltage stability, if the motor load proportion in the load components of the load substation reaches 40%, voltage stability verification needs to be performed on the load substation;
for a load transformer substation with poor voltage stability, directly carrying out voltage stability verification on the load transformer substation;
the step of judging whether the voltage instability of the load transformer substation occurs according to the simulation result comprises the following steps:
in the transient process after the direct current system has a blocking fault, if the voltage of the high-voltage side bus j of the load substation cannot be recovered to 80% or more of the reference voltage within 10 seconds, the voltage of the load substation is unstable.
2. The utility model provides a load transformer substation voltage unstability judgement device which characterized in that includes:
the calculation module is used for calculating a power transfer voltage reduction coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
the first judgment module is used for judging the voltage stability of the load transformer substation according to a power transfer voltage reduction coefficient between a converter bus of the direct current system and a high-voltage side bus of the load transformer substation;
the second judgment module is used for judging whether voltage stability verification needs to be carried out on the load transformer substation according to the voltage stability of the load transformer substation, if so, simulating by using power system simulation software to obtain a simulation result, and judging whether voltage instability occurs in the load transformer substation according to the simulation result;
the calculation module is used for calculating a power transfer voltage drop coefficient between a converter bus of the direct current system and a high-voltage side bus of the load substation according to the following formula:
Figure FDA0002914069350000031
wherein alpha isijIs a power transfer voltage drop coefficient, U, between a converter bus i of a direct current system and a high-voltage side bus j of a load substationj0The voltage of a high-voltage side bus j of a load substation under the normal operation state of a receiving-end power grid,
Figure FDA0002914069350000032
is composed of
Figure FDA0002914069350000033
The real part of (a) is,
Figure FDA0002914069350000034
is the equivalent impedance of a converter bus i of a direct current system to a high-voltage side bus j of a load substation,
Figure FDA0002914069350000035
calculated as follows:
Figure FDA0002914069350000036
wherein, Ui0Is the voltage, U, of a current conversion bus i of a direct current system in the normal running state of a receiving-end power gridi1Voltage, U, of a commutation bus i of a direct current system after a change in the power delivered to the direct current systemj1Voltage, I, of a high-voltage side bus j of a load substation after a change in the power delivered to the DC systemi0Injecting current of alternating current power grid into current conversion bus I of direct current system under normal operation state of receiving end power gridi1Injecting current I of alternating current network into current converting bus I of direct current system after power transmission of direct current system is changedi0Calculated as follows:
Figure FDA0002914069350000037
wherein, Pi0、Qi0Respectively the active power and the reactive power absorbed by a converter bus i of the direct current system under the normal operation state of a receiving-end power grid,
Figure FDA0002914069350000038
is Ui0The conjugate complex number of (a);
Ii1calculated as follows:
Figure FDA0002914069350000039
wherein, Pi1、Qi1Of dc systems with altered power supplied separatelyThe active power and reactive power absorbed by the converter bus i,
Figure FDA00029140693500000310
is Ui1The conjugate complex number of (a);
the first judging module is specifically configured to:
when alpha isij<When the voltage is 0.1 hour, the voltage stability of the load transformer substation is good;
when 0.1<αij<When 0.2 hour, the voltage stability of the load transformer substation is general;
when 0.2<αijIn time, the voltage stability of the load substation is poor;
the second judging module includes a first judging unit, and the first judging unit is specifically configured to:
for a load substation with good voltage stability, if the motor load in the load components of the load substation is 70%, voltage stability verification needs to be performed on the load substation;
for a load substation with general voltage stability, if the motor load proportion in the load components of the load substation reaches 40%, voltage stability verification needs to be performed on the load substation;
for a load transformer substation with poor voltage stability, directly carrying out voltage stability verification on the load transformer substation;
the second determining module further includes a second determining unit, and the second determining unit is specifically configured to:
in the transient process after the direct current system has a blocking fault, if the voltage of the high-voltage side bus j of the load substation cannot be recovered to 80% or more of the reference voltage within 10 seconds, the voltage of the load substation is unstable.
CN201710806125.7A 2017-09-08 2017-09-08 Load substation voltage instability judgment method and device Active CN107658894B (en)

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CN103107530A (en) * 2013-01-21 2013-05-15 云南电网公司电网规划研究中心 Multi-direct-current urgent coordination control method based on sensitivity
CN105207275A (en) * 2015-09-21 2015-12-30 中国电力科学研究院 Method for recognizing alternating-current busbar voltage weak points during direct-current power transfer

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103107530A (en) * 2013-01-21 2013-05-15 云南电网公司电网规划研究中心 Multi-direct-current urgent coordination control method based on sensitivity
CN105207275A (en) * 2015-09-21 2015-12-30 中国电力科学研究院 Method for recognizing alternating-current busbar voltage weak points during direct-current power transfer

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