CN110542827B - Method and system for judging fault direction of power distribution network containing inverter type power supply - Google Patents

Method and system for judging fault direction of power distribution network containing inverter type power supply Download PDF

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CN110542827B
CN110542827B CN201910095891.6A CN201910095891A CN110542827B CN 110542827 B CN110542827 B CN 110542827B CN 201910095891 A CN201910095891 A CN 201910095891A CN 110542827 B CN110542827 B CN 110542827B
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fault
power supply
protection
iigmax
type power
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CN110542827A (en
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郑涛
朱逸凡
张嘉琴
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North China Electric Power University
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North China Electric Power University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
    • 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
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Inverter Devices (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses a method for judging the fault direction of a power distribution network containing an inverter type power supply, which comprises the following steps: determining the access position of the inverter power supply, so that the minimum short-circuit current provided by the power system is constantly larger than the maximum short-circuit current provided by the inverter power supply; calculating the phase angle of the positive sequence fault component measuring impedance at the protection installation; if the phase angle is in the range of more than-135 degrees and less than-45 degrees, then the positive direction fault is protected; comparing the measured current at the protective installation with a maximum short circuit current provided by the inverter type power supply if the phase angle is in the range of greater than-45 ° and less than 0 ° or the phase angle is in the range of greater than-180 ° and less than-45 °: and judging the fault direction through comparison of the current amplitude. The invention improves the sensitivity of judging the fault direction at the junction of the positive fault and the negative fault.

Description

Method and system for judging fault direction of power distribution network containing inverter type power supply
Technical Field
The invention relates to the technical field of relay protection, in particular to a method and a system for judging the fault direction of a power distribution network containing an inverter power supply.
Background
In recent years, new energy power generation is rapidly developed, and the installed capacity of distributed power sources such as wind power and photovoltaic power is continuously increased. However, a large number of distributed power supplies are connected to a power distribution network, so that a traditional radial network becomes a double-end or multi-end network, and the staged current protection is not applicable any more. To solve this problem, it has been proposed to add protection and direction elements to the double-ended power supply network upstream of the distributed power supply to prevent current protection glitches in the event of a reverse direction fault. However, the structural features and control methods of the distributed power supply are different from those of the conventional synchronous generator, the fault characteristics are quite complex, and the conventional directional element may have adaptability problems. The working principle of the conventional positive sequence fault component direction element is as follows:
fig. 1 is a positive sequence fault attached network of a conventional double-ended power supply system, in which, when a positive direction fault occurs in n-side protection, there are:
Figure BDA0001964529990000011
in the formula:
Figure BDA0001964529990000012
respectively positive sequence voltage break variable, positive sequence voltage after fault and voltage before fault at n-side protection installation position；
Figure BDA0001964529990000013
Respectively positive sequence current break variable, positive sequence current after fault and current before fault at the protection installation position of the n side; znThe equivalent impedance of the n-side system can be approximated to pure inductance, and
Figure BDA0001964529990000014
when the n-side protection fails in the reverse direction,
Figure BDA0001964529990000015
and
Figure BDA0001964529990000016
the ratio of (A) is the sum of the equivalent impedance of the opposite side system and the line impedance
Figure BDA0001964529990000021
The criterion for obtaining the positive protection direction by considering a certain margin is as follows:
Figure BDA0001964529990000022
however, the structural features and control method of the distributed power supply are different from those of the traditional synchronous generator, and the fault characteristics of the distributed power supply are very complex, so that the reliable action of the traditional directional element is greatly influenced. For ease of discussion, the equivalent positive sequence delta impedance Δ Z is defined for an inverter-type power supply1：
Figure BDA0001964529990000023
Wherein the content of the first and second substances,
Figure BDA0001964529990000024
to protect the post-fault positive sequence voltage and the pre-fault voltage at the installation site;
Figure BDA0001964529990000025
in order to protect the post-fault positive sequence current and the pre-fault current at the installation site, the positive direction is that the bus points to the line.
Taking the positive direction fault of n-side protection as an example, according to this definition,
Figure BDA0001964529990000026
and
Figure BDA0001964529990000027
phase angle difference of
Figure BDA0001964529990000028
Δ Z if the system is powered by a conventional double ended power supply1Equal to the equivalent impedance of the system on the back side of the protective installation, with a phase angle of 90. It is pointed out in the literature that for inverter type power supplies, the equivalent positive sequence delta impedance phase angle may vary from 0 ° to 180 °, protecting the installation site
Figure BDA0001964529990000029
Wandering at the intersection of the positive and negative directions may cause the directional element to have poor sensitivity or even erroneous judgment.
Disclosure of Invention
The invention aims to provide a method and a system for judging the fault direction of a power distribution network containing an inverter power supply, which improve the sensitivity and reliability of a fault component judging method.
In order to achieve the purpose, the invention provides the following scheme:
a method for judging the fault direction of a power distribution network with an inverter type power supply comprises the following steps:
determining the access position of the inverter power supply to minimize the short-circuit current I provided by the power systemsminConstant-larger maximum short-circuit current I provided by inverter type power supplyIIGmax；
Calculating phase angle of fault component measurement impedance at protective installation
Figure BDA0001964529990000031
Wherein, arg () represents a phase angle,
Figure BDA0001964529990000032
representing a positive sequence fault component voltage at the protection installation,
Figure BDA0001964529990000033
representing a positive sequence fault component current at the protective installation;
if it is not
Figure BDA0001964529990000034
Then the positive direction of the protection fails;
if it is not
Figure BDA0001964529990000035
Or
Figure BDA0001964529990000036
Measuring the current I to the protection installationmAnd the maximum short-circuit current I provided by the inverter type power supplyIIGmaxAnd (3) comparison:
for the power system side protection, if:
Im＞1.5IIIGmaxif the system side protection is not in the positive direction, the system side protection is carried out;
Im＜1.5IIIGmaxif the system side is protected by the system, the system side is protected by the protection device;
for the inverter type power supply side protection, if:
Im＜1.5IIIGmaxif the positive direction fault of the inverter type power supply side protection is detected, judging that the positive direction fault of the inverter type power supply side protection is a positive direction fault;
Im＞1.5IIIGmaxand if the fault is the reverse fault of the inverter type power supply side protection.
Optionally, the minimum short-circuit current I provided by the power systemsminIs constantly larger than the maximum short-circuit current I provided by the inverter type power supplyIIGmaxThe method specifically comprises the following steps:Ismin＞kIIIGmaxwherein k is an integer greater than or equal to 2.
Optionally, the fault component at the protective installation measures the phase angle of the impedance
Figure BDA0001964529990000037
In
Figure BDA0001964529990000038
Figure BDA0001964529990000039
And
Figure BDA00019645299900000310
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure BDA00019645299900000311
and
Figure BDA00019645299900000312
the protection installation position is respectively a post-fault positive sequence current and a pre-fault current.
Optionally, the maximum output power of the inverter-type power supply is 1.5 MW.
The invention also discloses a system for judging the fault direction of the power distribution network containing the inverter power supply, which comprises the following components:
an access position determining module of the inverter power supply for determining the access position of the inverter power supply to ensure the minimum short-circuit current I provided by the power systemsminConstant-larger maximum short-circuit current I provided by inverter type power supplyIIGmax；
A calculation module for calculating the phase angle of the fault component measuring impedance at the protective installation
Figure BDA0001964529990000041
Wherein, arg () represents a phase angle,
Figure BDA0001964529990000042
representing a positive sequence fault component voltage at the protection installation,
Figure BDA0001964529990000043
representing a positive sequence fault component current at the protective installation;
a judging module for protecting the phase angle of the fault component measuring impedance at the installation position and judging the fault direction if the fault direction is judged
Figure BDA0001964529990000044
Then the positive direction of the protection fails;
the judging module for the phase angle of the fault component measuring impedance at the protection installation position comprises a current amplitude comparison unit, and the judging module for judging that the phase angle meets the requirement when the judging module for the phase angle of the fault component measuring impedance at the protection installation position judges that the phase angle meets the requirement
Figure BDA0001964529990000045
Or
Figure BDA0001964529990000046
Measuring current I at the protective installationmAnd the maximum short-circuit current I provided by the inverter type power supplyIIGmaxAnd (3) comparison:
for the power system side protection, if:
Im＞1.5IIIGmaxif the system side protection is not in the positive direction, the system side protection is carried out;
Im＜1.5IIIGmaxif the system side is protected by the system, the system side is protected by the protection device;
for the inverter type power supply side protection, if:
Im＜1.5IIIGmaxif the positive direction fault of the inverter type power supply side protection is detected, judging that the positive direction fault of the inverter type power supply side protection is a positive direction fault;
Im＞1.5IIIGmaxand if the fault is the reverse fault of the inverter type power supply side protection.
Optionally, the minimum short-circuit current I provided by the power systemsminIs constantly greater than the inverseMaximum short-circuit current I provided by modified power supplyIIGmaxThe method specifically comprises the following steps: i issmin＞kIIIGmaxWherein k is an integer greater than or equal to 2.
Optionally, the fault component at the protective installation measures the phase angle of the impedance
Figure BDA0001964529990000047
In
Figure BDA0001964529990000051
Figure BDA0001964529990000052
And
Figure BDA0001964529990000053
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure BDA0001964529990000054
and
Figure BDA0001964529990000055
the protection installation position is respectively a post-fault positive sequence current and a pre-fault current.
Optionally, the maximum output power of the inverter-type power supply is 1.5 MW.
According to the invention content provided by the invention, the invention discloses the following technical effects: the invention provides a method and a system for judging the fault direction of a power distribution network containing an inverter power supply
Figure BDA0001964529990000056
Or
Figure BDA0001964529990000057
The measured current at the protective installation position and the maximum short-circuit current of the inverter power supply are compared to judge the fault direction, so that the fault direction at the junction of the positive fault and the negative fault is improvedAnd the judgment sensitivity is improved, so that the sensitivity and the accuracy of fault direction judgment are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a diagram of a positive sequence fault attach network for a conventional dual ended power supply system;
fig. 2 is a schematic flow chart of a method for determining a fault direction of a power distribution network including an inverter type power supply according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a system for determining a fault direction of a power distribution network including an inverter type power supply according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a power distribution network model including an inverter-type power supply according to an embodiment of the present invention;
FIG. 5 shows K in FIG. 41The impedance phase angle diagram of the positive sequence break variable is shown in protection 3 and protection 4 when three-phase fault occurs;
FIG. 6 shows K in FIG. 41The impedance phase angle diagram of the positive sequence break variable of the protection 3 and the protection 4 when two-phase fault occurs;
FIG. 7 shows K in FIG. 41Positive sequence break variable impedance phase angle diagrams for protection 3 and 4 at two phase ground fault.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a method and a system for judging the fault direction of a power distribution network containing an inverter power supply, which realize the judgment of the fault direction at the junction of a positive fault and a negative fault and improve the sensitivity and the accuracy of the fault direction judgment.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a method for determining a fault direction of a power distribution network including an inverter power supply according to an embodiment of the present invention, and as shown in fig. 1, the method for determining a fault direction of a power distribution network including an inverter power supply according to the present invention includes:
step 101: determining the access position of the inverter power supply to minimize the short-circuit current I provided by the power systemsminConstant-larger maximum short-circuit current I provided by inverter type power supplyIIGmaxWith a certain margin, i.e. Ismin＞kIIIGmaxWherein k is a threshold value, and k takes the value of 2;
step 102: calculating phase angle of fault component measurement impedance at protective installation
Figure BDA0001964529990000061
Wherein, arg () represents a phase angle,
Figure BDA0001964529990000062
representing a positive sequence fault component voltage at the protection installation,
Figure BDA0001964529990000063
representing a positive sequence fault component current at the protective installation;
step 103: judging whether the phase angle satisfies
Figure BDA0001964529990000064
If yes, go to step 104: judging that the fault direction is the positive direction fault of the protection;
if not, go to step 105;
step 105: judging whether the phase angle satisfies
Figure BDA0001964529990000065
Or
Figure BDA0001964529990000066
If yes, go to step 107, if not, go to step 106;
step 107: measuring current I to the protection installationmAnd the maximum short-circuit current I provided by the inverter type power supplyIIGmaxAnd (3) comparison:
under the condition of satisfying Ismin＞2IIIGmaxOn the premise of (1.5I)IIGmaxFor setting value, the short-circuit current property can be distinguished through amplitude comparison:
(1) if the short-circuit current at the protective installation position is more than 1.5IIIGmaxIf the short-circuit current is provided by the system equivalent power supply;
(2) if the short-circuit current at the protective installation position is less than 1.5IIIGmaxThe short circuit current is supplied by the inverter type power supply.
Then the current and 1.5I are measured according to the protection installation positionIIGmaxThe direction element can judge the positive and negative direction faults as a result of the comparison.
Wherein, step 107 specifically comprises:
for the power system side protection, if:
Im＞1.5IIIGmaxif the system side protection is not in the positive direction, the system side protection is carried out;
Im＜1.5IIIGmaxif the system side is protected by the system, the system side is protected by the protection device;
for the inverter type power supply side protection, if:
Im＜1.5IIIGmaxif the positive direction fault of the inverter type power supply side protection is detected, judging that the positive direction fault of the inverter type power supply side protection is a positive direction fault;
Im＞1.5IIIGmaxthen, the reverse fault of the inverter type power supply side protection is detected
Step 106: and judging that the power system has a reverse fault.
Fig. 4 is a schematic diagram of a power distribution network model including an inverter type power supply according to an embodiment of the present invention, and as shown in fig. 4, protection with a system equivalent power supply on the back side is referred to as system side protection, such as protection 1 and protection 3; protection with the Inverter type power supply on the back side is referred to as IIG (Inverter-interface Generation) side protection, such as protection 2 and protection 4.
In the relay protection field, defining the positive direction of short-circuit current at a protection installation position as the bus flowing to a line, for the protection 1 and the protection 3, when the positive direction of the short-circuit current fails, the short-circuit current flowing through the protection installation position is provided by a system equivalent power supply, and when the negative direction of the short-circuit current fails, the short-circuit current flowing through the protection installation position is provided by an IIG; for the protection 2 and 4, when the positive direction of the protection fails, the short-circuit current flowing through the protection installation is provided by the IIG, and when the negative direction of the protection fails, the short-circuit current flowing through the protection installation is provided by the system equivalent power supply.
Based on the above conclusion, by limiting the access position of the inverter type power supply, the system side and IIG side directional elements adopt different discrimination logics:
(1) side protection of the power system (protections 1 and 3) if
Im＞1.5IIIGmaxIf the system side protection is not in the positive direction, the system side protection is carried out;
Im＜1.5IIIGmaxand then the system side protection is a reverse direction fault.
(2) Protection of inverter type power supply side (protections 2 and 4) if
Im＜1.5IIIGmaxIf the positive direction fault of the inverter type power supply side protection is detected, judging that the positive direction fault of the inverter type power supply side protection is a positive direction fault;
Im＞1.5IIIGmaxand if the fault is the reverse fault of the inverter type power supply side protection.
In the formula: i ismMeasuring the current magnitude for protecting the installation, IIIGmaxThe maximum short-circuit current provided for the inverter type power supply.
Based on the criterion, the system side and the inverter type power supply side can accurately identify the positive and negative direction faults only according to the short-circuit current.
Under the condition of satisfying Ismin＞2IIIGmaxOn the premise of PSCAD (Power Systems Computer Aide)dd design) is established, and the model parameters are shown in table 1:
table 1: model parameters of IIG-containing distribution network
Figure BDA0001964529990000081
The PSCAD is used for respectively simulating three-phase, two-phase and two-phase grounding short circuits of k1 (tail end of a line L2), k2 (position B1 km away from a bus on the line L3) and k3 (head end of a line L4), and the judgment conditions of the positive sequence fault component measurement impedance phase angle and the short-circuit current amplitude value and the positive and negative directions of the protection 3 (system side protection) and the protection 4(IIG side protection) are shown in tables 2, 3 and 4 (1.5I)IIGmax＝0.279kA)
In addition, taking the k1 fault as an example, the measurement results of the positive sequence fault component direction elements of the protections 3 and 4 are shown in fig. 5, 6 and 7, and the gray areas indicate areas where the next amplitude comparison is not needed.
Table 2: judgment of protection in case of k1 failure
Figure BDA0001964529990000091
Note: "to" means that there is no need to compare the short-circuit current amplitude
Table 3: judgment of protection in case of k2 failure
Figure BDA0001964529990000092
Table 4: judgment of protection in case of k3 failure
Figure BDA0001964529990000093
Figure BDA0001964529990000101
As shown in tables 2, 3, and 4, for the system side protection 3, the fault direction can be already determined by using the positive sequence fault component direction element, and for the IIG side protection 4, the impedance angle measured by the positive sequence fault component may fall at the boundary, which causes the sensitivity of the protection to be insufficient, and after entering the amplitude comparison link, the fault direction can be accurately determined
By comparing the current amplitude values, the accuracy of fault direction judgment is improved when the fault component measurement impedance corner is at the boundary, and therefore the sensitivity of protection of a protection installation position is improved.
Wherein, step 102 specifically includes: phase angle of fault component measuring impedance at said protective installation
Figure BDA0001964529990000102
In
Figure BDA0001964529990000103
Figure BDA0001964529990000104
And
Figure BDA0001964529990000105
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure BDA0001964529990000106
and
Figure BDA0001964529990000107
the protection installation position is respectively a post-fault positive sequence current and a pre-fault current.
Wherein, the maximum output power of the inverter power supply in step 101 is 1.5 MW.
Fig. 2 is a schematic structural diagram of a system for determining a fault direction of a power distribution network including an inverter power supply according to an embodiment of the present invention, and as shown in fig. 2, the system for determining a fault direction of a power distribution network including an inverter power supply according to the present invention includes:
an access position determining module 201 of the inverter type power supply, configured to determine an access position of the inverter type power supply, so that a minimum short-circuit current I provided by the power system is providedsminConstant voltage greater than that provided by inverter type power supplyLarge short-circuit current IIIGmaxWith a certain margin, i.e. Ismin＞2IIIGmax；
A calculation module 202 for calculating a phase angle of the fault component measured impedance of the protection installation
Figure BDA0001964529990000111
Wherein, arg () represents a phase angle,
Figure BDA0001964529990000112
representing a positive sequence fault component voltage at the protection installation,
Figure BDA0001964529990000113
representing a positive sequence fault component current at the protective installation; phase angle of fault component measuring impedance at said protective installation
Figure BDA0001964529990000114
In
Figure BDA0001964529990000115
Figure BDA0001964529990000116
And
Figure BDA0001964529990000117
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure BDA0001964529990000118
and
Figure BDA0001964529990000119
respectively a post-fault positive sequence current and a pre-fault current at the protection installation position;
a phase angle of the fault component measuring impedance at the protection installation 203, for determining the fault direction,
if it is not
Figure BDA00019645299900001110
The positive direction of the power system is failed;
the judging module 203 for the phase angle of the fault component measuring impedance at the protection installation comprises a current amplitude comparison unit, and is used for judging that the phase angle meets the requirement when the judging module for the phase angle of the fault component measuring impedance at the protection installation judges that the phase angle meets the requirement
Figure BDA00019645299900001111
Or
Figure BDA00019645299900001112
Measuring current I at the protective installationmAnd the maximum short-circuit current I provided by the inverter type power supplyIIGmaxAnd (3) comparison:
for the power system side protection, if:
Im＞1.5IIIGmaxif the system side protection is in positive direction fault, the protection installation part measures current ImIs provided by the equivalent power source of the power system;
Im＜1.5IIIGmaxif the system side protection fails in the reverse direction, the protection installation part measures the current ImSupplied by the inverter-type power supply;
for the inverter type power supply side protection, if:
Im＜1.5IIIGmaxif the positive direction fault of the inverter type power supply side protection exists, the protection installation position measures current ImSupplied by the inverter-type power supply;
Im＞1.5IIIGmaxif the fault is the reverse fault of the inverter type power supply side protection, the current I is measured at the protection installation positionmIs provided by the equivalent power source of the power system.
Phase angle of fault component measuring impedance at said protective installation
Figure BDA0001964529990000121
In
Figure BDA0001964529990000122
Figure BDA0001964529990000123
And
Figure BDA0001964529990000124
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure BDA0001964529990000125
and
Figure BDA0001964529990000126
the protection installation position is respectively a post-fault positive sequence current and a pre-fault current.
The maximum output power of the inverter type power supply is 1.5 MW.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (8)

1. A method for judging the fault direction of a power distribution network with an inverter type power supply is characterized by comprising the following steps:
determining the access position of the inverter power supply to minimize the short-circuit current I provided by the power systemsminConstant larger than maximum short-circuit current provided by inverter type power supplyIIIGmax；
Calculating phase angle of fault component measurement impedance at protective installation
Figure FDA0002510252540000011
Wherein, arg () represents a phase angle,
Figure FDA0002510252540000012
representing a positive sequence fault component voltage at the protection installation,
Figure FDA0002510252540000013
representing a positive sequence fault component current at the protective installation;
if it is not
Figure FDA0002510252540000014
Then the positive direction of the protection fails;
if it is not
Figure FDA0002510252540000015
Or
Figure FDA0002510252540000016
Measuring the current I to the protection installationmAnd the maximum short-circuit current I provided by the inverter type power supplyIIGmaxAnd (3) comparison:
for power system side protection, if:
Im＞1.5IIIGmaxif the system side protection is not in the positive direction, the system side protection is carried out;
Im＜1.5IIIGmaxif the system side is protected by the system, the system side is protected by the protection device;
for the inverter type power supply side protection, if:
Im＜1.5IIIGmaxif the positive direction fault of the inverter type power supply side protection is detected, judging that the positive direction fault of the inverter type power supply side protection is a positive direction fault;
Im＞1.5IIIGmaxand if the fault is the reverse fault of the inverter type power supply side protection.
2. The method according to claim 1, wherein the minimum short-circuit current I provided by the power system is the minimum short-circuit current IsminIs constantly larger than the maximum short-circuit current I provided by the inverter type power supplyIIGmaxThe method specifically comprises the following steps: i issmin＞kIIIGmaxWherein k is an integer greater than or equal to 2.
3. The method according to claim 1, wherein the phase angle of the impedance is measured as a fault component of the protection installation site
Figure FDA0002510252540000021
In
Figure FDA0002510252540000022
Figure FDA0002510252540000023
And
Figure FDA0002510252540000024
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure FDA0002510252540000025
and
Figure FDA0002510252540000026
the protection installation position is respectively a post-fault positive sequence current and a pre-fault current.
4. The method according to claim 1, wherein the maximum output power of the inverter-type power supply is 1.5 MW.
5. A system for determining a fault direction in a power distribution network including an inverter-type power supply, the system comprising:
an access position determining module of the inverter power supply for determining the access position of the inverter power supply to ensure the minimum short-circuit current I provided by the power systemsminConstant-larger maximum short-circuit current I provided by inverter type power supplyIIGmax；
A calculation module for calculating the phase angle of the fault component measuring impedance at the protective installation
Figure FDA0002510252540000027
Wherein, arg () represents a phase angle,
Figure FDA0002510252540000028
representing a positive sequence fault component voltage at the protection installation,
Figure FDA0002510252540000029
representing a positive sequence fault component current at the protective installation;
a judging module for protecting the phase angle of the fault component measuring impedance at the installation position, which is used for judging the fault direction,
if it is not
Figure FDA00025102525400000210
Then the positive direction of the protection fails;
the judging module for the phase angle of the fault component measuring impedance at the protection installation position comprises a current amplitude comparison unit, and the judging module for judging that the phase angle meets the requirement when the judging module for the phase angle of the fault component measuring impedance at the protection installation position judges that the phase angle meets the requirement
Figure FDA00025102525400000211
Or
Figure FDA00025102525400000212
Measuring current I at the protective installationmAnd the inverter type power supplyMaximum short-circuit current I ofIIGmaxAnd (3) comparison:
for power system side protection, if:
Im＞1.5IIIGmaxif the system side protection is not in the positive direction, the system side protection is carried out;
Im＜1.5IIIGmaxif the system side is protected by the system, the system side is protected by the protection device;
for the inverter type power supply side protection, if:
Im＜1.5IIIGmaxif the positive direction fault of the inverter type power supply side protection is detected, judging that the positive direction fault of the inverter type power supply side protection is a positive direction fault;
Im＞1.5IIIGmaxand if the fault is the reverse fault of the inverter type power supply side protection.
6. The system according to claim 5, wherein the minimum short-circuit current I provided by the power system is the minimum short-circuit current IsminIs constantly larger than the maximum short-circuit current I provided by the inverter type power supplyIIGmaxThe method specifically comprises the following steps: i issmin＞kIIIGmaxWherein k is an integer greater than or equal to 2.
7. The system according to claim 5, wherein the fault component at the protection installation measures a phase angle of the impedance
Figure FDA0002510252540000031
In
Figure FDA0002510252540000032
Figure FDA0002510252540000033
And
Figure FDA0002510252540000034
respectively a post-fault positive sequence voltage and a pre-fault voltage at the protection installation site;
Figure FDA0002510252540000035
and
Figure FDA0002510252540000036
the protection installation position is respectively a post-fault positive sequence current and a pre-fault current.
8. The system according to claim 5, wherein the maximum output power of the inverter-type power supply is 1.5 MW.
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