CN111398851A - MMC-HVDC direct current transmission line fault detection method - Google Patents

MMC-HVDC direct current transmission line fault detection method Download PDF

Info

Publication number
CN111398851A
CN111398851A CN202010239546.8A CN202010239546A CN111398851A CN 111398851 A CN111398851 A CN 111398851A CN 202010239546 A CN202010239546 A CN 202010239546A CN 111398851 A CN111398851 A CN 111398851A
Authority
CN
China
Prior art keywords
mmc
direct current
hvdc
fault
positive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010239546.8A
Other languages
Chinese (zh)
Inventor
奚鑫泽
邢超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electric Power Research Institute of Yunnan Power Grid Co Ltd
Original Assignee
Electric Power Research Institute of Yunnan Power Grid Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Electric Power Research Institute of Yunnan Power Grid Co Ltd filed Critical Electric Power Research Institute of Yunnan Power Grid Co Ltd
Priority to CN202010239546.8A priority Critical patent/CN111398851A/en
Publication of CN111398851A publication Critical patent/CN111398851A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
    • 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
    • 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
    • H02H7/268—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 dc 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

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The application belongs to the technical field of power transmission line protection, and particularly relates to a fault detection method for an MMC-HVDC direct current power transmission line. For an MMC-HVDC system, the current differential protection method has the problems of low fault identification rate, poor reliability and insufficient fault type judgment. The MMC-HVDC direct current transmission line fault detection method provided by the application obtains, compares and calculates the sum P of the direct current power value of the anode of the rectifying side and the direct current power value of the cathode of the inverting sideKMAnd the sum P of the DC power value of the negative electrode at the rectification side and the DC power value of the positive electrode at the inversion sideMK(ii) a Simultaneous PKMAnd PMKThe data analysis and comparison are carried out, so that the type of the fault in the MMC-HVDC system is accurately judged, and the judgment is very highThe protection of the MMC-HVDC direct-current transmission line is effectively and simply realized. The pilot protection method of the MMC-HVDC system based on the power quantity has better applicability and reliability and has higher engineering application value.

Description

MMC-HVDC direct current transmission line fault detection method
Technical Field
The application relates to the technical field of power transmission line protection, in particular to a fault detection method for an MMC-HVDC direct current power transmission line.
Background
High voltage direct current transmission (HVDC) is the preferred technology for long distance, high capacity power transmission. The Modular Multilevel Converter (MMC) adopts a modular cascade structure, so that direct series connection of switching devices is avoided, difficulty in manufacturing and engineering realization is greatly reduced, and the MMC is adopted in a flexible direct current transmission technology. The MMC-based flexible direct current transmission technology (MMC-HVDC) has the advantages of high waveform quality, strong fault processing capacity, small loss and the like, and therefore, the MMC-HVDC has wide application in the construction of direct current power grids.
In order to ensure the power supply reliability of the flexible direct-current power grid, after a direct-current fault occurs, a fault interval can be reliably identified, and the safe and stable operation of the rest part is ensured. Compared with the traditional alternating current system protection, the flexible direct current power grid protection is more difficult to realize the selectivity of the protection. For overcurrent protection, it ensures the selectivity of the protection action by the time step difference of the protection action and reliable tripping of the circuit breaker. In the flexible direct-current power grid, on one hand, the protection actions of adjacent direct-current lines have low discreteness; on the other hand, the performance of the dc circuit breaker is still not perfect. Therefore, for a flexible dc network, it is difficult to ensure the selectivity of protection by current protection. Unlike the conventional alternating current system in which current protection can meet the requirement of protection four, the existing flexible direct current system engineering is configured with over-current protection for fault detection.
In principle, the current differential protection allows fault detection and fault section localization for dc lines. Therefore, in order to achieve reliable identification of faults, actual flexible direct current transmission engineering is generally configured with line differential protection. However, in order to avoid the influence of the line distributed capacitance current, the line differential protection generally prevents the protection from malfunction by delaying, which also results in poor protection speed, and it is difficult to meet the requirement of the flexible dc power grid on protection speed. The current differential protection principle based on the berlon circuit model and the frequency variation parameter model can eliminate the influence of the line distributed capacitance current, but the protection principle also has some disadvantages: on one hand, the algorithm is more complex; on the other hand, problems such as data synchronization and channel delay exist, and the hardware cost and the protection action speed are also adversely affected. Therefore, for dc systems, such current differential protection is generally only used as backup protection. In addition, according to the fault characteristics of the MMC type dc system, if the grounding mode is configured properly, no significant fault current occurs when the dc grid has a unipolar ground fault.
As described above, in the MMC-HVDC system using the dc-side grounding method, if a unipolar ground fault occurs, the protection method based on the dc line current differential cannot detect the differential current, and thus cannot ensure the reliable operation of the protection device.
Disclosure of Invention
The application provides a fault detection method for an MMC-HVDC direct-current transmission line, which aims to solve the problems of low fault recognition rate, poor reliability and insufficient fault type judgment of a current differential protection method in the MMC-HVDC direct-current transmission line.
The technical scheme adopted by the application is as follows:
a fault detection method for an MMC-HVDC direct current transmission line comprises the following steps:
acquiring the positive and negative direct current power values of the rectifying side and the inverting side;
calculating the sum of the DC power value of the positive electrode at the rectification side and the DC power value of the negative electrode at the inversion side, and recording as PKMCalculating the sum of the DC power value of the negative electrode at the rectification side and the DC power value of the positive electrode at the inversion side, and recording as PMK；
If it is not
Figure BDA0002432101340000021
Judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault,
if it is not
Figure BDA0002432101340000022
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure BDA0002432101340000023
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure BDA0002432101340000024
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
Optionally, before the step of obtaining the positive and negative dc power values at the rectifying side and the positive and negative dc power values at the inverting side, the method further includes:
measuring positive and negative DC voltage value U of rectifying side1、U2Measuring the direct current value I of the positive and negative electrodes at the rectifying side1、I2Measuring the positive and negative DC voltage values U of the inverter side3、U4Measuring the DC current value I of the positive and negative electrodes on the inversion side3、I4The value of the direct current voltage U1-U4For a voltage to ground, the value of said direct current I1-I4Taking the flow direction of the direct current transmission line as a reference positive direction;
and calculating the direct current power values of the positive electrode and the negative electrode on the rectifying side and the direct current power values of the positive electrode and the negative electrode on the inverting side.
Optionally, in simultaneous comparison PKMAnd PMKThe step for determining the fault type of the MMC-HVDC system specifically comprises the following steps:
if it is not
Figure BDA0002432101340000025
Judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault,
if it is not
Figure BDA0002432101340000026
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure BDA0002432101340000027
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure BDA0002432101340000028
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
Optionally, in simultaneous comparison PKMAnd PMKThe step of determining the fault type of the MMC-HVDC system further comprises the following steps:
if it is not
Figure BDA0002432101340000029
And judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault.
Optionally, in the step of obtaining the positive and negative dc power values at the rectifying side and the positive and negative dc power values at the inverting side, the method further includes:
and performing sliding average filtering processing on the rectification side positive and negative direct current power values and the inversion side positive and negative direct current power values within preset time t to obtain a power average value within the preset time t.
Optionally, the power average is an arithmetic average.
Optionally, the preset time t is 5 ms.
Optionally, in simultaneous comparison PKMAnd PMKThe step of determining the fault type of the MMC-HVDC system further comprises the following steps:
if it is not
Figure BDA0002432101340000031
Judging that the MMC-HVDC system normally operates in a steady state or an AC side fault occurs, and not starting the protection action of the DC line;
if it is not
Figure BDA0002432101340000032
Judging that the MMC-HVDC system has an anode ground fault, starting a protection action, and disconnecting the anode of the MMC-HVDC direct-current transmission line;
if it is not
Figure BDA0002432101340000033
Judging that the MMC-HVDC system has a negative pole ground fault, starting a protection action, and disconnecting the negative pole of the MMC-HVDC direct-current transmission line;
if it is not
Figure BDA0002432101340000034
And judging that the MMC-HVDC system has a bipolar short-circuit fault, starting a protection action, and disconnecting the anode and the cathode of the MMC-HVDC direct-current transmission line at the same time.
Optionally, after performing filtering processing on the sliding average value within a preset time t on the rectification side positive and negative dc power values and the inversion side positive and negative dc power values, obtaining a power arithmetic average value within the preset time t, and determining the fault type through the following steps:
if it is not
Figure BDA0002432101340000035
Judging the normal steady-state operation or the AC side fault of the MMC-HVDC system, wherein P isKM_fAnd PMK_fAre respectively PKMAnd PMKA value after the sliding average filtering process;
if it is not
Figure BDA0002432101340000036
Determining the DC side fault of MMC-HVDC system, wherein PsetIs a set threshold value, and Pset＝0.1PN，PNThe rated transmission power of the MMC-HVDC system is obtained.
Optionally, if
Figure BDA0002432101340000037
In the step of judging that the MMC-HVDC system has direct current side fault, the method further comprises the following steps:
if it is not
Figure BDA0002432101340000038
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure BDA0002432101340000039
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure BDA00024321013400000310
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
The technical scheme of the application has the following beneficial effects:
the MMC-HVDC direct current transmission line fault detection method provided by the application obtains, compares and calculates the sum P of the direct current power value of the anode of the rectifying side and the direct current power value of the cathode of the inverting sideKMAnd the sum P of the DC power value of the negative electrode at the rectification side and the DC power value of the positive electrode at the inversion sideMK(ii) a Simultaneous PKMAnd PMKAnd data analysis and comparison are carried out, so that the type of the fault in the MMC-HVDC system is accurately judged, and the protection of the MMC-HVDC direct-current transmission line is realized very efficiently and simply. The method has better applicability and reliability and has larger engineering application value.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an MMC-HVDC system in the present application;
FIG. 2 is a schematic diagram of the fault principle of the MMC-HVDC system of the present application;
FIG. 3 is a flow chart of one embodiment of the present application;
FIG. 4 is a flow chart of another embodiment of the present application;
illustration of the drawings: FIG. 1 is a schematic block diagram of an MMC-HVDC system known to those skilled in the art; FIG. 2 is a schematic diagram of the fault principle of an MMC-HVDC system, wherein a rectifier station AC side fault f1AC side fault f of inverter station2And DC line fault f3The definitions of the parameters in the figures are described in detail in the examples, which are incorporated herein by referenceAnd are not described in detail. Fig. 4 is a flow chart of another embodiment of the present application, in fact, the technical solutions of various exemplary embodiments rather than only one embodiment are depicted in the flow chart, and those skilled in the art can easily conceive of more embodiments from the technical idea of the various embodiments.
Detailed Description
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following examples do not represent all embodiments consistent with the present application. But merely as exemplifications of systems and methods consistent with certain aspects of the application, as recited in the claims.
In the present application, the "MMC-HVDC direct current transmission line" and the "MMC-HVDC system" do not substantially differ, and belong to the description of the same object from different angles, which is well known to those skilled in the art, and should not be understood mechanically, nor should it be interpreted as a system with differences that are not well known to those skilled in the art.
Fig. 1 is a schematic structural diagram of an MMC-HVDC system in the present application.
The application provides a fault detection method for an MMC-HVDC direct current transmission line, which comprises the following steps:
acquiring the positive and negative direct current power values of the rectifying side and the inverting side;
calculating the sum of the DC power value of the positive electrode at the rectification side and the DC power value of the negative electrode at the inversion side, and recording as PKMCalculating the sum of the DC power value of the negative electrode at the rectification side and the DC power value of the positive electrode at the inversion side, and recording as PMK；
If it is not
Figure BDA0002432101340000041
Judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault,
if it is not
Figure BDA0002432101340000051
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure BDA0002432101340000052
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure BDA0002432101340000053
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
Referring to fig. 2, a schematic diagram of a fault principle of the MMC-HVDC system in the present application is shown. In the embodiment, the applicant analyzes the principle and the characteristics of the fault of the MMC-HVDC direct-current transmission line, when the fault on the alternating-current side occurs, the alternating-current voltage of the MMC-HVDC system and the power exchange between the alternating-current system and the direct-current system are both greatly reduced, and the voltage of the direct-current line and the current of the direct-current line are changed along with the change. The distributed capacitive current and its resulting voltage drop generated by the dc lines during an ac side fault transient is negligible compared to the fault current. Therefore, when an alternating current side fault occurs, the currents of the direct current line ends of the converter stations at two ends of the MMC-HVDC system are approximately equal, and the voltage amplitude of the direct current line end of the inverter station is smaller than the voltage amplitude of the direct current line end of the rectifier station but approximately equal. In the present application, unless otherwise specified, the two-end converter stations refer to a rectifier station and an inverter station; the dc side is relative to the rectifying side and the inverting side, and refers to the sum of the entire dc lines that are converted from the rectifying side to dc and then sent to the inverting side.
When a single-pole ground fault occurs, if the distributed capacitance of the direct-current line is not considered, the direct-current side fault superposition network does not have an earth circuit loop, and a loop formed by the direct-current line and the equivalent inductor of the current converter does not have a power supply, so that no current flows in each branch in the superposition network, and no superposed voltage exists in the equivalent inductor of the current converter. From this analysis it can be seen that: when the positive pole earth fault occurs, the voltage drop of the positive pole direct current line end of the converter stations at the two ends is zero, the voltage of the negative pole direct current line end is doubled, and the current flowing through the direct current line ends of the converter stations at the two ends is unchanged; when the negative pole earth fault occurs, the voltage drop of the negative pole direct current line end of the converter stations at the two ends is zero, the voltage of the positive pole direct current line end is doubled, and the current flowing through the direct current line ends of the converter stations at the two ends is unchanged.
When a bipolar short-circuit fault occurs, the current value and the voltage value of the direct-current line end of the converter stations at two ends exist tens of microseconds after the fault
Figure BDA0002432101340000054
In the formula iKpIs positive direct current of a rectification side; i.e. iKnIs rectified side negative pole direct current; i.e. iMpThe direct current is the positive electrode direct current of the inversion side;i Mnthe negative pole direct current is the inversion side direct current; u. ofKpIs a positive direct-current voltage at the rectifying side; u. ofKnIs a rectification side negative electrode direct current voltage; u. ofMpThe voltage is the positive direct current voltage of the inversion side; u. ofMnAnd inverting the negative DC voltage of the side.
The fault characteristics of the AC side and the DC side of the MMC-HVDC system are analyzed to obtain that: when a single-pole ground fault occurs, the voltages of the direct current positive and negative electrode lines are suddenly changed, and the currents of the direct current positive and negative electrode lines are not obviously changed; when a bipolar short-circuit fault occurs, the voltage and the current of the direct-current positive and negative electrode lines are greatly changed. The dc link side power is defined by integrating the dc link voltage and current values as P ═ ui, where u and i represent the voltage and current at the dc link side, respectively.
TABLE 1 MMC-HVDC System Electrical parameter values under various conditions
Figure BDA0002432101340000061
In the table, UdcAnd IdcAnd respectively representing the direct-current interelectrode voltage value and the direct-current line current value when the MMC-HVDC system is in normal steady-state operation. From table 1, the sum of the dc power values of different polar lines of the two-end converter stations (i.e. the sum of the dc power value of the positive pole at the rectification side and the dc power value of the negative pole at the inversion side, and the sum of the dc power value of the negative pole at the rectification side and the dc power value of the positive pole at the inversion side) is zero when the MMC-HVDC system is in normal steady-state operation and the ac side fails, and is zero when the single pole is in a ground fault and the double pole isAnd the short-circuit fault is not zero. The sum of the positive DC power at the rectification side and the negative DC power at the inversion side is recorded as PKMThe sum of the DC power of the negative electrode on the rectification side and the DC power of the positive electrode on the inversion side is denoted as PMKDefinition of PKMAnd PMKFor differential power:
Figure BDA0002432101340000062
if the MMC-HVDC system normally operates in a steady state or a fault occurs at the AC side, the fault can be obtained
Figure BDA0002432101340000063
If the positive pole of the MMC-HVDC system has a grounding fault, the method can be obtained
Figure BDA0002432101340000064
If the negative pole of the MMC-HVDC system has a ground fault, the method can be obtained
Figure BDA0002432101340000065
If a bipolar short-circuit fault occurs in the MMC-HVDC system, the fault can be obtained
Figure BDA0002432101340000066
By combining the analysis with the graph 3, the power values at the two ends of the rectifying side and the inverting side are selected and compared in a pilot mode, the fault type of the MMC-HVDC system can be efficiently and accurately judged, the applicability and the reliability are high, data collection is convenient and easy, the economic cost is saved, and the method has a high engineering application value.
Optionally, before the step of obtaining the positive and negative dc power values at the rectifying side and the positive and negative dc power values at the inverting side, the method further includes:
measuring the rectification side elevation,Negative DC voltage value U1、U2Measuring the direct current value I of the positive and negative electrodes at the rectifying side1、I2Measuring the positive and negative DC voltage values U of the inverter side3、U4Measuring the DC current value I of the positive and negative electrodes on the inversion side3、I4The value of the direct current voltage U1-U4For a voltage to ground, the value of said direct current I1-I4Taking the flow direction of the direct current transmission line as a reference positive direction;
and calculating the direct current power values of the positive electrode and the negative electrode on the rectifying side and the direct current power values of the positive electrode and the negative electrode on the inverting side.
In this embodiment, since the actual directly measured electrical physical quantities in the engineering application are generally voltage and current, the required voltage and current are directly measured in the early stage, and then the positive and negative dc power values at the rectifying side and the positive and negative dc power values at the inverting side are conveniently and quickly calculated.
Optionally, in simultaneous comparison PKMAnd PMKThe step for determining the fault type of the MMC-HVDC system specifically comprises the following steps:
if it is not
Figure BDA0002432101340000071
Judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault,
if it is not
Figure BDA0002432101340000072
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure BDA0002432101340000073
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure BDA0002432101340000074
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
Optionally, in simultaneous comparison PKMAnd PMKStep for determining fault type of MMC-HVDC systemIn the step, the method further comprises the following steps:
if it is not
Figure BDA0002432101340000075
And judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault.
In this embodiment, because the MMC-HVDC system inevitably has some interference of measurement errors or noise in practical application, where the measurement errors or noise refer to electrical physical quantities existing in a circuit, it is difficult to achieve an ideal zero equaling effect.
Optionally, in the step of obtaining the positive and negative dc power values at the rectifying side and the positive and negative dc power values at the inverting side, the method further includes:
and performing sliding average filtering processing on the rectification side positive and negative direct current power values and the inversion side positive and negative direct current power values within preset time t to obtain a power average value within the preset time t.
Referring to fig. 4, in this embodiment, since the instantaneous value may encounter measurement misalignment, interference, fluctuation, and other problems, the power average value obtained by selecting a certain short preset time t through the sliding average filtering process has high reliability. It should be noted that t should not be set too long or too short, otherwise the rapidity of fault determination is reduced. A relatively reasonable short preset time needs to be set to meet the requirement of data reliability.
Optionally, the power average is an arithmetic average.
Optionally, the preset time t is 5 ms.
In the embodiment, the preset time is not longer or shorter, the longer time cannot meet the timeliness, the shorter time can cause misjudgment due to the fluctuation of the value, and therefore in the practical engineering application, the preset time t is set to be 5ms, the reliability of data can be guaranteed, the instant physical quantity response of the MMC-HVDC system is met, and the effect is good in practice.
Optionally, in simultaneous comparison PKMAnd PMKThe step of determining the fault type of the MMC-HVDC system further comprises the following steps:
if it is not
Figure BDA0002432101340000076
Judging that the MMC-HVDC system normally operates in a steady state or an AC side fault occurs, and not starting the protection action of the DC line;
if it is not
Figure BDA0002432101340000077
Judging that the MMC-HVDC system has an anode ground fault, starting a protection action, and disconnecting the anode of the MMC-HVDC direct-current transmission line;
if it is not
Figure BDA0002432101340000081
Judging that the MMC-HVDC system has a negative pole ground fault, starting a protection action, and disconnecting the negative pole of the MMC-HVDC direct-current transmission line;
if it is not
Figure BDA0002432101340000082
And judging that the MMC-HVDC system has a bipolar short-circuit fault, starting a protection action, and disconnecting the anode and the cathode of the MMC-HVDC direct-current transmission line at the same time.
Referring to fig. 4, in the present embodiment, the fault type determination is combined with the protection action, which is beneficial to the safe operation of the power grid. In the actual grid operation process, it is a common practice to associate a fault with a protection action. In the embodiment, the fault type is determined through data judgment, and then the protection action corresponds to the fault type, so that the safety of a power grid system is effectively protected, and accidents and property loss are prevented.
Optionally, after performing filtering processing on the sliding average value within a preset time t on the rectification side positive and negative dc power values and the inversion side positive and negative dc power values, obtaining a power arithmetic average value within the preset time t, and determining the fault type through the following steps:
if it is not
Figure BDA0002432101340000083
Judging the normal steady-state operation or the AC side fault of the MMC-HVDC system, wherein P isKM_fAnd PMK_fAre respectively PKMAnd PMKA value after the sliding average filtering process;
if it is not
Figure BDA0002432101340000084
Determining the DC side fault of MMC-HVDC system, wherein PsetIs a set threshold value, and Pset＝0.1PN，PNThe rated transmission power of the MMC-HVDC system is obtained.
Referring to fig. 4, in this embodiment, since absolute zero is generally impossible to occur in reality, when determining that the MMC-HVDC system is operating normally in a steady state or an ac side fault occurs, the method employs
Figure BDA0002432101340000085
The judgment mode approximately equal to zero is more practical, and meanwhile, the condition of normal steady-state operation or AC side fault can be accurately judged.
Illustratively, to better apply to practice, 0.02P is chosenNIs used to perform a discrimination of approximately zero according to the formula
Figure BDA0002432101340000086
When it occurs
Figure BDA0002432101340000087
When it is considered to be
Figure BDA0002432101340000088
Therefore, the MMC-HVDC system is judged to be in normal steady-state operation or to have an AC side fault. Similarly, in order to avoid measurement errors or noise interference, when the direct current side fault of the MMC-HVDC system is judged, a threshold value is set, and the practicability and reliability of data are further guaranteed. 0.1PNWork ofThe rate quantities are already significant and it is generally considered that the effects of measurement errors or noise interference can be rejected.
Optionally, if
Figure BDA0002432101340000089
In the step of judging that the MMC-HVDC system has direct current side fault, the method further comprises the following steps:
if it is not
Figure BDA00024321013400000810
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure BDA0002432101340000091
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure BDA0002432101340000092
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
The MMC-HVDC direct current transmission line fault detection method provided by the application obtains, compares and calculates the sum P of the direct current power value of the anode of the rectifying side and the direct current power value of the cathode of the inverting sideKMAnd the sum P of the DC power value of the negative electrode at the rectification side and the DC power value of the positive electrode at the inversion sideMK(ii) a Simultaneous PKMAnd PMKAnd data analysis and comparison are carried out, so that the type of the fault in the MMC-HVDC system is accurately judged, and the protection of the MMC-HVDC direct-current transmission line is realized very efficiently and simply. The method has better applicability and reliability and has larger engineering application value.
The embodiments provided in the present application are only a few examples of the general concept of the present application, and do not limit the scope of the present application. Any other embodiments extended according to the scheme of the present application without inventive efforts will be within the scope of protection of the present application for a person skilled in the art.

Claims (10)

1. A fault detection method for an MMC-HVDC direct current transmission line is characterized by comprising the following steps:
acquiring the positive and negative direct current power values of the rectifying side and the inverting side;
calculating the sum of the DC power value of the positive electrode at the rectification side and the DC power value of the negative electrode at the inversion side, and recording as PKMCalculating the sum of the DC power value of the negative electrode at the rectification side and the DC power value of the positive electrode at the inversion side, and recording as PMK；
If it is not
Figure FDA0002432101330000011
Judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault,
if it is not
Figure FDA0002432101330000012
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure FDA0002432101330000013
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure FDA0002432101330000014
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
2. The MMC-HVDC direct current transmission line fault detection method of claim 1, further comprising, before the step of obtaining the rectification side positive and negative direct current power values and the inversion side positive and negative direct current power values:
measuring positive and negative DC voltage value U of rectifying side1、U2Measuring the direct current value I of the positive and negative electrodes at the rectifying side1、I2Measuring the positive and negative DC voltage values U of the inverter side3、U4Measuring the DC current value I of the positive and negative electrodes on the inversion side3、I4The value of the direct current voltage U1-U4For a voltage to ground, the value of said direct current I1-I4Taking the flow direction of the direct current transmission line as a reference positive direction;
and calculating the direct current power values of the positive electrode and the negative electrode on the rectifying side and the direct current power values of the positive electrode and the negative electrode on the inverting side.
3. The MMC-HVDC direct current transmission line fault detection method of claim 2, characterized in that P is compared simultaneouslyKMAnd PMKThe step for determining the fault type of the MMC-HVDC system specifically comprises the following steps:
if it is not
Figure FDA0002432101330000015
Judging that the MMC-HVDC system normally operates in a steady state or has an AC side fault,
if it is not
Figure FDA0002432101330000016
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure FDA0002432101330000017
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure FDA0002432101330000018
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
4. The MMC-HVDC direct current transmission line fault detection method of claim 3, characterized in that P is compared simultaneouslyKMAnd PMKThe step of determining the fault type of the MMC-HVDC system further comprises the following steps:
if it is not
Figure FDA0002432101330000019
Determining MMC-HVDC systemNormal steady state operation or an ac side fault.
5. The MMC-HVDC direct current transmission line fault detection method of claim 1, wherein in the step of obtaining the values of the positive and negative direct current power at the rectifying side and the values of the positive and negative direct current power at the inverting side, further comprising:
and performing sliding average filtering processing on the rectification side positive and negative direct current power values and the inversion side positive and negative direct current power values within preset time t to obtain a power average value within the preset time t.
6. The MMC-HVDC direct current transmission line fault detection method of claim 5, wherein the power average is an arithmetic average.
7. The MMC-HVDC direct current transmission line fault detection method of claim 5, wherein the preset time t is 5 ms.
8. The MMC-HVDC direct current transmission line fault detection method of claim 1, characterized in that P is compared simultaneouslyKMAnd PMKThe step of determining the fault type of the MMC-HVDC system further comprises the following steps:
if it is not
Figure FDA0002432101330000021
Judging that the MMC-HVDC system normally operates in a steady state or an AC side fault occurs, and not starting the protection action of the DC line;
if it is not
Figure FDA0002432101330000022
Judging that the MMC-HVDC system has an anode ground fault, starting a protection action, and disconnecting the anode of the MMC-HVDC direct-current transmission line;
if it is not
Figure FDA0002432101330000023
Judging that the MMC-HVDC system has a negative pole ground fault, starting a protection action, and disconnecting the negative pole of the MMC-HVDC direct-current transmission line;
if it is not
Figure FDA0002432101330000024
And judging that the MMC-HVDC system has a bipolar short-circuit fault, starting a protection action, and disconnecting the anode and the cathode of the MMC-HVDC direct-current transmission line at the same time.
9. The MMC-HVDC direct current transmission line fault detection method of claim 5, characterized in that after the sliding average filtering processing within a preset time t is performed on the rectification side positive and negative direct current power values and the inversion side positive and negative direct current power values, a power arithmetic average within a preset time t is obtained, and the fault type is judged through the following steps:
if it is not
Figure FDA0002432101330000025
Judging the normal steady-state operation or the AC side fault of the MMC-HVDC system, wherein P isKM_fAnd PMK_fAre respectively PKMAnd PMKA value after the sliding average filtering process;
if it is not
Figure FDA0002432101330000026
Determining the DC side fault of MMC-HVDC system, wherein PsetIs a set threshold value, and Pset＝0.1PN，PNThe rated transmission power of the MMC-HVDC system is obtained.
10. The MMC-HVDC direct current transmission line fault detection method of claim 9, wherein the if is
Figure FDA0002432101330000031
In the step of judging that the MMC-HVDC system has direct current side fault, the method further comprises the following steps:
if it is not
Figure FDA0002432101330000032
Determining that the positive earth fault occurs in the MMC-HVDC system,
if it is not
Figure FDA0002432101330000033
Determining that the negative pole of the MMC-HVDC system has a ground fault,
if it is not
Figure FDA0002432101330000034
And judging that the MMC-HVDC system has a bipolar short-circuit fault.
CN202010239546.8A 2020-03-30 2020-03-30 MMC-HVDC direct current transmission line fault detection method Pending CN111398851A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010239546.8A CN111398851A (en) 2020-03-30 2020-03-30 MMC-HVDC direct current transmission line fault detection method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010239546.8A CN111398851A (en) 2020-03-30 2020-03-30 MMC-HVDC direct current transmission line fault detection method

Publications (1)

Publication Number Publication Date
CN111398851A true CN111398851A (en) 2020-07-10

Family

ID=71434852

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010239546.8A Pending CN111398851A (en) 2020-03-30 2020-03-30 MMC-HVDC direct current transmission line fault detection method

Country Status (1)

Country Link
CN (1) CN111398851A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111999595A (en) * 2020-07-30 2020-11-27 国网天津市电力公司电力科学研究院 MMC-HVDC power transmission line fault judgment method
CN112290517A (en) * 2020-10-19 2021-01-29 国网江苏省电力有限公司南京供电分公司 Flexible controller protection method based on power quantity
CN114583669A (en) * 2020-12-02 2022-06-03 上海交通大学 MMC-HVDC power transmission line protection method based on virtual energy adjustment deviation

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106711969A (en) * 2017-01-17 2017-05-24 西安科技大学 Pilot protection method for double ultrahigh voltage direct current transmission line based on modulus saltation
CN106877298A (en) * 2017-03-27 2017-06-20 上海交通大学 MMC HVDC system dc line protection methods
CN107064737A (en) * 2017-03-27 2017-08-18 上海交通大学 MMC HVDC transmission line fault detection methods based on mutation power
US20170331390A1 (en) * 2015-08-26 2017-11-16 Zhejiang University An lcc and mmc series-connected hvdc system with dc fault ride-through capability
CN107565590A (en) * 2017-09-06 2018-01-09 合肥工业大学 The mixed high-voltage DC transmission system sent outside suitable for wind-powered electricity generation
CN110361627A (en) * 2019-06-24 2019-10-22 昆明理工大学 A kind of single-ended traveling wave fault location method based on MMC-HVDC

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170331390A1 (en) * 2015-08-26 2017-11-16 Zhejiang University An lcc and mmc series-connected hvdc system with dc fault ride-through capability
CN106711969A (en) * 2017-01-17 2017-05-24 西安科技大学 Pilot protection method for double ultrahigh voltage direct current transmission line based on modulus saltation
CN106877298A (en) * 2017-03-27 2017-06-20 上海交通大学 MMC HVDC system dc line protection methods
CN107064737A (en) * 2017-03-27 2017-08-18 上海交通大学 MMC HVDC transmission line fault detection methods based on mutation power
CN107565590A (en) * 2017-09-06 2018-01-09 合肥工业大学 The mixed high-voltage DC transmission system sent outside suitable for wind-powered electricity generation
CN110361627A (en) * 2019-06-24 2019-10-22 昆明理工大学 A kind of single-ended traveling wave fault location method based on MMC-HVDC

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
宁连营: "MMC-HVDC 直流输电线路保护原理研究", 《中国优秀博硕士学位论文全文数据库(硕士)工程科技Ⅱ辑(月刊)》 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111999595A (en) * 2020-07-30 2020-11-27 国网天津市电力公司电力科学研究院 MMC-HVDC power transmission line fault judgment method
CN111999595B (en) * 2020-07-30 2024-01-26 国网天津市电力公司电力科学研究院 MMC-HVDC power transmission line fault judging method
CN112290517A (en) * 2020-10-19 2021-01-29 国网江苏省电力有限公司南京供电分公司 Flexible controller protection method based on power quantity
CN114583669A (en) * 2020-12-02 2022-06-03 上海交通大学 MMC-HVDC power transmission line protection method based on virtual energy adjustment deviation

Similar Documents

Publication Publication Date Title
CN106707081B (en) flexible direct current power distribution network monopole grounding fault identification and fault protection method
CN106680670B (en) A kind of flexible direct current power distribution network monopolar grounding fault recognition methods and device
CN108469576B (en) Direct-current fault detection method for multi-terminal alternating-current and direct-current hybrid power distribution network
CN111398851A (en) MMC-HVDC direct current transmission line fault detection method
CN108226708B (en) Quick fault discrimination method for multi-terminal direct-current power grid containing MMC
CN114295935B (en) Low-voltage measurement-based low-current system medium-voltage single-phase grounding fault positioning method
CN109617026B (en) Ultrahigh-speed protection method for earth fault of direct-current power grid converter station
CN109617027B (en) High-frequency sudden-change distance protection method for flexible direct-current power distribution system
CN107069682A (en) A kind of HVDC transmission line back-up protection method based on DC control system
CN110350493B (en) Medium-voltage flexible direct-current system fault detection method based on line current second-order derivative
CN110609215A (en) Flexible direct-current transmission line fault detection method and system based on transient current
CN111740391B (en) Transient high-frequency power protection method and device for annular direct-current ship power distribution network
CN105071426A (en) Fault recovery control method and system for multi-infeed direct-current power transmission system
CN111289843B (en) MMC-MTDC system direct-current line interelectrode fault distance measurement method
CN112578198A (en) Transient current characteristic-based ship MMC-MVDC rapid fault protection method
CN108808634B (en) High-voltage direct-current transmission line pilot protection method based on smoothing reactor voltage
CN112083280B (en) Method for identifying fault interval of hybrid multi-terminal direct-current power transmission system
CN110323726B (en) Self-adaptive line protection method and device for direct-current power distribution network
CN108599116B (en) Direct-current line protection method suitable for alternating-current and direct-current hybrid power distribution network
CN116417976A (en) Direct current distribution network ground fault protection method based on positive and negative current correlation
CN109510177B (en) Voltage sudden change protection method for direct current transmission line
CN115425623A (en) Transient current ratio-based multi-terminal flexible direct-current transmission line pilot protection method
CN114744596B (en) Flexible direct current system pilot protection method and system based on voltage matching factor
CN113659548B (en) Power distribution network pilot protection method and system based on positive sequence fault component energy direction
CN111682510A (en) First-removal and then-isolation protection method for ground fault of symmetrical unipolar direct-current microgrid

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication
RJ01 Rejection of invention patent application after publication

Application publication date: 20200710