• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for triggering a distance protection relay monitoring a zone, in which a line impedance value is determined at predetermined time steps. In order to allow a reliable fault location before the decay of transient transition effects, despite the use of voltage transformers with an unfavorable transmission behavior, it is proposed that each time step, the amount of change of a change vector between the particular for the respective time step and the respective preceding time step line impedance value and from the to associated with each time step, determined line impedance value and a zone limit impedance value determined change amount limit value (10) and, if a predetermined number of each time step associated change amounts below the respective time step associated change amount limit (10), the line impedance value of the last time step to generate a trigger signal (8) is output as a function of the zone limit impedance value.
    公开号:AT520806A1
    申请号:T50013/2018
    申请日:2018-01-11
    公开日:2019-07-15
    发明作者:Kleemann Michael
    申请人:Sprecher Automation Gmbh；
    IPC主号:
    专利说明:

    Summary
    A method for triggering a distance protection relay monitoring a zone is described, in which a line impedance value is determined in predetermined time steps. In order to enable reliable fault location determination before the transient transition effects have subsided, despite the use of voltage transformers with an unfavorable transmission behavior, it is proposed that each time step the change amount of a change vector between the line impedance value determined for the respective time step and the previous time step, as well as one from the each time step is assigned a specific line impedance value and a zone limit impedance value determined change amount limit value (10) and, if a predetermined number of change amounts assigned to a time step lies below the change amount limit value (10) assigned to the respective time step, the line impedance value of the last time step to generate a trigger signal (8) depending on the zone limit impedance value.
    (Fig. 1) / 11 (41834) IV
    The invention relates to a method for triggering a distance protection relay monitoring a zone, in which a line impedance value is determined in given magazines.
    Distance protection relays are used in power supply networks in order to enable selective shutdown of an affected line section in the event of a fault. In order to be able to determine the fault location as precisely as possible, the line impedance must be determined exactly by measuring the current and voltage. The voltage measurement is often carried out via inductive voltage converters, since they can follow the voltage curve on the top very well and thus have good transmission behavior. With increasing voltage, however, inductive voltage converters are becoming increasingly uneconomical to use due to the associated increase in size. Capacitive voltage transformers (CVT) are therefore preferably used for voltage measurement in voltage ranges above 100 kV, but they have the serious disadvantage that they are subject to strong transient transition effects in the event of a fault and therefore impair the determination of the fault location. This means that CVTs have a significantly poorer transmission behavior than inductive voltage converters.
    In order to enable the use of CVTs as voltage converters for distance protection relays, it is known from the prior art to wait a fixed period of time between the occurrence of a line fault and the disappearance of all transient transition effects. With this method, disadvantageously, valuable time elapses before the distance protection relay is triggered. Of
    2/11
    Furthermore, it is proposed in US20080239602A1 to compensate for transient effects using recursive filters. However, this type of compensation requires high computing power and leads to comparatively long settling times. In addition, it is known from the prior art to improve the transmission behavior by using inverse transmission functions, which, however, requires exact mathematical models which require precise knowledge of the CVT used and the method used to determine the line impedance.
    The invention is therefore based on the object of providing a method which, despite the use of a voltage converter with an unfavorable transmission behavior, enables reliable determination of the fault location before the transient transition effects have subsided.
    The invention achieves the object in that each time step is assigned the amount of change in a change vector between the line impedance value determined for the respective time step and the previous time step, as well as a change amount limit value determined from the respective time step and a zone limit impedance value, and if a predetermined number of change amounts assigned to a time step is below the change amount limit value assigned to the respective time step, the line impedance value of the last time step for generating a trigger signal is output as a function of the zone limit impedance value.
    The method according to the invention is based on the knowledge that the amounts of change in the change vectors during the decay of the transient transition effects decrease over time after the occurrence of most line faults, thereby making it possible to estimate the progress of the transient transition effects without a mathematical model of the transmission behavior of the voltage converter for this is needed. For this purpose, the line impedance value is determined in predetermined time steps in a manner known to the person skilled in the art
    3/11, in which the instantaneous values of current and voltage are usually measured and from this the complex line impedance value is determined. For each time step, the change amount is then determined as the vectorial amount of the change vector between the respective and the preceding complex line impedance value. In addition, a change amount limit value is determined for each time step, taking into account the zone limit impedance value specified for the respective distance protection relay and the line impedance value determined for the respective time step. The ratio of these two values to each other allows a conclusion to be drawn as to how close any line fault is to the border of the monitored zone. The amount of change limit is therefore determined in such a way that it decreases the closer a possible line fault is to the boundary of the monitored zone, and that it increases the further a possible line fault is from the boundary of the monitored zone and is therefore clearly within the zone. As soon as a predetermined number of change amounts assigned to a time step, preferably immediately following one another, is below the change amount limit value assigned to the respective time step, it can be assumed for most line faults that the transient transition effects of the voltage converter have decayed to such an extent that it can be determined with sufficient certainty. whether the line fault occurred inside or outside the monitored zone, regardless of which voltage transformer is used for the measurement and which method is used to determine the complex line impedance values. For this purpose, the line impedance value is used which was determined at the time step at which the predetermined number of change amounts below the respective change amount limit values was reached. This number can preferably be between 3 and 5. The trigger signal itself can also be derived in a manner known to those skilled in the art from the relationship between the line impedance value and the zone limit impedance value. In order to be able to rule out the influence of offset errors as far as possible, it is proposed according to the invention that the trigger signal be determined only on the basis of the reactance, that is to say the imaginary part of the line impedance value and the zone limit impedance value. As a result of the measures according to the invention
    4/11, a reliable tripping signal can be issued before the transient transition effects die down, on the basis of which the distance protection relay trips the assigned circuit breaker.
    Since, in particular, the line impedance in the event of line faults occurring close to the zone boundary must be precisely determined for the generation of a correct trigger signal, it is proposed that the change amount limit value for a magazine decrease with a narrowing distance between the line impedance value and the zone limit impedance value. As a result, the line impedance value for the trigger signal in the event of line faults close to the zone boundary is only used when the transient transition effects have already subsided considerably. Particularly favorable triggering conditions arise in this context if the change amount limit value reaches a predetermined minimum with a ratio between the line impedance value and the zone limit impedance value by 1 and increases linearly from this minimum value as the ratio increases or decreases up to a predetermined maximum value. In this way, a distance protection relay for carrying out the method according to the invention can be configured with particularly few parameters.
    Although the proposed method is suitable for many types of line faults, arcing leads to change amounts which are not, or only at a very late point in time, successively below the determined change amount limit values. In order to be able to recognize the formation of arcs at an early stage, it is proposed that the rate of change in the angle of the change vector be assigned to each magazine and, if the rate of change exceeds a predetermined rate of change in the arc angle, a trigger signal is output. Since the rate of change of the angle of the change vector in arcs typically follows the random principle and can thus be distinguished from conventional line faults in which the angle of the change vector remains essentially constant, an arc can be reliably detected and the affected line section can be switched off immediately.
    5/11
    The subject matter of the invention is shown in the drawing, for example.
    Show it
    1 shows a schematic illustration of a distance protection relay for carrying out the method according to the invention in a block diagram,
    2 is a diagram showing an example relationship between the change amount limit value and the relationship between the line impedance value and the zone limit impedance value
    3 shows the time course of the change amounts and the change amount limit value also in a diagram.
    A distance protection relay for carrying out the method according to the invention comprises a current transformer 1 and a voltage transformer 2 for measuring the instantaneous current and voltage values of a power line 3. A line impedance value is determined from the measured current and voltage values at predetermined time steps, by means of an impedance measuring device 4. Die Individual line impedance values are transferred to a stability monitor 5, which stores the respective line impedance value in a memory 6 in order first to form the amount of change in the change vector between the line impedance value determined for the respective time step and the previous time step and to also store this in the memory 6. In addition, in the stability monitor 5 a change amount limit value determined from the line impedance value for the respective time step and a predetermined zone limit impedance value is determined, which is also stored in the memory 6 and is associated with the associated change amount that was determined at the same time step.
    The memory 6 is queried by a trigger unit 7, which checks for a predetermined number of change amounts in the memory 6 whether these are below the associated change amount limit values, which are also stored in the memory 6. If this is the case, the tripping unit 7 determines on the basis of the last line impedance value, which is used for this purpose by the stability monitor 5
    6/11 is passed and the predefined zone limit impedance value the estimated position of the line fault and outputs a trigger signal 8 for the assigned circuit breaker if the line fault lies within the monitored zone.
    In order to detect line faults at an early stage, which are based on the formation of arcs, the distance protection relay can have a monitoring unit 9, which determines the rate of change of the angle of the change vector at each time step and emits a trigger signal 8 prematurely if the rate of change exceeds a predetermined rate of change in the arc angle.
    2 schematically shows the relationship between the change amount limit value 10 and the ratio 11 between the line impedance value and the zone limit impedance value. The change amount limit value 10 increases linearly from a minimum value 12 at a ratio 11 by 1 on both sides up to a maximum value 13. Accordingly, the change amount limit value 10 changes in a plurality of successive time steps 14 when the ratio 11 between the line impedance value and the zone limit impedance value also changes, as is shown, for example, in FIG. 3. Only when a predetermined number of change amounts 15 is below the respective change amount limit value 10, a trigger signal 8 is output via the trigger unit 7.
    7/11
    patent attorneys
    Dipl.-Ing. Helmut Hübscher
    Dipl.-Ing. Gerd pretty
    Dipl.-Ing. Karl Winfried Hellmich
    Spittelwiese 4, 4020 Linz (41834) IV
    权利要求:
    Claims (3)
    [1]
    claims
    1.Procedure for triggering a distance monitoring relay monitoring a zone, in which a line impedance value is determined in predetermined time steps, characterized in that each time step the amount of change in a change vector between the line time value determined for the respective time step and the previous time step as well as one from that for the respective time step Time step is assigned to a specific line impedance value and a change limit value (10) determined for a zone limit impedance value and, if a predetermined number of change amounts assigned to a time step lies below the change amount limit value (10) assigned to the respective time step, the line impedance value of the last time step to generate a trigger signal (8) in Dependency of the zone limit impedance value is output.
    [2]
    2. The method according to claim 1, characterized in that the change amount limit value (10) for a magazine decreases with a decreasing distance between the line impedance value and the zone limit impedance value.
    [3]
    3. The method according to any one of claims 1 to 2, characterized in that the rate of change of the angle of the change vector is assigned to each time step and, if the rate of change exceeds a predetermined arc angle change rate, a trigger signal (8) is output.
    8/11
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP2008187825A|2007-01-30|2008-08-14|Mitsubishi Electric Corp|Distance relaying apparatus|
    WO2009095040A1|2008-01-31|2009-08-06|Siemens Aktiengesellschaft|Distance protection and method for monitoring an electrical power transmission line|
    WO2010048972A1|2008-10-27|2010-05-06|Siemens Aktiengesellschaft|Fault location in electrical power supply grids using the distance protection principle|CN111525523A|2020-05-13|2020-08-11|中国大唐集团科学技术研究院有限公司华东电力试验研究院|New energy power station relay protection fixed value checking method and system based on big data|DE2237854C3|1972-08-01|1980-09-04|Siemens Ag, 1000 Berlin Und 8000 Muenchen|Distance protection relay with a polygonal tripping characteristic|
    DE19920654A1|1999-05-05|2000-11-09|Abb Research Ltd|Determining conductor impedance threshold involves automatically deriving threshold value from predefined threshold value depending on determined degree of dependability of current value|
    US7457088B2|2004-09-29|2008-11-25|Schweitzer Engineering Laboratories, Inc.|Systems and methods for protection of electrical networks|
    US8736297B2|2008-07-17|2014-05-27|Siemens Aktiengesellschaft|Method for production of a fault signal, and an electrical protective device|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50013/2018A|AT520806B1|2018-01-11|2018-01-11|Procedure for triggering a distance protection relay monitoring a zone|ATA50013/2018A| AT520806B1|2018-01-11|2018-01-11|Procedure for triggering a distance protection relay monitoring a zone|
    EP19151252.4A| EP3521841B1|2018-01-11|2019-01-10|Method for tripping a zone monitored by a distance protection relay|
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