CN108627739B - Fault area determination method and system for full-line quick-action protection - Google Patents
Fault area determination method and system for full-line quick-action protection Download PDFInfo
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- 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
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Abstract
The invention relates to a fault area judgment method and a system for full-line quick-action protection, wherein the method comprises the following steps: acquiring voltage traveling waves measured by a protection device; judging whether a line where the protection device is located has a fault according to the voltage traveling wave and a preset voltage setting value upper limit; if so, acquiring the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current moment by taking the moment of detecting the fault as the current moment; if the voltage change rate is smaller than the preset reference change rate, judging that the fault area is positioned on the line side of the smoothing reactor; and if the voltage change rate is greater than the preset reference change rate, judging that the fault area is positioned on the bus side of the smoothing reactor. Therefore, on one hand, the voltage traveling wave is analyzed, so that the speed is high, and the requirement on the speed of a protection system can be met; on the other hand, the voltage change rate within the preset time after the fault occurs is utilized to analyze and judge the fault area, and the judgment accuracy is high.
Description
Technical Field
The invention relates to the technical field of power systems, in particular to a fault area judgment method and system for full-line quick-action protection.
Background
The direct current transmission line can be divided into three types of overhead lines, cable lines and overhead-cable hybrid lines. The transmission power of the direct current transmission line is high, and after a fault occurs, the protection device is required to act as fast as possible to remove the fault, otherwise, the whole system is greatly impacted, and the safe and stable operation of the system is threatened. Full line snap protection is a measure for rapidly protecting a line by a protection device (such as a relay) on a direct current transmission line after detecting a fault.
In the traditional method for carrying out full-line quick-acting protection on a high-voltage direct-current transmission line, protection is usually carried out after a fault area is judged by adopting a power frequency protection method or a traveling wave distance measurement method. For power frequency protection, the requirements of high-voltage direct-current transmission line protection are difficult to meet due to the slow action speed and the large time consumption of the power frequency protection; for traveling wave ranging, a high-voltage direct-current transmission line is generally connected in series with a smoothing reactor, one end of the smoothing reactor is a bus side, and the other end of the smoothing reactor is a line side; because the smoothing reactor has certain interference to the traveling wave, whether the fault area is on the bus side of the smoothing reactor or the line side of the smoothing reactor cannot be accurately judged, and the fault protection efficiency is low.
Disclosure of Invention
In view of the above, it is desirable to provide a fault area determination method and system for full-line quick-action protection, which improves the fault protection efficiency.
A fault area judgment method for full-line quick-action protection comprises the following steps:
acquiring voltage traveling waves measured by a protection device;
judging whether a line where the protection device is located has a fault according to the voltage traveling wave measured by the protection device and a preset voltage setting value upper limit;
if so, acquiring the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current moment by taking the moment of detecting the fault as the current moment;
if the voltage change rate is smaller than a preset reference change rate, determining that the fault area is located on the line side of the smoothing reactor;
and if the voltage change rate is greater than the preset reference change rate, determining that the fault area is located on the bus side of the smoothing reactor.
A failure region determination system for full-line snap-action protection, comprising:
the traveling wave acquisition module is used for acquiring voltage traveling waves measured by the protection device;
the fault judging module is used for judging whether a line where the protection device is located has a fault according to the voltage traveling wave measured by the protection device and a preset voltage setting value upper limit;
the voltage change rate acquisition module is used for acquiring the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current moment by taking the moment of detecting the fault as the current moment when the fault occurs;
the first area judgment module is used for judging that the fault area is positioned on the line side of the smoothing reactor when the voltage change rate is smaller than a preset reference change rate;
and the second region judgment module is used for judging that the fault region is positioned on the bus side of the smoothing reactor when the voltage change rate is greater than the preset reference change rate.
According to the fault area judging method and system of the full-line quick-action protection, whether a line where the protection device is located has a fault is judged according to the voltage traveling wave measured by the protection device and the preset voltage setting value upper limit, and if the line where the protection device is located has the fault, the voltage change rate of the voltage traveling wave measured in the preset time after the fault occurrence moment is detected is compared with the preset reference change rate; if the voltage change rate is smaller than the preset reference change rate, judging that the fault area is positioned on the line side of the smoothing reactor; and if the voltage change rate is greater than the preset reference change rate, judging that the fault area is positioned on the bus side of the smoothing reactor. Therefore, on one hand, the voltage traveling wave is analyzed, so that the speed is high, and the requirement on the speed of a protection system can be met; on the other hand, the voltage change rate within the preset time after the fault occurs is utilized to analyze and judge the fault area, and the judgment accuracy is high; therefore, the accuracy and efficiency of fault discrimination can be improved, and the efficiency of fault protection can be improved.
Drawings
FIG. 1 is a partial block diagram of a DC cable;
FIG. 2 is a flow chart of a method for determining a fault region for full line snap action protection in one embodiment;
FIG. 3 is a flow chart of a method for determining a fault region for full line snap action protection in another embodiment;
FIG. 4 is a block diagram of a fault region determination system for full line snap action protection in one embodiment;
fig. 5 is a block diagram of a fault area determination system for full line snap action protection in another embodiment.
Detailed Description
When the direct current transmission line has a fault, a fault voltage traveling wave and a current traveling wave are generated at a fault point due to the charging and discharging processes of the distributed capacitance and inductance of the direct current transmission line and respectively flow to buses at two sides of the direct current transmission line. When a high-voltage direct-current overhead line breaks down, the process of short-circuit failure is divided into three stages in terms of failure characteristics: an initial traveling wave phase, a transient phase, and a steady state phase.
And (3) initial traveling wave stage: after a fault, the line capacitor discharges through line impedance, and energy stored in the line electric field and the line magnetic field is converted into fault current traveling waves and corresponding voltage traveling waves. Wherein the current traveling wave amplitude depends on the line wave impedance and the dc voltage value at the fault point immediately before the fault. The current of the arc channel of the line to ground fault point is the sum of traveling wave currents flowing to the fault point from two sides, and the current is not controlled by a control system of the two-end converter station before the traveling wave is reflected or refracted for the first time. After back and forth reflection and refraction, the fault current shifts to a transient state.
Transient state stage: the main components of the fault current of the direct current line are as follows: a direct current component with pulsation and varying amplitude (forced component) and a transient oscillation component (free component) determined by the direct current main loop parameters. At this stage, the constant current control in the control system starts to play a more remarkable role, the rectifying side and the inverting side respectively adjust to increase the hysteresis trigger angle, and the current flowing to the fault point at the two ends of the line is restrained. The traditional protection principle based on current, voltage amplitude or phase variation is to use fault components in the transient phase, but the action performance is far inferior to that of traveling wave protection: firstly, the reaction speed is much slower than that of traveling wave protection; secondly, due to the action of constant current control, the amplitude and the change rate of fault current and voltage are reduced, the difficulty of fault identification is increased, and even the direction of the fault current can be changed, so that incorrect protection action is caused.
And (3) steady-state stage: finally, the fault current enters a steady state, fault current steady-state values provided by the fault currents on the two sides are controlled to be respectively equal to setting values of the respective constant current controllers, the directions of the currents flowing into fault points on the two sides are opposite, and the difference between the currents on the fault points is the current margin.
The fault transient characteristic analysis of the high-voltage direct-current transmission line is as follows:
smoothing reactors are connected in series at two ends of a direct current cable of the high-voltage direct current transmission system to filter current harmonics. Fig. 1 shows a partial structure of a dc cable, in which protection devices (relays and breakers) are R, devices between F1 and F2 are smoothing reactors, F1 denotes a fault point on a line side of the smoothing reactor, F2 denotes a fault point on a bus side of the smoothing reactor, F3 denotes a fault point on the other side of the protection device R, a first section is a first protection region of the protection device R, and a second section is a second protection region of the protection device R.
After a fault, the voltage and current measured at the cable end can be represented by a traveling wave. As in fig. 1, the characteristics of a fault F1 or F2 can be represented by a grid diagram represented by the time axis t, a travelling wave being generated by the fault location and propagating to the protection device R, and then a part of the wave being reflected back to the fault location and another part of the wave being refracted to other parts of the grid. During this time period, the voltage wave or the current wave reflected from the other end is superimposed in the cable. The protection device R measures the first reflected wave, i.e. U, of the voltage current generated at the fault point F1 or F2RAnd IRThe following formulas (1) to (2).
UR＝(1+)*A*Ufault(1)；
IR＝(1-)*A*Ifault(2)；
Wherein, the reflection coefficient is determined by the characteristic impedance of the cable and the cable termination impedance; a represents the wave propagation coefficient on the cable, determined by the cable parameters and the cable length; u shapefaultAnd IfaultThe voltage and the current of a cable fault point are determined by a fault position and fault impedance; the first reflection of the traveling wave is determined only by the faulty cable characteristics and the termination impedance of the cable in which it is located.
1) Let the fault point F1 occur on the smoothing reactor line side at the end of the cable. The fault voltage is expressed by the fault resistance and the cable impedance as the following equation (3).
Wherein, Ufault，F1Is the fault voltage, U, of the fault point F10Is the pre-fault voltage at fault point F1; rfIs a fault resistance, ZcIs the cable wave impedance, 1/2 in equation because the fault resistance is in series with the cable impedance at both ends. Likewise, the fault F2 is a fault voltage U of a metallic faultfault，F2Namely, the following formula (4).
Wherein L is the inductance value of the smoothing reactor, sL is the frequency domain value of the smoothing reactor, ZcIs the wave impedance of the cable, U0U0 is the voltage before the F2 point fault. The difference between the equations (3) and (4) is that the series inductance L filters out Ufault，F2Middle high frequency component, fault resistance RfMake Ufault，F1The amplitude decays.
2) Terminal reflection: the reflection coefficient links the traveling wave and the reflected wave. The metallic fault occurs to the uniform lossless pure inductive terminal circuit, and the time domain values of the formula (1) and the formula (2) are as follows:
wherein u isfaultIs the amplitude of the voltage travelling wave, ifaultIs the value of the current wave, time constant L/ZcE is the base of the natural logarithm, e is 2.718; t is a time variable.
Based on the analysis, the invention provides a fault area judgment method for full-line quick-action protection.
Referring to fig. 2, a method for determining a fault region of full-line snap-action protection in an embodiment includes the following steps.
S110: and acquiring the voltage traveling wave measured by the protection device.
The protection device refers to a device for realizing line fault protection, such as a relay and a circuit breaker. And acquiring the voltage travelling wave measured by the protection device in real time.
S130: and judging whether the line where the protection device is positioned has a fault according to the voltage traveling wave measured by the protection device and the preset voltage setting value upper limit. If yes, go to step S150.
The preset voltage setting value upper limit is used for judging the fault state and the normal state and can be stored in advance.
In one embodiment, referring to fig. 3, step S130 includes step S131.
S131: and judging whether the voltage value of the voltage traveling wave measured by the protection device is smaller than the upper limit of the preset voltage setting value. If yes, it is determined that the line in which the protection device is located has a fault, and step S150 is executed.
The fault characteristics of the line are that the voltage value is reduced and the current value is increased; the voltage traveling wave is mostly reflected by the series inductor, and the current wave is slowly increased. Therefore, the voltage value of the voltage traveling wave is lower than the upper limit of the preset voltage setting value and serves as a fault occurrence criterion, whether a fault occurs can be analyzed according to the voltage traveling wave, and the criterion is simple and high in accuracy.
In one embodiment, the preset voltage setting upper limit is 85% of the line voltage when the line in which the protection device is located is normal. Through careful research, test and selection, the 85% voltage value of the line voltage under the normal state of the line is used as a dividing point between the fault state and the normal state and is used for comparing with the voltage value of the voltage traveling wave to judge whether the fault occurs, and the accuracy is higher.
S150: and acquiring the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current moment by taking the moment of detecting the fault as the current moment.
The preset duration can be specifically set according to actual needs. Obtaining the voltage change rate of the voltage traveling wave measured by the protection device within the preset time after the current moment, including: obtaining a voltage value of the voltage traveling wave measured by the protection device at a corresponding moment with a preset time length after the current moment to obtain a first voltage value; calculating the difference value between the first voltage value and the voltage value of the voltage traveling wave measured by the protection device at the current moment; and dividing the difference value by a preset time length to obtain the voltage change rate.
The voltage change rate may represent a rate of voltage change of the voltage traveling wave within a preset time period. The voltage change rate is acquired when the fault is detected, so that the subsequent area analysis is carried out according to the voltage change rate.
S170: and if the voltage change rate is smaller than the preset reference change rate, judging that the fault area is positioned on the line side of the smoothing reactor.
The preset reference change rate can be preset and stored according to actual needs.
The biggest difference between a fault on the line side of the smoothing reactor and a fault on the bus side of the smoothing reactor is the high frequency component in the voltage. The transient of the fault on the line side of the smoothing reactor is attenuated by the fault resistance. The transient high-frequency component of the fault on the bus side of the smoothing reactor is filtered by the inductor. Since the fault on the line side of the smoothing reactor is close to the protection device, the rate of reduction of the voltage value at the time of the fault on the line side of the smoothing reactor is higher than the rate of reduction of the voltage value on the bus side of the smoothing reactor, and the rate is used as a reference for region determination.
Since the voltage value decreases at the time of failure, the voltage change rate takes a negative value. If the voltage change rate is smaller than the preset reference change rate, the change rate of the voltage value is higher than the rate corresponding to the preset reference change rate, the voltage change is fast, and at the moment, the fault area is judged to be the smoothing reactor line side.
S190: and if the voltage change rate is greater than the preset reference change rate, judging that the fault area is positioned on the bus side of the smoothing reactor.
If the voltage change rate is larger than the preset reference change rate, the change rate of the voltage value is lower than the rate corresponding to the preset reference change rate, the voltage change is slow, and at the moment, the fault area is judged to be the bus side of the smoothing reactor.
According to the fault area judgment method of the full-line quick-action protection, whether a line where the protection device is located has a fault is judged according to the voltage traveling wave measured by the protection device and a preset voltage setting value upper limit, and if the line where the protection device is located has the fault, the voltage change rate of the voltage traveling wave measured in a preset time after the fault occurrence moment is detected is compared with a preset reference change rate; if the voltage change rate is smaller than the preset reference change rate, judging that the fault area is positioned on the line side of the smoothing reactor; and if the voltage change rate is greater than the preset reference change rate, judging that the fault area is positioned on the bus side of the smoothing reactor. Therefore, on one hand, the voltage traveling wave is analyzed, so that the speed is high, and the requirement on the speed of a protection system can be met; on the other hand, the voltage change rate within the preset time after the fault occurs is utilized to analyze and judge the fault area, and the judgment accuracy is high; therefore, the accuracy and efficiency of fault discrimination can be improved, and the efficiency of fault protection can be improved.
In an embodiment, with continued reference to fig. 3, after step S150, steps S161 to S163 are further included.
S161: and acquiring the voltage traveling wave measured by the protection device at a preset time point after the current moment.
The preset time point refers to a certain fixed time after the current time. Preferably, the preset time point is a time corresponding to a short time after the current time, so that inaccurate analysis caused by excessive voltage value reduction is avoided.
S163: and judging whether the voltage value of the voltage traveling wave measured by the protection device at the preset time point is smaller than the lower limit of the preset voltage setting value. And the lower limit of the preset voltage setting value is smaller than the upper limit of the preset voltage setting value.
If yes, go to step S170; if not, it indicates that the voltage value of the voltage traveling wave measured by the protection device at the preset time point is greater than or equal to the preset voltage setting value lower limit and less than the preset voltage setting value upper limit (at this time, it is confirmed that a fault occurs, and therefore the voltage value of the voltage traveling wave is less than the preset voltage setting value upper limit), and at this time, step S190 is executed.
There may be a small difference in discriminating the fault region based only on the voltage change rate due to measurement error and noise. The voltage traveling wave measured by the protection device is obtained at a preset time point, the step S170 is executed when the voltage value of the voltage traveling wave corresponding to the preset time point is smaller than the preset voltage setting value lower limit, the step S190 is executed when the voltage value of the voltage traveling wave corresponding to the preset time point is larger than or equal to the preset voltage setting value lower limit and smaller than the preset voltage setting value upper limit, the fault area judgment can be considered together with the voltage change rate of the voltage traveling wave at the preset time point, and the judgment accuracy can be further improved.
In an embodiment, with continued reference to fig. 3, after step S150, step S162 is further included.
S162: and acquiring the current change rate of the current traveling wave measured by the protection device within a preset time after the current moment.
Correspondingly, in this embodiment, step S180 is further included after step S170.
S180: and if the current change rate is larger than zero, judging the fault as a positive fault.
Step S162 may be executed before step S170, or may be executed after step S170, and it is sufficient to ensure that step S162 is executed before step S180. In the present embodiment, step S162 is executed before step S163.
In an embodiment, the preset time point is a current time when the fault is detected. The forward fault discrimination model of the smoothing reactor line side is as follows:
wherein t _ start is the current time, t _ end is the time after the preset duration of the current time, and Ug(t _ end) is the voltage value of the voltage traveling wave measured by the protection device at the moment corresponding to t _ end, Ug(t _ start) is the voltage value dU of the voltage travelling wave measured by the protection device at the moment corresponding to t _ startsIn order to preset the reference variation amount,
to preset a reference rate of change, Ig(t _ end) is the current value of the current traveling wave measured by the protection device at the moment corresponding to t _ end, Ig(t _ start) is the current value of the current traveling wave measured by the protection device at the moment corresponding to t _ start, Uset2And is a preset voltage setting value lower limit.
Since the voltage contains no information of the fault direction, it is not possible to distinguish between a forward fault and a reverse fault. After step S170, it is determined that the fault region is located on the line side of the smoothing reactor. However, as can be seen from fig. 1, F3 is also located in close proximity to the protection device. Therefore, in order to distinguish the direction of the fault, the current change rate within the preset time length after the current moment is obtained for analysis, if the current change rate is larger than zero, the current value is increased, and the fault can be judged to be a forward fault at the moment. Otherwise, if the current change rate is less than zero, the fault can be determined to be a reverse fault. Therefore, the fault area can be further accurate, and the accuracy of judging the fault area is further improved.
In an embodiment, step S180 is followed by: respectively obtaining a voltage traveling wave measured by the protection device at a time after a preset sampling interval at the current time, a voltage traveling wave measured by the protection device at a time after a preset sampling interval at a preset time corresponding to the current time, a voltage traveling wave measured by the protection device at a time after twice the preset sampling interval at the current time, and a voltage traveling wave measured by the protection device at a time after a preset sampling interval at a time twice the preset time corresponding to the current time, so as to obtain a finally confirmed fault area. The forward fault discrimination model of the smoothing reactor line side is as follows:
wherein t _ sample is a preset sampling interval.
And when the three fault determinations meet the conditions, determining that the fault area is the line side of the smoothing reactor. The finally determined fault area is obtained by adopting continuous 3 times of judgment and analysis, so that the accuracy of fault judgment can be improved.
The fault discrimination model of the bus side of the smoothing reactor is as follows:
wherein, Uset1And setting the upper limit of the preset voltage.
Step S190 may be followed by: respectively obtaining a voltage traveling wave measured by the protection device at a time after a preset sampling interval at the current time, a voltage traveling wave measured by the protection device at a time after a preset sampling interval at a preset time corresponding to the current time, a voltage traveling wave measured by the protection device at a time after twice the preset sampling interval at the current time, and a voltage traveling wave measured by the protection device at a time after a preset sampling interval at a time twice the preset time corresponding to the current time, so as to obtain a finally confirmed fault area. The fault discrimination model of the bus side of the smoothing reactor is as follows:
similarly, when the three fault determinations all meet the conditions, the fault area can be determined to be the line side of the smoothing reactor. The finally determined fault area is obtained by adopting continuous 3 times of judgment and analysis, so that the accuracy of fault judgment can be improved.
Referring to fig. 4, the system for determining a fault region of full line fast-acting protection in an embodiment includes a traveling wave obtaining module 110, a fault determining module 130, a voltage change rate obtaining module 150, a first region determining module 170, and a second region determining module 190.
The traveling wave acquiring module 110 is used for acquiring the voltage traveling wave measured by the protection device.
The fault determination module 130 is configured to determine whether a line in which the protection device is located has a fault according to the voltage traveling wave measured by the protection device and a preset voltage setting upper limit.
In one embodiment, the preset voltage setting upper limit is 85% of the line voltage when the line in which the protection device is located is normal.
Through careful research, test and selection, the 85% voltage value of the line voltage under the normal state of the line is used as a dividing point between the fault state and the normal state and is used for comparing with the voltage value of the voltage traveling wave to judge whether the fault occurs, and the accuracy is higher.
In an embodiment, the fault determination module 130 is configured to determine whether a voltage value of the traveling voltage wave measured by the protection device is smaller than a preset voltage setting upper limit, and determine that a fault occurs in a line where the protection device is located if the voltage value of the traveling voltage wave measured by the protection device is smaller than the preset voltage setting upper limit.
The voltage change rate obtaining module 150 is configured to, when a fault occurs, obtain a voltage change rate of the voltage traveling wave measured by the protection device within a preset time after a current time by using a time when the fault occurs as the current time.
The first region determination module 170 is configured to determine that the fault region is located on the line side of the smoothing reactor when the voltage change rate is smaller than a preset reference change rate.
The second area determination module 190 is configured to determine that the fault area is located on the bus side of the smoothing reactor when the voltage change rate is greater than a preset reference change rate.
In the fault area determination system for full-line quick-action protection, the traveling wave acquisition module 110 acquires a voltage traveling wave measured by a protection device, the fault determination module 130 determines whether a line in which the protection device is located has a fault according to the voltage traveling wave measured by the protection device and a preset voltage setting value upper limit, and if so, the voltage change rate acquisition module 150 acquires the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current time by taking the time when the fault is detected as the current time; when the voltage change rate is smaller than the preset reference change rate, the first region judgment module 170 judges that the fault region is positioned on the line side of the smoothing reactor; the second region determination module 190 determines that the fault region is located on the smoothing reactor bus side when the voltage change rate is greater than a preset reference change rate. Therefore, on one hand, the voltage traveling wave is analyzed, so that the speed is high, and the requirement on the speed of a protection system can be met; on the other hand, the voltage change rate within the preset time after the fault occurs is utilized to analyze and judge the fault area, and the judgment accuracy is high; therefore, the accuracy and efficiency of fault discrimination can be improved, and the efficiency of fault protection can be improved.
In an embodiment, referring to fig. 5, the system for determining a fault region of full-line fast moving protection further includes a preset time point detecting module 160, configured to obtain a voltage traveling wave measured by the protection device at a preset time point after a current time after the voltage change rate obtaining module 150 obtains the voltage change rate, and determine whether a voltage value of the voltage traveling wave measured by the protection device at the preset time point is smaller than a preset voltage setting lower limit; if so, the first region determination module 170 determines that the fault region is located on the line side of the smoothing reactor when the voltage change rate is smaller than a preset reference change rate; if not, the second area determination module 190 determines that the fault area is located on the bus side of the smoothing reactor when the voltage change rate is greater than the preset reference change rate. And the lower limit of the preset voltage setting value is smaller than the upper limit of the preset voltage setting value.
There may be a small difference in discriminating the fault region based only on the voltage change rate due to measurement error and noise. The voltage traveling wave measured by the protection device is acquired at the preset time point through the preset time point detection module 160 and is compared with the lower limit of the preset voltage setting value, and the voltage traveling wave at the preset time point and the voltage change rate can be considered together to judge the fault area, so that the judgment accuracy can be further improved.
In an embodiment, referring to fig. 5, the system for determining a fault region of the full line snap action protection further includes a fault direction analyzing module 180.
The fault direction analysis module 180 is configured to obtain a current change rate of the current traveling wave measured by the protection device within a preset time after the current time after the voltage change rate obtaining module 150 obtains the voltage change rate; and for determining that the fault is a positive fault when the rate of change of current is greater than zero after the first zone determination module 170 determines that the fault zone is on the smoothing reactor line side.
Since the voltage contains no information of the fault direction, it is not possible to distinguish between a forward fault and a reverse fault. By adding the analysis of the current change rate to distinguish the forward fault from the reverse fault, the fault area can be further precise, and the accuracy of judging the fault area is further improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A fault area judgment method of full-line quick-action protection is characterized by comprising the following steps:
acquiring voltage traveling waves measured by a protection device;
judging whether a line where the protection device is located has a fault according to the voltage traveling wave measured by the protection device and a preset voltage setting value upper limit;
if so, acquiring the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current moment by taking the moment of detecting the fault as the current moment;
if the voltage change rate is smaller than a preset reference change rate, determining that the fault area is located on the line side of the smoothing reactor;
if the voltage change rate is larger than the preset reference change rate, determining that a fault area is located on the bus side of the smoothing reactor;
after the time when the fault is detected is taken as the current time and the voltage change rate of the voltage traveling wave measured by the protection device within the preset time length after the current time is obtained, the method further comprises the following steps:
acquiring the current change rate of the current traveling wave measured by the protection device within the preset time length after the current moment;
if the voltage change rate is smaller than a preset reference change rate, after the step of determining that the fault area is located on the line side of the smoothing reactor, the method further comprises the following steps:
and if the current change rate is larger than zero, judging that the fault is a positive fault.
2. The method for determining the fault region of the full-line quick-acting protection according to claim 1, wherein the step of determining whether the line where the protection device is located has a fault according to the traveling voltage wave measured by the protection device and a preset voltage setting value upper limit comprises:
judging whether the voltage value of the voltage traveling wave measured by the protection device is smaller than the preset voltage setting value upper limit or not;
and if the voltage value of the voltage traveling wave measured by the protection device is smaller than the preset voltage setting value upper limit, the step of obtaining the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current time by taking the detected fault time as the current time is executed.
3. The method for determining the fault region of the full-line quick-acting protection according to claim 1, wherein after the time when the fault is detected is taken as a current time and the voltage change rate of the voltage traveling wave measured by the protection device within a preset time period after the current time is obtained, the method further comprises:
acquiring voltage traveling waves measured by the protection device at a preset time point after the current moment;
judging whether the voltage value of the voltage traveling wave measured by the protection device at the preset time point is smaller than a preset voltage setting value lower limit, wherein the preset voltage setting value lower limit is smaller than a preset voltage setting value upper limit;
if so, executing the step of judging that the fault area is positioned at the line side of the smoothing reactor if the voltage change rate is smaller than a preset reference change rate;
and if not, executing the step of judging that the fault area is positioned on the bus side of the smoothing reactor if the voltage change rate is greater than the preset reference change rate.
4. The method for determining the fault region of the full-line quick-acting protection according to claim 1, wherein after the time when the fault is detected is taken as a current time and the voltage change rate of the voltage traveling wave measured by the protection device within a preset time period after the current time is obtained, the method further comprises:
and acquiring a fault area according to the voltage traveling wave of the protection device at the moment after the preset sampling interval at the current moment, the voltage traveling wave of the protection device at the moment after the preset sampling interval at the moment after the preset time length corresponding to the moment after the current moment, the voltage traveling wave of the protection device at the moment after twice the preset sampling interval at the current moment and the voltage traveling wave of the protection device at the moment after the twice the preset sampling interval at the preset time length corresponding to the moment after the current moment.
5. The method for determining the fault region of the all-line snap-action protection according to claim 1, wherein the preset voltage setting upper limit is 85% of the line voltage when the line where the protection device is located is normal.
6. A system for determining a fault region in full-line snap-action protection, comprising:
the traveling wave acquisition module is used for acquiring voltage traveling waves measured by the protection device;
the fault judging module is used for judging whether a line where the protection device is located has a fault according to the voltage traveling wave measured by the protection device and a preset voltage setting value upper limit;
the voltage change rate acquisition module is used for acquiring the voltage change rate of the voltage traveling wave measured by the protection device within a preset time length after the current moment by taking the moment of detecting the fault as the current moment when the fault occurs;
the first area judgment module is used for judging that the fault area is positioned on the line side of the smoothing reactor when the voltage change rate is smaller than a preset reference change rate;
the second area judgment module is used for judging that the fault area is positioned on the bus side of the smoothing reactor when the voltage change rate is greater than the preset reference change rate;
the fault direction analysis module is used for acquiring the current change rate of the current traveling wave measured by the protection device within the preset time length after the current moment after the voltage change rate is acquired by the voltage change rate acquisition module; and the fault is determined to be a positive fault when the current change rate is larger than zero after the first region determination module determines that the fault region is positioned on the line side of the smoothing reactor.
7. The system according to claim 6, wherein the fault determination module is configured to determine whether the voltage value of the traveling voltage wave measured by the protection device is smaller than the preset voltage setting upper limit, and determine that the line on which the protection device is located has a fault if the voltage value of the traveling voltage wave measured by the protection device is smaller than the preset voltage setting upper limit.
8. The system for determining a fault region of full-line quick-acting protection according to claim 6, further comprising a preset time point detection module, configured to, after the voltage change rate obtaining module obtains the voltage change rate, obtain a voltage traveling wave measured by the protection device at a preset time point after the current time, and determine whether a voltage value of the voltage traveling wave measured by the protection device at the preset time point is smaller than a preset voltage setting value lower limit; if so, the first area judgment module judges that the fault area is positioned on the line side of the smoothing reactor when the voltage change rate is smaller than a preset reference change rate; if not, the second area judgment module judges that the fault area is located on the bus side of the smoothing reactor when the voltage change rate is larger than the preset reference change rate; the lower limit of the preset voltage setting value is smaller than the upper limit of the preset voltage setting value.
9. The system according to claim 6, wherein the first area determination module and the second area determination module are further configured to obtain the fault area according to the voltage traveling wave measured by the protection device at the time after the preset sampling interval at the current time, the voltage traveling wave measured by the protection device at the time after the preset sampling interval at the time corresponding to the preset duration after the current time, the voltage traveling wave measured by the protection device at the time after twice the preset sampling interval at the current time, and the voltage traveling wave measured by the protection device at the time after the preset sampling interval at the time corresponding to the twice the preset duration after the current time, respectively.
10. The fault region determination system of the all-line snap-action protection according to claim 6, wherein the preset voltage setting upper limit is 85% of a line voltage when a line in which the protection device is located is normal.
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| CN110995038A (en) * | 2019-11-21 | 2020-04-10 | 中国电力科学研究院有限公司 | MMC (modular multilevel converter) and DC fault isolation method and system based on MMC |
| CN111751654B (en) * | 2020-05-18 | 2022-06-03 | 深圳供电局有限公司 | Power system fault processing method and device, computer equipment and medium |
| CN111896840B (en) * | 2020-07-15 | 2023-06-27 | 武汉三相电力科技有限公司 | Method and system for judging fault interval in hybrid line based on fault traveling wave voltage |
| CN112698145B (en) * | 2020-11-11 | 2023-02-21 | 国电南瑞科技股份有限公司 | Fault distance measuring method and device suitable for power transmission line containing series reactor |
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