JP5287036B2 - AC ΔI type fault detection method and fault detection apparatus - Google Patents

Description

  The present invention relates to an AC ΔI type fault detection method and a fault detection apparatus for detecting a fault in an AC feeder circuit that supplies AC power to an electric vehicle from a substation through a train line.

As a fault detection method for this type of AC feeder circuit, for example, in an AC electric railway that supplies AC power to an electric vehicle from a substation through a train line, the load current vector of the electric vehicle is set to [I _L ], and the train line When the failure current vector when a failure occurs is [I _S ],
[ΔI] = [I _S ] − [I _L ]
There has been proposed an AC ΔI type fault selection method in which a fault is selected when the magnitude of the difference vector [ΔI] calculated by (1) exceeds a predetermined value (see, for example, Patent Document 1).
JP-A-9-93791

However, in the conventional example described in Patent Document 1 above, failure detection can be easily performed even in the case of a PWM control vehicle, but in the case where an electric vehicle load current is flowing through the train line. The current vector diagram is as shown in FIG. As shown in FIG. 4 (a), when the case fault current I _S that electric vehicle load current I _L flows are superimposed simultaneously, the current difference vector [[Delta] I _11] which rises at the time of failure to be determined by the following formula Small value.
[ΔI ₁₁ ] = [I _S ] − [I _L ]

On the other hand, between the time t0~t1 of FIG. 5 (a), when the normal electrical vehicle load current I _L is flowing, the Denden stream Ki indicated by the characteristic curve L1, as shown in FIG. 5 (b), The third harmonic component or the like of about 20% or less indicated by the characteristic curve L2 is included, and during the failure after the time t1 in FIG. 5A, the feeding voltage decreases, and the electric vehicle load current includes the harmonic component. I _S increases, as shown by the characteristic curve L2 in FIG. 5 (b), the harmonic components of the feeding circuit current (third harmonic, etc.) is reduced. Utilizing these, multiplied by inhibiting suppression coefficient Kf _L pre-fault current to the current vector [I _L], further, by multiplying suppressing reduction coefficient Kf _S the post-fault current to the current vector [I _S], failure As shown in FIG. 4B, ΔI ₁₂ that sometimes rises apparently increases, and failure detection can be facilitated. Note that suppression coefficient Kf _S, since it becomes a harmonic component of the feeding circuit current (third harmonic, etc.) approximately 0, the Kf _S ≒ 1.
[ΔI ₁₂ ] = [I _S ] × Kf _S − [I _L ] × Kf _L

However, a transient harmonic component (the third harmonic or the like) is generated due to a current change at the time of failure, and the harmonic content may exceed 100%. Under this influence, there is an unsolved problem that it is difficult to detect an AC ΔI type fault by accurate harmonic suppression.
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and is not affected by the transient harmonic component generated by the current change at the time of failure, and the harmonic content before and after the failure is determined. It is an object of the present invention to provide an AC ΔI type fault detection method and fault detection apparatus that can detect a fault that has occurred on a train track with high sensitivity by obtaining it accurately.

  In order to achieve the above object, an AC ΔI type fault detection method according to claim 1 calculates a current difference vector ΔI for a fault of an AC feeder circuit that supplies AC power from a substation to an electric vehicle through a train line. And detecting the current supplied to the train line, calculating the harmonic content based on the fundamental component and the harmonic component of the detected current, Detecting the minimum harmonic content that is the minimum value from the high-frequency content in the period going back a predetermined amount of time when a transient harmonic component occurs at the time of failure, and calculating the suppression coefficient based on the minimum harmonic content, The harmonic suppression current is calculated by multiplying the suppression coefficient and the detected fundamental wave component of the current, and the current harmonic suppression current and the transient harmonic component generated at the time of failure from the current time exceeds the predetermined time. Dating back A harmonic suppression current at the point, calculates a current difference vector ΔI based on, is characterized by the failure detection by comparing the current difference vector ΔI and settings.

Further, the AC ΔI type fault detection apparatus according to claim 2 detects an AC ΔI fault detecting a fault of an AC feeding circuit that supplies AC power from a substation to an electric vehicle through a train line by calculating a current difference vector ΔI. Type fault detection device,
A current detection unit for detecting a current supplied to the train line, a filter unit for extracting a fundamental wave component and a harmonic component of the detected current, and a harmonic content based on the extracted fundamental wave component and the harmonic component A high-frequency content rate calculating unit, a high-frequency content rate storage unit that sequentially stores the calculated high-frequency content rate, a current high-frequency content rate calculated by the harmonic content rate calculating unit, and the high-frequency content rate storage unit A high-frequency content rate in a period that goes back a predetermined amount of time when a transient harmonic component is generated at the time of failure from the stored current, and a minimum harmonic content rate detection unit that detects a minimum harmonic content rate that is a minimum value, A harmonic suppression current calculation unit that calculates a suppression coefficient based on the detected minimum harmonic content and multiplies the calculated suppression coefficient by the fundamental component of the current extracted by the filter unit. And the high In the harmonic suppression current storage unit that sequentially stores the harmonic suppression current calculated in the wave suppression current calculation unit, the current harmonic suppression current calculated in the harmonic suppression current calculation unit, and the harmonic suppression current storage unit A current difference vector calculation unit for calculating a current difference vector ΔI based on a harmonic suppression current at a time point that goes back beyond a predetermined time when a transient harmonic component generated at the time of failure attenuates from the stored current; And a failure detection unit that detects a failure by comparing the current difference vector ΔI with a set value.

  According to the present invention, when obtaining the suppression coefficient for calculating the harmonic suppression current before and after the failure, the harmonic content ratio for a certain time exceeding the period in which the transient harmonic component generated by the current change at the time of the failure exists. Since the suppression coefficient Kf is obtained based on the minimum value of the power line, when a failure occurs in the train line of the AC feeder circuit, the failure can be detected reliably and at high speed. It becomes possible to open the circuit breaker, and it is possible to prevent the failure point and various facilities and equipment from being damaged and to minimize the expansion of the failure.

  The harmonic current (third harmonic etc.) included in the electric vehicle load current is often when the electric vehicle is a diode rectifier vehicle or a thyristor phase control vehicle, and the failure detection method and apparatus of the present invention is effective. The harmonic current included in the electric vehicle load current of the PWM control vehicle is decreasing, but it is necessary to calculate the current difference vector ΔI so as not to be affected by the transient harmonic component generated by the current change at the time of failure. The present invention is the same, and according to the present invention, accurate AC ΔI type fault detection can be performed regardless of the train control system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a basic configuration diagram showing an AC feeding system to which an AC ΔI type fault detection apparatus according to the present invention is applied.
In FIG. 1, reference numeral 1 denotes an AC power feeding system. The AC power feeding system 1 is supplied with AC power output from a substation 2 to a train track 3, and AC power supplied to the train track 3. Is supplied to the electric vehicle 5 traveling on the rail 4 via the pantograph 6.

The AC voltage applied to the train line 3 is stepped down by the instrument transformer 7 and input as an input voltage to the AC ΔI type failure detection device 8. The AC ΔI type failure detection device 8 is disposed on the train line 3. The input current Ii detected by the current transformer 9 is input.
The AC ΔI type failure detection device 8 is constituted by a microcomputer, for example, and is shown in FIG. 2 in a functional block diagram.

That is, first, the input current Ii detected by the current transformer 9 is supplied to the filter unit 11, and the filter unit 11 extracts the fundamental wave component If1 and the third harmonic component If3 of the electric vehicle load current. To do. Then, the extracted fundamental wave component If1 and third harmonic component If3 are supplied to the harmonic content calculating unit 12. In the harmonic content calculation unit 12, when the fundamental wave component If1 is substantially zero, the harmonic content nf (t) is set to “1” which is the maximum value, and the fundamental wave component If1 is not substantially zero. Sometimes, the harmonic content nf (t) is calculated according to the following equation (1).
nf (t) = | If3 | ÷ | If1 | (1)

Then, the harmonic content rate nf (t) calculated by the harmonic content rate calculation unit 12 is sequentially stored in the harmonic content rate storage unit 13 including a shift register set to a predetermined number of stages.
Then, the harmonic content storage within a predetermined time exceeding the period in which the transient harmonic component generated by the current change at the time of the failure is included in the harmonic content nf (t) calculated by the harmonic content calculation unit 12. The harmonic content rate nf (t) stored in the unit 13 is supplied to the minimum harmonic content calculation unit 14. For example, if the predetermined time exceeding the period in which the transient harmonic component generated due to the current change at the time of failure is 2 cycles, the harmonic content nf (t) at the latest time t, the time t−1 before 1 cycle The harmonic content rate nf (t-1) and the harmonic content rate nf (t-2) at time t-2 two cycles before are supplied to the minimum harmonic content calculation unit 14.

The minimum harmonic content rate calculation unit 14 calculates the minimum harmonic content rate nfmin by performing the calculation of the following equation (2).
nfmin = min {nf (t), nf (t−1),..., nf (t−P)} (2)
Here, min {} is a function for obtaining the minimum value in {}, and P is the number of cycles for a predetermined time exceeding the period in which the transient harmonic component generated by the current change at the time of failure exists.

  Since the harmonic content rate nf (t) when a transient harmonic is generated at the time of the failure is higher than the harmonic content rate nf (t) before the failure and during the failure where the transient harmonic is attenuated, Thus, by calculating the minimum harmonic content rate nfmin, the harmonic content rate nf (t) in the case where a transient harmonic is generated at the time of failure occurrence is removed.

Then, the minimum harmonic content rate nfmin calculated by the minimum harmonic content rate calculation unit 14 is supplied to the suppression coefficient calculation unit 15. The suppression coefficient calculator 15 first calculates the suppression coefficient Kf by calculating the following equation (3).
Kf = 1−nfmin × K (3)
Here, K is a correction coefficient, and when the electric vehicle load current is flowing, the third harmonic contained in the feeding current is about 20% or less, so that the maximum current suppressing effect is secured. For example, K = 3.33 is set so that the suppression coefficient Kf does not become a negative value. However, since Kf may be a negative value, Kf = 0 is reset in such a case. For example, when the main wave component If1 is substantially zero, nfmin = 1, which corresponds to this case. Then, the suppression coefficient Kf calculated by the suppression coefficient calculation unit 15 and the fundamental wave component If1 extracted by the filter unit 11 are supplied to the harmonic suppression current calculation unit 16. The harmonic suppression current calculation unit 16 calculates the harmonic suppression current Ifs (t) by performing the calculation of the following equation (4).
Ifs (t) = If1 × Kf (4)

Then, the harmonic suppression current Ifs (t) calculated by the harmonic suppression current calculation unit 16 is sequentially stored in the harmonic suppression current storage unit 17 configured by, for example, a shift register.
Then, if the cycle in which the transient harmonic component exists at the time of the failure is exceeded and the cycle in which the transient harmonic is attenuated is Q, the harmonic suppression current Ifs (t (t) calculated by the harmonic suppression current calculation unit 16 is assumed. ) And the harmonic suppression current If (t−Q) before the Q cycle stored in the harmonic suppression current storage unit 17 are supplied to the current difference vector calculation unit 18. For example, when the transient harmonic component exceeds the period in which the transient harmonic component exists at the time of occurrence of the failure in 3 to 5 cycles and the transient harmonic is attenuated, the harmonic suppression currents If (t-3), If (t-4) and One of If (t-5), for example, If (t-4) is supplied to the current difference vector calculation unit 18.

The current difference vector calculation unit 18 calculates the current difference vector ΔIf by calculating the following equation (5).
ΔIf = | Ifs (t) −Ifs (t−Q) | (5)
By performing the calculation of equation (5), Ifs (t) represents the harmonic suppression current after the failure, and Ifs (t-Q) represents the harmonic suppression current before the failure, the following (6) It can represent with Formula and (7) Formula.
[I _S ] × Kf _S = Ifs (t) (6)
[I _L ] × Kf _L = Ifs (t−Q) (7)

Therefore, the equation (5) calculates the current difference vector [ΔI] that is not affected by the transient harmonic component generated by the current change at the time of failure.
[ΔI] = [I _S ] × Kf _S − [I _L ] × Kf _L (8)
The current difference vector ΔI calculated by the current difference vector calculation unit 18 is supplied to the failure detection unit 19. The failure detection unit 19 determines whether or not the input current difference vector ΔI is greater than or equal to a predetermined value ΔIs. If ΔI <ΔIs, it is determined that no failure has occurred, and ΔI ≧ ΔIs. Sometimes, it is determined that a failure has occurred, and a failure detection signal BS for opening the AC feeder breaker 20 is output.

Further, the AC ΔI type failure detection device 8 executes the failure detection process shown in FIG.
As shown in FIG. 3, this failure detection process is executed as a timer interruption process at predetermined time intervals. First, in step S1, the train line current Ii detected by the instrument current transformer 9 is read, and then the step The process proceeds to S2, and a filter process is performed to extract a fundamental wave component If1 and a third harmonic component If3 of the train line current Ii.

  Subsequently, the process proceeds to step S3, where it is determined whether or not the absolute value of the extracted fundamental wave component If1 is equal to or less than a predetermined value δI and is substantially “0” (| If1 | <δI), and the fundamental wave component If1 is substantially “ When it is “0”, the process proceeds to step S4, the harmonic content rate nf (t) is set to “1” and then the process proceeds to step S6, and when the fundamental wave component If1 is not substantially “0”, the process proceeds to step S5. Then, the harmonic content nf (t) is calculated by performing the calculation of the equation (1).

  Next, the process proceeds to step S6, where the calculated harmonic content ratio nf (t) is stored in the harmonic content storage area of the shift register configuration formed in the RAM or the like, and then the process proceeds to step S7. Here, assuming that the number of cycles in a predetermined time exceeding the time in which the transient harmonic component generated due to the current change at the time of failure is P, the harmonic content nf (t) calculated in step S4 or S5, and the harmonic Read from the harmonic content ratio nf (t-1) one cycle before stored in the content storage area to the harmonic content ratio nf (t-P) before P cycle, and perform the calculation of equation (2) above To calculate the minimum harmonic content nfmin.

Next, the process proceeds to step S8, the suppression coefficient Kf is calculated by performing the calculation of the equation (3) based on the minimum harmonic content rate nfmin calculated in step S7, and then the process proceeds to step S9. It is determined whether or not the coefficient Kf is a negative value. If Kf <0, the process proceeds to step S10, the calculated suppression coefficient Kf is changed to “0”, the process proceeds to step S11, and Kf ≧ 0. If so, the process proceeds to step S11.
In step S11, the suppression coefficient Kf calculated in step S8 or S10 is multiplied by the fundamental wave component If1 extracted in step S2 to calculate the harmonic suppression current Ifs (t). To step S12.

  In this step S12, the harmonic suppression current Ifs (t) calculated in step S11 is stored in a harmonic suppression current storage area of a shift register configuration formed in a RAM or the like, and then the process proceeds to step S13 and calculated in step S12. The harmonic suppression current Ifs (t) and the harmonic suppression current storage area stored in the storage region of the harmonic suppression current exceed the period in which the transient harmonic component is present and the cycle Q before the transient harmonic is attenuated. The harmonic suppression current Ifs (t-Q) is read, and based on these, the calculation of the equation (5) is performed to calculate the current difference vector ΔI, and then the process proceeds to step S14.

  In step S14, it is determined whether or not the current difference vector ΔI calculated in step S13 is greater than or equal to a preset set value ΔIs. If ΔI <ΔIs, it is determined that no failure has occurred in the train line 3. Then, the timer interruption process is terminated as it is, and the routine returns to the predetermined main program. When ΔI ≧ ΔIs, it is determined that a failure has occurred in the train line 3, and the process proceeds to step S15, and the AC feeder After the failure signal BS is output to the circuit breaker 20, the failure detection process is terminated.

  In the process of FIG. 3, the process of step S <b> 2 corresponds to the filter unit 11, the process of steps S <b> 3 to S <b> 5 corresponds to the harmonic content calculating unit 12, and the process of step S <b> 6 is stored in the harmonic content storage unit 13. Correspondingly, the processing of step S7 corresponds to the minimum harmonic content calculation unit 14, the processing of steps S8 to S9 corresponds to the suppression coefficient calculation unit 15, and the processing of step S11 corresponds to the harmonic suppression current calculation unit 16. The process in step S12 corresponds to the suppressed current storage unit 17, the process in step S13 corresponds to the current difference vector calculation unit 18, and the processes in steps S14 and S15 correspond to the failure detection unit 19.

Next, the operation of the above embodiment will be described with a specific example.
If it is assumed that the train load current flowing through the train track 3 continues to be substantially zero, the input current Ii input to the AC ΔI type fault detection device 8 is also substantially zero, and thus is extracted in step S2. The fundamental wave component If1 is also substantially zero, and is a value equal to or less than the set value δI. For this reason, the harmonic content nf (t) calculated by shifting from step S3 to step S4 continues to be “1”. Note that the number of cycles P for a predetermined time exceeding the time during which a transient harmonic component generated due to a current change at the time of failure exists is set to two cycles, the period of time when the transient harmonic component at the time of the failure is exceeded, and the transient harmonic The cycle number Q at which the wave attenuates is 4 cycles.

  Therefore, the minimum harmonic content rate nfmin calculated by the minimum harmonic content rate calculation unit 14 is “1”, but the suppression coefficient Kf calculated by the above equation (3) is a negative value, so step S9. From step S10, the suppression coefficient Kf is set to "0". For this reason, the suppression current Ifs (t) calculated by the equation (4) is Ifs (t) = If1 × Kf = If1 × 0 = 0, which is substantially the same as the input current Ii. Since the suppression current Ifs (t-4) four cycles before is also “0”, the current difference vector ΔI calculated in step S14 is also “0”, which is less than the predetermined value ΔIs. It is determined that the timer is normal, the timer interrupt is terminated, and the program returns to a predetermined main program.

  When the train load current flows from the state where the train load current is substantially zero, the harmonic content rate nf (t) starts to flow from nf (t) = 1 when the train load current is substantially zero. If the high frequency content nf (t-1) exceeds 20% of the normal value due to transient harmonics and the suppression coefficient Kf calculated by the above equation (3) becomes a negative value, the process proceeds to step S10 and is suppressed. Since the coefficient Kf is changed to “0”, even when the high-frequency content ratio nf (t) due to the transient harmonic increases, the suppression current Ifs (t) calculated by the equation (4) becomes “0”. The current difference vector ΔI calculated by the equation (5) maintains “0”.

After that, when the train load current is stabilized and the transient harmonics are settled, the third harmonic component If3 becomes 20% or less of the fundamental component If1, and the harmonic content nf (t) is 0.2 or less. It becomes.
Therefore, nf (t) <nf (t-1), nf (t-2), and the minimum harmonic content rate nfmin = nf (t). Based on this minimum harmonic content rate nfmin, (3) The suppression coefficient Kf is calculated by the equation.

  Therefore, the suppression coefficient Kf is calculated without being affected by the transient harmonic, and the suppression coefficient Kf is multiplied by the fundamental wave component If1 to be a relatively small value corresponding to the harmonic content nf (t). The suppression current Ifs (t) is calculated, and the current difference vector ΔI is calculated by subtracting the suppression current Ifs (t-4) four cycles before from the suppression current Ifs (t). ΔI does not exceed the set value ΔIs, and can be reliably prevented from being erroneously determined as a failure due to transient harmonics.

  When the AC feeding system fails from the state where the train load current is flowing, as shown in FIG. 5 (b), the feeding voltage decreases, and the electric vehicle load current including the harmonic component increases, After the transient harmonics are settled, the third harmonic component If3 of the feeding current is reduced to near zero. Therefore, the suppression coefficient Kfs for suppressing the current after failure at this time becomes Kfs≈1.0, and the current before failure. Since the harmonic wave component content nf (t-4) is larger than the suppression coefficient Kf = 0.33 when the normal value is 0.2, the fundamental wave component If1 also increases. The current difference vector ΔI calculated by the equation (5) becomes a large value and exceeds the set value ΔIs, so that it is determined that there is a failure and the failure signal BS is supplied to the AC feeder circuit breaker 20. The feeder circuit breaker 20 is controlled to be opened. As a result, it is possible to prevent failure points and various facilities and equipment from being damaged and to minimize the expansion of failures.

The harmonic current (third harmonic etc.) included in the electric vehicle load current is often when the electric vehicle is a diode rectifier vehicle or a thyristor phase control vehicle, and the failure detection method and apparatus of the present invention is effective. The harmonic current included in the electric vehicle load current of the PWM control vehicle is decreasing, but it is necessary to calculate the current difference vector ΔI so as not to be affected by the transient harmonic component generated by the current change at the time of failure. The present invention is the same, and according to the present invention, accurate AC ΔI type fault detection can be performed regardless of the train control system.
In the above embodiment, the minimum value of a predetermined time (for example, three points between two cycles) exceeding the time during which the transient harmonic component exists is obtained, and the calculation time point of the pre-failure current is 3 cycles to 5 cycles before. Although the case where the cycle is between has been described, the present invention is not limited to this, and it may be set to a value two cycles before the predetermined time.

It is a schematic block diagram which shows one Embodiment at the time of applying this invention to an AC feeder system. It is a functional block diagram of an AC ΔI type fault detection device. It is a flowchart which shows an example of the failure detection processing procedure performed with an alternating current ΔI type failure detection device. It is a vector diagram explaining the failure detection principle when the load current and the failure current of the conventional example overlap. It is a characteristic diagram explaining the relationship between the load current and the fault current and the transient harmonic when the current changes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... AC feeding system 2 ... Substation 3 ... Train line 4 ... Rail 5 ... Electric vehicle 7 ... Instrument transformer 8 ... AC delta type I fault detection device 9 ... Instrument current transformer 11 ... Filter part 12 ... Harmonic Content calculation unit 13 ... Harmonic content storage unit 14 ... Minimum harmonic content calculation unit 15 ... Suppression coefficient calculation unit 16 ... Harmonic suppression current calculation unit 17 ... Harmonic suppression current storage unit 18 ... Current difference vector calculation unit 19 ... Failure detection unit 20 ... AC feeder circuit breaker

Claims (2)

An AC ΔI type fault detection method for detecting a fault in an AC feeding circuit that supplies AC power to an electric car from a substation through a train line by calculating a current difference vector ΔI,
Detecting the current supplied to the train track;
Calculate the harmonic content based on the detected fundamental and harmonic components of the current,
Detects the minimum harmonic content that is the minimum value from the high frequency content in the period that goes back a predetermined time when transient harmonic components occur at the time of failure from the present,
Calculate a suppression coefficient based on the minimum harmonic content,
Multiplying the suppression coefficient and the fundamental component of the detected current to calculate the harmonic suppression current,
A current difference vector ΔI is calculated based on the current harmonic suppression current and the harmonic suppression current at the time of going back beyond a predetermined time when the transient harmonic component generated at the time of failure attenuates from the present,
An AC ΔI type fault detection method, wherein fault detection is performed by comparing the current difference vector ΔI with a set value. An AC ΔI type fault detection device that detects a fault in an AC feeding circuit that supplies AC power to an electric vehicle from a substation through a train line by calculating a current difference vector ΔI,
A current detection unit for detecting a current supplied to the train line, a filter unit for extracting a fundamental wave component and a harmonic component of the detected current,
A harmonic content calculation unit that calculates the harmonic content based on the extracted fundamental wave component and harmonic component;
A high-frequency content storage unit for sequentially storing the calculated high-frequency content,
The current high-frequency content rate calculated by the harmonic content rate calculation unit, and the high frequency in a period that goes back beyond a predetermined time when a transient harmonic component is generated at the time of failure from the current value stored in the high-frequency content rate storage unit A minimum harmonic content detection unit that detects the minimum harmonic content that is the minimum value from the content rate;
A harmonic suppression current calculation unit that calculates a suppression coefficient based on the detected minimum harmonic content and multiplies the calculated suppression coefficient by the fundamental component of the current extracted by the filter unit. When,
A harmonic suppression current storage unit that sequentially stores the harmonic suppression current calculated by the harmonic suppression current calculation unit;
When the current harmonic suppression current calculated by the harmonic suppression current calculation unit and the transient harmonic component generated at the time of failure from the present stored in the harmonic suppression current storage unit go back beyond a predetermined time A current difference vector calculation unit that calculates a current difference vector ΔI based on the harmonic suppression current at
A failure detection unit that detects the failure by comparing the calculated current difference vector ΔI with a set value;
An AC ΔI type fault detection apparatus comprising:

Images