JPH0993791A - Ac deltai type failure selection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To open the circuit breaker by executing particular vector difference calculation between a failure current vector and an electric train load current vector to judge a failure if an amplitude of vector difference exceededs the predetermined value. SOLUTION: An AC ΔI type failure selection apparatus 1 converts, when a failure is generated, a feed current of an electric train 4 into a low voltage and small current and also calculates a difference between an input load current IL of electric train and a failure current IS in terms of vector. Failure selection is performed depending on this vector difference. That is, when an electric train load current vector is defined as [IL] and a failure current when a failure is generated as [IS], vector difference [ΔI] for failure detection is obtained from the expression, [ΔI]=[IS]-[IL ]. If a value of the vector difference [ΔI] has exceeded a value preset by the AC ΔI type failure selection apparatus 1, such event is selected as 'failure'. In this case, a protection output is output to a circuit breaker to open the circuit breaker.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC ΔI type fault selecting device for feeding circuit protection in railways that perform AC feeding, and more particularly to a PWM (Pulse Width Modula).
tion: pulse width modulation) The present invention relates to a method for selecting an AC ΔI type failure that enables easy failure detection when a failure occurs in a train line while a controlled vehicle is running.

[0002]

2. Description of the Related Art In an AC electric railway, extra-high voltage single-phase AC power from a substation is supplied (powered) to an electric car through a train line. In this case, when a fault such as a ground fault occurs on the train line, a fault current flows rapidly, and the AC ΔI type fault selection device at the substation detects the fault.

Conventional alternating current ΔI when a diode rectifier vehicle or a thyristor phase control vehicle is adopted as an electric vehicle.
The principle of the type fault selection device is shown in FIGS. As shown in FIG. 4, when a failure occurs in the train track, a failure current I _S
Rapidly rises above the set value ΔI ₀ of the AC ΔI type failure selection device. In this case, assuming that the rising value of the fault current I _S is ΔI ₁₁ , the AC ΔI type fault selecting device indicates “fault” when the condition of the following equation ΔI ₁₁ > ΔI ₀ (1) is satisfied. Select and output protected output. As a result, the circuit breaker is opened, and damage points and damage accidents of various equipment are prevented.

Next, an electric car load current flows on the train track.
If a fault current flows when
As shown in FIG. As shown in the figure, the electric vehicle load current I_LFlow
Fault current I_SIf the two overlap at the same time,
Scalar value ΔI of current₁₂Is small,
Failure detection by (1) becomes difficult. For this reason,
Is 1 when the electric vehicle load current is flowing.
Utilizes that the third harmonic of about 5 to 20% is included
Then, the electric vehicle load current I, which is the basic current for failure detection, _LTo
Suppress analogly, I_L ^'Was being generated. This process
Causes the current value ΔI to rise at the time of failure₁₃The process
Rising current value ΔI₁₂Apparently larger than
Therefore, the failure detection by the above formula (1) is facilitated.

[0005]

However, in the case of PWM controlled vehicles, which are expected to increase in the future, the power factor is high and the content ratio of the third harmonic is 1 compared with the conventional diode rectifier vehicle or thyristor phase controlled vehicle. Since it is as small as / 3 or less, suppression of the basic current due to the third harmonic as described above cannot be expected, and it becomes difficult to detect a failure during powering. Further, it becomes difficult to detect a failure even during regeneration.

The present invention has been made in order to solve such a problem, and the problem to be solved by the present invention is an alternating current ΔI which can easily detect a failure even in the case of a PWM control vehicle. The purpose is to provide a method for selecting a fault.

[0007]

Means for Solving the Problems To solve the above problems,
Therefore, the present invention applies to electric vehicles from substations through train tracks.
In an AC electric railway that supplies current power,
The load current vector is [I_L] And because of the train line
The vector of the fault current when a failure occurs is [I _S〕age
Then, the following formula [ΔI] = [I_S]-[I_L] The magnitude of the difference vector [ΔI] calculated by
It is characterized in that it is selected as a failure when the value exceeds.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings and the like. FIG.
FIG. 1 is a diagram showing a basic configuration of an AC ΔI type fault selecting device 1 adopting an AC ΔI type fault selecting method according to the present invention and a feeding system including this device.

As shown in the figure, in this feeder system, an AC ΔI type fault selecting device 1, an instrument transformer (PT) 2, and an instrument current transformer (C) are installed in an electric railway substation.
T) 3. The instrument transformer 2 converts the feeding voltage V ₁ of the train line 5 into a low voltage V ₂ , and the instrument current transformer 3 transforms the feeding current I ₁ of the electric vehicle 4 into a small current I ₂ . Then
These voltages and currents are input to the AC ΔI type fault selection device 1.

When a failure occurs, the AC ΔI type failure selecting apparatus 1 converts the difference between the electric vehicle load current I _L and the failure current I _S which are converted into the low voltage V ₂ and the small current I ₂ as described above and input. The calculation is performed with a vector amount, and the fault is selected based on this difference vector. That is, the electric vehicle load current vector is [ _IL ]
And the fault current vector at the time of fault occurrence is [I _S ], the fault detection difference vector [ΔI] is obtained by the following formula [ΔI] = [I _S ] − [I _L ] ... (2) . When the magnitude of the above difference vector [ΔI] exceeds the predetermined value set in the AC ΔI type fault selecting device 1, “fault” is selected and the protective output is output to the circuit breaker (not shown). As a result, the circuit breaker (not shown) is opened, and a failure point and damage accidents of various equipments and the like are prevented. Therefore, the spread of failures can be minimized.

FIG. 2 is a vector diagram for explaining a method of detecting a difference vector for failure detection when a failure occurs on the train track 5 while the PWM control vehicle is powering, and FIG. 3 is during regeneration of the PWM control vehicle. It is a vector diagram explaining the detection method of the difference vector for failure detection when a failure occurs in the train track 5.

Since the load power factor angle of the PWM control vehicle is 0 ° during power running and 180 ° during regeneration, the PWM
The electric vehicle load current vector during power running of the control vehicle is [I _L1 ] and the electric vehicle load current vector during regeneration of the PWM control vehicle is [I _L2 ], which is about the voltage during power running and during regeneration. The vector amount is significantly different from the fault current vectors [I _S1 ] and [I _S2 ] forming 70 °. For this reason, the following vector operation [ΔI ₁ ] = [I _S1 ] − [I _L1 ] ... (3) [ΔI ₂ ] = [I _S2 ]-[I _L2 ] ... (4) When the difference vector [ΔI ₁ ] is calculated during power running and the difference vector [ΔI ₂ ] is calculated during regeneration, and the magnitude of this difference vector is taken as the current value for failure detection, failure detection is performed both during power running and during regeneration. The current value for use can be made much larger than that of the conventional method, the fault current can be sufficiently followed even when the PWM control vehicle is running, and the fault can be easily detected.

When a failure occurs in the train track, the feeding voltage drops, and generally the converter of the PWM control vehicle immediately stops. Therefore, the fault current does not include the electric vehicle load current and does not affect the fault detection by the protective relay.

Further, if the converter of the PWM control vehicle does not stop at the time of failure, the failure current vector when the regenerative vehicle does not receive the load current, that is, the difference vector of the vector [I _S3 ] in FIG. 3 can be detected. .

[0015]

As described above, according to the present invention,
Since the vector difference between the fault current vector and the electric vehicle load current vector is calculated and the fault is detected based on the magnitude of the difference vector, the power factor is high and the content of low-order harmonics is very low. Even in the case of a PWM control vehicle that is completely different from the above, the failure detection current value can be made larger than that in the conventional failure selection method, and failure detection can be performed without any trouble. Therefore, it is possible to prevent failure points and damage accidents of various equipments and the like when the PWM control vehicle is running, and it is possible to minimize the spread of failures.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an AC ΔI type fault selecting apparatus 1 adopting an AC ΔI type fault selecting method according to the present invention and a feeding system including the apparatus.

FIG. 2 is a vector diagram illustrating a method of detecting a difference vector for failure detection when a failure occurs in the train track shown in FIG. 1 while the PWM control vehicle is powering.

FIG. 3 is a vector diagram illustrating a method of detecting a difference vector for failure detection when a failure occurs on the train track shown in FIG. 1 during regeneration of a PWM control vehicle.

FIG. 4 is an alternating current Δ in a conventional alternating current ΔI type fault selecting device.
It is a figure explaining the principle of an I type failure selection method.

FIG. 5 is a vector diagram for explaining a failure detection method when a load current and a failure current overlap in a conventional AC ΔI type failure selection method.

[Explanation of symbols]

1 AC ΔI type failure selection unit 2 potential transformer 3 current transformer 4 electric vehicle 5 railroad track 6 Rail [I _L] electric vehicle load current vector [I _S] fault current vector [ΔI] failure detecting difference vector

Claims (1)

[Claims] 1. An AC electric railway for supplying AC power to an electric car from a substation through a train line, wherein a vector of a load current of the electric car is [ _IL ], and a fault occurs when the train line fails. when the vector of current and [I _S], the following formula [ΔI] = [I _S] - select a malfunction when the magnitude of the difference vector is calculated by [I _L] [ΔI] exceeds a predetermined value AC that is characterized by
Type I fault selection method.