JPS6292701A - Protective device for ac electric rolling stock - Google Patents

Abstract

PURPOSE:To open an AC breaker only at the time required, and to prevent the lowering of passenger service by deciding DC-circuit ground or AC-circuit ground by discriminating voltage waveforms applied at both ends of a ground relay. CONSTITUTION:AC voltage appears at a neutral point 44 to ground on the AC side and DC voltage to ground on the DC side. The voltage waveforms are discriminated by a discriminating circuit 121, and an output relay 125 is operated when AC voltage is discriminated, and an output relay 124 is worked when DC voltage is discriminated. A line breaker 7 is opened by the operation of the output relay 124, and an AC breaker 3 is opened by the working of the output relay 125. An AC electric rolling stock is protected by opening the line breaker from a ground fault on the DC side, thus requiring no break of the AC breaker, then preventing the interruption of an auxiliary power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a protection device for an electric vehicle, and particularly to a protection device suitable for an electric vehicle running in an AC section.

[Background of the invention]

As a method for detecting the grounding of an AC electric vehicle, for example, as shown in Figure 5.28 in "Essentials of AC Electric Vehicles" by Yuji Yozoe, edited by Electric Vehicle Study Group, p. 155, A grounding relay ACGR is installed between the voltage neutral point and the vehicle body (earth), and when any part of the high voltage circuit (AC circuit or DC circuit) is grounded, voltage is applied to the grounding relay ACOR, and the AC circuit breaker (quoted above) is In the literature, the air shield 11ABB) is opened to provide grounding protection. This method is usually called the neutral point grounding method, and has the advantage that the withstand voltage to the ground of the main circuit equipment is half that of the DC negative side grounding method, especially in AC trains where motors are often used in series. It is widely used in

However, in this conventional technology, if a grounding accident occurs, the AC breaker is immediately opened as a protective operation, so even if the motor DC circuit is grounded, the AC breaker is opened, and as a result, the auxiliary power The service will also be turned down, and various service equipment will also be shut down. In other words, shutting down lighting and heating and cooling means a decline in passenger service, which is a major problem in rail transportation.

As a countermeasure to the above problem, the motor circuit and the auxiliary circuit are separated, and an AC breaker is installed on each AC winding, and when the motor circuit (AC side and DC circuit) is grounded, the AC circuit is cut off on the motor circuit side. It is conceivable to open only the auxiliary circuit but not the auxiliary circuit.

However, it is not economical as it requires the installation of a new AC circuit breaker.

It is undeniable that this will be disadvantageous to the mounting pillars and maintainability.

[Purpose of the invention]

An object of the present invention is to provide a protection device for an AC electric vehicle that prevents deterioration of passenger service.

[Summary of the invention]

The present invention focuses on the fact that in a neutral point grounding type, the voltage waveform applied to both ends of a grounding relay is different when the AC side is grounded and when the DC side is grounded, and by identifying this voltage waveform, the DC The system is characterized in that it instructs to open a DC breaker when a circuit is grounded, and instructs to open an AC breaker when an AC circuit is grounded.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. 1st
In the figure, 1 is a contact wire, 2 is a panda graph, 3 is an AC breaker, and 4 is a transformer, which has a primary winding 11A41°, a secondary winding 42, and a tertiary winding M (auxiliary winding) 43. 44 indicates the neutral point of the secondary winding 42.

The black dots shown on the windings 41 and 42 represent polarity.

5 is the vehicle body ground, and the potential is almost equal to the ground potential.

6 is a rectifier, 7 is a current breaker for opening the DC circuit, 8 is a current smoothing reactor, and 9 is a variable resistor for speed control.

10 is an armature of a DC motor, and 11 is a field winding. 1
2 is a grounding detector according to the present invention, 121 is a detection voltage identification circuit, 122 and 123 are amplification circuits, and 124 is an output relay, and the operation of this output relay 124 automatically opens the current interrupter 7. .

Furthermore, it is assumed that the AC breaker 3 is automatically opened by the operation of the other output relay 125. Note that the output relay 12
4 and 125 are self-maintained once activated, and are reset by the driver.

Next, the operation of ground detection will be explained.

In FIG. 1, four representative grounding points are selected and illustrated as points A, B, C, and D. A and B assuming that two points are never grounded at the same time.

The second diagram shows how the voltage waveform applied between the neutral point 44 and the vehicle body potential 5 changes with respect to the secondary winding voltage waveform when each point C and D are completely grounded. It is a diagram. In Figure 2, e4! is the secondary winding voltage waveform, e^ is the first
In the figure, the voltage waveform to the ground at the neutral point 44 (that is, the input voltage waveform of the detection voltage identification circuit 121) when only point A is completely grounded is shown * 6B * (10 and 60 are also e^
2 shows the voltage waveforms to the ground at the neutral point 44 when grounded at points B, 0, and D, respectively. With respect to ground on the side, a DC voltage appears at neutral point 44. This voltage waveform is identified by the identification circuit 121, and if AC voltage is identified, the amplification circuit 123 is driven to operate the output relay 125, and if DC voltage is identified, the amplification circuit 122 is driven to operate the output relay 124. It is something that makes you According to this embodiment, protection against a grounding accident on the DC side is achieved by opening the current breaker, so there is no need to turn off the AC circuit breaker and the auxiliary power is not cut off as in the conventional case. The frequency of grounding is overwhelmingly higher on the DC side, considering the number of electrical components connected and the length of the wiring.

Therefore, it can be expected that the number of times the auxiliary power supply is "cut off" due to a grounding accident can be reduced to the point where it can be practically ignored by applying this embodiment.

FIG. 3 shows another embodiment according to the invention. The same numbers as in Figure 1 indicate the same function and the same name. In Figure 3, 421 and 422 are the divided two parts of the transformer.
The next winding is shown. 13.14 is a resistor, 61 to 68 are rectifier diode arms of the rectifier 6, and the diode bridges 61 to 64 and the diode bridges 65 to 68 are connected in cascade so that DC voltages are added as shown. Ru. In AC electric cars, the secondary side of the transformer is often divided into multiple parts in order to improve the power factor and reduce harmonic currents included in the contact line current (Figure 3 is an example of two parts) ). In such cases.

Generally, a grounding relay is connected between the neutral point 45 on the DC side and the vehicle body 5.

In this embodiment, the grounding detector 12 explained in Fig. 1 is installed at the above-mentioned grounding joint ftft to distinguish between AC side grounding and DC side grounding, and provides the same grounding protection as shown in Fig. 1. be.

Figure 4 shows the ground voltage of the neutral point 44 when a grounding fault occurs at each of the representative grounding points E, F, G, and H in Fig. 3. The neutral point 44ft pressure is equal to the voltage between the A- and E points of the diode 61, and the neutral point 4 at the time of a grounding accident.
4W1 voltage is equal to the voltage across A- of the diode 64. In this case, unlike in Fig. 2, the ground detection m12 identifies a half-wave rectified waveform in the case of an AC side grounding fault, and a full-wave rectified waveform in the case of a DC side grounding fault. I will do it.

Figures 1 and 313! ! In both cases, the rectifier 6 was explained as a full-wave rectifier, but even in the case of a controlled rectifier composed of a mixed bridge of thyristors and diodes or an all-thyristor bridge, the waveform identification function of the grounding detector should be adapted. Therefore, it is possible to apply this embodiment.

Furthermore, in both FIGS. 1 and 3, the explanation was given by taking the example of grounding the indexing motor circuit, but the auxiliary circuit also has AC vI1. When converting power from a source to DC to supply power to auxiliary equipment (air conditioning equipment, lighting, etc.), identify the grounding on the DC circuit side, open only the DC circuit of the auxiliary circuit, and disconnect the index motor circuit from the It is also possible to continue. In this case, it is possible to avoid a situation where the train is unable to operate, and in this sense, a decline in passenger service can be prevented.

Regarding the type of electric vehicle, the present invention can be applied not only to AC-only electric vehicles but also to AC/DC dual-purpose electric vehicles.

〔Effect of the invention〕

According to the present invention, since the AC circuit breaker is opened only when necessary in the event of a grounding accident, it is possible to provide a protection device for an AC electric vehicle that prevents deterioration of passenger service.

[Brief explanation of drawings]

FIG. 1 is a circuit explanatory diagram showing an example of application of the present invention, FIG. 2 is a supplementary explanatory diagram of FIG. 1, FIG. 3 is a circuit explanatory diagram showing another embodiment of the present invention, and FIG. FIG. 3 is a supplementary explanatory diagram of FIG. 3. 3... AC breaker, 4... Transformer, 6... Rectifier, 7... Current breaker, 12... Earthing detector.

Claims (1)

[Scope of Claims] 1. A transformer that steps down the voltage of the overhead contact line, and an AC electric vehicle provided with a grounding relay between the neutral point of the low-voltage side winding circuit of this transformer and the vehicle body potential. 1. A protection device for an AC electric vehicle, comprising a grounding detection device that reads the voltage applied between a point and a vehicle body potential and instructs a circuit to be opened. 2. The protection device for an AC electric vehicle according to item 1, characterized in that when the voltage is AC, the AC main circuit is cut off. 3. The protection device for an AC electric vehicle according to item 1 or 2, characterized in that when the voltage is DC, only the DC main circuit is cut off.