JPH02174520A - Capacitor power source protective system - Google Patents

Abstract

PURPOSE:To limit the short-circuit current flowing to a capacitor unit in failure by connecting a resistor between a connecting cable and a shorted equipment in an accident caused by the dielectric breakdown of a capacitor unit. CONSTITUTION:Suppose pressure tight reduction is caused by the dielectric breakdown of a capacitor unit 1A and the leakage current is increased for self-explosion. As a result of this short-circuit accident of the capacitor unit 1A, a shorted equipment 3 is so operated that a lead wire 4 shorts both terminals of capacitor units 1A and 1B. Due to the short-circuit of the capacitors 1A and 1B no current from the other capacitor unit will flow into the self- exploded capacitor but into the lead wire 4 through a resistor 5. The short- circuit current I1 through this resistor 5 will not be a 1a large current flow as it is reduced by the resistance 5. No oil fire, etc., will thereby be induced, either.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to a protection system for a capacitor power supply for slow discharge.

[Conventional technology]

Figure 4 shows, for example, the Institute of Electrical Engineers of Japan, Stationary Equipment Study Group (1,980
(December 11, 2012) Proceedings, Kunioi Kozumi, 2 Lessons - ``Protection system and case destruction protection method for low-speed discharge capacitor banks,'' ), and in the figure, LA, IBIC, and ID are capacitor units, and IA particularly indicates an accidental capacitor. 2 is a coaxial cable that connects LA, IB, IC, and ID in parallel. A short circuit that shorts the terminals when one of the many capacitor units connected in parallel causes a short circuit (insulation breakdown), 4 is a lead wire, 10 is a main discharge switch, 11 is a load. Next, we will explain the operation. First, in general, in a capacitor power supply for low-speed discharge, the "unit IA"
, IB, IC, and ID are connected in parallel without using any special decoupling elements. Therefore, when a short circuit (insulation breakdown) occurs in one capacitor unit, the energy stored in other healthy capacitor units concentrates and flows into the faulty capacitor unit IA, and the electromagnetic mechanical force acting on the cable causes the capacitor unit to The case and insulator were destroyed, and the accident capacitor unit IA
This may lead to dangerous situations such as oil leakage, oil ignition, or even fire. In order to prevent this, the accident capacitor unit I
A is electrically cut off from 1 to ICID in the event of an accident with other capacitors. Alternatively, it is necessary to take a method such as short-circuiting the faulty capacitor unit IA with a low inductance circuit. Figure 4 shows an example of this.For example, when two capacitors fail, 1. LA and IB are connected in parallel, and one terminal thereof is connected to a coaxial cable 2 for wiring through a short circuit 3. A lead wire 4 is connected to the short circuit 3,
The other end of the lead wire is connected to the opposite electrode side terminals of the capacitor units LA and IB. The short circuit 3 is made of a material such as thin aluminum foil, and the lead wire 4
It is insulated from the side. Here, capacitor unit IA
When the IB is operating normally, it is charged with a certain amount of energy, but if one of the paired IBs (in case of an accident)
For example, when capacitor unit IA is short-circuited, a large current flows from the other capacitor units I, IB to ID. Most of this current flows through the short circuit, so a large current flows in a short period of time. As a result, the aluminum foil that is the material of the short circuit 3 evaporates explosively, breaks the insulating material, and is electrically connected to the lead wire 4 located outside. On the other hand, the first short-circuit current 11 flowing into the accident capacitor accident 1-IA from the capacitor units 1-, which were connected in parallel other than the paired capacitor units IB, flows from the coaxial cable 2 used for wiring. Therefore, the circuit into which this current flows has a large inductance. Therefore, the paired normal capacitor unit IB
The short-circuit current I2 flows in with a time delay from the second short-circuit current I2 that flows into the short circuit 3 and operates the short circuit 3. As described above, the first
The short circuit current 11 flows into the lead wire 4 side and does not flow into the fault capacitor unit IA. That is, by bypassing the first short-circuit current I, which is a large current, to the lead wire 4, a fire from the accidental condensation IA is prevented.

[Problem B that the invention attempts to solve]

Conventional protection systems for capacitor power supplies are configured as described above, so when a capacitor accident occurs due to insulation breakdown, an extremely large (first) short-circuit current flows through the coaxial cable, and the electromagnetic mechanical force at that time causes damage to the cable. Insulators etc. may be destroyed. Therefore, there was a problem that it was not possible to construct a large capacity capacitor power supply. This invention was made to solve the above-mentioned problem, and by preventing large short-circuit current from flowing in the capacitor power supply wiring etc. in the event of a capacitor unit accident, electromagnetic damage caused by short-circuit current can be prevented. The purpose of the present invention is to obtain a protection system for a capacitor power supply that can prevent this.

[Means to solve the problem]

The protection system for a capacitor power supply according to the present invention limits the first short-circuit current flowing into the faulty capacitor unit from other capacitor unit groups connected in parallel through the connection cable in the event of an accident due to dielectric breakdown of the capacitor unit. For this purpose, a resistor is connected between the connecting cable and the short circuit. The short circuit is used in case of a capacitor accident.
By electrically connecting the lead wire and one end of the capacitor unit using the short circuit current, the first short circuit current limited through the lead wire is bypassed.

[Effect]

The protection system for a capacitor power supply according to the present invention electrically connects the lead wire and the faulty capacitor unit in the event of a fault in the capacitor unit. The first short-circuit current flowing from other parallel-connected capacitor unit groups passes through a resistor connected in series with the coaxial cable, and is reduced and bypassed through the path of the short circuit and the lead wire.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 4 are indicated by the same reference numerals. In FIG. It is connected to the capacitors connected in parallel, and the other end is connected to the terminals of the three short circuits of the capacitor units IA and ]B. Next, the operation will be explained. First, let us assume that (at the time of the capacitor accident shown in FIG. 1) the insulation of the IA deteriorated, the withstand voltage decreased, the leakage current increased, and the capacitor self-destructed. Condensed Suu Uniso 1
~The energy stored in the IA is not large enough to cause a fire due to an insulation short circuit, so a major accident will not occur. Also, the other capacitor unit IB connected in parallel
From the capacitor power supply that self-destructed, an excessive second
The short circuit current ■2 flows into the circuit. FIG. 2 shows a characteristic model diagram of the short-circuit current, and the second short-circuit current I2 flowing through the short circuit 3 is indicated by reference numeral 6. The reason for the large current is that the impedance is very low, and the vibration frequency at this time is also high. This capacitor unit 1. As a result of the short-circuit accident of A, the short circuit 3 operates, and at time L1, the Riet wire 4 short-circuits both ends of 1-IA and IB at the time of the capacitor failure. At the time of this capacitor accident, the current from the other capacitor units does not flow into the self-destructed capacitor because of the short circuit between l-1, A, and IB, but flows into the lead wire 4 via the resistor 5. The first short-circuit current 1.6 that passes through the resistor 5 is reduced by the resistor 5, so that it does not become a large current and therefore does not cause an oil fire or the like. Since the first short-circuit current 1.7 has a large inductance of wiring (including the coaxial cable 2), it rises more slowly than the second short-circuit current 1.6. In addition, the maximum current value is kept low by the resistor 5. Therefore, the electromagnetic force acting on the wiring system is significantly reduced (electromagnetic force is proportional to the square of the current), so the soundness (protection coordination) of the capacitor power supply installation is ensured. In addition, in the above embodiment, 2 of the capacitor unit IAIB
Although we have described a capacitor power supply that uses one short circuit 3 in each unit, it may also be configured so that one short IH 3 is provided in one capacitor unit, as shown in FIG.
The same effects as in the above embodiment are achieved.

【Effect of the invention】

As described above, according to the present invention, the lead wire that bypasses the short circuit current in the event of a capacitor accident is connected to the short circuit,
In addition, since one end of the capacitor unit is connected to the coaxial cable via a resistor, it not only prevents oil fires in the accidental capacitor unit, but also prevents damage to the insulator due to electromagnetic mechanical force in the event of an accident, and explosion of the lead part of a healthy capacitor unit.
This has the effect that it is possible to prevent the occurrence of the next accident, to achieve system maintenance coordination, and to design and manufacture a large capacitor power supply with high reliability.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a protection system for a capacitor power supply according to an embodiment of the present invention, Fig. 2 is a short-circuit current waveform diagram at the time of a capacitor accident in Fig. 1, and Fig. 3 is a diagram showing one capacitor in one capacitor unit. FIG. 4 is a diagram showing the configuration of a conventional protection system for a capacitor power supply. In the figure, LA and IB are capacitor units, 2 is a coaxial cable, 3 is a short circuit, 4 is a lead wire, and 5 is a resistor. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] It is provided corresponding to one set of capacitor units among a group of capacitor units connected in parallel by a connecting cable, and when a short-circuit accident occurs in one capacitor unit of the one set of capacitor units, the above-mentioned 1
A protection system for a capacitor power supply, comprising: a short circuit that bypasses a current flowing into a capacitor; and a resistor inserted between the short circuit and the connection cable.