JPS6229986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects dielectric breakdown or partial discharge of a discharge charge amount exceeding a set value in a specimen (for example, a capacitor, a resistor, a cable, etc.) connected to a high-voltage side terminal on the secondary side of a transformer. voltage suppression that suppresses follow-on current or extinguishes partial discharge by holding the specimen at a low potential to reduce the standard deviation of the dielectric breakdown voltage value or partial discharge voltage value of the specimen. Regarding equipment.

Conventionally, when dielectric breakdown occurs in power equipment, a discharge current flows into the power system, but in order to protect the equipment, the system is configured to operate a disconnector and disconnect the power from the power system. It is common that However, a follow-on current flows into the specimen from the power supply side during the time from when the specimen undergoes dielectric breakdown until the mustard circuit breaker operates (hereinafter referred to as operating time). This follow-on current causes more damage to the electrode surface and more damage to the deterioration traces of the insulator under test. Additionally, when the breaker operates, overvoltage may be induced on the secondary side via the transformer due to electromagnetic induction, and this overvoltage may further damage the electrode surface and cause signs of deterioration of the insulator under test. There was a problem in that the damage expanded and affected the next dielectric breakdown voltage value and partial discharge voltage value.

In addition, such a long-time follow-on current causes irregularities in the electrode surface and produces discharge deterioration products, which is extremely inconvenient for investigating discharge characteristics under certain conditions.

As an improved method of the above-mentioned primary side insulation failure method, when dielectric breakdown occurs in the specimen on the secondary side of the transformer, the discharge current is used to connect the specimen in parallel to the primary side of the transformer. There is a method of operating the semiconductor device and then turning off the power. We also improved this method,
There is a method of operating a semiconductor element connected in series to the primary side of a test transformer to quickly turn off the power.
Since these methods quickly disconnect the primary side of the test transformer, overvoltage may be induced on the secondary side of the test transformer in the same way as described above.

Therefore, there is a need for a method to directly suppress the flow following the operation of the shingle breaker. As a method for suppressing such follow-on currents, a method is known in which an air gap connected in parallel with the specimen is controlled using, for example, a thyratron. However, even in this method, since an air gap is used, discharge degradation products are formed due to the spark voltage of the gap, and the specimen cannot be controlled under constant conditions.

Therefore, it has been considered to further replace the thyratron and the like with semiconductor elements. A controlled rectifying element (hereinafter referred to as SCR) such as a thyristor is suitable as such a semiconductor element, but at present the withstand voltage of SCR is about 1800 volts, so
In order to prevent a voltage higher than this withstand voltage from being applied to a single SCR, it is necessary to use a plurality of SCRs connected in series.

When a plurality of SCRs are connected in series and used in this way, a particular problem arises regarding the ignition means for turning on all the SCRs at once. In other words, multiple SCRs connected in series
This is because if the SCRs were not fired at the same time, a voltage higher than the withstand voltage would be applied to the unfired SCRs, resulting in destruction of the SCRs.

Therefore, various ignition means have been developed and provided for this type of device in which a plurality of SCRs are connected in series.

First, many SCRs are connected in series or in parallel.
As a means of igniting the SCRs all at once, a pulse transformer with the same number of SCRs as the SCRs is installed, and each secondary winding is
An ignition means is provided which is disposed between the gate and cathode of the SCR and has a primary winding commonly connected to a pulse current generator.

Ignition means with this configuration, especially when connected in series, are often used at high voltages, making it difficult to insulate the pulse transformer, resulting in high insulation costs and additional costs. However, the disadvantage was that a highly efficient pulse transformer could not be obtained.

Secondly, a follow-up ignition method may be considered in which the ignition of one SCR is performed and the next SCR is accordingly ignited. According to this method, when the number of SCRs connected in series is small, there is no problem because the ignition delay time is small, but when the number of SCRs is large, the first SCR
Since the firing is delayed sequentially from the firing of
The ignition of the first one will be delayed considerably. Therefore, a problem arises in that a voltage higher than the withstand voltage is instantaneously applied to the SCR, resulting in decreased reliability or destruction.

For this reason, the third method is to connect multiple SCRs in series, and to connect a resistor and an optical signal between the control electrode (hereinafter referred to as "gate") and cathode (hereinafter referred to as "cathode") of each SCR. A photoelectric element for converting into a photoelectric element is arranged in series, and an ignition power source is arranged between the cathode and the connection point of the resistor and the photoelectric element, and a flexible light pipe is used to ignite the photoelectric element. A method of controlling the ignition by inputting an optical signal for the purpose is also considered, but this method has the disadvantage that the flexible light pipe is very expensive, and when making the flexible light pipe long, the optical signal cannot be used. There was a problem in that a light source with sufficiently high brightness was required because the light was attenuated.

Furthermore, fourthly, as an ignition means for simultaneous ignition, multiple SCRs are connected in series and radio waves are used, the ignition signal generator is a wireless transmitter, and the ignition circuit is an ignition circuit including a wireless receiver. A method of configuring it as a circuit and firing all at once is considered, but if the modulation method is an amplitude modulation method, it will be susceptible to noise and there is a risk of malfunction, which is disadvantageous, and if the modulation method is a frequency modulation method, the entire device will be complicated. However, there were disadvantages in that the cost was high.

Moreover, all of the above-mentioned ignition means are for direct current high voltage and cannot be used with alternating current high voltage, which is an extremely inconvenient problem.

The present invention has been made in view of the above-mentioned points, and is caused by a follow-on current or partial discharge flowing through the specimen during the period from when the specimen undergoes dielectric breakdown until the primary side circuit breaker operates. It is possible to completely suppress current, reduce damage to the electrode surface of the specimen, and minimize changes in dielectric breakdown voltage or partial discharge voltage over time, making economical design easier in the insulation design of power equipment. It is an object of the present invention to provide a voltage suppression device for reducing the formation of discharge degradation products.

In order to achieve the above object, the present invention includes a means for detecting a discharge current generated in a specimen and operating a disconnector provided on the primary side of a transformer; A first circuit formed by connecting a resistor in series to a circuit in which a plurality of rectifying elements are connected in series in the forward direction, and this first circuit is connected in parallel in the opposite direction and has the same circuit configuration as the first circuit. a second circuit, a resistor provided in parallel to each control rectifier of the first and second circuits, a voltage source that applies an ignition voltage to each control electrode of each control rectifier; a photoelectric element that controls the coupling between the voltage source and the control electrode; an ignition signal forming circuit that detects and amplifies the discharge current from the specimen to produce an ignition signal; The voltage suppression device includes a light emitting element that controls the photoelectric element according to a signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to illustrated embodiments. In FIG. 1, reference numeral 1 is an AC power supply, 2 is a disconnector, 3 is a voltage regulator, 4 is a current detector, and 5 is a test transformer.
The transformer 5 detects an excessive current on the primary side of the transformer 5, operates the shield breaker 2, and can stop the application of AC power to the transformer 5. The transformer 5 derives a power supply voltage V ₀ on its secondary side, and has a current limiting resistor R on one voltage line (also called a voltage terminal) H.
_D is connected. The following circuit is interposed between this voltage line H and the other voltage line L.

That is, SR ₁₁ , SR ₁₂ , ..., SR _1o are SCRs, and their polarities are connected in series in the forward direction, and each SCR (SR ₁₁ , SR ₁₂ , ..., SR _1o ) has a
Resistors R ₁₁ , R ₁₂ , . . . , R _1o are connected in parallel to average the shared voltages. This SCR (SR ₁₁ ,
SR ₁₂ ,…, SR _1o ) and resistance (R ₁₁ , R ₁₂ ,…, R _1o )
The first circuit is constructed by further connecting a resistor R _A in series to the series parallel circuit of the voltage terminal H and the voltage terminal H. There is.

Each gate of each SCR (SR ₁₁ , SR ₁₂ , ..., SR _1o ) is connected to an ignition power source E ₁₁ , E ₁₂ , ..., E _1o
are connected to each positive electrode, and each cathode is connected to
One end of each of the resistors R _a1 , R _a2 , . . . , R _ao is connected to each other. The other ends of the resistors R _a1 , R _a2 , ..., R _ao are connected to a power source via photoelectric elements LS ₁₁ , LS ₁₂ , ..., LS _1o that act as switching elements for ignition control.
It is connected to the negative electrode of E ₁₁ , E ₁₂ , ..., E _1o , and when the photoelectric elements LS ₁₁ , LS ₁₂ , ..., LS _1o become conductive, an ignition voltage is applied to the gate. It's summery.

Next, the second circuit has the same configuration as the first circuit, and the difference is that the second circuit is provided between the voltage terminals L and H so that the forward characteristic is directed from the voltage terminal L to the same terminal H. It is that you are.

That is, SCRs (SR ₂₁ , SR ₂₂ , ..., SR _2o ) are connected in series in the forward direction, and resistors R ₂₁ , R ₂₂ , ..., R _2o are connected in parallel to these SCRs to equalize the shared voltage of each SCR. It is connected. This resistance R ₂₁ , R ₂₂ ,
..., R _2o ) and SCR (SR ₂₁ , SR ₂₂ , ..., SR _2o ) by further connecting a resistor R _B in series to form a second circuit.
It constitutes a circuit.

In addition, an ignition power supply is connected between each gate and each cathode of each SCR (SR ₂₁ , SR ₂₂ ,..., SR _2o ).
E ₂₁ , E ₂₂ , ..., E _2o , and a photoelectric element LS ₂₁ for ignition control that couples and controls the ignition power source.
Construct a series circuit for each subcharacter of each code consisting of LS ₂₂ ,..., LS _2o and resistors R _b1 , R _b2 ,..., R _bo ,
In other words, it is configured as a series circuit with one set of E ₂₁ - LS ₂₁ - R _b1 , a series circuit with one set of E ₂₂ - LS ₂₂ - R _b2, etc., and these series circuits are represented by the subscript of each SCR code. It is connected between the gate and cathode of each SCR corresponding to the

Next, these SCRs (SR ₁₁ , SR ₁₂ ,…,
As a light source for igniting the light emitting elements LD ₁₁ , LD _{12 ,} ..., LD 1o , SR _1o , SR _{21 , SR 22 ,} ..., SR _2o ,
It consists of LD ₂₁ , LD ₂₂ , ..., LD _2o connected in series, and in addition, a power source E ₀ for the light source and an ignition control SCR (SR _C ) for controlling blinking of the light source are connected in series.
Between the gate and cathode of this SCR (SR _C ), there is an ignition control device that detects discharge current etc. and controls ignition.
CTL is connected.

The other end of the control device CTL for ignition control is provided with an input end for detecting discharge, etc., and one end is connected to voltage terminal L and the other end is connected to voltage terminal H via a coupling capacitor C _K. has been done. Further, a test object _CX such as a capacitor or a cable is connected between the voltage terminals H and L.

Furthermore, in this example, the photoelectric elements LS ₁₁ ,
LS ₁₂ ,..., LS _1o and light emitting elements LD ₁₁ , LD ₁₂ ,...,
For each pair with LD _1o and photoelectric element LS ₂₁ ,
LS ₂₂ ,..., LS _2o and light emitting elements LD ₂₁ , LD ₂₂ ,...,
The LD _2o is constructed by being housed in a pressurized container filled with an insulating gas, or by housing the entire device in a pressurized insulating gas. This means that V _S =
According to Patsien's law f(Pd), the distance d between the photoelectric element and the light emitting element can be shortened even if the dielectric breakdown voltage V _S is the same under pressurized conditions and under normal conditions. Obtainable. Note that P is pressure.

In addition, the ignition power source (E ₁₁ , E ₁₂ , ..., E _1o ,
E ₂₁ , E ₂₂ , ..., E _2o ) are composed of solar cells, etc.
This is obtained by constantly inputting light from a light source (not shown).

The operation of the embodiment of the present invention having the above configuration will be described below.

Now, if the specimen C _X starts (partially) discharging _for some reason, the coupling capacitor _C
A discharge current will flow through. This current is formed as a ignition control signal via a ignition control device CTL.

The ignition control signal generated by the ignition control device CTL is applied between the gate and cathode of the ignition control SCR (SR _C ). Then SCR
(SR _C ) is turned on, and each light emitting element LD ₁₁ ,
LD ₁₂ , ..., LD _1o , LD ₂₁ , LD ₂₂ , ..., LD _2o are supplied with current from the light source power source E ₀ and emit light.

And photoelectric elements LS ₁₁ , LS ₁₂ ,..., LS _1o ,
LS ₂₁ , LS ₂₂ , ..., LS _2o conduct at each instant, and each
SCR (SR ₁₁ , SR ₁₂ ,…, SR _1o , SR ₂₁ , SR ₂₂ ,
..., SR _2o ), current is supplied from the ignition power supplies E ₁₁ , E ₁₂ , ..., E _1o , E ₂₁ , E ₂₂ , ..., E _2o between the gates and cathodes of the ignition power sources E 11 , E 12 , . In this case, each SCR
(SR ₁₁ , SR ₁₂ ,…, SR _1o , SR ₂₁ , SR ₂₂ ,…,
In order to speed up the turn-on time, a current that does not turn on is set in advance at the gate cathode of SR _2o by resistors R _a1 to _{R ao} and R _b1 to R _bo .

As mentioned above, when a current is supplied between the gate and cathode of the SCR, the SCR (SR ₁₁ , SR ₁₂ ,
..., SR _1o , SR ₂₁ , SR ₂₂ , ..., SR _2o ) are instantaneous (on the order of microseconds). ), they are turned on all at once in each cycle.

As a result, the voltage terminal HL is the resistance value of the first rectifier circuit [the resistance value that is the sum of the forward resistance of each SCR (SR ₁₁ , SR ₁₂ , ..., SR _1o ) and the resistance R _A ] or Resistance value of the second rectifier circuit [each SCR (SR ₂₁ ,
SR ₂₂ , ..., SR _2o ) and the resistance R _B are combined in a short-circuit state.

Therefore, the resistor R _D and each SCR of this voltage suppressor
The voltage between the voltage terminals H and _L decreases due to the conduction effect of be able to.

Furthermore, due to the distribution of resistance values between the resistor R _D and the resistors R _A and R _B , the voltage terminal H
-L voltage _VX can be set to a desired value.

In FIG. 2, the horizontal axis represents time t, and the vertical axis represents voltage V.

The waveform in FIG. 2A represents an example of the voltage waveform of the power supply _V0 , and the waveform in FIG.
This indicates that the next circuit is operating and the voltage between the voltage terminals HL is suppressed.

In FIG. 2B, the waveform example shows the voltage across the resistor R _A , and the waveform example shows the voltage across the resistor R _B.

When the first circuit is operating, a voltage appears on the resistor R _A , and a sine wave part appears as shown in (), and when the second circuit is operating, a voltage appears as shown in (). A sine wave part appears.

In addition, the operation display device can be easily installed by using the ignition control device CTL, and the operation status can be confirmed by adding the operation display device to the resistors R _A and R _B. It's easy to do.

In this way, when a discharge occurs in the specimen _C
The discharge pulse current can be suppressed or extinguished instantly, and the generation of discharge deterioration products on the electrode surface of specimen C _X can be extremely reduced, and pressure changes in the voids of specimen _C can be prevented. For this reason, the specimen _C When it comes to connections, it saves resources and achieves a reliable insulation design.

Further, in the specimen whose discharge current is suppressed according to the present invention, discharge deterioration products are formed in spots corresponding to the number of discharges and are concentrated in one small area. Therefore, it is possible to know the influence of discharge deterioration products generated by multiple discharges on the dielectric breakdown voltage value or the partial discharge inception voltage. One result of this was that the discharge currents were similar despite differences in the electrode surface conditions.

As described above, according to the present invention, the high voltage applied to the specimen is short-circuited at high speed based on the discharge current at the start of discharge of the specimen.
The current can be suppressed at the moment of discharge, reducing damage to the surface of the specimen and suppressing changes in the breakdown voltage value over time, making it possible to realize insulation designs for power equipment at low cost and reliably. There is an effect.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of the present invention, Figure 2 A is a diagram showing the relationship between the power supply and voltage terminals, and Figure 2 B is a diagram showing the voltage waveforms across resistors R _A and R _B. This is a diagram. 1... AC power supply device, 2... Line breaker, 3... Voltage regulator, 4... Current detector, 5... Test transformer,
SR ₁₁ , SR ₁₂ ,…, SR _1o , SR ₂₁ , SR ₂₂ ,…, SR _2o
...controlled rectifier, LS ₁₁ , LS ₁₂ , ..., LS _1o ,
LS ₂₁ , LS ₂₂ , ..., LS _2o ... photoelectric element, LD ₁₁ ,
LD ₁₂ ,..., LD _1o , LD ₂₁ , LD ₂₂ ,..., LD _2o ...Light emitting element, E ₁₁ , E ₁₂ ,..., E _1o , E ₂₁ , E ₂₂ ,..., E _2o
...Power supply for ignition, C _K ...coupling capacitor, SR _C ...thyristor for ignition control, E ₀ ...power supply for light source.

Claims (1)

[Claims] 1. If dielectric breakdown or partial discharge with a discharge charge amount exceeding a set value occurs in a specimen connected to the high-voltage side terminal on the secondary side of a transformer, the high-voltage part of this specimen is A device that suppresses follow-on current or extinguishes partial discharge by maintaining a low potential, and is connected to a circuit in which a plurality of controlled rectifying elements are connected in series in the forward direction, and is installed in parallel with the specimen. a first circuit formed by connecting resistors in series to set the voltage between the terminals at the time; and a second circuit connected in parallel in the opposite direction to the first circuit and having the same circuit configuration as the first circuit. , a voltage sharing resistor provided in parallel with each control rectifier of the first and second circuits, and an ignition voltage source between each control electrode of each control rectifier and one main electrode. a ignition signal forming circuit that detects and amplifies a discharge current from a coupling capacitor connected in parallel to the specimen to generate an ignition signal; and a ignition signal forming circuit that is optically coupled to the photoelectric element and Light-emitting elements connected in series, and a switch connected in series to the series connection of these light-emitting elements via a light-emitting voltage source, the opening and closing of which is controlled by a signal from the ignition signal forming circuit. 1. A voltage suppressing device comprising: a switching means, wherein the photoelectric element and the light receiving element are housed in an insulating pressurized gas.