JPH0479213B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a power supply device that supplies driving power to various measurement circuits by applying power to high voltage equipment such as a closed gas switch or a transformer. Regarding.

(Technical Background of the Invention) FIG. 1 shows an example of a partial discharge measurement method in a closed gas switch. This switch is
The high-voltage section is covered with a metal casing 1 for closing, which is electrically divided in the longitudinal direction via insulating spacers 2. At its center, a center conductor 3 electrically connected to a power transmission line (not shown) is supported by a spacer 2 . The casing 1 is grounded by a grounding wire (not shown).

The spacer 2 is provided with an electrode 4 for voltage detection, and a capacitor 5 for partial discharge detection is connected between the electrode 4 and the casing 1. An electric-to-optical converter (hereinafter referred to as an E/O converter) 7 is connected to both terminals of the capacitor 5 via a signal lead-in line 6.

When a high voltage is applied to the center conductor 3, the stray capacitance _C1 existing between the center conductor 3 and the electrode 4 and the capacitor 5 form a voltage divider, and a shared voltage is generated across the capacitor 5. do. When a partial discharge occurs in the switch, a high frequency component caused by the discharge is superimposed on this shared voltage, so the high frequency component is separated in the E/O converter 7 and Converts electricity to light and converts it into optical fiber 8
A partial discharge in the switch can be detected by transmitting the signal to a monitoring unit (not shown) via the switch.

(Problems with the background technology) Now, in such a partial discharge measurement method,
Conventionally, batteries, batteries, etc. have been separately connected or built into the E/O converter 7 as a power supply device, so it has been necessary to charge or replace these power supply devices in a short period of time. In addition, since the partial discharge signal is a weak signal, when an external power source is used instead of a battery for the E/O converter 7, if noise enters through the power supply line, it may be difficult to accurately detect the partial discharge. Otherwise, there was a risk that the E/O converter 7 would be destroyed by the intrusion of high voltage surge.

(Object of the Invention) An object of the present invention is to provide a power supply device that can supply the power necessary for driving various measurement circuits without performing charging or replacement work and with almost no influence of noise. It is about providing.

(Summary of the Invention) The present invention extracts part of the energy of the electric field generated when applying electricity to high-voltage equipment as a shared voltage,
After rectifying this, a capacitor is charged, and the electrical energy stored in the capacitor is maintained at a voltage necessary for the operation of the measuring circuit and is applied intermittently.

(Embodiments of the Invention) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows a part of a closed gas switch in which partial discharge is to be detected and a circuit configuration of a power supply device 9 according to the present invention. When opening and closing, a high voltage is applied from a power transmission line (not shown), and the casing 1 is equipped with a center conductor 3 used for cutting the power transmission line.
are electrically divided in the longitudinal direction via spacers 2 made of an insulator.

The power supply device 9 of the present invention includes a detection electrode 4 provided on the spacer 2 and a capacitor 5 provided between the electrode 4 and the casing 1 as a shared voltage generating means. A rectifier 10 is connected to both terminals of the capacitor 5 via a lead-in line 6 for extracting an induced voltage containing high frequency components. This rectifier 10 includes a plurality of diodes 1
It has a bridge type full-wave rectifier circuit configuration with 1. A charging capacitor 12 that is charged by a rectified voltage is connected to the rectifier 10, and a combination of a constant voltage diode 13 and a gas discharge tube 14 for detecting capacitor voltage is connected in parallel to this charging capacitor 12. . Further, the charging capacitor 12 is connected to an input terminal 22 of a power supply regulator 15 that stabilizes and outputs the voltage.
The power supply regulator stabilizes the voltage input from the input terminal 22 and outputs it to the output terminal 23, and is configured with a well-known transistor type stabilization circuit. The output side of this power supply regulator 15 is connected to a partial discharge measuring circuit 16, while the input terminal 2 of a clock generator 18 is connected via a diode 17.
5. The output terminal 26 of the clock generator 18 is connected to the base of a switching transistor 19 whose collector is connected to the output control terminal of the power supply regulator 15. In addition, a gas discharge tube 14 is connected to the input terminal of the clock generator 18.
The output side of is connected via a diode 20. The clock generator 18 is composed of an RC circuit or a well-known transistor circuit for adjusting the current input from the input terminal 25 and outputting the current necessary for switching the transistor 19 from the output terminal 26.

Next, the operation of the power supply device according to the present invention will be explained.

First, when a high voltage of commercial frequency, that is, 50 or 60 [Hz] is applied from the power transmission line to the center conductor 3, a stray capacitance C1 and a capacitor ₅ occur between the center conductor 3 and the electrode 4. constitute a voltage divider, and a shared voltage of 50 or 60 [Hz] is generated in the capacitor 5. This shared voltage is led to the rectifier 10 via the lead-in line 6, so the rectifier 10 rectifies this induced voltage and charges the charging capacitor 12 with the rectified voltage.

The potential of the charging capacitor 12 increases after a certain period of time due to this charging, and as shown in FIG. 3, the terminal voltage _V1 increases to, for example, a maximum of 200 [V]. on the other hand,
The gas discharge tube 14 is preset to start discharging at a voltage around 200 [V], and when the voltage V ₁ of the charging capacitor 12 rises to around 200 [V], it starts discharging and its terminal voltage increases. The discharge is maintained for t seconds like I ₂ until the discharge decreases to such an extent that the discharge cannot be maintained. This discharge current is input to the clock generator 18 via the diode 20. Zener diode 13 stabilizes this input voltage. Clock generator 18 receives this discharge current as a voltage detection signal of charging capacitor 12, and outputs a clock pulse having a width of t seconds as shown in FIG. 3 to the base of transistor 19. As a result, the transistor 19 is turned on and the power regulator 15 is turned on. Therefore, the output voltage of the charging capacitor 12 is stabilized by the power supply regulator 15 and applied to the partial discharge measuring circuit 16 as a voltage indicated by _V3 in FIG. Although the gas discharge tube 14 stops discharging after t seconds, current is supplied from the power regulator 15 to the clock generator 18 through the diode 17, so the transistor 19 continues to be in the ON state. When the terminal voltage of the capacitor 12 decreases and it becomes impossible to stabilize the output voltage, the voltage V ₃ at the output terminal 23 of the power supply regulator 15 begins to decrease.
For this voltage, terminal 26 of clock generator 18
The output current from transistor 19 decreases, causing transistor 19 to
It becomes OFF. As a result, the partial discharge measuring circuit 16
As shown at _I4 , the circuit operates for T seconds until the clock pulse falls, and only during this period measures the partial discharge generated within the switch, and transmits the measurement signal to the monitoring section via the optical fiber 8.

If the power supply regulator 15 is operated intermittently by the clock pulse of the clock generator 18 in this way, even if the electrical energy obtained by the shared voltage generator is small, the charging capacitor 1
2 can be used to supply the power necessary for the operation of the partial discharge measuring circuit 16. Therefore, the partial discharge measuring circuit 16 can be operated reliably and accurately, albeit intermittently.

By the way, high frequency components are superimposed on the shared voltage obtained from both ends of the capacitor 5, as shown in FIG. This high-frequency component is generated when a partial discharge occurs within the hermetic container.
superimposed on the induced voltage. Since a high frequency transformer 21 is connected in series to the lead-in line 6 for outputting the induced voltage to the rectifier 10, the high frequency component superimposed on the induced voltage is extracted by the high frequency transformer 21 as a detection signal Vs. , are input to the partial discharge measuring circuit 16 as shown in FIG. By analyzing the detection signal Vs from the measurement circuit 16, it is possible to know the state of partial discharge within the switch.

Note that in the above embodiment, the clock generator 1
The width t seconds of the clock pulse outputted by 8 is, for example,
If one cycle of 50 [Hz] is measured by the measurement circuit 16 as one unit, 20 [msec] or more is required, and during this 20 [msec], the terminal voltage of the charging capacitor 12 increases to 200 [msec]. Assuming that the voltage drops from [V] to 100 [V] and the discharge current during this period is 100 [mA], the charging capacitor 12 should be 20 [mA].
It is sufficient to use one with a capacity of [μF]. If the operating cycle of the power supply regulator 15 is, for example, 10 [msec], the overall circuit current of the power supply device 9 is 200 [μA].

Note that the power supply device 9 of the present invention can be used as a power source for measuring instruments of high voltage equipment such as transformers and power transmission lines in addition to the above embodiments.

In addition to partial discharge measurement circuits, various measurement circuits such as temperature measurement circuits can be considered as measurement circuits.
These circuits can also be operated stably by applying voltage intermittently.

(Effects of the Invention) According to the present invention, the induced voltage induced by energizing a high voltage device is rectified, a charging capacitor is charged with this rectified voltage, and the terminal voltage of the capacitor is intermittently measured. By adding the induced voltage to the circuit, the measurement circuit can be stably operated by effectively utilizing the induced voltage. Therefore, since an external power supply device such as a battery is not required, there is no need to perform charging or replacement work.

Additionally, since power is extracted directly from high-voltage equipment, the effects of external noise can be almost completely eliminated. Therefore, it is possible to reliably and accurately measure partial discharge and the like.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing a conventional partial discharge measurement method, Fig. 2 is a circuit diagram showing an example of application of the power supply device according to the present invention to partial discharge measurement, and Fig. 3 is the power supply device of Fig. 2. FIG. 4 is a timing chart for explaining the operation of FIG. 4, and is a waveform diagram of induced voltage. 3... Center conductor, 4... Electrode, 5, 12... Capacitor, 6... Signal lead-in line, 7... E/O converter, 8... Optical fiber, 9... Power supply device, 10...
... Rectifier, 13... Zener diode, 14...
...Gas discharge tube, 15...Power regulator, 16
... Partial discharge measuring circuit, 18 ... Clock generator, 21 ... High frequency transformer.

Claims (1)

[Scope of Claims] 1. A shared voltage generating means that generates a shared voltage by applying power to a high voltage device, a rectifier that rectifies the output voltage from the shared voltage generating means, and a device that is charged with the output voltage from the rectifier. a detection means for detecting that the capacitor is charged and held at a predetermined voltage; a clock generator for outputting a clock pulse upon receiving a detection signal from the detection means; and a clock generator that operates at the rising edge of the clock pulse. and a power regulator that stabilizes the output voltage from the capacitor and intermittently applies the output voltage to the measurement circuit. 2. The power supply device according to claim 1, wherein the measurement circuit is a partial discharge measurement circuit for measuring partial discharge generated in the high voltage equipment.