JPH0789693B2 - Inductive power supply for power line monitoring sensor - Google Patents

Description

Description: [Industrial application] The present invention uses a current flowing in a power transmission line as a power source to obtain direct current power for driving a power transmission line monitoring sensor It relates to a power supply device.

[Prior Art] Conventionally, as an induction power supply device that obtains electric power from a transmission line, when relatively large electric power is required, the overhead ground wire electrically connected to the transmission line tower is usually insulated from the tower. By doing so, an electrostatic induction voltage determined by the mutual capacitance between the transmission line main line and the overhead ground wire and the self electrostatic capacitance of the overhead ground wire is generated, and the target device is utilized by using this electrostatic induction voltage. There is one that obtains a driving AC power supply or a DC power supply.

In addition, when a sensor that can measure the main line condition is installed on the main line of the transmission line, it is necessary to obtain power from the main line of the transmission line.In this case, a current transformer is usually attached to the main line of the transmission line and Generally, the output of the secondary winding of the current transformer is rectified and the power required for the circuit shown in FIG. 3 is taken. Third
In the circuit shown in the figure, the magnetic flux due to the current in the power transmission line 1 is picked up by the iron core of the current transformer 2 to generate an AC voltage in the secondary winding 2a. This AC voltage is rectified by the rectifier circuit 3, and is maintained at a constant DC voltage level by the Zener diode ZD, which is the constant voltage element 4, and the voltage regulator 7, and is used as a sensor driving power supply.

[Problems to be Solved by the Invention] However, when a predetermined power source is obtained from an overhead ground wire, as described above, it is necessary to insulate the overhead ground wire from a transmission line tower.
In addition to requiring extremely large-scale work on the facility, there are drawbacks such that the original purpose, "the effect of lightning protection," cannot be expected because the overhead ground wire is insulated.

Therefore, in order to obtain a predetermined power source from the overhead ground wire, it is possible to apply the circuit of FIG. 3 that takes the power source from the main line of the power transmission line as it is, but there are the following problems.

In the circuit of FIG. 3, a voltage corresponding to the constantly changing current of the transmission line 1 is induced in the output of the secondary winding 2a of the current transformer 2. After the induced voltage is rectified by the rectifier circuit 3, a constant DC voltage is generated by the series circuit of the constant voltage element 4 and the limiting resistor 5 (resistor R).
Only the difference between the output voltage of the secondary winding 2a and the constant voltage level,
Current Iz flows. That is, if the output voltage of the secondary winding 2a of the current transformer 2 is Va at the AC peak value and the voltage level of the constant voltage element 4 is Vz, the current Iz = (Va-Vz) / R in the constant voltage element 4 is obtained. Flows. As the current Iz increases, the constant voltage element 4 needs to have a capacity to withstand the flowing current.
This was a major obstacle to making the circuit compact.

The operating principle of the circuit shown in FIG. 3 will be described in more detail with reference to FIG. FIG. 4 (a) shows the waveform after the secondary winding output of the current transformer 2 is rectified by the rectifier in the rectifier circuit 3, and the output of this peak value Va passes through the smoothing circuit in the rectifier circuit 3. As a result, the voltage is smoothed as shown in FIG. 4 (b), and the zener diode ZD outputs a constant voltage level Vz as shown in FIG. 4 (c). In this case, since the power loss P of the Zener diode ZD is P = Vz × Iz, when the current Iz flowing through the Zener diode ZD increases, that is, when the output of the secondary winding of the current transformer 2 increases, the transmission There is a relationship that the power loss P of the Zener diode ZD increases as the wire current increases, and the temperature also rises thermally. FIG. 4 (d) shows that the current Iz = (Va−V) flowing by the difference between the output voltage Va of the secondary winding 2a of the current transformer 2 and the constant voltage level Vz of the Zener diode ZD.
z) / R is shown.

For this reason, it is difficult for the circuit shown in FIG. 3 to obtain a stable direct current by covering a current region that varies over a wide range, and this circuit cannot be applied as it is.

An object of the present invention is to solve the drawbacks of the prior art and to provide an inductive power supply device for a power transmission line monitoring sensor that can easily obtain high-quality DC power from an overhead ground wire current.

[Means for Solving the Problems] The present invention uses an electric current flowing in a power transmission line as a power source to obtain electric power for driving a monitoring sensor of a power transmission line facility, and the like. Current transformer to be obtained, rectifier circuit connected to the secondary winding output terminal of the current transformer, DC constant voltage control circuit connected to the rectifier circuit, and connected to the secondary winding output terminal of the current transformer Connected in parallel to the secondary winding output terminal of the current transformer, and a series circuit composed of a constant voltage element that outputs a signal when a certain voltage is reached, and a limiting resistance. It has a control input terminal connected to the connection point, receives the signal output from the constant voltage element as a control input and conducts, and is non-conducting when the alternating voltage polarity of the secondary winding output of the current transformer is reversed during conduction. With a thyristor of switching element Is.

[Operation] When the AC voltage obtained by the current transformer fluctuates from the current flowing in the power transmission line, that is, the overhead ground wire current, and especially when the voltage reaches the constant voltage specified by the constant voltage element, The signal is output. This signal is applied to the control input terminal of a switching element connected in parallel with the secondary winding output terminal of the current transformer, causing the switching element to conduct. Therefore,
The secondary winding output terminal of the current transformer is short-circuited by the switching element. Therefore, the voltage applied to the constant voltage element drops below the constant voltage specified by the constant voltage element, and a large current exceeding the withstand capacity of the constant voltage element does not flow. The switching element becomes non-conductive and automatically recovers when the alternating voltage polarity of the output of the secondary winding of the current transformer is reversed during conduction.

As described above, the circuit configuration in which the output of the current transformer is short-circuited at the predetermined voltage level makes it possible to easily and economically obtain a stable DC voltage from the constant current region to the large current region.

[Examples] The present invention will be described below with reference to illustrated examples.

FIG. 1 shows a concrete example of a power supply device of the present invention, which has a current transformer 2 penetrating an overhead ground wire 1a of a transmission line, and a secondary winding 2a of the current transformer 2 is rectified. The circuit 3 is connected to the output terminal of the rectifier circuit 3. The voltage regulator 7 is connected to a series circuit including a Zener diode ZD that is a constant voltage element 4 and a resistor R that is a limiting resistor 5. Furthermore, the current transformer 2
A thyristor 6 as a switching element is connected in parallel to the secondary winding 2a, and a gate serving as a control input terminal of the thyristor 6 is connected to a coupling point x between the Zener diode ZD and the limiting resistor 5.

The operation of the above configuration will be described with reference to FIG.

The output of the secondary winding 2a of the current transformer 2 is rectified by the rectifier in the rectifier circuit 3 as shown in FIG. It is smoothed by the smoothing circuit inside as shown in FIG. If the smoothed voltage Va is equal to or lower than the operating voltage level Vz of the Zener diode ZD, the voltage regulator 7 changes the voltage to a constant voltage value to obtain a DC voltage.

The overhead ground wire current increases and the output voltage Va of the rectifier circuit 3 increases.
(Fig. 2 (b)) becomes higher and Zener diode ZD
2 becomes higher than the operating voltage level Vz, the voltage of the output line of the rectifier circuit 3 (potential at point y in FIG. 1) is as shown in FIG. 2 (c) due to the action of the Zener diode ZD. It is suppressed to the Zener operating voltage Vz. At this time, the terminal voltage of the limiting resistor 5 (potential at point x), which was at zero potential before the operation of the Zener diode ZD, is almost equal to the difference (Va-V) between the rectifier circuit output voltage Va and the Zener operating voltage Vz.
It becomes the potential corresponding to z). Therefore, the potential of the gate (point z) of the thyristor 6 connected to point x rises,
The thyristor 6 turns on and becomes conductive.

When the thyristor 6 is turned on, the output of the secondary winding of the current transformer 2 is short-circuited at its terminals, as shown in FIG. Therefore, Va≈Vz, and the current Iz flowing through the Zener diode 4 hardly flows.

While the secondary winding output of the current transformer 2 is positive, the thyristor 6 maintains the same state even if the potential at the z point of the gate drops once short-circuited, and the secondary current of the current transformer 2 is maintained. When the winding output has a negative polarity and is in the reverse blocking state, it is turned off again and becomes non-conductive.

By repeating the above, the voltage waveform at the point y on the output line of the rectifier circuit 3 in consideration of the operation of the thyristor 6 becomes as shown in FIG. 2 (e), and the Zener operating voltage Vz is always the peak value. It will hold the voltage. By inputting this rectified output voltage to the voltage regulator 7, a stable DC voltage V dc (FIG. 2 (f)) is output.
The voltage regulator 7 operates so that there is no voltage fluctuation from the time when the thyristor 6 is turned on to the time when the secondary winding output of the current transformer 2 crosses from zero to zero.
That is, a constant direct current is output from the operating voltage level Vz of the Zener diode 4 in FIG. 2 (e) to the voltage level Vzo.

By using the above-described circuit configuration of the induction power supply device, even if the overhead ground wire current changes significantly, the current Iz flowing through the Zener diode ZD becomes negligibly small, and the circuit can be configured with extremely small elements. . Also, thyristor 6
, A current flows when the output of the secondary winding 2a of the current transformer 2 is short-circuited. However, since the forward direction impedance of the thyristor 6 is small, its power consumption is small, and the overall circuit configuration is It becomes extremely compact.

[Effects of the Invention] As described above, the induction power supply device of the present invention has a circuit configuration in which the output of the current transformer is short-circuited to a predetermined voltage level. Power can be obtained easily and economically.

In addition, since it is possible to generate high-quality DC power that can drive sensors etc. from the overhead ground wire current, it is possible to install a sensor that can easily monitor the equipment status on the transmission line tower, which is great for maintenance and monitoring of the transmission line. Be effective. In particular,
If it is used as a power source for a wind direction sensor, which is often installed on a tower, as a sensor for monitoring transmission line equipment, the effect is even greater.

Furthermore, since the transmission line current is used as the power source, the induction power supply device continues to operate as long as the current of the transmission line is flowing, so that a maintenance-free and replacement-free power source can be obtained extremely efficiently.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration example of an induction power supply device of the present invention,
2 (a) to (f) are diagrams used for explaining the operation thereof, FIG. 3 is a diagram showing a configuration example of a conventional induction power supply device, and FIGS. 4 (a) to (d) are operation explanatory diagrams thereof. FIG. In the figure, 1 is a transmission line main line, 1a is an overhead ground line, 2 is a current transformer, and 2a
Is a secondary winding of a current transformer, 3 is a rectifier circuit, 4 is a constant voltage element,
5 is a limiting resistor, 6 is a thyristor (switching element),
Reference numeral 7 indicates a voltage regulator.

Claims (1)

[Claims] 1. An inductive power supply device that obtains electric power for driving a monitoring sensor of a power transmission line by using a current flowing in the power transmission line as a power source, and an AC device for obtaining an AC voltage from an overhead ground line current and a current transformer. A rectifier circuit connected to the secondary winding output terminal; a series circuit connected to the rectifier circuit, comprising a constant voltage element for outputting a signal when the output of the rectifier circuit reaches a certain voltage level and a limiting resistor; A voltage regulator connected to the circuit and a secondary winding output terminal of the current transformer are connected in parallel, having a control input terminal connected to the connection point of the constant voltage element and the limiting resistor, It is provided with a thyristor of a switching element that receives a signal from a voltage element at a control input terminal to be conductive, and becomes non-conductive when the AC voltage polarity of the secondary winding output of the current transformer is reversed when conductive. Transmission line monitoring Induction power supply for support.