JPS5822983B2 - Line phase detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase detection device for an overhead power transmission line in which multiple circuits are installed together.

Conventionally, when an overhead power transmission line is newly installed, expanded, or replaced, it is checked whether the start and end sides correspond to each other before starting power transmission. It is called.

The mega-filter method and the method of applying a line voltage by turning on a line switch for each phase are well known for phase detection of overhead power transmission lines.1. In these phase detection methods, when multiple circuits are installed together, the induced voltage from the line during power transmission is high, which makes phase detection uncertain, and the work is time consuming and labor-intensive. There were problems such as the need for safety protection against

For this reason, a method is generally adopted in which one busbar of the substation at the end of the overhead power transmission line is opened and a three-phase, eight-pin transformer is used for phase detection. However, system switching is often not possible due to major constraints due to the capacity of the bus and the switching operation in the event of a bus fault, and it is not possible to carry out phase detection on the transmission line of the line under test alone. It has disadvantages such as being unable to do so.

The present invention eliminates the above-mentioned drawbacks, and its purpose is to provide a device that can safely and reliably perform phase detection on a single failure line in a short time without stopping the power transmission line. Specifically, when one end of a power line connected to a power transmission line is grounded, an induced current flows from the power transmission line through the power line through the power line due to electrostatic induction, and the induced current flows into the ground. For example, in the case of an overhead power transmission line with two circuits running side by side, the current can be shown as shown in Figure 1 A. Now, when one end of the A phase of the circuit is grounded, the overhead power transmission line There are some differences depending on the geometrical arrangement of the track, but the electrostatically induced current flowing into the ground■.

is shown by the i+ constant formula.

Here, Ea: Healthy circuit during power transmission A-phase Taiji Denoh Caa, Cba, CCa: Healthy circuit during power transmission a Saikichi failure 1 trial circuit a, b, c The capacitance between each phase is now 275 KV. When the length of the overhead power transmission line is 70/an, the sum of the capacitances (Caa + Cb
A value of 0.1.63 μF has been reported for a+Cca), and the electrostatic induced current I in this case.

From formula (1), it becomes 2.03A.

The value of an electrostatically induced current of 1°, which must be taken into consideration when performing normal phase detection, is considered to be a maximum of 3A, although it depends on the length of the circuit.

In addition to electrostatic induction, if both ends of the circuit are grounded, electromagnetic induction current will return to the earth due to the load current flowing through the power transmission line, and this electromagnetic induction current will flow, for example, in both circuits. In the case of an overhead power transmission line, it can be shown as shown in Figure 1.

Electromagnetic induction current at this time 1. Although there are some differences depending on the geometrical arrangement of the overhead power transmission line, it is generally possible to roughly estimate it using the following formula.

That is, here 1■7: Load current flowing through a healthy line during power transmission Normally, the maximum value of electromagnetic induction current ■2 that must be taken into consideration when performing phase detection is 20OA (maximum load current 1■4m
ax-200OA) is assumed to flow through the earth as a return route.

” = As mentioned above, since electrostatic induction current and electromagnetic induction current flow in the failure test line where multiple circuits are installed together, each phase of the test line can be grounded by grounding the line under test at one end or both ends. By determining whether the induced current flowing in the circuit is only the electrostatic induced current or the sum of the electrostatic induced current and the electromagnetic induced current, it is possible to check whether each phase on the starting and ending sides of the line under test corresponds. This allows confirmation, that is, phase detection.

The present invention has been made with attention to this point, and below, an example in which it is applied to an overhead power transmission line where two circuits are installed together will be explained with reference to FIG. (hereinafter referred to as the healthy line), 2 is the line under test that has been newly installed, expanded, or replaced, and is installed alongside the healthy line 1, and each phase on the starting end side is a + b.
+c, and the phases on the terminal side are X, , Y, and Z.

Reference numeral 3 denotes grounding switches 4a and 4b inserted and connected between each phase of the terminal side X, Y, and Z of the line under test 2 and the ground, respectively.

4c is a phase-specific phase detection circuit connected to each phase of the starting end side a, b, and c of the above-mentioned self-destructive circuit 2, and the input side of the phase-specific phase detection circuits 4a, 4b, and 4c is as follows. An induced voltage consisting of a shunt resistor that is connected to each phase of the starting end side a, b, and c of the line under test 2 and grounded, so that the electrostatic induced current and electromagnetic induced current are derived at a low voltage. Reduction elements 5a, 5b.

5c, and the induced voltage reducing elements 5a, 5b.

Between the terminals of the shunt resistor 5c is a rectifier element (ia
, 5b, 5c, a compression element 7a consisting of a linear approximation compression circuit, etc., which converts the amplification degree when the input reaches a predetermined value.
+ 71) l7c are connected to the output terminals of the compression elements 7a, 7b, 7c, respectively, and display elements 8a, 8b, 8c consisting of voltmeters are connected to the output terminals of the compression elements 7a, 7b, 7c. The instructions are given by output.

Therefore, the predetermined value for converting the amplification degree of the compression elements γa, 7b, and 7c is such that, for example, if the assumed maximum value of the electrostatic induced current is 3A, the conversion is performed by an input of about twice that value. The compression elements 7a and γb are set.

Display element g a , 8 +) receiving the output of 7c,
The scale of the voltmeter 8c is the compression element γa, 7b, 7c.
The scale is enlarged up to the predetermined value corresponding to the predetermined value of , and the input voltage is displayed on the current scale so that the indicated value can be easily distinguished.

Note that if the display elements 8a, sb, and 8c are set to the maximum indication value, the indication values can be distinguished even more easily.

Furthermore, the compression elements 7a, 7b, and 7c may be configured as logarithmic amplifier circuits, since they may be formed to convert the amplification degree when the input reaches a predetermined value.

Next, to explain the phase detection operation, phase-specific phase detection circuits 4a, 4b,
Connect the input sides of the induced voltage reduction elements 5a + 5b +50 of 4c, respectively, and turn on the grounding switch 3 inserted into each phase of the terminal side X, Y, Z of the above-mentioned catastrophic circuit 2. Ground both ends of the line under test 2 for each phase.

By grounding both ends, a current equal to the sum of the electrostatic induced current flowing into the ground and the electromagnetic induced current flowing through the ground as a return path flows through the shunt resistors of the induced voltage reduction elements 5a, 5b, and 5c due to the healthy line 1. Therefore, the rectifying elements 5a, 5b, and 5c, which receive the inter-terminal voltage generated between the terminals of the shunt resistor as input, rectify this and apply a smoothed DC level output voltage to the rectifying elements 7a, 7b, and 7c, respectively. .

The reduction element 7a receives this. 7b and 7c supply the display elements 8a, 8b, and 8c with output voltages amplified by a preset amplification degree according to the input voltage, so that the display elements F3a, 8
The voltmeters b, 8(?,) each indicate according to the input.

This instruction value is recorded and stored, and then the grounding switch 3 connected to the terminal side X phase of the line under test 2 is opened.

Due to this open circuit, if we assume that the a phase on the starting end side of the line under test 2 and the X phase on the terminating side are in phase, then the line under test 2
Since the starting end side A phase and the terminal end 91+I X phase have been switched from both ends grounded to one end grounded,
The voltmeter of the display element 8a of the phase-specific phase detection circuit 4a connected to the starting end side a-phase of the
If 3A- is specified from 3A-, it is confirmed that they are in phase and the phase is immediately detected.

At this time, the display element sb of the other phase-specific phase detection circuits 4b and 4c
, 8c, the readings on the electric frequency meter of 8c are indications that hardly change because each phase of the start end side, c, and each phase of the end side, Y, Z, of the line under test 2 are grounded at both ends. For example, the value is 200A.

In addition, if the starting end side a phase and the terminating end side The indicated value of the voltmeter on the display element 8b of the phase-specific phase detection circuit 4a connected to the starting end side of the phase changes to an electrostatic induction current value (for example, 3 A-), and the other phase-specific phase detection circuits 4a, 4c display element 8a,
If the indication of the 8C voltmeter does not change much as described above, it is determined that the starting end side phase and the terminating end side X phase of the failed circuit 2 are in phase.

Thereafter, as described above, the terminal side X, , Y of the line under test 2
.

By sequentially opening the grounding switches 3 inserted in each phase of Z, phase-specific phase detection circuit 4 a + 4 b + 40
The phase is detected by discrimination based on changes in the indicated values of the voltmeters of the display elements 8a, sb, and 8c.

Although the embodiment has been described with respect to an overhead power transmission line in which two circuits are installed together, it is of course applicable to an overhead power transmission line in which multiple circuits are installed in parallel.

In addition, in the embodiment, the phase-specific phase detection circuit has been described as indicating the electric FF of the induced voltage reduction element using a voltmeter, but it is explained that the electric FF of the induced voltage reduction element is indicated by a digital FF via the voltage-current conversion element. Needless to say, the dirt can be indicated by display.

As described above, the present invention provides phase-by-phase detection in which induced current is detected and displayed at a low voltage between each phase on the starting end side of the line under test of a multi-line power transmission line, and between Shitomochi 1. Connect the circuits respectively and ground or unground each phase on the terminal side of the circuit under test.1 Therefore, the electrostatic induced current and the electrostatic induced current.

The phase is detected by distinguishing the sum of current and current for each phase by 1"c'+L, and the induced current flowing in the line under test is determined by the low current , 7 Detection - Bow 7. Therefore, it is safe to use during phase inspection.
'Se is (-11), which is relatively high, and since the power of phase detection can be reduced by a simple operation of grounding or ungrounding the terminal side of the line under test, the effort required for phase detection can be significantly reduced. Since the power supply for the device can be as small as one drive of a voltmeter, a built-in power source such as a dry battery can be used, and the device can be made cordless.

In addition, since phase detection can be performed on the line under test alone, there is no need to install a stop device on the line during power transmission or switch the busbar system, further improving the reliability of power supply (-7). Moreover, since the phase detection circuit uses a phase-specific phase detection circuit to detect and display the induced current that clearly changes due to grounding at one end or both ends of the circuit, accurate phase detection is possible. In addition to improving the discrimination reliability, the device detects and displays the induced current flowing through -C by grounding, and can be manufactured with a simple configuration, making it possible to provide a compact and optimally portable device. It is effective.

[Brief explanation of the drawing]

Figure 1 is an equivalent circuit diagram of induced current in an overhead power transmission line with two circuits running side by side. Fig. 2 is a block diagram showing an embodiment of the present invention in an overhead power transmission line where two circuits are installed together. 1... Healthy line, 2... Line under test,
3... Grounding switches 1', 4a, 4b, 4c.
...Phase-specific phase detection circuit.

Claims (1)

[Claims] 1. A grounding switch is installed for each phase on the terminal side of the line under test that is installed alongside the power transmission line, and a ground switch is installed on the starting end of the line under test to reduce the induced current. A line phase detection device characterized in that a phase-specific phase detection circuit is provided for each phase, and the induced current is discriminated and phase detected by opening and closing of the grounding switch.