CN107271775B - electric power overhead line phase detection method - Google Patents

Abstract

The invention discloses a phase inspection method for a power overhead line, and belongs to the field of power systems. It solves the technical problems in the prior art that the operator faces personal danger and the operating instrument is easily damaged by breakdown in the high induced potential environment in the line. The invention adopts the capacitive voltage division method to measure the voltage at one end of the line, and determines whether it is the same phase by the technical means of observing the change of the voltage at one end of the detection phase. The adopted technical means are safe, convenient, efficient, time-saving and labor-saving, which can satisfactorily solve the technical problems of personal and instrument danger existing in the prior art, and complete the technical task of phase inspection of overhead lines.

Description

A method for phase inspection of power overhead lines

technical field

The invention belongs to the technical field of electric power systems, and in particular relates to a phase inspection method for an electric power overhead line.

Background technique

High-voltage transmission lines are generally distributed in areas with complex terrain and changing climatic conditions. Faults are prone to occur, and line inspection and maintenance are difficult. At present, after the overhead line of the power system is installed, the phase inspection of the overhead line must be completed in accordance with GB 50150-2016 "Standards for Electrical Equipment Handover Test for Electrical Installation Installation Engineering".

At this stage, a multimeter or a phase detector is routinely used to check the phase. The phase detector is used in the phase verification and phase sequence verification of power lines and substations, and has functions such as phase checking, phase sequence measurement, and electricity inspection. It has strong anti-interference, meets the requirements of (EMC) standards, and is suitable for various electromagnetic field interference occasions. The measured high-voltage phase signal is taken out by the collector, and directly transmitted after processing. It is received by the receiver and compared with the phase, and the result after the phase check is qualitative.

Today's conventional inspection method is to ground any phase at one end of the line first when the induced electricity is small, and then measure the resistance to the ground with a shaker or a multimeter. When the resistance is detected to be small, it means that it is the same phase. Otherwise, not the same phase. When the inductive electricity is large, at the power supply end of the line to be checked, first disassemble any two phases, and then connect a phase voltage transformer to the other end of the line to be checked. Add the running voltage to the power supply terminal, when the opposite terminal voltage transformer detects the running voltage for the second time, it means that it is the same phase. Otherwise, not the same phase.

It can be seen from the above that the conventional inspection method uses a shaking meter or a multimeter, and the application is complicated, and due to the parallel, staggered, and crossed high-voltage transmission lines, an induced voltage is formed on the line under test, and this induced voltage will give test personnel and test instruments. cause certain damage, which is very dangerous and inconvenient in such an environment.

The prior art discloses some overhead line phase inspection methods.

The literature (“Test methods and precautions for phase inspection of cable lines”, Ma Xuehua et al., Power and Electrical Engineering, No. 6, 2016) discloses the phase inspection method. The battery method is used to check the phase, and the grounding switch at both ends of the cable is pulled. on to fully discharge the cable. All three phases on the opposite side are left unconnected. At one end of the cable, phase A is connected to the positive pole of the battery pack, and phase B is connected to the negative pole of the battery pack; at the other end of the cable, use a DC voltmeter to measure any two-phase core wire. When the DC voltmeter is positive, the positive pole of the DC voltmeter is A Phase, the negative phase is B phase, and the remaining phase is C phase.

When using the insulation resistance meter method to check the phase, open the line grounding switch at both ends of the cable, fully discharge the cable, all three phases on the opposite side are suspended, connect one end of the measuring line to the "L" end of the insulation resistance meter, and the other end to the insulation Rod, the "E" terminal of the insulation resistance meter is grounded. Inform the person on the opposite side to ground one phase of the cable (take phase A as an example) and open the other two phases. The tester drives the insulation resistance meter, and connects the insulation rods to the three-phase core wires of the cable respectively. The core wire when the insulation resistance is zero is phase A. After the test is completed, the insulation rod is separated from the phase A of the cable, and then the insulation resistance meter is stopped. Discharge the cable and record. After completing the above operations, notify the test personnel on the opposite side to connect the ground wire to the other phase of the line, and repeat the above operations until all three phases are grounded once.

As mentioned above, the above method uses a voltmeter or an insulation resistance meter for measurement, and the phase detection method is carried out in the environment of a strong induced potential. The detection personnel cannot get rid of the dangerous operation, and the operating instrument has the risk of being broken down.

The patent document whose publication number is CN 103983853 A discloses a method for checking the phase of a high-voltage cable cross-connection system, and the inventive method comprises: Step 1: the detection personnel perform wiring at the first section of the high-voltage cable; Step 2: the detection personnel arrive at the high-voltage cable Step 3: Check the phase of the cross-connection system by the inspection personnel to the No. 2 joint box of the high-voltage cable; Step 4: Repeat the above steps until the phase inspection of all the cross-connection systems is completed. Work.

Described step 1: First, the inspector performs wiring at the first section of the high-voltage cable. The a-phase of the metal sheath is directly grounded, the b-phase is grounded through a resistance of 100 ohms, and the c-phase is suspended and not grounded.

Described step 2: the inspector checks the phase of the cross-connection system to the No. 1 joint box of the high-voltage cable. At the No. 1 joint box, the metal sheath of the two cables will be led out to the cross-connect box through the coaxial cable during the construction of the cable joint. Therefore, there will be 6 phases, that is, the inner core of the coaxial cable is 3 phases and the outer core is 3 phases. Use the resistance (ohm) gear of the multimeter to measure the inner and outer cores of the coaxial cable respectively to the ground. At this time, the resistance of zero is the phase a at the head end of the cable, the resistance of about 100 ohms is phase b, and the resistance of phase c is infinite. The resistances of the remaining 3-phase cores (al, bl, cl) are also infinite, and the 3-phase cores point to the No. 2 connector box. Then directly ground the al phase of the metal sheath, ground the b1 phase through a 100 ohm resistor, and leave the c1 phase floating and not grounded, so as to prepare for the next phase inspection work.

It can be seen from the above that when the above technical solution is tested, the resistance is grounded through a 100 ohm resistance, and the resistance is measured by a multimeter. The measuring instrument works in the environment of dangerous induced potential, not only the staff cannot avoid the construction danger, but also there is a breakdown of the instrument. technical issues.

SUMMARY OF THE INVENTION

In order to ensure the safety of people and the tester, we have summed up our experience and repeated practice in the actual work on site, and finally found a method for phase inspection of power overhead lines. This method is simple and practical, and can complete the phase verification work of large overhead lines with induction electricity in a simple and timely manner.

When the power overhead line under test is not grounded, the AC voltage of the power overhead line to the ground is distributed according to the magnitude of the capacitance impedance to the ground. When one end of the power line is grounded, the capacitance of the high-voltage overhead line to the ground changes, and the AC voltage of the power overhead line to the ground also changes.

As shown in Figure 1, the main capacitor 1 and the voltage dividing capacitor 2 are connected in series, and the induced voltage of the overhead line is detected at one end of the line by the capacitive voltage dividing method. At the other end of the line, the phases to be detected are grounded respectively. When the voltage drop is detected, it means that it is the same overhead line and the phase is the same; when the detected voltage does not change, it means that it is not the same overhead line and the phases are different.

The beneficial effects of the present invention are:

1. After the installation of the power system or the erection of the overhead line, it is necessary to check the phase according to the national standard, and the method of checking the phase in the prior art conventionally uses instruments such as multimeters or detectors, and the parallel and staggered erection methods of the overhead lines are generated on the line. The higher induced potential may threaten the personal safety of the staff, and for the detection instrument, there is also the danger of being broken down. In order to overcome the above problems, a safe, efficient, simple and practical method for phase inspection of overhead lines has been explored in long-term engineering practice. The method utilizes the capacitive voltage divider to measure the voltage, and the work can be completed quickly, accurately and safely only by grounding and measuring whether the voltage changes;

2. Avoid operating overvoltage in the process of power outage and transmission, and provide a guarantee for the safety and stability of the power system;

3. There is no need to power off the line, saving operation time;

4. Compared with the conventional phase inspection, there is no need for the participation of more personnel in scheduling, operation and maintenance, and testing, saving manpower.

Description of drawings

Figure 1. The connection diagram of the voltage detection device for the phase inspection method of the power overhead line;

Figure 2. Schematic diagram of phase inspection of power overhead lines.

Detailed ways

In order to better understand the present invention, the content of the present invention is further described below in conjunction with the embodiments, but the protection content of the present invention is not limited to the following embodiments. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without one or more of these details.

The method will be further described below with reference to the accompanying drawings.

As shown in Figure 1, the following steps are performed to realize the installation of the high-voltage detection device: First, select a small-capacity high-voltage capacitor (1000pF, 10kV) as the main capacitor, use two large-capacity low-voltage capacitors (0.02μF, 400V) as the voltage divider capacitor, and connect the three The branch capacitors are welded together in series. From Q=CU, U _master =U _points *10000/1000=100 U _points .

Then, the capacitors connected in series are installed in the PVC pipe, and the outer leads of the capacitors are fixed with binding posts.

See Figure 2, the use and discrimination methods are as follows:

1. Open the grounding switch at both ends of the overhead line, and the overhead line is suspended;

2. The test staff first ground the low-voltage power 5 side of the device at one end of the overhead line. Then connect the 4-side leads of the high-voltage capacitor of the device to any phase of the overhead line with insulating rods;

3. Detect the indicated value of the low-voltage capacitor voltage of this device, and record it; telephone to inform the opposite end of the line A to ground phase respectively, and the grounding operation can be performed by connecting the insulating rod 2 to the flexible wire 3. At this time, if the indication of the voltmeter 6 drops, It means that the two ends of the wire have the same phase and are the same wire. If the voltmeter does not change, it means that the phases of the two ends of the wire are inconsistent and not the same wire. According to this, the phase checking work is completed to achieve the purpose of checking the phase.

The following test voltages are converted to line side voltages.

Example 1

Table 1

It can be seen from the above table that the phase inspection method of the present invention is used for inspection, and the above steps are carried out for the three phases in turn. It can be seen that when the A phase is inspected, the test voltage drops to 21v. Therefore, it is concluded that the A phase is the same principle. A check of the other two phases is obtained.

Example 2

Table 2

It can be seen from the above table that the phase inspection method of the present invention is used for inspection, and the above steps are carried out for the three phases in turn. It can be seen that when the A phase is inspected, the test voltage drops to 6V. Therefore, it is concluded that the A phase is the same principle. A check of the other two phases is obtained.

Example 3

Table 3

It can be seen from the above table that the phase inspection method of the present invention is used for inspection, and the above steps are carried out for the three phases in turn. It can be seen that when the A phase is inspected, the test voltage drops to 12V. Therefore, it is concluded that the A phase is the same principle. A check of the other two phases is obtained.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention, as long as they do not depart from the spirit of the technical solutions of the present invention and The scope should be included in the scope of the claims of the present invention.

Claims (1)

1, electric power overhead line phase position inspection method, characterized by, including:

step , measuring the voltage at the end of the overhead line ;

grounding the other end of the overhead line, observing whether the voltage drops, if so, judging the overhead line to be in-phase, and if not, judging the overhead line to be out-of-phase;

the method comprises the following steps of , selecting a low-capacity high-voltage capacitor as a main capacitor, using a high-capacity low-voltage capacitor as a voltage dividing capacitor, and welding the capacitors in series;

in step , the earthing knife switch at the two ends of the overhead line is pulled open, the overhead line is suspended, the low-voltage capacitor side is earthed at the end of the overhead line, then the lead wire at the high-voltage capacitor side is lapped on any phase of the overhead line by an insulating rod, and the indicated value of the voltage is recorded;

in the second step, the other ends of the overhead line are grounded respectively, and are connected with the flexible conductor through the insulating rod.

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