CN101833046A - Extra high-voltage AC non-contact distance-measuring type electricity testing method - Google Patents

Abstract

The present invention provides a UHV AC non-contact distance-measuring method. Its flow consists of six stages: self-inspection, detection, distance measurement, data processing, comparison, and sound and light alarm. First, self-inspection, self-inspection After passing, the detection will be carried out; the detection uses the induction principle of the parallel plate capacitance method to detect the electricity, and the electric field strength at the working position of the electroscope is collected at a certain frequency, and the value obtained by multiple tests is used as the alarm threshold; The distance value obtained is based on the field strength curve and change trend of the space electric field to obtain the corresponding field strength value as the electric test value; compare the alarm threshold with the electric test value; reflect whether the tested wire is detected through the alarm of sound and light signals Charged, this method uses the distance measurement method to obtain the electric test value, which is more accurate and precise than the previous method for obtaining the electric test value, and can effectively detect whether the tested wire is charged.

Description

Ultra-high voltage AC non-contact distance-measuring electrical inspection method

technical field

The invention belongs to the field of research methods of safety tools for UHV AC power transmission and transformation equipment, and specifically relates to a UHV AC non-contact distance-measuring electric inspection method.

Background technique

Operation and maintenance work is an important means to grasp the operation status of power grid equipment, discover and deal with equipment defects in time. The "State Grid Corporation Electricity Safety Work Regulations (Power Line Part)" clearly stipulates that before working on some electrical equipment that is powered off or installing grounding wires in the working section of a power outage line, an electrical test must be performed to verify that the equipment or lines are indeed without voltage. The electroscope is one of the common tools used to detect whether there is voltage on the electric equipment. Through the electroscope, it can be clearly verified whether there is no voltage on the equipment to be repaired, and then other operations are performed to prevent the occurrence of charged grounding wires (closing the grounding knife switch) ), accidentally touching electric equipment and other vicious accidents.

In the Chinese patent 200910060796.9 "1000kv UHV AC non-contact electric inspection method and its electroscope", the electric inspection reference value is obtained by the data processing module at a certain frequency to collect data from the electric field strength of this working position, and the alarm threshold is obtained by multiple on-site The test is reasonably selected according to the changing trend of the electric field. Since there are many live equipment in the substation and the converter station, the interference between the live equipment is relatively large, resulting in complex and changeable synthetic field strength around the live equipment. Large interference, so the acquisition of the reference value and alarm threshold in this patent is easily subject to external interference, and the accuracy is not high.

Contents of the invention

The purpose of the present invention is to provide a UHV AC non-contact distance-measuring electrical inspection method, which uses the method of comparing the distance measurement value and the electrical inspection value to detect whether the object under test is charged, and is used for UHV AC power transmission and transformation line projects In the process of measuring whether there is electricity in the power transmission and transformation line, it plays a role of safety protection.

In order to achieve the above-mentioned purpose, the technical solution of the present invention is: UHV AC non-contact distance-measuring electrometry method, which is divided into self-inspection, data processing, comparison and sound-light alarm, and is characterized in that: it also includes distance-measuring and detection stages, After the self-test is passed, the test will be carried out; the test uses the induction principle of the parallel plate capacitance method to test the electric field, and collects data at a certain frequency. Measure the distance value between the electroscope and the wire, and get the corresponding field strength value according to the field strength curve and change trend of the space electric field, and use the distance value as the electroscope value; compare the alarm threshold with the electroscope value; pass Sound and light signal alarm to reflect whether the measured object is electrified. This method uses distance measurement to obtain the electric test value, which is more effective, more accurate, and more accurate than the previous method for obtaining the electric test value. It can be effective Detect whether the wire under test is live.

The beneficial effect of the present invention is: because the present invention is based on measuring the distance between the electroscope and the wire and according to the field strength curve and the change trend of the space electric field to determine the electroscope value of the electroscope to carry out the electroscope, compared with the previous method Compared with higher accuracy, it can effectively detect whether the object under test is charged or not, and solve the problem of poor repeatability and low accuracy of the electric test results caused by the interference of the charged object adjacent to the device under test on the spatial field strength.

The invention satisfies the safety protection requirements of my country's AC and AC ultra-high voltage transmission line engineering operations, fills up the gap in my country's research method on safety tools for ultra-high voltage power transmission and transformation equipment, and is suitable for the inspection of UHV power transmission and transformation lines.

Description of drawings

Fig. 1 is a flow chart of the implementation of the method of the embodiment of the present invention.

Fig. 2 is a schematic diagram of the AC signal acquisition module of the detection part in Fig. 1 .

Fig. 3 is a schematic diagram of the signal amplification module of the detection part in Fig. 1 .

Fig. 4 is a schematic diagram of the rectification circuit in the signal processing module of the detection part in Fig. 1 .

Fig. 5 is a schematic diagram of the interface circuit between the analog-to-digital conversion circuit and the control chip.

Fig. 6 is a corresponding diagram of the height from the wire and the electric test value according to the embodiment of the present invention.

specific implementation plan

The UHV AC non-contact distance-measuring electrometry method of the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the flowchart of the invention of the method. The UHV AC non-contact distance measuring method is divided into six stages: self-inspection, detection, distance measurement, data processing, comparison, and sound and light alarm. First, self-inspection, detection Whether the system can work normally, if the self-inspection fails, the electric inspection work will be canceled immediately, and if the self-inspection is passed, the inspection will be carried out; the electric field value at the working position of the electroscope is obtained and stored as Alarm threshold; distance measurement Use the corresponding laser rangefinder to measure the distance of the measured wire, and measure the distance between the electroscope and the wire; the obtained distance value is based on the field strength curve and change trend of the space electric field to obtain the corresponding field Strong value, as the electric test value, and then compare the two values. If the electric test value is greater than the alarm threshold, it means that the measured object is charged, and an audible and visual alarm is issued; otherwise, it means that the measured object is not charged, and the next alarm can be continued. The measured object is measured.

The detection part in Fig. 1 can be further divided into a signal amplification module, a signal processing module and a signal acquisition module.

As shown in Figure 2, the signal acquisition module is designed based on the principle of electromagnetic induction to collect voltage signals; a parallel plate capacitor and a resistor are connected in parallel, and the voltage at both ends of the parallel plate capacitor can be obtained by using the voltage at both ends of the measured resistance to calculate the position of the electroscope. The electric field strength of the space environment.

The signal amplification module of the detection part can be realized by the method in Figure 3, as shown in Figure 3, it uses an operational amplifier circuit to amplify the differential signal to suppress common-mode interference signals; the input stage in Figure 3 is generally composed of BJT, JFET Or a differential amplifier circuit composed of MOSFETs, which can improve the common-mode rejection ratio of the entire circuit by using its symmetrical characteristics, and its two input terminals constitute the inverting input terminal and the non-inverting input terminal of the entire circuit. The main function of the voltage amplifier stage is to increase the voltage gain, which can be composed of one-stage or multi-stage amplifier circuits. The output stage is generally composed of a voltage follower or a complementary voltage follower to reduce the output resistance and improve the load capacity. The bias circuit is to provide suitable working current for each stage. In addition, there are some auxiliary links, such as level shifting circuit, overload protection circuit and high frequency compensation link.

The signal processing module consists of a pre-stage second-order filter, a rectifier circuit and a post-stage second-order filter. The pre-stage filter is used to reduce high-frequency interference signals, and the post-stage filter is used to filter ripples; rectification is to convert AC signals into AC signal can be realized by precision rectification circuit. As shown in Figure 3, the rectifier circuit is composed of two operational amplifiers and peripheral resistors and diodes: the first operational amplifier and the corresponding resistors and diodes form an equal-proportional amplification circuit; the second operational amplifier and the pre-signal form an addition circuit , You can change the magnification of the rectifier circuit by changing the value of R14. The resistance values of R8, R9, R10, R11, R12, R13, and R14 are: 10K, 10K, 10K, 20K, 10K, 10K, 20K, respectively.

The signal acquisition module, data processing, comparison and sound and light alarm can be composed of an analog-to-digital conversion chip and a single-chip computer. The signal acquisition module can be realized by the single-chip computer controlling the analog-to-digital converter, and the acquisition is performed at a certain frequency. The acquisition frequency can be determined by the sampling rate of the analog-to-digital conversion chip. Any analog-to-digital conversion chip whose accuracy meets the system requirements can be used Data acquisition, the collected data is processed by the single-chip microcomputer and stored in the single-chip microcomputer, as shown in Figure 5; data processing, comparison and sound and light alarm can be realized by the software control single-chip microcomputer, no other peripheral circuits are needed, and the requirements of the system for the single-chip microcomputer are also Not high, any MCU with 51 cores or above can meet the system requirements.

Example:

There are different field strength values at different distances X below the AC transmission wire, and the alarm threshold Y of the electroscope is different according to the field strength value, so the value collected by the electroscope at a distance of x meters below the wire according to a certain voltage level is compared with the alarm threshold y Judging whether the AC transmission wire is charged or not, where x is a range of distance from the wire, and its size changes according to the change of voltage level (for example, x for 500kV AC is 18m~23m, and the alarm threshold y is 2.1 (2.1 is multiple times on site) According to the experimental measurement, the value of y is different in different occasions, and it should be determined according to the specific situation)).

Electricity test process

1. Select a suitable working point, try to minimize the number of live equipment around, and reduce the interference of other live equipment on the electroscope.

2. Carry out self-inspection on the electroscope, and start the electroscope work after the self-inspection passes.

3. The electroscope measures the distance d from the conductor at the working point. If d is in the range of x, that is, 18m<d<23m, the electroscope will continue to work on the electric test. If d is not in the range of x, the electric test will stop. Find the operating point where d satisfies the requirement of x.

4. The electroscope collects the electroscope value z of the working point and compares it with the previously set alarm threshold y. If z>y, the device under test is electrified.

Table 1 is the on-site measured data: (the relationship between the distance from the conductor height and the electrical test value is shown in Figure 6, that is, the field strength curve and change trend diagram of the space electric field)

500kV, the wire is live.

Table 1

Height from conductor (m) Electricity value z Alarm threshold y 18 3.12 2.1 19 2.89 2.1 20 2.76 2.1 twenty one 2.61 2.1 twenty two 2.49 2.1 twenty three 2.36 2.1

Claims (1)

1. The UHV AC non-contact distance measuring method is divided into self-inspection, data processing, comparison and sound and light alarm. It is characterized in that: it also includes the distance measurement and detection stages. Use the induction principle of parallel plate capacitance method to detect electricity, and collect data at a certain frequency The electric field strength at the working position of the electroscope, the value obtained by multiple collections is reasonably selected as the alarm threshold; then measure the distance between the electroscope and the wire , the obtained distance value is based on the field strength curve and change trend of the space electric field to obtain the corresponding field strength value as the electric test value; compare the alarm threshold with the electric test value; reflect the measured value through the alarm of sound and light signals Whether the object is charged.

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