CN107356867B - Ampere-second characteristic test system for lightning arrester disconnector - Google Patents

Abstract

The invention relates to an ampere-second characteristic test system, which belongs to the field of electric equipment, in particular to an ampere-second characteristic test system for a disconnector of a lightning arrester. Including: an impulse voltage generating device, an acquisition card connected to the impulse voltage generating device, the acquisition card is an acquisition card of model NI-USB 6009, and the high level is given through the IO interface of the acquisition card to drive an external relay, A valid signal is given to the impulse voltage generator, and the time when the acquisition card starts to record the waveform is earlier than the time when the IO interface gives a high level.

Description

Ampere-second characteristic test system for arrester disconnector

technical field

The invention relates to an ampere-second characteristic test system, which belongs to the field of electric equipment, in particular to an ampere-second characteristic test system for a disconnector of a lightning arrester.

Background technique

As a supporting product of the arrester, the disconnector for the arrester (referred to as the disconnector) is used in series with the arrester. Generally, it is directly installed on the grounding side of the arrester to isolate the arrester from the ground potential. The disconnector can be used to prevent the continuous failure of the system, that is, when the arrester fails, the arrester can be disconnected from the system, and a visible mark is given to the naked eye, so that the maintenance personnel can find and replace the faulty arrester as soon as possible.

If the performance and quality of the disconnector can be effectively guaranteed, the use of the disconnector can greatly reduce the accident risk of the arrester, make the arrester truly maintenance-free, and further improve the operational reliability of the system. However, since most manufacturers do not have the test conditions for the disconnector, it is difficult to check and control the production quality of the disconnector in the first place.

In view of this, we try to introduce a set of low-cost detacher quality inspection system. Since there is no national standard for the detection of the disconnector, only the general requirements for the electrical performance of the disconnector are put forward in the arrester standard. According to multiple lightning arrester standards at home and abroad, GB7327-2008 puts forward requirements for the basic electrical performance of the disconnector, mainly focusing on the following two aspects:

(1) The tolerance of the disconnector. The disconnector should be the same as the arrester, and must pass the two tests of long-duration current impact and action load, which are mainly to simulate the working conditions that the arrester should be able to withstand when it works normally.

(2) Action performance of the disconnector. When the arrester fails, the disconnector should have good ampere-second characteristics, that is, it can act timely, accurately and reliably to avoid vicious accidents. The ampere-second characteristic test is an important test to verify the action performance of the disconnector. This test is more difficult to do, and it is also impossible for most manufacturers to complete.

Therefore, a set of low-cost ampere-second characteristic test system is the main content of the disconnector quality inspection system. How to realize correct ampere-second characteristic measurement at low cost is a problem to be solved in the present invention.

Contents of the invention

The present invention mainly solves the above-mentioned technical problems existing in the prior art; it provides an ampere-second characteristic testing system for a disconnector of a lightning arrester.

Above-mentioned technical problem of the present invention is mainly solved by following technical scheme:

A kind of ampere-second characteristic testing system used for lightning arrester disconnector, comprising: impulse voltage generator, the acquisition card that is connected with impulse voltage generator, described acquisition card is the acquisition card that model is NI-USB 6009, through acquisition card automatically The IO interface of the belt gives a high level, drives the external relay, and gives a valid signal to the impulse voltage generator, and the time when the acquisition card starts recording the waveform is earlier than the time when the IO interface gives a high level.

Optimized, the above-mentioned ampere-second characteristic test system for arrester disconnectors, add a while loop in the collection process, each step of the loop takes one second, and the length of the collected data is also one second. The collection module in VI Put it in the loop, and superimpose the data into the shift register. After the loop is over, the data in the register is taken out and stored.

Optimized, the above-mentioned ampere-second characteristic test system for arrester disconnectors compares the collected voltage or current with the preset threshold value at each cycle, and automatically detects when overvoltage or overcurrent occurs Stop experimenting.

Optimized, the above-mentioned ampere-second characteristic test system for arrester disconnectors, at the beginning of each cycle, the collected waveform data will be converted into TDMS format, and the data collected in each cycle will be real-time The superimposition is stored in a corresponding temporary file on the hard disk. After the cycle collection is completed, the data in the temporary file is transferred to another data file to realize real-time storage of test data.

Optimized, the above-mentioned ampere-second characteristic test system for arrester disconnectors uses TDMS storage to store and collect data in each cycle.

Optimized, the above-mentioned ampere-second characteristic test system for arrester disconnector, in each cycle, also includes a voltage dividing resistor connected to the sample to be tested, a piezoresistor, and the acquisition card is connected to the piezoresistor .

Optimally, the above-mentioned ampere-second characteristic test system for arrester disconnectors also includes a current-measuring resistor connected in series with the sample to be tested during each cycle, and the acquisition card is connected to the current-measuring resistor.

Therefore, the present invention has the following advantages: 1. Low cost, safe experiment process, simple operation, and no special requirements for operators.

Description of drawings

Accompanying drawing 1 is a kind of schematic diagram of the present invention;

Accompanying drawing 2 is the working interface figure of the present invention;

Detailed ways

The technical solutions of the present invention will be further specifically described below through the embodiments and in conjunction with the accompanying drawings.

Example:

The present invention is based on the Labview program development language, which was developed by National Instruments (NI). As a virtual instrument development platform, the program language, device drivers, and functional modules are integrated into the software in a manner similar to building circuit diagrams, and users can quickly select It is very simple and time-saving to program the required content.

A set of low-cost ampere-second characteristic test system is the main content of the disconnector quality inspection system. How to realize the correct ampere-second characteristic measurement at low cost is the main problem to be studied in this embodiment.

For the ampere-second characteristic test, it is necessary to perform overvoltage or overcurrent thermal explosion on the disconnector sample, and at the same time measure and collect its current-time characteristics. The general experimental equipment includes an impulse voltage generator and an oscilloscope, and a certain voltage divider is also required to reduce the voltage for normal measurement. At present, there is almost no ampere-second characteristic measuring instrument specifically for disconnectors in China. For this reason, the present embodiment provides a kind of body-type industrial computer, collects data and uses cheap NI-USB 6009 type acquisition card; Impulse voltage is selected from the impulse voltage generation device in the prior art, and its operation and trigger automatically through the acquisition card The IO interface with the belt is connected to the relay control.

The experimental process can be completed only by clicking the mouse, the experimental results are automatically calculated, and the experimental data are automatically saved. Users do not need to be trained, they only need to have basic electrician knowledge to complete the test.

In the ampere-second characteristic test system, it is necessary to achieve simultaneous measurement and control. The computer sends commands to the impulse voltage generating device to trigger a large current to detonate the disconnector; at the same time, the data acquisition card collects the voltage and current signals of the disconnector, and performs data processing on the results.

According to NI's general measurement platform construction mode, when it comes to trigger signals, the acquisition card needs to have a level trigger function or a pulse trigger function, and its waveform recording time should be several seconds. However, through experimental verification, it is found that the acquisition card that wants to realize this function often costs tens of thousands, which does not meet the demand for low cost. However, the commonly used USB6009 series acquisition cards only have PFI trigger function, no level trigger, and no pre-trigger function, which will lead to the loss of the wave head of the trigger waveform and affect the result of data processing. Secondly, after using the acquisition card to record the data for several seconds, the system will convert the data afterwards, and the software will be stuck for several seconds or even tens of seconds, which will affect the experimental effect and may even cause user errors. operate. Without solving the above problems, the measurement system cannot be established.

Through research, we found a solution.

First, on the issue of trigger signals. The conventional blasting experiment is to extract the required waveform signal by detecting the impact voltage level and pre-triggering by percentage.

Since the USB6009 does not have a pre-trigger function, the wave head signal before the trigger signal will be lost, and this signal is the process of the impulse voltage rising from zero potential to the trigger level.

The loss of the signal here will affect the subsequent processing results. So in order to solve this problem, the only way to change the trigger mechanism is to change the external trigger to internal trigger. That is, the mouse clicks the "Start" button, and the acquisition card starts to record the waveform, and records all the subsequent data. At the same time, the IO interface of the USB6009 provides a high level, drives the external relay, and gives the impulse voltage generator a valid signal. Through this arrangement, a natural delay can be generated between the start of waveform recording and before the shock voltage occurs, and this delay can be adjusted manually, thereby avoiding the problem of wave head signal loss.

However, this arrangement also brings about another problem. Since the experiment time ranges from a few seconds to more than ten seconds, for the acquisition card, under the condition of a certain sampling frequency, due to the limited memory of the acquisition card, it cannot support unlimited length of acquisition points. Too many acquisition points will cause the software to freeze or even crash. If the time is limited, a sampling time also needs to be given in advance for one collection, which will lead to the rigidity of the experimental process. It may happen that the detachment device will explode after the predetermined time, and the experimental data will be missed, or the detachment device has been blasted after the predetermined time is too long. The experiment cannot be stopped.

Due to the above drawbacks that may occur in fixed collection, we try to change the collection mode to continuous loop collection, add a while loop in the collection process, the time of each step of the cycle is one second, and the length of the collected data is also one second. The acquisition module is placed in the loop, and the data is superimposed into the shift register. After the loop is over, the data in the register is taken out and stored. Adopting the acquisition program of this structure can flexibly realize simple synchronous processing of data, mainly for two purposes. One is that when overvoltage or overcurrent occurs, the test can be automatically stopped by comparing the collected maximum values; the other is that when the time exceeds the setting and no valid data is generated, the test can be automatically ended and the user is prompted to stop the test. circuit ground. The above two functions can be completed by a simple numerical comparison module, which is much more flexible than fixed acquisition.

However, this acquisition method encounters a problem. After the data collected by the while loop is put into the shift register, the amount of data will be superimposed, and the shift register that comes with Labview is less efficient in calling the memory. When the amount of data is large May cause a crash. The amount of data in this program is not too large, but with the superposition of cycles, the operation of the program will be affected in the last few cycles of a measurement, resulting in delays in data acquisition and distortion in recorded waveforms.

In order to solve this problem, we adopt the TDMS storage method. TDMS storage is a built-in data storage module in Labview, which is specially designed for high-speed data acquisition and storage. At the beginning of the acquisition, the acquired waveform data will be converted into TDMS format, and the data acquired in each cycle will be superimposed and stored in a corresponding temporary file on the hard disk in real time. After the cycle acquisition is completed, the data in the temporary file will be dumped It is another data file to realize real-time storage of test data. Since the TDMS storage method is to directly call the CPU and memory resources, it does not need to go through the 10M limit of the system memory by Labview, so its storage and processing speed is very fast, which can reach 100M/s, and is compatible with almost all PCI, PXI and USB on the market. capture card.

Through the transformation of the TDMS storage method, we will modify the acquisition cycle to the present (see Figure 2). The software controls the test process. Before starting the test, the test environment can be modified, the current intensity can be selected, the alarm level can be set, and the test timeout can be set. After clicking the start button, the acquisition cycle starts, and after a delay of 1 second, the IO port sends a trigger signal to control the discharge of the impulse voltage device. Under normal circumstances, the disconnector sample explodes, the test voltage and current waveform recording is completed, the test ends automatically, the test results are automatically processed and a test report is generated. Under abnormal conditions, if the voltage exceeds the limit or the sample does not explode after the test timeout, the test will stop automatically. The alarm lamp lights up and the alarm bell sounds.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Claims (6)

1. An ampere-second characteristic testing system for a surge arrester disconnector, comprising: the device comprises an impulse voltage generating device and an acquisition card connected with the impulse voltage generating device, and is characterized in that the acquisition card is an acquisition card with the model of NI-USB 6009, a high level is given out through an IO interface carried by the acquisition card, an external relay is driven, an effective signal is given to an impulse voltage generator, and the time when the acquisition card starts to record waveforms is earlier than the time when the IO interface gives out the high level;

Adding a while loop in the acquisition process, wherein the time of each step of the loop is one second, the length of the acquired data is one second, putting an acquisition module in a virtual instrument program in the loop, superposing the data and putting the data into a shift register, and taking out and storing the data in the register after the loop is finished.

2. The ampere-second characteristic test system for a lightning arrester disconnector according to claim 1, wherein the collected voltage or current is compared with a preset threshold value at each cycle, and the test is automatically stopped when it is judged that the overvoltage or overcurrent occurs.

3. The ampere-second characteristic testing system for the arrester disconnector according to claim 1, wherein the collected waveform data is converted into a TDMS format at the beginning of collection, the collected data in each cycle is stored in a corresponding temporary file on the hard disk in a real-time overlapping manner, and after the collection of the cycle is finished, the data in the temporary file is stored in another data file to realize the real-time storage of the test data.

4. The ampere-second characteristic testing system for the arrester disconnector according to claim 1, wherein the acquired data is stored by a TDMS storage mode.

5. The ampere-second characteristic testing system for the arrester disconnector according to claim 1, further comprising a voltage dividing resistor and a voltage measuring resistor connected to a sample to be tested, wherein the acquisition card is connected to the voltage measuring resistor.

6. the ampere-second characteristic testing system for the arrester disconnector according to claim 1, further comprising a current measuring resistor connected in series with a sample to be tested, wherein the acquisition card is connected with the current measuring resistor.