CN201780353U

CN201780353U - Fault line selection device for distribution line of low current grounding system

Info

Publication number: CN201780353U
Application number: CN2009201596454U
Authority: CN
Inventors: 齐天来; 刘崇静
Original assignee: Beijing Hengtianbeidou Technology Co ltd
Current assignee: Beijing Hengtianbeidou Technology Co ltd
Priority date: 2009-06-11
Filing date: 2009-06-11
Publication date: 2011-03-30
Anticipated expiration: 2019-06-11

Abstract

The utility model relates to a fault line selection device of a low current grounding system, which comprises a convertor board, a data acquisition board, a central processing unit board, a result output interface board, a power supply board, a buzzer and a liquid crystal screen, wherein the convertor board is connected with a secondary side of a zero sequence current mutual inductor; the data acquisition board is used for converting an analog voltage signal from the convertor board into a digital signal and saving the digital signal in a data memory and also used for acquiring current travelling waves; the central processing unit board is used for processing data from the data acquisition board, executing fault line judgment, and outputting judgment results to the result output interface board for being output, and the central processing unit board analyzes a travelling wave signal by using wavelet transform, extracts the amplitude characteristics and the polarity of the travelling wave signal, and selects a line with the maximum amplitude value and polarity opposite to other lines as a fault line; the result output interface board is used for outputting the results from the central processing unit board, displays the results through the liquid crystal display screen and informs duty staff through the buzzer; and the power supply board is used for supplying working power for the whole device. The fault line selection device can be used for timely and accurately selecting a single-phase grounding fault line in the low current grounding system.

Description

A kind of distribution line of small-current grounding system fault line selection device

Technical field

The utility model relates to a kind of low current neutral grounding system fault route selecting device, belongs to the relay protection of power system technical field.

Background technology

During small current neutral grounding system generation singlephase earth fault, because the not direct ground connection of neutral point, so, can not form short-circuit loop, therefore there is not short-circuit current, have only the little capacitance current of numerical value to flow to the trouble spot.This is an objective phenomenon.

Although do not form short-circuit loop, the fault ground electric current is also little,, this situation can not long-term existence.Non-fault phase voltage can raise on the one hand, and line insulation is threatened; The flame current of earth point can burn out circuit on the other hand, causes the circuit permanent damages.So China's operation power rules regulation: the single-phase earthing duration must not surpass 2 hours, and faulty line must withdraw from from electrical network.Therefore, being this problem of ground path with regard to having proposed that circuit---fault wire is selected problem.

Around this problem, carried out countless research both at home and abroad, also developed many devices.For example use the failure line selection of zero sequence power current etc.Because power frequency zero-sequence current numerical value is very little, the uneven zero-sequence current when being difficult to normal operation is distinguished mutually, so can't correctly select fault wire.Root problem is to have used the power frequency electric parameters.Cause not having up to now a kind of device fundamentally to solve the low current grounding circuit and select problem.

Summary of the invention

The purpose of this utility model is thoroughly to change to use power current or voltage to carry out failure line selection, the present situation that the route selection effect is bad.The utility model adopts the transient state travelling wave electric current that produces after the fault to select fault wire, the capable wave amplitude maximum of faulty line, and polarity is opposite with non-fault line.Because row ripple and neutral grounding mode are irrelevant:, therefore utilize the fault line selection device of row ripple can fundamentally solve low current neutral grounding system fault line options problem no matter whether initial transient current travelling waves all will occur in neutral ground.

The utility model proposes a kind of distribution line of small-current grounding system fault line selection device, it is characterized in that this device comprises:

Converter plate, the secondary side of it and zero sequence current mutual inductor links, and the big electrorheological that will come from zero sequence current mutual inductor changes 5 volts voltage signal into, and this voltage signal is exported to data acquisition board.

Data acquisition board: it converts the analog voltage signal from converter plate to digital signal, and is stored in the data-carrier store, and fault is exported to the central processing unit plate after taking place; Institute's data acquisition board of carrying is gathered current traveling wave.

The central processing unit plate: it handles the data from data acquisition board, carries out faulty line and judges, and judged result is exported to output interface plate output as a result; Institute's central processing unit plate of carrying adopts the wavelet transformation analysis travelling wave signal, extracts travelling wave signal amplitude Characteristics and polarity, and will go the wave amplitude maximum, and the circuit that polarity is opposite with All other routes is chosen as faulty line.

Output interface plate as a result: this plank shows the result's output from the central processing unit plate, and notifies the operator on duty by hummer by LCD screen.

Power panel: for package unit provides working power.

The utility model characteristics and beneficial effect:

1, can accurately select faulty line, no matter be metallicity fault or transient fault;

2, can select faulty line in real time, take place from earth fault, be selected to faulty line, the time is no more than 50 milliseconds;

3, can monitor nearly 24 times distribution lines simultaneously.

4, can be applied to various earth neutral systems: isolated neutral system; The neutral by arc extinction coil grounding system; Neutral point is through the high resistance ground system; Hinder earthed system in the neutral point warp; Neutral point is through low-impedance earthed system system and solidly earthed neutral system.

Description of drawings

Fig. 1 low-current ground fault line selection device structural drawing

Fig. 2 data acquisition board block diagram

Fig. 3 central processing unit sheet frame figure

Embodiment

The utility model proposes a kind of distribution line of small-current grounding system fault line selection device, reach embodiment in conjunction with the accompanying drawings and be described in detail as follows:

The interface board that the utility model is exported by converter plate, data acquisition board, central processing unit plate and result, power panel, hummer, LCD screen etc. are formed an organic whole device, as shown in Figure 1.

The composition of each plank be connected as follows:

1. converter plate: its changes the big electrorheological that comes from zero sequence current mutual inductor into 5 volts analog voltage signal, can connect 24 zero sequence current mutual inductors at most, and this simulating signal is offered the data acquisition board use.

2. data acquisition board: its converts all 5 volts of analog voltage signals that come from converter plate to digital signal, and is stored in the data-carrier store;

This plank is made up of two unit: hardware-initiated unit I of earth fault and data acquisition unit II, and as Fig. 2.

Wherein:

Hardware-initiated unit is an input current and a threshold value (definite value) relatively, if when the 3～10Khz transient state component in the input current reaches threshold value, and the comparer output low level.Ground connection has been taken place in the judgement system.

Data acquisition unit is made up of multicircuit switch, high-speed AD converter chip, data-carrier store and correspondent control circuits.(analog to digital conversion) 24 tunnel current data are ceaselessly gathered in the high-speed AD converter circulation, and store in the data-carrier store.

8 AD803 that the analog to digital converter chip adopts AD company to produce, the AD9300 that 8 multi-way switchs (each multi-way switch is connected four tunnel simulating signal timesharing to 8 AD) adopt the said firm to produce.The loop-around data storer adopts dual port RAM.

3. central processing unit plate: its carries out Filtering Processing and wavelet transform process to the transient current travelling waves data that come from data acquisition board, the failure judgement circuit, and the result exported to output interface plate as a result, as Fig. 3.

This plate is made up of DSP chip and correspondent peripheral circuit.It mainly carries out wavelet transform process, obtains the capable wave amplitude of zero-sequence current and the polar character on 24 loop line roads, and will go the wave amplitude maximum, and the circuit that polarity is opposite with All other routes is chosen as faulty line.

Digital signal processor adopts the TMS320C32 DSP chip of TI company.Among Fig. 3, RAM is a data-carrier store, and Flash is a program storage.16D, 32D represent 16 or 32 s' data bus or program bus respectively.

4. output interface plate as a result: this plank shows the result's output that comes from central processing unit result of calculation (digital quantity), and notifies the operator on duty by hummer by LCD screen.

5. power panel: the working power of package unit is provided, and power module adopts the Shanghai weighing apparatus to inspire confidence in the Switching Power Supply that Industrial Co., Ltd. produces.

The utility model course of work:

If one single-phase earthing has taken place circuit, this device will start work, and its course of work is as follows:

1. by being installed on the zero sequence current mutual inductor on every loop line road, the zero-sequence current on every loop line road (can reach the electric current on 24 loop line roads) is introduced into converter plate;

2. each transducer electrorheological about 5 amperes (or 1 amperes) coming from current transformer changes 5 volts analog voltage signal into;

3. the start unit of data acquisition board front will detect the disturbance generation, hardware-initiated unit starting, output triggering level;

4. the data acquisition board continuous image data that circulates, hardware-initiated element reads 128 sampled points of the capable wave datum of zero-sequence current on every loop line road after starting from cyclic store;

5. these every time 128 capable wave datum that reach 24 times are carried out wavelet transformation;

According to every loop line road correspondence the wavelet transformation eigenwert, relatively select faulty line.

7. selection result (digital quantity, 0 representative is not a fault wire, 1 represent fault wire) is outputed to and exports plate as a result.

8. output board will provide the hummer cry as a result, notify the operator on duty, and selection result is presented on the LCD screen.

Claims

1. distribution line of small-current grounding system fault line selection device is characterized in that this device comprises:

Converter plate, the secondary side of it and zero sequence current mutual inductor links, and the big electrorheological that will come from zero sequence current mutual inductor changes 5 volts voltage signal into, and this voltage signal is exported to data acquisition board;

Data acquisition board: it converts the analog voltage signal from converter plate to digital signal, and is stored in the data-carrier store, and fault is exported to the central processing unit plate after taking place; Institute's data acquisition board of carrying is gathered current traveling wave;

The central processing unit plate: it handles the data from data acquisition board, carries out faulty line and judges, and judged result is exported to output interface plate output as a result;

Output interface plate as a result: this plank shows the result's output from the central processing unit plate, and notifies the operator on duty by hummer by LCD screen;

Power panel: for package unit provides working power.