CN100529772C - Power network overvoltage signal frequency conversion sampling method - Google Patents

Abstract

The present invention provides an overvoltage signal frequency conversion sampling method in a power grid, and relates to the overvoltage signal sampling method in power grid. The method includes the following procedures: firstly, initialization operation; secondly, starting A/D to sample; thirdly, sampling circularly using the high frequency sampling frequency; fourthly, judging whether triggering signal exists; fifthly, pre-triggering frequency conversion sampling; sixthly, reading and storing data by the upper computer. The method of the present invention can record the overvoltage signals inside or outside the power grid completely by less storage capacity, the data quantity is small, the data collected is not distorted, the signal before the accident of the power grid can be retrospected, so that the present invention can be widely used in collecting the overvoltage signal of the power grid, and can also be used in capturing and recording the malfunction wave shape in other fields.

Description

A kind of power network overvoltage signal frequency conversion sampling method

Technical field

The present invention relates to the High-Voltage Test Technology field, relate to a kind of method of power network overvoltage waveform acquisition.

Background technology

Operating experience shows that the various insulation fault major parts that take place in the electrical network are owing to superpotential in the system causes.Superpotential type in the electric system is varied, it produces reason and harm also has nothing in common with each other, and for the correct analysis culprit, improves line insulation and cooperates, external overvoltage accident in preventing, operation department needs the power network overvoltage real-time monitoring system of a kind of high-performance, robotization.

Data acquisition unit is one of core of superpotential on-line monitoring system, it in the future the simulating signal of autobiography sensor change into digital signal, so that microsystem analysis, processing and preservation etc., its technology and precision have directly determined the performance of over-voltage monitoring system.Superpotential in the electric system is searched to the bottom and can be divided into internal overvoltage and exterior overvoltage two major types, and internal overvoltage can be divided into switching overvoltage and temporary overvoltage again.Exterior overvoltage is an atmospheric over-voltage, its wave head is steep, amplitude is high, the duration is short, the wave head of the standard lightning wave of IEC and CNS, half-peak time are respectively 1.2 ± 30% μ s and 50 ± 20% μ s, its wave head equivalent frequency is up to more than the 1MHz, and the sample frequency that requires capture card is 2MHz at least.The switching overvoltage wave head is more slow, but the duration is longer relatively, the superpotential wave head of standard operation, half-peak time are respectively 250 ± 20% μ s and 2500 ± 60% μ s, the equivalent frequency of temporary overvoltage is lower, but its duration is longer relatively, continue more than 1 second, if want the complete various internal overvoltages that occur in the electric system of catching, then require the sampling time be at least 1s promptly more than.Under the certain condition of buffer memory capacity, sample frequency and sampling time length are conflicting.Trigger circuit in the present superpotential on-line monitoring system all are the threshold triggers that adopts the voltage magnitude absolute value, collecting unit can not discern superpotential type takes place, when sampling with the sample frequency that satisfies the lightning surge measurement requirement, when if superpotential is internal overvoltage, because the restriction of memory span, can cause the sampling time to shorten, thereby can not complete collection internal overvoltage data; If with the complete collection internal overvoltage of sample frequency at a high speed, then data volume big, need jumbo storer, to data storage, transmission, analyze and preserve and all can increase many troubles.How lightning surge and the long-term internal overvoltage of waveform that can the complete documentation high frequency under than the storer condition of low capacity is the technological difficulties of superpotential capture card.

At present, be applied between the general 1kHz～20kHz of sample frequency in the fault wave recording device of electric system, and sample frequency is fixed value, therefore can't complete documentation electric system exterior overvoltage waveform.And mostly the data acquisition that is applied to the superpotential on-line monitoring system is to adopt fixed sampling frequency that fault-signal is sampled, and unavoidably can lose long-term internal overvoltage waveform.It as application number 89106209.2 Chinese patent, the acquisition method of disclosed " on-line overvoltage monitor for electric power system " is: whole sampling process is sampled, and branch A adopts, B adopts two parts, it is to recollect sampling that A adopts, adopt lower sample frequency, it is the regular record of superpotential that B adopts, and uses higher sample frequency.When superpotential appearred in electrical network, sample frequency was adopted by A automatically and is transferred B to and adopt.Obvious this acquisition method has its limitation, and first B adopts the sample frequency of part and fixes, if with the 10M frequency sampling, and at all can not complete documentation internal overvoltage waveform; Two what be that trigger circuit adopt is that amplitude thresholds triggers for it, when lightning surge occurring, adopted by A and to transfer B to and adopt process need certain switching time, and that A adopts frequency is low, does not satisfy the measurement requirement of lightning wave head, can cause the measured waveform distortion in conversion.

Summary of the invention

The objective of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of power network overvoltage signal frequency conversion sampling method is provided, can be with than the inside and outside overvoltage signal in the storer complete documentation electric system of low capacity.

The realization technical scheme that the present invention relates to a kind of power network overvoltage signal frequency conversion sampling method is as follows:

A kind of power network overvoltage signal frequency conversion sampling method the steps include:

Step 1, initialization operation, the initialized concrete steps of being finished capture card by host computer are:

(a) capture card state zero clearing;

(b) address zero clearing;

(c) the A/D pattern is set;

(d) high frequency sample frequency F1 and low-frequency sampling frequency F2 control word are set;

(e) pre-triggering length is set;

(f) frequency-change sampling length is set;

(g) the frequency-change sampling frequency control word is set;

Step 2, startup A/D conversion;

Step 3, circulating sampling, capture card carries out the circulation storage of data acquisition and data in the circulating sampling process according to the high frequency sample frequency F1 that sets:

After finishing initialization and capture card and receiving the A/D conversion command, capture card provides A/D sampled clock signal, starts the address generator of internal counter 0 as storer simultaneously, and the clock of address generator and A/D sampled clock signal are synchronous; When carrying out every point sampling, programmable logic device (CPLD) provides static memory address ram signal and write signal synchronously, the data that at every turn collect is deposited among the RAM of correspondence, and increases the address automatically; If sampling number surpasses the max cap. of storer, new data covers the legacy data step 4, has judged whether trigger pip:

If have, turn to step 5 to trigger frequency-change sampling in advance, if do not have, turn to step 3 to carry out circulating sampling;

Step 5, trigger frequency-change sampling in advance, concrete steps are as follows:

After trigger pip arrived, CPLD started its inner counter 1 sum counter 2 and counts from zero respectively, carried out data acquisition and preservation with high frequency sample frequency F1 simultaneously; When counter 2 counting steps are that memory length L-triggers length L in advance ₁-frequency conversion length L ₂After, the clock frequency of A/D sampling and address generator is switched to the frequency F of setting ₂When counter 1 count down to length is that memory length L-triggers length L in advance ₁In time, stop to sample, and sending sampling and finishing signal, notice host computer reading of data;

Step 6: host computer receives sampling and finishes signal, begins to read the data in the capture card buffer memory, after data run through, turns to step 1, and circulation execution in step one is to step 6, up to shutdown.

Adopt a kind of power network overvoltage signal frequency conversion sampling method of the present invention, can be with the less inside and outside overvoltage signal of memory capacity complete documentation electrical network, data volume is little, does not have data distortion, and can recollect the preceding signal of accident of electrical network.

Description of drawings

Fig. 1 is the hardware block diagram of the embodiment of the invention

Fig. 2 is the main program flow chart of the embodiment of the invention

Fig. 3 is the initialize routine FB(flow block) of the embodiment of the invention

Fig. 4 is the pre-triggering frequency-change sampling flow chart of the embodiment of the invention

Fig. 5 gathers the figure as a result of actual electric network over-voltage waveform for adopting the embodiment of the invention

Fig. 6 gathers actual electric network internal overvoltage waveform for adopting the embodiment of the invention

Fig. 7 gathers actual electric network induction lightening over-voltage waveform for adopting the embodiment of the invention

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described as follows:

The structured flowchart of the hardware platform of realizing a kind of power network overvoltage signal acquisition method has been described in Fig. 1, comprise input channel, signal condition loop, analog to digital conversion (ADC) circuit, storage unit circuit, internal clocking, triggering steering logic, memory interface, clock/sequential control, bus interface, specifically be described below:

The signal input channel of capture card comprise three structures identical, function independently analog signal input circuit and an external trigger signal input circuit.Input reference signal is ± 1V or ± 5V, can select by wire jumper; Signal conditioning circuit will be imported the input signal that analog signal conversion becomes the modulus conversion chip requirement, mainly be made up of follow circuit and differential amplifier circuit, the integrated chip that signal conditioning circuit is partly used in this enforcement has operational amplifier OPA690 and differential operational amplifier AD8138; The A/D change-over circuit comprise three structures identical, function circuit independently.The A/D conversion chip adopts 12 bit stream pipeline type modulus conversion chip ADS807 at a high speed in the present embodiment; Storage unit circuit comprise three structures identical, function circuit independently, be used for preserving the data of collection; The storage chip that is adopted is the static RAM IS61LV25616 of 256k word in the present embodiment; The control core of system mainly realizes clock/sequential control, triggers functions such as logic control, A/D controlling of sampling, data storage, computer command decoding.Programming device (CPLD) EPM3256ATC144 of ALTERA company in the present embodiment samples.

Master routine at first carries out initialization operation by host computer to capture card in Fig. 2; After host computer is finished initialization and is started sampling the sampling card, sampling sticks into the line data circle collection, capture card is to carry out the circulation storage of data acquisition and data according to setting high frequency sample frequency F1 in the circulating sampling process: after capture card receives the A/D conversion command, A/D is provided conversion clock, start the address generator of internal counter 0 as storer simultaneously, the clock of address generator and A/D sampled clock signal are synchronous; When carrying out every point sampling, CPLD provides address ram signal and write signal synchronously, each data that collect is deposited among the RAM of correspondence, and increase the address automatically; If sampling number surpasses the max cap. of storer, new data covers legacy data; Judged whether trigger pip,, then still carried out circulating sampling,, then carried out frequency conversion and trigger sampling in advance if having if do not have.After data are filled with, stop sampling, the notice computing machine reads in buffer memory with data; Host computer receives sampling and finishes signal, begins to read the data in the capture card buffer memory, and after data ran through, computing machine reinitialized the sampling card and starts sampling, so circulation.

Fig. 3 has provided the initialization operation program flow diagram, and concrete steps are: the zero clearing of capture card state; The address zero clearing; The A/D pattern is set; The sample frequency control word is set; Pre-triggering length is set; Frequency-change sampling length is set; The frequency-change sampling frequency control word is set.

Fig. 4 provides the procedure chart of pre-triggering frequency-change sampling: after trigger pip arrived, CPLD started its inner counter 1 sum counter 2 and counts from zero respectively, when counter 2 counting steps are that memory length L-triggers length L in advance ₁-frequency conversion length L ₂After, the clock of AD sampling and address generator is switched to the frequency F of setting ₂When counter 1 count down to length is that memory length L-triggers length L in advance ₁In time, stop to sample, and sends to stop sampled signal notice host computer reading of data.

Test findings

Fig. 5 gathers the figure as a result of actual over-voltage waveform for the embodiment of the invention, 50000 data of A point are for recollecting grid voltage waveform among the figure, totally 25000 data points of A～B is the over-voltage waveform of gathering with the high frequency sample frequency of 10Mbps, is the voltage waveform of gathering with the sample frequency of 100kbps after the B point.

Fig. 6 is an embodiment of the invention 10kV electrical network internal overvoltage waveform, and Fig. 7 is the lightning induced voltage waveform that collects.

Can find out by above analysis result, adopt a kind of power network overvoltage signal frequency conversion sampling method of the present invention, can be with the less inside and outside overvoltage signal of memory capacity complete documentation electrical network, data volume data little, that gather are undistorted, can recollect the preceding signal of power grid accident, so can be widely used in the collection of power network overvoltage signal, the fault waveform that also can be used for other field is caught record.

Claims (1)

1, a kind of power network overvoltage signal frequency conversion sampling method is characterized in that, the step of described method is:

Step 1, initialization operation are finished initialization to capture card by host computer, and concrete step is:

(a) capture card state zero clearing;

(b) address zero clearing;

(c) the A/D pattern is set;

(d) high frequency sample frequency F1 and low-frequency sampling frequency F2 control word are set;

(e) pre-triggering length is set;

(f) frequency-change sampling length is set;

(g) the frequency-change sampling frequency control word is set;

Step 2, startup A/D conversion;

Step 3, circulating sampling, capture card carries out the circulation storage of data acquisition and data in the circulating sampling process according to the high frequency sample frequency F1 that sets:

After finishing initialization and capture card and receiving the A/D conversion command, capture card provides A/D sampled clock signal, starts the address generator of internal counter 0 as storer simultaneously, and the clock of address generator and A/D sampled clock signal are synchronous; When carrying out every point sampling, programmable logic device (CPLD) provides static memory address ram signal and write signal synchronously, the data that at every turn collect is deposited among the RAM of correspondence, and increases the address automatically; If sampling number surpasses the max cap. of storer, new data covers legacy data;

Step 4, judged whether trigger pip:

If have, turn to step 5 to trigger frequency-change sampling in advance, if do not have, then turn to step 3 to carry out circulating sampling;

Step 5, trigger frequency-change sampling in advance, concrete steps are as follows:

After trigger pip arrived, CPLD started its inner counter 1 sum counter 2 and counts from zero respectively, carried out data acquisition and preservation with high frequency sample frequency F1 simultaneously; When counter 2 counting steps are that memory length L-triggers length L in advance ₁-frequency conversion length L ₂After, the clock frequency of A/D sampling and address generator is switched to the frequency F of setting ₂When counter 1 count down to length is that memory length L-triggers length L in advance ₁In time, stop to sample, and sending sampling and finishing signal, notice host computer reading of data;

Step 6: host computer receives sampling and finishes signal, begins to read the data in the capture card buffer memory, after data run through, turns to step 1, and circulation execution in step one is to step 6, up to shutdown.

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