CN102095938A - High-precision signal processing method for insulation online monitoring of high-voltage electric-power capacitive equipment - Google Patents

Abstract

The invention discloses a signal processing and calculating method for insulation dielectric dissipation factors with the characteristics of high precision and immunity to electromagnetic interference, which developed by aiming at high-voltage electric-power capacitive equipment for realizing insulation online monitoring technology in the equipment life cycle management of an intelligent power grid. In the scheme, based on distributing type remote synchronous signal collection and through carrying out complete-frequency discrete sampling on the leakage current and the busbar voltage of the high-voltage capacitive equipment in a timing way, an infinite impulse response filter group (IIRG) consisting of a point-pass filter, a low-pass filter, a high-pass filter and a necessary point-resistance filter is arranged by aiming at the interference characteristics of high-voltage electric power equipment, input signal sequences adaptive to the time constants of the IIRG are obtained through signal extension, filter output with 50Hz of power frequency signals is obtained through the IIRG, the phasor phase difference of the leakage current and the busbar voltage of the high-voltage capacitive equipment are obtained with a phase algorithm, and further the insulation dielectric dissipation factors with high precision are obtained.

Description

The high-precision signal disposal route of the capacitive apparatus insulated on-line monitoring of high-tension electricity

Technical field

The present invention relates to the insulated on-line monitoring of high-tension electricity capacitive apparatus, belong to the cycle equipment life-cycle monitoring management field of high voltage electric power equip ment repair based on condition of component and on-line monitoring field and intelligent grid.

Background technology

Power industry is the main body of energy industry, and UHV (ultra-high voltage), UHV transmission can be realized farther distance and more high efficiency power transfer, and the High-Voltage Insulation technology is a gordian technique wherein.Most faults of extra-high voltage, supergrid show as insulation and wreck.High voltage electric power equip ment except that power transmission line is all concentrated and is placed in the transformer station, comprise main-transformer, primary cut-out, current transformer (CT), capacitance type potential transformer (CPT), sleeve pipe, coupling condenser, lightning arrester etc., wherein most equipment are capacitive apparatus.The status monitoring of realizing high voltage capacitive apparatus can prevent because the capacitive apparatus insulated electric network fault that causes.Now, intelligent grid is being built in electrical network and electric system, the life-cycle cycle management that a key content of intelligent grid is exactly a power equipment, and the status monitoring that promptly relies on high voltage electric power equip ment is realized preventative control and repair based on condition of component.Real-time insulating monitoring and diagnostic techniques are the bases of repair based on condition of component, high voltage electric power equip ment is carried out on-line monitoring, in time prediction and tracing trouble all have great importance to the normal operation of guaranteeing power equipment, the reliability that improves electrical network and to equipment and operations staff's safety.

The monitoring of high voltage electric power equip ment insulation status is at present usually based on to its dielectric dissipation factor tan δ, dielectric leakage electric current I _PMonitoring with electric capacity C.The test philosophy of dielectric loss can be sketched to current signal and voltage signal with measurand are sent to measurement mechanism, and the phase place with two signals compares then, thereby obtains the dielectric loss value of equipment.Existing capacitive apparatus insulated monitoring technology is difficult to practicality.The leakage current of capacitive apparatus is the 10mA level, belongs to tiny signal.And capacitive apparatus all is a high-tension apparatus, and there are a large amount of high pressure flashovers and discharge in the scene, and electromagnetic interference (EMI) is very serious, contains a large amount of undesired signals in the sampled signal; Monitor the leakage current signal and the equipment voltage signal of capacitive apparatus insulated this equipment of needs, the latter's sensor (voltage transformer (VT)) position and this capacitive apparatus distance are far, if being delivered to electric room through cable connection, the leakage current signal of capacitive apparatus measures small leakage current again, to further enter Errors Catastrophic and undesired signal, it is practical to make that this scheme is difficult to, and measurement result lacks confidence level.

Therefore, adopt novel tiny signal measuring technique, realize that the association collection of diverse location signal and processing are the keys that solves high voltage capacitive apparatus insulated monitoring.

This patent proposes a kind of high precision of IIRG IIR filter group, jamproof insulating monitoring signal processing method and algorithm of adopting, improve the sensing ability of signal by distributed in-site collecting tiny signal, realize the strange land synchronized sampling of leakage current and voltage by the Zigbee radio communication, obtain the better resisting interference effect by signal Processing and IIRG filtering algorithm, the accurate problems of measurement of high voltage capacitive apparatus leakage current phasor can be solved, all higher resolution and stability must be obtained aspect phasor phase place and the amplitude.This algorithm requires that special data acquisition and communication mode are arranged, and can incorporate in the intelligent grid high voltage capacitive apparatus condition monitoring system as gordian technique.

Summary of the invention

The present invention relates in the equipment life-cycle of intelligent grid cycle management, realize the insulated on-line monitoring technology at the high-tension electricity capacitive apparatus, disclose a kind ofly have high precision, to the insulation dielectric loss factor computing method of electromagnetic interference (EMI) immune characteristic.This scheme is based on distributed strange land signals collecting, utilize different leakage current collection unit and busbar voltage collecting unit to realize the leakage current and the busbar voltage sampling of high voltage capacitive apparatus respectively, realize the synchronized sampling of different acquisition units by the clock synchronization of collecting unit, the regularly discrete sampling that the discrete leakage current and the busbar voltage of high voltage capacitive apparatus are done the complete cycle ripple, the signal list entries that adapts by signal continuation acquisition and modal filter group time constant, interference characteristic at high voltage electric power equip ment, setting is by a bandpass filter, low-pass filter, the IIR filter group (IIRG) that Hi-pass filter and some resistance wave filter are formed, obtain the filtering output of 50Hz power frequency component by IIRG, by electric power phase quantity algorithm, obtain the phasor phase differential of high voltage capacitive apparatus leakage current and busbar voltage, and then obtain high-precision insulation dielectric loss factor.This method adopts the Zigbee wireless sensor network as the communication mode between the distributed measurement unit, and configuration busbar voltage node is that Zigbee coordinator node, leakage current node and master node are the Zigbee routing node.

The present invention is applicable to the insulating monitoring of high voltage capacitive power equipment of the various electric pressure transformer station of industrial trades such as electric system (electrical network and generating plant) and metallurgy, chemical industry, railway, can realize high voltage capacitive apparatus status monitoring, safe early warning and the life-cycle cycle management function of intelligent grid.

The concrete steps and the technical essential of the high-precision signal processing scheme of the capacitive apparatus insulated on-line monitoring of realization high-tension electricity are as follows:

1) the distributed measuring unit on the spot of employing is realized the measurement on the spot to high voltage capacitive apparatus leakage current and corresponding bus lines voltage respectively.Wherein the bus voltage measurement unit is placed in the pulpit or special electric room, directly measures the secondary side output signal of bus-bar potential transformer (PT).Distributed leakage current measurement unit is installed near the scene the capacitive apparatus, adopts the punching small electric current sensor to measure the electric current of the end screen ground wire of capacitive apparatus.The sensor iron core adopts shielding and the output line of shielding layer grounding, sensor is adopted shielding and as far as possible short the leakage current measurement unit that is connected to.The measurement of single-phase current, voltage can be realized in each distributed measurement unit, also can realize the measurement of three-phase current, voltage.The main website of capacitive apparatus on-line monitoring is set, the double engineer station who does this system in electric room.

2) distributed leakage current measurement unit and distributed bus voltage measurement unit adopt the Zigbee network communication of wireless sensor.Each node of capacitive apparatus on-line monitoring system can be divided into different Zigbee networks by different electric pressures, be applied as example with 220kV, the leakage current measurement unit of each capacitive apparatus of configuration 220kV is a routing node, has relay function, configuration 220kV bus voltage measurement unit is the Zigbee coordinator node, coordinator node is the host node of this Zigbee network, and configuration capacitive apparatus on-line monitoring main website is the Zigbee routing node.Content of Communication between all kinds of Zigbee nodes comprises: coordinator node broadcasting busbar voltage information; Each current measuring unit node (routing node) transmits the result of calculation of this capacitive apparatus medium loss factor to master node (routing node).

3) synchronized sampling is realized based on clock synchronization in distributed Voltage measuring unit and distributed leakage current measurement unit.Clock synchronization adopts wireless mode, the GPS that can select to use miniature antenna to the time, or the IEC1588 of wireless ethernet to the time etc.Distributed leakage current measurement unit and distributed bus voltage measurement unit be through clock synchronization, by the sampling of period T 1 start timing signal, a cycle (20ms) data of sampling, be designated as S (0), S (1) ..., S (N-1); Wherein the T1 value can be from several ms to tens second, and for example value is 1 second, with time-division date and the whole second startup sampling of absolute time.Sampling rate is not less than 1.6kHz.Finish this cycle sampling back and stop the sampling interruption, open sampling when waiting next T1 to arrive constantly once more and interrupt.

4) in distributed leakage current measurement unit and bus voltage measurement unit, calculate phasor respectively accurately, comprise phasor real part and imaginary part, comprise phasor phase place and amplitude information.Calculate and adopt identical algorithm and processing procedure, the details step is as follows:

4.1) with cycle data of this sampling S (0), S (1) ..., S (N-1) do pre-service, obtain long data field by periodic extension, to overcome the time lag characteristic of IIRG bank of filters.Constant T time lag of the amount of cycles M of continuation and IIRG bank of filters _DelayRelevant, M 〉=T _Delay/ 20ms+2.The sampled signal continuation solves the matching relationship of periodic samples analysis and IIR filter group.

4.2) make up IIRG bank of filters at the 50Hz common frequency power network.Bank of filters adopts a plurality of IIR filter cascades to form, the some resistance filtering IIR that comprises 40Hz high pass IIR, 60Hz low pass IIR, the logical IIR of 50Hz point and can select to dispose.Its mid point resistance filtering is considered may have the large-scale power electronic equipment that adopts IGBT near the high-tension electricity capacitive apparatus, for example power equipment such as STACOM, SVG.These equipment may cause the harmonic wave of some characteristic frequency, between capacitive apparatus on-line monitoring system limber up period, can in 40Hz～60Hz, whether there be serious mark subharmonic by isolated-phase buses voltage, determines whether that collocation point resistance iir filter is used for the influential mark subharmonic of special filtering in the IIRG bank of filters.Wave filter cascade quantity and sampling rate have determined constant time lag of IIRG bank of filters.

4.3) Fourier phase quantity algorithm is used in the filtering output of IIRG bank of filters, calculate phasor real part imaginary part.By the voltage phasor real part imaginary part of bus voltage measurement unit (Zigbee coordinator node) this this calculating of node of Zigbee Web broadcast under it, transmit timing signal in the communication simultaneously.Each leakage current measurement unit (Zigbee routing node) utilizes leakage current phasor that calculates and the busbar voltage phasor calculation that receives to obtain the insulation dielectric loss of this capacitive apparatus.

5) the insulation dielectric loss that will calculate by the Zigbee network of each distributed leakage current measurement unit (Zigbee routing node) is given master node (Zigbee routing node) in real time.Realize trend analysis and the safe early warning that each is capacitive apparatus insulated by main website.

Description of drawings

Fig. 1 is the on-the-spot synoptic diagram of the capacitive apparatus insulated monitoring of high-tension electricity.Bus and one group of high-voltage capacitor of certain electric pressure have been illustrated.Busbar voltage is measured by voltage transformer (VT) (PT), and the secondary side output of voltage transformer (VT) is gathered in distributed bus voltage measurement unit, is positioned at electric room.The capacitive apparatus leakage current is measured by the little electric current punching mutual inductor of special configuration, and distributed leakage current measurement unit is placed near the capacitive apparatus, to improve the reliability of leakage current signal sensing.

Fig. 2 is the signal processing flow synoptic diagram.Strictness by bus voltage measurement unit and leakage current measurement unit to the time performance period property signal distributions gather, a cycle sampled signal continuation is obtained to adapt to the input signal of IIRG bank of filters, utilization obtains the insulation dielectric loss of this capacitive apparatus through the leakage current with accurate phase information and the bus voltage signal of IIRG bank of filters filtering output through Fourier phasor algorithm computation.

Fig. 3 is the classification synoptic diagram of Zigbee node in the capacitive apparatus insulated monitoring system.Illustrated the configuration of Zigbee coordinator node and Zigbee routing node.1. communication step preface between the Zigbee node is pressed, is 2. marked.

Fig. 4 is the signal curve of applicating example example 1 (normal condition), and left figure is a cycle sampled signal of leakage current and busbar voltage, and right figure is the curve after the IIRG bank of filters is handled, and wherein black curve is that electric current, red curve are voltage.

Fig. 5 is the signal curve of applicating example example 2 (insulation degradation state), and left figure is a cycle sampled signal of leakage current and busbar voltage, and right figure is the curve after the IIRG bank of filters is handled, and wherein black curve is that electric current, red curve are voltage.

Embodiment

Below with the dynamic simulation test data of capacitive apparatus insulated deterioration as data source, the present invention is described in further details.

With leakage current and the busbar voltage thereof that the sampling rate of 2500Hz is gathered capacitive apparatus in real time, process IIRG bank of filters (constituting) by 60Hz low pass IIR, 40Hz high pass IIR and the logical IIR of 50Hz point.Acquisition system is set regularly periodically started sampling and data processing in 5 seconds, the concrete startup constantly is beginning in zero second in whole minute of satellite clock (GPS).Table 1 is an IIRG bank of filters coefficient.

Table 1 IIRG bank of filters coefficient

The capacitive apparatus impedance parameter is R=2.4K Ω, C=0.6uF.The insulated on-line monitoring of this patent is calculated as follows, and table 2 provides the raw data of a cycle of distributed measurement and control unit sampling, comprises the AD sampled voltage data of the sensor secondary output signal of capacitive apparatus leakage current, busbar voltage.Fig. 4 provides signal crude sampling waveform and through the output of IIRG bank of filters filtering, left figure is the sample waveform that comprises under the electromagnetic interference environment after the signal progress of disease error, right figure is the output signal after the Filtering Processing, and wherein black curve is that electric current, red curve are voltage.Table 3 provides a cycle signal data after the IIRG bank of filters is handled.

The original sampling data of table 2 distributed measurement unit

Sequence number k i[k] u[k]	Sequence number k i[k] u[k]	Sequence number k i[k] u[k]
			0 2.5800 2.7600	17 2.3600 2.4800	34 2.5200 2.3200
1 2.5600 2.8000	18 2.3800 2.4800	35 2.5400 2.4000
			2 2.5600 2.8000	19 2.3400 2.4400	36 2.5600 2.3600
3 2.5400 2.8000	20 2.3400 2.4400	37 2.5400 2.4400
			4 2.5200 2.7600	21 2.3600 2.3600	38 2.5600 2.4400

5 2.5000 2.8400	22 2.3400 2.3600	39 2.5800 2.4800
			6 2.4800 2.8400	23 2.3800 2.3600	40 2.5800 2.5200
7 2.4600 2.7600	24 2.3600 2.3200	41 2.6000 2.5600

The sampled data of table 3 after IIRG handles

Sequence number k i[k] u[k]	Sequence number k i[k] u[k]	Sequence number k i[k] u[k]
			0 1.5691 4.0734	17 -2.0254 -0.5972	34 0.6007 -3.4513
1 1.3817 4.2754	18 -2.0792 -1.1506	35 0.8504 -3.0599
			2 1.1727 4.4111	19 -2.1012 -1.6843	36 1.0874 -2.6209
3 0.9457 4.4766	20 -2.0925 -2.1901	37 1.3055 -2.1415
			4 0.7029 4.4687	21 -2.0497 -2.6627	38 1.5015 -1.6270
5 0.4484 4.3932	22 -1.9751 -3.0948	39 1.6749 -1.0883
			6 0.1863 4.2542	23 -1.8687 -3.4752	40 1.8220 -0.5316
7 -0.0792 4.0444	24 -1.7325 -3.8005	41 1.9406 0.0344
			8 -0.3428 3.7701	25 -1.5702 -4.0687	42 2.0290 0.5980
9 -0.6016 3.4362	26 -1.3831 -4.2735	43 2.0849 1.1505
			10 -0.8501 3.0482	27 -1.1732 -4.4121	44 2.1076 1.6859
11 -1.0848 2.6128	28 -0.9451 -4.4804	45 2.0971 2.1957
			12 -1.3031 2.1321	29 -0.7040 -4.4752	46 2.0524 2.6722
13 -1.5005 1.6190	30 -0.4510 -4.4023	47 1.9758 3.1057

14 -1.6742 1.0818	31 -0.1892 -4.2632	48 1.8700 3.4896
			15 -1.8203 0.5266	32 0.0762 -4.0582	49 1.7356 3.8183
16 -1.9379 -0.0352	33 0.3409 -3.7860

His-and-hers watches 3 The data Fourier phasor algorithm computation phasors are calculated as follows:

$\mathrm{Re}=\underset{i=0}{\overset{49}{\mathrm{\Σ}}}(\cos (\frac{2\mathrm{\π}}{50}\·i)\·X\left(i\right)),$ $\mathrm{Im}=\underset{i=0}{\overset{49}{\mathrm{\Σ}}}(\sin (\frac{2\mathrm{\π}}{50}\·i)\·X\left(i\right)),$ $A=\sqrt{{\mathrm{Re}}^2+{\mathrm{Im}}^2},$

$\mathrm{\θ}=\mathrm{arctg}\left(\frac{\mathrm{Im}}{\mathrm{Re}}\right),$ tanδ＝tan(π/2-(θ _i-θ _u))

Wherein, X (i) is the sample sequence of input signal, and Re is that phasor real part, Im are the phasor imaginary parts, and A is a phasor amplitude, and θ is the phasor phase place, and tan δ is insulation dielectric loss factor.

Result of calculation is as shown in table 4.Insulation dielectric loss factor is 0.4337.

Table 4 phasor calculation result

	Real part imaginary part phase place
		I	-35.0843 39.2763 -0.8417
U	47.0384 101.8971 1.1383

The capacitive apparatus insulated horizontal deterioration of following surface analysis in above-mentioned test, resistance value has 2.4k Ω to drop to 1k Ω, and electric capacity is constant, and the insulation dielectric loss behind the analysis insulation degradation is calculated.Table 5 provides the synchronized sampling value to leakage current and busbar voltage, the cycle of sampling.Table 6 is through the filtered signal of IIRG bank of filters, visible filter effect ideal.

The crude sampling of table 5 distributed measurement unit

Leakage current and the bus voltage signal of table 6 after IIRG handles

Sequence number k i[k] u[k]	Sequence number k i[k] u[k]	Sequence number k i[k] u[k]
			0 -1.6262 3.4439	17 -0.6911 -4.6652	34 2.3624 1.5658
1 -1.8434 2.9964	18 -0.3897 -4.7743	35 2.2581 2.1199
			2 -2.0337 2.5026	19 -0.0807 -4.8050	36 2.1179 2.6416
3 -2.1906 1.9732	20 0.2310 -4.7600	37 1.9455 3.1228
			4 -2.3119 1.4142	21 0.5392 -4.6405	38 1.7413 3.5514
5 -2.3985 0.8297	22 0.8367 -4.4440	39 1.5100 3.9235
			6 -2.4467 0.2316	23 1.1200 -4.1742	40 1.2554 4.2361
7 -2.4549 -0.3707	24 1.3874 -3.8408	41 0.9806 4.4849
			8 -2.4245 -0.9702	25 1.6335 -3.4495	42 0.6899 4.6613
9 -2.3575 -1.5524	26 1.8520 -2.9995	43 0.3880 4.7607
			10 -2.2551 -2.1084	27 2.0411 -2.5008	44 0.0799 4.7895
11 -2.1181 -2.6321	28 2.1979 -1.9665	45 -0.2323 4.7453

12 -1.9476 -3.1155	29 2.3191 -1.4002	46 -0.5397 4.6270
			13 -1.7441 -3.5488	30 2.4041 -0.8113	47 -0.8363 4.4343
14 -1.5121 -3.9231	31 2.4520 -0.2115	48 -1.1213 4.1709
			15 -1.2581 -4.2355	32 2.4597 0.3897	49 -1.3878 3.8439
16 -0.9825 -4.4840	33 2.4288 0.9852

Fig. 5 has illustrated sampling original waveform behind the insulation degradation (left figure) and IIRG filtering output waveform (right figure) thereof, and wherein black is current signal, and redness is a voltage signal.As seen comparison diagram 5 right figure and the right figure of Fig. 4 can judge insulation degradation from the relative phase relation of signal.The phasor value of calculation of filtered output data is as shown in table 7, and its insulation dielectric loss factor is 0.0478, with 0.4337 before the deterioration bigger difference is arranged.

Table 7 phasor calculation result

	Real part imaginary part phase place
		I	-46.1643 -40.6982 0.7226
U	-83.5404 86.1065 -0.8005

Claims (3)

1. high-precision signal disposal route that is used for the capacitive apparatus insulated on-line monitoring of high-tension electricity, this method disposes independently leakage current measurement unit and bus voltage measurement unit at capacitive apparatus, two measuring units are realized sampling based on the signal Synchronization of communication, specifically comprise step:

1) distributed leakage current measurement unit and distributed bus voltage measurement unit be through clock synchronization, by the sampling of period T 1 start timing signal, a cycle (20ms) data of sampling, be designated as S (0), S (1) ..., S (N-1); Wherein the T1 value can be from several ms to tens second, and for example value is 1 second;

2) sampled value of a cycle is done periodic extension, obtains the data of M identical cycle, be designated as S (0), S (1) ..., S (N-1) ..., S ((M-1) * N), S ((M-1) * N+1) ..., S ((M-1) * N+N-1);

3) by IIRG bank of filters (mainly being made of 40Hz high pass IIR, the logical IIR of 50Hz point and 60Hz low pass IIR cascade) M after the continuation cycle sampled signal carried out Filtering Processing, filtered signal is desirable power frequency leakage current and bus voltage signal;

4) utilize the fourier algorithm of phasor to calculate output signal respectively, obtain phasor value, comprise phasor real part, imaginary part based on this sampling clock through the filtering of iir filter group;

5) utilize Zigbee network communication of wireless sensor between distributed leakage current measurement unit and the bus voltage measurement unit, real part, the imaginary part of busbar voltage phasor is sent to the leakage current measurement unit in time T 1;

6) real part of the local leakage current phasor of calculating of leakage current measurement unit by using, imaginary part and calculate the insulation dielectric loss factor that obtains this high voltage capacitive apparatus through real part, the imaginary part of the busbar voltage phasor of communications reception.

2. IIRG bank of filters collocation method according to claim 1, it is characterized by: the IIRG bank of filters is made of low pass IIR, high pass IIR and the logical IIR cascade of point, for the 50Hz electrical network, the cutoff frequency of low pass IIR is that the cutoff frequency of 60Hz, high pass IIR is that 40Hz, the centre frequency of putting logical IIR are 50Hz.

3. sampled signal continuation preprocess method according to claim 1, the intermittent sampling of this method realization cooperates with the IIRG bank of filters, it is characterized by the signal lag T that determines the iir filter group according to signal sampling rate _Delay, the cycle M that needs continuation is according to T _DelayCalculate and obtain M 〉=T _Delay/ 20ms+2.

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