CN102866304A - Current phasor group-based online insulation monitoring method for high-voltage power capacitive equipment - Google Patents

Abstract

The invention relates to the field of state monitoring of high-voltage power equipment of power grids, and discloses a capacitive equipment insulating medium loss online monitoring method for the online insulation monitoring of high-voltage power capacitive equipment. The voltage of the capacitive equipment is not required to be measured, and only leakage current is measured. A satellite clock synchronization-based synchronization technology is used for performing distributed synchronous phasor measurement on the leakage current of the capacitive equipment at the same voltage levels, leakage current phasor groups of the capacitive equipment at the same voltage levels are constructed in a phasor and phase normalization way, inertial center current phasors and inertial center voltage phasors of the current phasor groups are calculated, and the equivalent insulating medium loss of each piece of capacitive equipment is calculated on the basis of the calculated inertial center voltage phasors to realize the online insulation monitoring of the capacitive equipment. According to the method, the relative comparison of insulation of the capacitive equipment is reflected, dependence on the measurement of generatrix voltage is avoided, the influence of interference of a cable load to a weak signal is avoided, and the method is more suitable for digital and intelligent transformer substations.

Description

Based on the capacitive apparatus insulated on-line monitoring method of electric current phasor group's high-tension electricity

Technical field

The present invention relates to the insulated on-line monitoring of high-tension electricity capacitive apparatus, belong to the high voltage electric power equip ment status monitoring field of electric system, also belong to intelligent grid and digitizing, Intelligent transformer station field.The present invention is applicable to electrical network and generating plant, and the insulating monitoring of the high voltage capacitive power equipment of the various electric pressure transformer station of the industrial trade such as metallurgy, chemical industry, railway, can realize high voltage capacitive apparatus status monitoring, safe early warning and the life cycle management management function of intelligent grid.

Background technology

Power industry is the main body of energy industry, UHV (ultra-high voltage), UHV transmission can be realized farther distance and more high efficiency Energy Transfer, the High-Voltage Insulation technology is gordian technique wherein, and most faults of extra-high voltage, supergrid show as insulation and wreck.High voltage electric power equip ment except transmission line of electricity 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 the high-tension electricity 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 management management that a key content of intelligent grid is exactly power equipment, and the status monitoring that namely relies on high voltage electric power equip ment is realized preventive 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, the high-tension electricity capacitive apparatus 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 capacitive apparatus insulated monitoring of high-tension electricity is at present usually based on the monitoring to its medium wasting factor tgδ (abbreviation dielectric loss).The test philosophy of dielectric loss can be sketched as current signal and voltage signal with measurand are sent to measurement mechanism, then the phase place of two signals is compared, thereby obtains this equipment dielectric loss value.There is following technical matters in existing capacitive apparatus insulated monitoring technology, and practical function is not good:

1. the Leakage Current signal of capacitive apparatus is small,, adopts in the long cable transmission process to be easy to be interfered between the hundreds of mA at hundreds of μ A.

2. if capacitive apparatus monitoring needs a large amount of on-site signal cable distributions then the engineering construction difficulty is large.

3. monitor synchronous leakage current and the equipment voltage phasor of capacitive apparatus insulated this equipment of needs, thereby need configuration current acquisition unit and voltage acquisition unit, the latter's voltage transformer (VT) position and this capacitive apparatus distance are far, so that system architecture is complicated; Usually the leakage current signal of capacitive apparatus and equipment voltage signal need to be delivered to electric room through cable connection measures again, thereby further introduce Errors Catastrophic and undesired signal, so that this scheme does not fundamentally have practicality, measurement result lacks confidence level.

With novel tiny signal measuring technique, realize that the related acquisition and processing of characteristic signal of diverse location is the key that solves high voltage capacitive apparatus insulated on-line monitoring.

This patent propose a kind of based on satellite to the time synchronous measurement technique the capacitive apparatus leakage current of same electric pressure is carried out distributed phasor measurement, make up equipment leakage current phasor group under each identical electric pressure by the phasor phase normalization, calculate this phasor group's center of inertia electric current phasor, then calculate this phasor group's center of inertia voltage phasor, calculate each capacitive apparatus equivalence insulation dielectric loss based on the center of inertia voltage phasor of calculating gained, realize insulated on-line monitoring to capacitive apparatus with this.The method and equivalent dielectric loss stress to have embodied relatively capacitive apparatus insulated, do not rely on the measurement of busbar voltage, can distribute and be placed down in capacitive apparatus and realize on the spot, be not subjected to cable load and the disturbing effect thereof of feeble signal, have better measuring accuracy and be more suitable for merging with Intelligent transformer station.

Summary of the invention

The present invention is directed to the insulated on-line monitoring technology of high-tension electricity capacitive apparatus, disclose a kind of strong capacitive apparatus insulated on-line monitoring method of high sensitivity, antijamming capability that need not to measure the capacitive apparatus voltage signal.

In order to measure better faint capacitive apparatus leakage current signal, adopt and configure on the spot special leakage current monitoring device at capacitive apparatus, directly utilize small electric current sensor to measure the capacitive apparatus leakage current.For different capacitive apparatus leakage current adopt based on satellite to the time signal unified synchronized sampling, acquisition has the capacitive apparatus leakage current phasor of same phase reference.Process by the phase normalization to A, B, C three-phase capacitive apparatus leakage current phasor, obtain the leakage current phase duration set of each capacitive apparatus under the same electric pressure, be defined as the phasor group.This phasor group's phasor is carried out the center of inertia electric current phasor that computing obtains to characterize the whole size and Orientation of this phasor group, definition center of inertia voltage phasor falls behind this center of inertia electric current phasor 90 degree in phase place, namely obtains the phase place of center of inertia voltage phasor.Do not carrying out under the prerequisite of voltage measurement, utilizing the leakage current phasor of this center of inertia voltage phasor and each capacitive apparatus to calculate the insulation dielectric loss of each capacitive apparatus.This dielectric loss is a kind of equivalent dielectric loss, can be used as the dielectric features signal of the capacitive apparatus insulated on-line monitoring of high-tension electricity.

Concrete steps and technical essential based on electric current phasor group's the capacitive apparatus insulated on-line monitoring of high-tension electricity are as follows:

1) capacitive apparatus insulated monitoring system framework.Monitoring system is made of high voltage capacitive power device leakage distribution of current formula measuring unit and capacitive apparatus insulated on-line monitoring main website.By the concrete configuring distributed on the spot monitoring means of capacitive apparatus (such as coupling capacitance, insulating sleeve, PT, CPT, lightning arrester etc.), each on the spot measuring unit can realize three-phase leakage current collection, calculating to capacitive apparatus.Each distributed monitoring unit will be measured the leakage current phasor that calculate to obtain and give capacitive apparatus insulated monitoring main website through communication, in main website, calculate center of inertia leakage current phasor and center of inertia voltage phasor, and the equivalent dielectric loss of each capacitive apparatus, and carry out monitoring and the warning of capacitive apparatus insulated state.

2) to the synchro measure of capacitive apparatus leakage current.The distributed capacitive apparatus monitoring means of transformer station's (containing power plant high voltage station) inner high voltage capacitive apparatus is divided into groups by electric pressure, the satellite clock time signal is accepted in the distributed measurement unit, when arriving, each pps pulse per second signal starts synchronized sampling, sampled signal is designated as S (i), i=0,1 ..., n-1.Sampling rate is made as 4.8K, i.e. every cycle 96 points.

3) to the digital filtering of leakage current sampled signal.In order to obtain better phasor measurement precision, the infinite impulse response digital filtering algorithm that employing can be calculated is continuously done filtering to the synchronous sampling signal of leakage current and is processed, adopt second order Butterworth bandpass filter, the center band connection frequency is 50Hz, lower-cut-off frequency is 35Hz, upper cut-off frequency is taken as 65Hz, and filter coefficient is as follows:

a[k]＝{1，0，-3，0，3，0，-1}

b[k]＝{1.0000，-5.9383，14.7055，-19.4389，14.4663，-5.7467，0.9520}

If the filtering of sampled signal S (i) is output as y (i), then:

y[k]＝-b[k-1]*y[k-1]-b[k-2]*y[k-2]-b[k-3]*y[k-3]-b[k-4]*y[k-4]-b[k-5]*y[k-5]-b[k-6]*y[k-6]+a[k]*s[k]+a[k-2]*s[k-2]+a[k-4]*s[k-4]+a[k-6]*s[k-6]

4) calculate the leakage current phasor.At filtering output signal time series y (k), (k=0,1 ..., n-1) in, take whole second constantly as starting point, get y (s), y (s+1), y (s+2),, y (s+95) is the filtering output signal of a cycle, calculates its 50Hz fundamental phasors, is designated as

A wherein _sBe phasor amplitude, θ _sBe this phasor with reference to whole second phase place, such as formula (1)～(4):

$\mathrm{Re}=\frac{2}{96}\underset{i=0}{\overset{95}{\mathrm{\Σ}}}(\cos \frac{2\mathrm{\πi}}{96}\·y(s+i))---\left(1\right)$

$\mathrm{Im}=\frac{2}{96}\underset{i=0}{\overset{95}{\mathrm{\Σ}}}(\sin \frac{2\mathrm{\πi}}{96}\·y(s+i))---\left(2\right)$

${\mathrm{\θ}}_s=\mathrm{arctg}\left(\frac{\mathrm{Im}}{\mathrm{Re}}\right)---\left(3\right)$

$A_s=\sqrt{{\mathrm{Re}}^2+{\mathrm{Im}}^2}---\left(4\right)$

In like manner obtain each capacitive apparatus leakage current phasor of same electric pressure.

5) the leakage current phasor of A, B, C three-phase being done phase normalization processes.Each capacitive apparatus leakage current phasor of the same electric pressure of mark is ${\stackrel{\·}{I}}_{m1a},{\stackrel{\·}{I}}_{m1b},{\stackrel{\·}{I}}_{m1c},{\stackrel{\·}{I}}_{m2a},{\stackrel{\·}{I}}_{m2b},{\stackrel{\·}{I}}_{m2c},\·\·\·\·\·\·,{\stackrel{\·}{I}}_{\mathrm{mNa}},{\stackrel{\·}{I}}_{\mathrm{mNb}},{\stackrel{\·}{I}}_{\mathrm{mNc}},$ Note

Take A phase phase place as benchmark, B phase, C phase phasor be multiply by respectively factor e ^J120, e ^-j120, namely rotate forward, backward 120 degree, such as formula (5) and (6),

${{\stackrel{\·}{I}}_{m1b}}^{\′}={\stackrel{\·}{I}}_{m1b}\·e^{j120}---\left(5\right)$

${{\stackrel{\·}{I}}_{m1c}}^{\′}={\stackrel{\·}{I}}_{m1c}\·e^{-j120}---\left(6\right)$

Like this, obtain the phasor group of each capacitive apparatus leakage current under the same electric pressure, mark is as follows:

$\{{\stackrel{\·}{I}}_{m1a},{{\stackrel{\·}{I}}_{m1b}}^{\′},{{\stackrel{\·}{I}}_{m1c}}^{\′},{\stackrel{\·}{I}}_{m2a},{{\stackrel{\·}{I}}_{m2b}}^{\′},{{\stackrel{\·}{I}}_{m2c}}^{\′},\·\·\·\·\·\·,{\stackrel{\·}{I}}_{\mathrm{mNa}},{{\stackrel{\·}{I}}_{\mathrm{mNb}}}^{\′},{{\stackrel{\·}{I}}_{\mathrm{mNc}}}^{\′}\}$

For the good capacitive apparatus of insulation under the same electric pressure, the phase place of above-mentioned phasor should approach unanimously.

6) the above-mentioned electric current phasor group's of calculating center of inertia leakage current phasor.Define above-mentioned electric current phasor group's center of inertia phasor, namely leakage current center of inertia phasor is

Adopt each leakage current phasor amplitude A _iAs the inertia time constant of each phasor, θ _i' be the normalization phase place of each leakage current phasor, this phasor group center of inertia phasor calculation such as formula (7) and (8):

${\mathrm{\θ}}_{\mathrm{Im\; OI}}=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(A_i\·{{\mathrm{\θ}}_i}^{\′}-A_{\max }\·{{\mathrm{\θ}}_{\max }}^{\′}-A_{\min }\·{{\mathrm{\θ}}_{\min }}^{\′})}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{A}_i-A_{\max }-A_{\min }}---\left(7\right)$

$A_{\mathrm{Im\; OI}}=\frac{1}{N-2}(\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{A}_i-A_{\max }-A_{\min })---\left(8\right)$

Wherein, A _Max, θ _Max' be amplitude and the phase place of the most leading phasor of phase place among the phasor group, A _Min, θ _Min' be amplitude and the phase place of the phasor that phase place lags behind most among the phasor group, removing the impact the most leading and phasor that lags behind most will be so that center of inertia phasor calculation be more stable.

Phase place hysteresis center of inertia leakage current phasor 90 degree of definition center of inertia voltage phasor, namely

7) with virtual inertia center voltage phasor

For reference voltage calculates each equivalence insulation dielectric loss.The phase theta of Leakage Current _sBe θ after normalized _s', calculating such as the formula (10) of the equivalence insulation dielectric loss of each phase of capacitive apparatus:

tgδ _s＝tg(90°-(θ _s′-θ _mOI))

＝tg(90°-θ _s′+θ _UmOI) (10)

＝tg(θ _ImOI-θ _s′)

Be the tangent of phase differential of the normalization leakage current phasor of this capacitive apparatus and leakage current phasor group's center of inertia electric current phasor based on each capacitive apparatus equivalence dielectric loss namely, with this characteristic quantity as apparatus insulated monitoring.

The equivalent Dielectric loss angle of definition capacitive apparatus is the phase differential of leakage current phasor after this equipment normalized and leakage current phasor group's center of inertia electric current phasor, and mark is as follows:

{δ _m1a、δ _m1b、δ _m1c，δ _m2a、δ _m2b、δ _m2c，……，δ _mNa、δ _mNb、δ _mNc}

The equivalent dielectric loss that is each capacitive apparatus is each equivalent dielectric loss tangent of an angle.

Description of drawings

Fig. 1 is the on-the-spot schematic diagram of the capacitive apparatus insulated monitoring of typical transformer station's inner high voltage.Illustrated the bus of same electric pressure and the N of this electric pressure to organize high voltage capacitive apparatus.At each capacitive apparatus the distributed measurement unit is set on the spot, measures the leakage current of capacitive apparatus ground wire by the little electric current punching mutual inductor of special configuration, by the satellite-signal antenna reception satellite time transfer signal of placing on the spot.

Fig. 2 is the treatment scheme schematic diagram to the leakage current phasor.By calculating the leakage current phasor of each capacitive apparatus after synchronized sampling and the bandpass filtering pre-service; Through the phasor phase normalization, three-phase phasor phase place under same coordinate of N group capacitive apparatus is comparable, consists of the phasor group again; Calculate this phasor group's center of inertia leakage current phasor and center of inertia voltage phasor; The equivalent Dielectric loss angle of each capacitive apparatus, the i.e. angle of this equipment normalization leakage current phasor and center of inertia leakage current phasor have been illustrated.

Embodiment

On-the-spot schematic diagram with reference to the capacitive apparatus insulated monitoring of typical transformer station's inner high voltage shown in Figure 1 arranges the distributed measurement unit on the spot to the high voltage capacitive apparatus under the same electric pressure in the transformer station, and unified addressing is 1 to N.Each distributed measurement unit is realized A, the B of one group of high voltage capacitive apparatus, the measurement of C three-phase leakage current.The insulating monitoring main frame is set, insulating monitoring main frame and on-the-spot each distributed measurement unit communication in transformer station's master-control room.

The distributed measurement unit receives the satellite time transfer signal, and uniform sampling is realized the synchro measure of each high voltage capacitive apparatus leakage current constantly, calculates through digital algorithm to obtain respectively to organize A, the B of capacitive apparatus, the phasor of C three-phase leakage current, does phase normalization and calculates.Each distributed measurement unit and insulating monitoring main-machine communication, on send this group high voltage capacitive apparatus three-phase leakage current phasor behind the phase normalization.The insulating monitoring main frame is done computing to this group phasor group, at first removes the phasor that phase place is the most leading and lag behind most, calculates this phasor group's center of inertia electric current phasor

With center of inertia voltage phasor

Obtain the equivalent Dielectric loss angle of each capacitive apparatus A, B, C phase, calculate again the equivalent dielectric loss of respectively organizing high voltage capacitive apparatus A, B, C phase.The insulating monitoring main frame is judged high voltage capacitive apparatus insulated health status by each high voltage capacitive apparatus equivalence dielectric loss size and historical trend thereof.Thereby realize not relying on the insulation measurement of high voltage capacitive apparatus voltage.

Claims (4)

1. capacitive apparatus insulated on-line monitoring method of the high-tension electricity based on the electric current phasor group, the method is only measured the leakage current of each high-tension electricity capacitive apparatus, make up leakage current phasor group, calculate its center of inertia leakage current phasor, calculate its center of inertia voltage phasor, the center of inertia voltage phasor that utilization calculates is calculated the equivalence insulation dielectric loss of each high-tension electricity capacitive apparatus, specifically comprises step:

1) the high-tension electricity capacitive apparatus in the transformer station is divided into groups by electric pressure, to the configuring distributed capacitive apparatus monitoring means of each high-tension electricity capacitive apparatus, receive the satellite clock time signal, start synchronized sampling when each pps pulse per second signal arrives, realize the synchro measure to high-tension electricity capacitive apparatus leakage current signal, sampled signal is designated as S (i), i=0,1 ..., n-1;

2) digital filter is set sampled signal S (i) is carried out Real-Time Filtering, digital filter adopts the narrow band filter of infinite impulse response, it is 35Hz that its lower-cut-off frequency is set, and upper cut-off frequency is 65Hz, and passband central frequency is 50Hz, passband is 5Hz, filtered output signal is designated as Y (i), i=0,1,, n-1;

3) utilize the 50Hz phasor of the output signal Y (i) after the phasor computing algorithm calculation of filtered, be designated as A wherein _sBe this phasor amplitude, θ _sBe the phase place of this phasor with reference to the whole second moment;

4) the leakage current phasor of each high-tension electricity capacitive apparatus under the same electric pressure is done the normalized of A, B, C three-phase, made up the high-tension electricity capacitive apparatus leakage current phasor group under this electric pressure;

5) calculation procedure 4) described in leakage current phasor group's center of inertia leakage current phasor, phase place hysteresis center of inertia leakage current phasor 90 degree of definition center of inertia voltage phasor;

6) take step 5) described in center of inertia voltage phasor phase place be reference, calculate the equivalence insulation dielectric loss of each high-tension electricity capacitive apparatus, with this characteristic quantity as the capacitive apparatus insulated monitoring of this high-tension electricity.

2. the capacitive apparatus insulated on-line monitoring method of a kind of high-tension electricity based on the electric current phasor group according to claim 1, being characterized as of high-tension electricity capacitive apparatus leakage current phasor group's construction method wherein: the capacitive apparatus insulated leakage current phasor of each high-tension electricity of same electric pressure multiply by respectively factor e to B phase, C phase phasor take A phase leakage current phasor phase place as reference ^J120, e ^-j120, namely rotate forward, backward 120 degree, consist of leakage current phasor group, be designated as:

$\{{\stackrel{\·}{I}}_{m1a},{{\stackrel{\·}{I}}_{m1b}}^{\′},{{\stackrel{\·}{I}}_{m1c}}^{\′},{\stackrel{\·}{I}}_{m2a},{{\stackrel{\·}{I}}_{m2b}}^{\′},{{\stackrel{\·}{I}}_{m2c}}^{\′},\·\·\·\·\·\·,{\stackrel{\·}{I}}_{\mathrm{mNa}},{{\stackrel{\·}{I}}_{\mathrm{mNb}}}^{\′},{{\stackrel{\·}{I}}_{\mathrm{mNc}}}^{\′}\}.$

3. the capacitive apparatus insulated on-line monitoring method of a kind of high-tension electricity based on the electric current phasor group according to claim 1, wherein being characterized as of the computing method of leakage current phasor group's center of inertia leakage current phasor: adopt each leakage current phasor amplitude A _iAs the inertia time constant of each phasor, remove two phasors the most leading and hysteresis of phase place among the leakage current phasor group after, with inertia time constant each phasor phase place is done weighted calculation, the phase theta of center of inertia leakage current phasor _ImOIComputing formula as follows:

${\mathrm{\θ}}_{\mathrm{Im\; OI}}=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(A_i\·{{\mathrm{\θ}}_i}^{\′}-A_{\max }\·{{\mathrm{\θ}}_{\max }}^{\′}-A_{\min }\·{{\mathrm{\θ}}_{\min }}^{\′})}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{A}_i-A_{\max }-A_{\min }}$

Wherein, A _i, θ _i' be amplitude and the phase place of each phasor among the leakage current phasor group, A _Max, θ _Max' be amplitude and the phase place of the most leading phasor of phase place among the leakage current phasor group, A _Min, θ _Min' be amplitude and the phase place of the phasor that phase place lags behind most among the leakage current phasor group.

4. the capacitive apparatus insulated on-line monitoring method of a kind of high-tension electricity based on the electric current phasor group according to claim 1, being characterized as of the computing method of each high-tension electricity capacitive apparatus equivalence insulation dielectric loss wherein: center of inertia voltage phasor phase place lags behind center of inertia electric current phasor 90 degree, capacitive apparatus equivalence insulation dielectric loss tg δ _sBe the tangent value of the phase differential of each leakage current phasor of leakage current phasor group and center of inertia electric current phasor, i.e. tg δ _s=tg (θ _ICOI-θ _s').

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