CN103197133B - A kind of shunting of the large ground network based on wireless transmission vector quantity measurement method - Google Patents
A kind of shunting of the large ground network based on wireless transmission vector quantity measurement method Download PDFInfo
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- CN103197133B CN103197133B CN201310100461.1A CN201310100461A CN103197133B CN 103197133 B CN103197133 B CN 103197133B CN 201310100461 A CN201310100461 A CN 201310100461A CN 103197133 B CN103197133 B CN 103197133B
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Abstract
The invention discloses a kind of large ground network based on wireless transmission shunting vector quantity measurement method, relate to transformer station, the grounding characteristics field of measuring technique of the large-scale grounding networks such as power plant, to operation generating plant, during grounding net of transformer substation grid grounding impedance measurement, adopt Radio Transmission Technology, in measuring current decanting point and wireless transmission phase information between each outlet framework and outlet cable measuring shunt point, obtain the phase differential between each point of flow vector and measuring current vector in real time, the vector that the alien frequencies obtaining flowing through each metal frame and the outlet cable oversheath be connected with outlet aerial earth wire by mathematics manipulation is shunted, comprise modulus value size and phase differential.This measuring method solves the on-the-spot difficult problem cannot measuring point flow vector in the past, and the diverting coefficient running transformer station's aerial earth wire and cable jacket for accurate Calculation provides technical guarantee.
Description
Technical field
The present invention relates to the measuring method of grounded screen in power industry, specifically refer to a kind of large ground network based on wireless transmission shunting vector quantity measurement method.
Background technology
Generating plant, grounding net of transformer substation are except providing common reference ground for various electrical equipment, more importantly, fault current of fast and effeciently releasing is played in system generation earth fault or when being struck by lightning, improve grounded screen and the distribution of earth's surface, place earth potential, ensureing the effect of first and second equipment and personal security, is the important measures safeguarding power system security reliability service, support personnel and device security.
Impedance ground is the important parameter characterizing earth mat performance.Impedance ground is defined as, and injects measuring current Im, then record earth mat corresponding current potential lifting U, impedance ground Z=U/Im with voltage table to earth mat.Visible, all test results of grounded screen are all based upon in this basic data of measuring current Im of injection earth mat.The real current value accurately obtaining injecting current earth mat is extremely important, directly affects test result.
After power plant and transformer station put into operation, the access of aerial earth wire and crosslinked cable screen layer, inevitably changes the topological structure of former grounded screen, creates larger shunting action to measuring current.Namely the measuring current that instrument exports all does not inject current earth mat, but has been diverted to a distant place by aerial earth wire.How accurately to get rid of the shunt influence of transformer station's aerial earth wire and cable, record the true impedance ground of substation ground network, become the difficult problem and challenge that perplex engineering technical personnel for a long time.
During Grounding impedance measurement, the conductor of grounded screen injects a power current or non-power-frequency current, electric current will form loop between grounded screen and electric current pole, obtain a Potential distribution on grounded screen surrounding earth surface, if grounded screen is independently, namely grounded screen and other metallic earthing body are without electrical connection, then measuring current all by grounded screen diffusing to be measured in the earth, now measurement result reflects the true impedance ground of grounded screen.And if grounded screen and other metallic ground body exist and are electrically connected, partial test electric current will be flowed out by other metallic ground body, and namely other grounding body is shunted measuring current, has made contribution to diffusing, the measuring current flow through from grounded screen reduces, and causes grid grounding impedance measurement result less than normal.
Substation ground network area is larger, underground grounding body becomes latticed and buries layout underground, ground metal frame is connected with extraneous aerial earth wire, numerous metal frame is connected by framework each other simultaneously, earth mat, metal frame, aerial earth wire, cable jacket are connected to each other together, together constitute a resistance-inductance network, the shunting of alternating-current measurement electric current on each Base Metal framework of injecting earth mat is not reverse completely, but there is certain phase differential.For the transformer station that some are large-scale, between metal frame framework, also there is circulation.
Due to test time to earth mat inject is an alternating current, its direction of current with the sine wave period of about 50 per second in real-time change.Measure the vector of metal frame shunting, first want to compare the phase differential of metal frame shunting relative to measuring current in real time.When substation ground network is measured, due to the restriction of technical merit and testing apparatus in the past, in a lot of situation or not geodesic line shunting completely, or only survey the modulus value size of metal frame shunting, and its phase place of accident.Accident is shunted, then do not consider the impact of aerial earth wire diffusing, the calculated value of final test electric current is bigger than normal; Survey shunting size (modulus value) and accident phase differential, then all shuntings all can only regard diffusing beyond earth mat, and its direction and the measuring current of injection earth mat are complete anti-phasely calculates, then the calculated value of final test electric current is less than normal; Sometimes the shunting modulus value measured by each metal frame is added the measuring current even having exceeded and injected, and cannot obtain logical test result.Only accurately measure the vector shunted everywhere, then measuring current and each shunting are asked vector sum, just can obtain the accurate current injecting earth mat.
Summary of the invention
The object of this invention is to provide a kind of large ground network based on wireless transmission shunting vector quantity measurement method, this measuring method is scientific and reasonable, can go out point flow vector of large ground network by in-site measurement, the diverting coefficient running transformer station's aerial earth wire and cable jacket for accurate Calculation provides technical guarantee.
This purpose of the present invention realizes by following technical solution: a kind of shunting of the large ground network based on wireless transmission vector quantity measurement method, the method comprises the steps:
(1) inject an alien frequencies measuring current at any position place of large ground network to be measured, and keep constant in test process, this alien frequencies measuring current phase place is defined as with reference to zero phase;
(2) utilize current transformer to sample and obtain the waveform of this alien frequencies measuring current, operational analysis is carried out again after frequency-selective filtering process is carried out to the waveform of this alien frequencies measuring current, extract the phase data that waveform is real-time, this phase data is sent by wireless launcher;
(3) phase data adopting radio receiver receiving step (2) to send, and send receiving the phase data come into frequency-selecting multimeter;
(4) frequency-selecting multimeter connects Luo-coil by interface, while injecting alien frequencies measuring current with step (1), Luo-coil circle is adopted to live a certain metal frame in this large ground network region or a certain cable, obtain a certain partial current signal, through frequency-selective filtering process, frequency-selecting multimeter is sent into after getting rid of the undesired signal in this certain partial current signal, obtain the modulus value size of this certain partial current, the alien frequencies measuring current phase information that a certain partial current obtained and step (1) obtain is carried out phase compare by frequency-selecting multimeter, draw phase differential and the amplitude size of a certain partial current, the i.e. point flow vector of a certain partial current,
(5) method identical with step (4) is adopted, calculate each metal frame in this large ground network region one by one vectorial with the current distributing of each cable jacket, the all current distributing vectors obtained are carried out addition and asks vector sum, obtain overall large ground network shunting vector value.
In the present invention, described large ground network refers to the large-scale grounding network of transformer station or power plant.
In the present invention, the alien frequencies measuring current injected in described step (1) refers to the non-power-frequency current of frequency range between 40 ~ 70Hz.
In the present invention, adopt wireless mode to transmit phase information between measuring current decanting point and partial current measurement point, wireless transmission coverage is greater than 50 meters.
In the present invention, the Luo-coil in described step (4) is the flexible Rogowski coil that length is greater than 300mm.
In the present invention, in described step (4), the undesired signal got rid of in a certain partial current signal refers to the undesired signal that frequency is 50Hz.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention is described in further details.
Fig. 1 is the schematic diagram of measuring method of the present invention.
Embodiment
Embodiment one
Based on a large-scale grounding network shunting vector quantity measurement method for the transformer station of wireless transmission, the method comprises the steps:
(1) inject the alien frequencies measuring current of 53Hz, a 10A at any position place of large ground network to be measured, and keep constant in test process, this alien frequencies measuring current phase place is defined as with reference to zero phase;
(2) utilize current transformer to sample and obtain the waveform of this alien frequencies measuring current, frequency-selective filtering process and operational analysis are carried out to the DFWF wireless frequency selecting communication instrument utilizing Shanghai great Fan Electric Appliance Equipment Co., Ltd to produce of this alien frequencies measuring current, extract the phase data that waveform is real-time, this phase data is sent by wireless launcher;
(3) phase data adopting radio receiver receiving step (2) to send, and will the DF9006 frequency-selecting multimeter of the phase data feeding Shanghai great Fan Electric Appliance Equipment Co., Ltd production come be received;
(4) DF9006 frequency-selecting multimeter connects Luo-coil by interface, this Luo-coil is the flexible Rogowski coil that length is greater than 300mm, while injecting alien frequencies measuring current with step (1), Luo-coil circle is adopted to live a certain metal frame in this large ground network region or a certain cable, obtain a certain partial current signal, through frequency-selective filtering process, the frequency got rid of in this partial current signal is the undesired signal of 50Hz, obtain the 53Hz waveform in this partial current, the 53Hz measuring current phase information that the partial current waveform obtained and step (3) obtain is carried out phase compare by DF9006 frequency-selecting multimeter, draw phase differential and the amplitude size of this partial current, the i.e. point flow vector of this partial current, wireless mode is wherein adopted to transmit phase information between measuring current decanting point and partial current measurement point, wireless transmission coverage is greater than 50 meters,
(5) method identical with step (4) is adopted, the current distributing vector of all metal frames in the large ground network of measurement amount one by one region and each cable jacket, record the partial current modulus value of each framework footing and cable, and and 53Hz measuring current between phase angle difference;
(6) using alien frequencies measuring current as with reference to vectorial I ∠ 0 °, calculate the shunting vector sum of the partial current vector of all framework footings and cable,
the shunting vector sum that each framework is total; I1 ∠ θ 1: point flow vector 1 measured by scene;
I2 ∠ θ 2: point flow vector 2 measured by scene; In ∠ θ n: the shunting vector n measured by scene;
Then deduct shunting vector sum with the vector of alien frequencies measuring current, namely obtain the actual current value I of large-scale grounding network diffusing
earth mat,
I
earth mat∠ θ: the current vector value that actual injection is fixed; I ∠ 0 °: the measuring current of injection, its phase angle position 0;
I ∑ ∠ θ ∑: the shunting vector sum that each framework is total;
Aerial earth wire and cable jacket can also be obtained to the diverting coefficient of measuring current simultaneously
η=(I
earth mat/ I) × 100%
As the conversion of the present embodiment, the alien frequencies measuring current injected in described step (1) can the non-power-frequency current of selecting frequency scope between 40 ~ 70Hz.
The measuring method of the present embodiment also can be applied to the large-scale grounding network of such as power plant etc., and measuring method is identical.
As shown in Figure 1, when doing grid grounding impedance measurement, according to the method for regulation in DL/T475-2006 " earthing device characterisitic parameter measures directive/guide ", with a frequency variation signal source, a non-power-frequency current Im is injected to earth mat, and keep this current stabilization in measurement whole process.Utilize current transformer to the measuring current sampling of injecting, through AD conversion and frequency-selective filtering calculation process, obtain waveform and the phase information of measuring current, this phase place is defined as reference phase, i.e. zero phase.
Launched by this reference phase information wireless, far-end frequency-selecting multimeter is built-in with radio receiver, can wireless receiving to this phase data, and the CPU of frequency-selecting multimeter will be sent into after this data processing.
Another port spreading degree of the multimeter of frequency-selecting is simultaneously the Luo-coil (flexible current mutual inductor) of more than 300mm, and enclose the metal frame be connected with aerial earth wire, sampling obtains the partial current signal on metal frame; Through AD conversion and frequency-selective filtering calculation process, get rid of 50Hz and other interference, extract the shape information of non-power-frequency current, also send into CPU.CPU computing compare and partial current phase place and wireless receiving to measuring current phase place compare, then can obtain size and the phase differential of this Base Metal framework shunting, the vector that this Base Metal framework is shunted can be obtained.
According to said method, measure the shunting on all metal frames be connected with aerial earth wire in transformer station, and the shunting on crosslinked cable oversheath, obtain the vector of each shunting.The vector of all shuntings is carried out plural number addition and ask vector sum, then can obtain overall ground wire point flow valuve.
During said method is implemented, there are the technological difficulties of several key: how (1) extracts faint shunting signal under strong jamming.Consider that framework footing, steel tower column foot and high-tension cable oversheath size are larger, applicant develops specially and both met dimensional requirement, ensure again the flexible Rogowski coil of enough accuracy, be called for short Luo-coil, solve the measuring shunt problem in the actual measurement of earth mat impedance ground.(2) on-the-spot institute surveys the filtering and frequency-selective filtering process that current signal disturbs.Develop corresponding anti-interference frequency-selective filtering disposal system at present, can process on-the-spot measured feeble signal.(3) the communication transmission of phase information.Because transformer station's area is comparatively large, and need within the scope of place, hold the traverse measurement everywhere of frequency-selecting multimeter during point current test, need to design the frequency-selecting multimeter that phase information is passed to far-end movement by set of device accurately and reliably.
The above embodiment of the present invention is not limiting the scope of the present invention; embodiments of the present invention are not limited thereto; according to foregoing of the present invention; according to ordinary technical knowledge and the customary means of this area; do not departing under the present invention's above-mentioned basic fundamental thought prerequisite; to the amendment of other various ways that said structure of the present invention is made, replacement or change, all drop within protection scope of the present invention.
Claims (6)
1., based on a large ground network shunting vector quantity measurement method for wireless transmission, the method comprises the steps:
(1) inject an alien frequencies measuring current at any position place of large ground network to be measured, and keep constant in test process, this alien frequencies measuring current phase place is defined as with reference to zero phase;
(2) utilize current transformer to sample and obtain the waveform of this alien frequencies measuring current, operational analysis is carried out again after frequency-selective filtering process is carried out to the waveform of this alien frequencies measuring current, extract the phase data that waveform is real-time, this phase data is sent by wireless launcher;
(3) phase data adopting radio receiver receiving step (2) to send, and send receiving the phase data come into frequency-selecting multimeter;
(4) frequency-selecting multimeter connects Luo-coil by interface, while injecting alien frequencies measuring current with step (1), Luo-coil circle is adopted to live a certain metal frame in this large ground network region or a certain cable, obtain a certain partial current signal, through frequency-selective filtering process, frequency-selecting multimeter is sent into after getting rid of the undesired signal in this certain partial current signal, obtain the modulus value size of this certain partial current, the alien frequencies measuring current phase information that a certain partial current obtained and step (1) obtain is carried out phase compare by frequency-selecting multimeter, draw a certain partial current amplitude size and and the alien frequencies measuring current that obtains of step (1) between phase differential, the i.e. point flow vector of a certain partial current,
(5) method identical with step (4) is adopted, calculate each metal frame in this large ground network region one by one vectorial with the current distributing of each cable jacket, the all current distributing vectors obtained are carried out addition and asks vector sum, obtain overall large ground network shunting vector value.
2. the shunting of the large ground network based on wireless transmission vector quantity measurement method according to claim 1, is characterized in that: described large ground network refers to the large-scale grounding network of transformer station or power plant.
3. the shunting of the large ground network based on wireless transmission vector quantity measurement method according to claim 1, is characterized in that: the alien frequencies measuring current injected in described step (1) refers to the non-power-frequency current of frequency range between 40 ~ 70Hz.
4. the shunting of the large ground network based on wireless transmission vector quantity measurement method according to claim 1, is characterized in that: adopt wireless mode to transmit phase information between measuring current decanting point and partial current measurement point, wireless transmission coverage is greater than 50 meters.
5. the shunting of the large ground network based on wireless transmission vector quantity measurement method according to claim 1, is characterized in that: the Luo-coil in described step (4) is the flexible Rogowski coil that length is greater than 300mm.
6. the shunting of the large ground network based on wireless transmission vector quantity measurement method according to claim 1, is characterized in that: in described step (4), the undesired signal got rid of in a certain partial current signal refers to the undesired signal that frequency is 50Hz.
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| CN113311266A (en) * | 2021-05-25 | 2021-08-27 | 国网陕西省电力公司电力科学研究院 | Comprehensive testing device and testing method for power frequency characteristics of ground network device |
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Address after: 510080 Dongfeng East Road, Dongfeng, Guangdong, Guangzhou, Zhejiang Province, No. 8 Patentee after: ELECTRIC POWER RESEARCH INSTITUTE OF GUANGDONG POWER GRID Co.,Ltd. Patentee after: SHANGHAI DAFAN ELECTRICAL EQUIPMENT Co.,Ltd. Address before: 510080 Dongfeng East Road, Guangdong, Guangzhou, water, Kong Kong, No. 8 Patentee before: ELECTRIC POWER RESEARCH INSTITUTE OF GUANGDONG POWER GRID Corp. Patentee before: SHANGHAI DAFAN ELECTRICAL EQUIPMENT Co.,Ltd. |
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Effective date of registration: 20220812 Address after: 510080 water Donggang 8, Dongfeng East Road, Yuexiu District, Guangzhou, Guangdong. Patentee after: ELECTRIC POWER RESEARCH INSTITUTE OF GUANGDONG POWER GRID Co.,Ltd. Patentee after: Shanghai Dafan Precision Measurement Technology Co.,Ltd. Address before: 510080 water Donggang 8, Dongfeng East Road, Yuexiu District, Guangzhou, Guangdong. Patentee before: ELECTRIC POWER RESEARCH INSTITUTE OF GUANGDONG POWER GRID Co.,Ltd. Patentee before: SHANGHAI DAFAN ELECTRICAL EQUIPMENT Co.,Ltd. |