CN103076485A - Medium-voltage power grid bus capacitance and current detection system - Google Patents
Medium-voltage power grid bus capacitance and current detection system Download PDFInfo
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- CN103076485A CN103076485A CN2012105850821A CN201210585082A CN103076485A CN 103076485 A CN103076485 A CN 103076485A CN 2012105850821 A CN2012105850821 A CN 2012105850821A CN 201210585082 A CN201210585082 A CN 201210585082A CN 103076485 A CN103076485 A CN 103076485A
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Abstract
The invention relates to a medium-voltage power grid bus capacitance and current detection system. The detection system is connected with a three-phase bus of a medium-voltage power grid and comprises a voltage transformer, a signal generator, a zero sequence voltage detection device and a processor, wherein the voltage transformer is connected with the three-phase bus of the medium-voltage power; the signal generator and the zero sequence voltage detection device are connected with the voltage transformer; and the processor is respectively connected with the signal generator and the zero sequence voltage detection device. Compared with the prior art, the medium-voltage power grid bus capacitance and current detection system has the characteristics of high safety, high detection precision and the like.
Description
Technical field
The present invention relates to a kind of electrical network detection system, especially relate to a kind of bus capacitor current detecting system for medium voltage network.
Background technology
With the expansion of urban distribution network, the increasing of cable outlet, system capacitive current increases greatly.When system's generation singlephase earth fault, its ground arc can not put out certainly, very easily produces intermittence arc grounding superpotential, and the duration one is long, also can develop into the line to line fault accident in the line insulation weakness.Therefore, when network is enough large, just needs to adopt the arc suppression coil compensation capacitance current or directly act on tripping operation through the earthing mode of resistance, this is the important technique measure that guarantees safe operation of power system.For avoiding unsuitable earthing mode to bring threat to safe operation of power system, at first correctly then the capacitance current value of mensuration system determines rational neutral operation method, could not affect selectivity and the reliability of relay protection.
Summary of the invention
Purpose of the present invention is exactly that a kind of safe, medium voltage network bus capacitor current detecting system that accuracy of detection is high is provided in order to overcome the defective that above-mentioned prior art exists.
Purpose of the present invention can be achieved through the following technical solutions:
A kind of medium voltage network bus capacitor current detecting system, this detection system is connected on the three-phase bus of medium voltage network, comprise voltage transformer (VT), signal generator, zero sequence voltage detection device and processor, described voltage transformer (VT) connects the three-phase bus of medium voltage network, described signal generator and zero sequence voltage detection device all are connected with voltage transformer (VT), and described processor connects respectively signal generator and zero sequence voltage detection device.
Described voltage transformer (VT) comprises winding and Secondary Winding, a described winding directly is connected with the three-phase bus of medium voltage network, described Secondary Winding and a winding coupled, and adopt the mode of connection of open-delta, described signal generator and zero sequence voltage detection device all are connected to the open delta end of Secondary Winding.
Described signal generator is used for the output frequency current signal different from the electrical network power-frequency voltage.
Compared with prior art, the present invention can detect the electric current on the ground capacitance of each phase bus exactly, realize the input of measuring-signal owing to having adopted the voltage transformer (VT) of open-delta connection access electrical network, and carry out the collection of detection signal from the Secondary Winding side, avoided contacting with the direct of electrical network with the tester, thus Effective Raise security.
Description of drawings
Fig. 1 is structural representation of the present invention;
Fig. 2 is the schematic diagram of voltage transformer (VT) access electrical network.
Embodiment
The present invention is described in detail below in conjunction with the drawings and specific embodiments.
Embodiment
As shown in Figure 1, a kind of medium voltage network bus capacitor current detecting system, this detection system is connected on the three-phase bus of medium voltage network 5, comprises voltage transformer (VT) 1, signal generator 2, zero sequence voltage detection device 3 and processor 4.
Voltage transformer (VT) 1 connects the three-phase bus of medium voltage network 5, its concrete connected mode as shown in Figure 2, because voltage transformer (VT) 1 comprises winding 11 and Secondary Winding 12, one time winding 11 directly is connected with the three-phase bus of medium voltage network 5, and Secondary Winding 12 and winding 11 couplings, and adopt the mode of connection of open-delta to connect signal generator 2 and zero sequence voltage detection device 3.Signal generator 2 and zero sequence voltage detection device 3 all are connected to the open delta end 13 of Secondary Winding 12, and 4 of processors connect respectively signal generator 2 and zero sequence voltage detection device 3.
Principle of work of the present invention is:
At first by the signal generator output frequency less current signal different from the electrical network power-frequency voltage, this current signal can induce an electric current that reduces in the umber of turn ratio in a winding side of voltage transformer (VT), because this current signal can not circulate between power supply and electrical network load, therefore can only form the loop by the ground capacitance on the three-phase bus, therefore for the invention provides theoretical foundation.Because the electric current that this winding side induces can produce pressure drop at winding resistance, leakage reactance and the electrical network wire ground capacitance of voltage transformer (VT), because each resistance of going up mutually of winding, the leakage reactance of voltage transformer (VT) are almost symmetries, and the three-phase bus ground capacitance also is basic equating, then the pressure drop of this electric current generation also is essentially identical, therefore can detect at the triangular opening end of Secondary Winding a residual voltage signal.By the current signal of the many groups of many groups signal generator output different frequency, and detect corresponding residual voltage signal, will organize these two signals more and input to processor, can calculate according to the relation of correspondence the electric current of medium voltage network median generatrix ground capacitance.
Claims (3)
1. medium voltage network bus capacitor current detecting system, this detection system is connected on the three-phase bus of medium voltage network, it is characterized in that, comprise voltage transformer (VT), signal generator, zero sequence voltage detection device and processor, described voltage transformer (VT) connects the three-phase bus of medium voltage network, described signal generator and zero sequence voltage detection device all are connected with voltage transformer (VT), and described processor connects respectively signal generator and zero sequence voltage detection device.
2. a kind of medium voltage network bus capacitor current detecting system according to claim 1, it is characterized in that, described voltage transformer (VT) comprises winding and Secondary Winding, a described winding directly is connected with the three-phase bus of medium voltage network, described Secondary Winding and a winding coupled, and adopt the mode of connection of open-delta, described signal generator and zero sequence voltage detection device all are connected to the open delta end of Secondary Winding.
3. a kind of medium voltage network bus capacitor current detecting system according to claim 1 is characterized in that, described signal generator is used for the output frequency current signal different from the electrical network power-frequency voltage.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2012105850821A CN103076485A (en) | 2012-12-28 | 2012-12-28 | Medium-voltage power grid bus capacitance and current detection system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012105850821A CN103076485A (en) | 2012-12-28 | 2012-12-28 | Medium-voltage power grid bus capacitance and current detection system |
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| CN103076485A true CN103076485A (en) | 2013-05-01 |
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| CN2012105850821A Pending CN103076485A (en) | 2012-12-28 | 2012-12-28 | Medium-voltage power grid bus capacitance and current detection system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104459335A (en) * | 2014-11-12 | 2015-03-25 | 国家电网公司 | Detecting device and method used for ground capacitance of power distribution network |
| CN106093682A (en) * | 2016-06-27 | 2016-11-09 | 国网天津市电力公司 | A kind of confirmation method of medium voltage distribution network neutral grounding mode |
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| JP2009058234A (en) * | 2007-08-29 | 2009-03-19 | Sbc Co Ltd | Leak current measuring instrument and measuring method |
| CN202042904U (en) * | 2011-04-26 | 2011-11-16 | 湖北中兴电力试验研究有限公司 | Automatic on-line tracking and monitoring device for capacitance and current of power grid |
| CN203117256U (en) * | 2012-12-28 | 2013-08-07 | 上海市电力公司 | System for detecting bus capacitive current of medium voltage power grid |
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2012
- 2012-12-28 CN CN2012105850821A patent/CN103076485A/en active Pending
Patent Citations (3)
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| JP2009058234A (en) * | 2007-08-29 | 2009-03-19 | Sbc Co Ltd | Leak current measuring instrument and measuring method |
| CN202042904U (en) * | 2011-04-26 | 2011-11-16 | 湖北中兴电力试验研究有限公司 | Automatic on-line tracking and monitoring device for capacitance and current of power grid |
| CN203117256U (en) * | 2012-12-28 | 2013-08-07 | 上海市电力公司 | System for detecting bus capacitive current of medium voltage power grid |
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| 丁然等: "基于信号注入法的电容电流测量仪研究", 《工矿自动化》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104459335A (en) * | 2014-11-12 | 2015-03-25 | 国家电网公司 | Detecting device and method used for ground capacitance of power distribution network |
| CN106093682A (en) * | 2016-06-27 | 2016-11-09 | 国网天津市电力公司 | A kind of confirmation method of medium voltage distribution network neutral grounding mode |
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Application publication date: 20130501 |