CN105548755B - The method for detecting inverter AC and DC side ground connection by single ground insulation impedance detection network - Google Patents
The method for detecting inverter AC and DC side ground connection by single ground insulation impedance detection network Download PDFInfo
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- CN105548755B CN105548755B CN201510919913.8A CN201510919913A CN105548755B CN 105548755 B CN105548755 B CN 105548755B CN 201510919913 A CN201510919913 A CN 201510919913A CN 105548755 B CN105548755 B CN 105548755B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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Abstract
The present invention provides a kind of methods detecting inverter AC and DC side ground connection by single ground insulation impedance detection network：Only ground connection ground insulation impedance detection network, detection DC side square formation anode voltage-to-ground V is added in solar battery input side in itPV+PEWith cathode voltage-to-ground VPV‑PEWaveform；Or only ground insulation impedance detection network, three phase-to-ground voltage V of detection exchange side are grounded in exchange outlet sideA‑PE、VB‑PE、VC‑PEWaveform；AC compounent in waveform is extracted to the former to judge exchange side Grounding, the DC component in waveform is extracted to the latter to judge DC side Grounding.It is an advantage of the invention that：A kind of ac/dc side ground detecting method is proposed, on the basis of only using input side/outlet side ground insulation impedance detection network, to judge the earth fault for exchanging outlet side/DC side, detection circuit is both saved, also simplifies system composition.
Description
Technical field
The present invention relates to a kind of sides for detecting inverter AC and DC side ground connection by single ground insulation impedance detection network
Method, the earth fault for detecting solar power system.
Background technology
In field of solar thermal power generation, earth fault exists as a kind of relatively common failure, in order to ensure the peace of personnel
Complete and equipment reliability service, Earth Fault Detection just become particularly significant.
From the point of view of earth point, it can be roughly divided into solar battery ground connection and exchange side output ground connection two categories, in order to
It can accurately detect to be grounded, traditional way is to be separately added into ground connection in solar battery input side and inverter outlet side
Insulation impedance detects network, by detecting the voltage change of impedance network over the ground, to judge inverter apparatus or solar energy side
The Grounding of battle array.This kind of scheme not only needs two sets of impedance detection networks and detection circuit, wastes detection resource and increase
Cost, and two impedance networks can also influence each other, and detection is caused error occur.
Traditional system earth detects network as shown in Figure 1, passing through the square formation ground insulation impedance detection of DC side respectively
Network and AC earth insulation impedance detect network and judge the earth fault of alternating current-direct current side, VPVIt is positive and negative for DC side square formation
Voltage between pole.After earth fault occurs, DC side is by judging square formation anode voltage-to-ground VPV+PEIt is electric over the ground with cathode
Press VPV-PEDC partial voltage situation carry out failure judgement, and exchange side is then carried out by directly detecting the voltage of exchange output over the ground
Judge, thus needs more set detection circuits and impedance network, and it mutually also suffers from influence, system constitutes more multiple
It is miscellaneous.
Invention content
The purpose of the present invention is overcoming the deficiencies in the prior art, provide a kind of by single ground insulation impedance inspection
The method that survey grid network detects inverter AC and DC side ground connection, one is passing through the sides PV (DC side) ground insulation impedance detection net
Network detects exchange side Grounding, and the alternating component detected by the sides PV judges exchange side Grounding；The second is passing through exchange
Side ground insulation impedance detection network detects DC side Grounding, detects the DC component in exchange side voltage-to-ground to judge
The sides PV Grounding.
1, the method that inverter ac side ground connection is detected by single DC side ground insulation impedance detection network, only
Ground insulation impedance detection network is added in solar battery input side, detects DC side solar battery anode voltage-to-ground
VPV+PEWith cathode voltage-to-ground VPV-PEWaveform；Under normal circumstances, detection waveform is DC quantity；After exchange side ground connection occurs,
The waveform that DC side detects at this time will be changed to：abs(VPV+PE)=abs (VPV-PE)=VPV/2+VINV-BUSN, wherein VPVIt is straight
Flow the voltage between the solar battery positive and negative anodes of side, VINV-BUSNIt is exported to inverter busbar mid-point voltage for inversion；Extract waveform
In AC compounent judge exchange side Grounding.I.e. DC side Grounding is directly detected by DC earthing insulation impedance
Network judges.
If extracting the AC compounent close to 0, judge that earth fault does not occur for exchange side, if close to
Vout/ 1.732, VoutFor inverter output line voltage virtual value, then judge that dead ground failure occurs for exchange side, if between 0
And VoutBetween/1.732, then judge that impedance earth (i.e. exchange side passes through certain impedance earth) occurs for exchange side.
2, the method that inverter direct-flow side ground connection is detected by single ground insulation impedance detection network, only in inversion
Ground insulation impedance detection network is added in device outlet side, and ground insulation impedance detection net is separately added into exchange side A, B, C three-phase
Network, detection A phase-to-ground voltages VA-PE, B phase-to-ground voltages VB-PE, C phase-to-ground voltages VC-PEWaveform；Under normal circumstances, detection waveform
For of ac；After DC side cathode ground connection occurs, the exchange side voltage-to-ground waveform that exchange side detects at this time will become
Change, detection virtual value will be changed to：Wherein VdcFor direct current point
Amount ,-VPV/2≤Vdc≤VPV/ 2, VPVFor the voltage between DC side solar battery positive and negative anodes, VINV-BUSNFor inversion output pair
Inverter busbar mid-point voltage；Extract the DC component V in waveformdcTo judge DC side Grounding.I.e. exchange side is grounded feelings
Condition directly detects network by AC earth insulation impedance and judges.
If extracting the DC component close to 0, judge that earth fault does not occur for DC side；If direct current point
The absolute value of amount is close to VPV/ 2, then judge that dead ground failure occurs for DC side；If the absolute value of DC component is between 0 He
VPVBetween/2, then judge that impedance earth (i.e. DC side passes through certain impedance earth) occurs for DC side.
The direct current component value is just, then it represents that DC side cathode is grounded, and it is negative to be worth, then it represents that DC side plus earth.
It is an advantage of the invention that：A kind of ac/dc side ground detecting method is proposed, input side/outlet side is only being used
On the basis of ground insulation impedance detection network, to judge the earth fault for exchanging outlet side/DC side, both saved
Detection circuit also simplifies system composition.
Description of the drawings
Fig. 1 is system earth detection network in the prior art.
Fig. 2 is that the present invention detects ground connection schematic diagram by DC side ground insulation impedance detection network.
Fig. 3 is schematic diagram of the present invention by DC side ground insulation impedance detection network detection ground connection.
Fig. 4 is the detection waveform of Fig. 3 DC sides under normal circumstances.
Fig. 5 is the DC side detection waveform that exchange side ground connection occurs.
Fig. 6 is the AC compounent gone out to the waveform extracting of Fig. 5.
Fig. 7 is that the present invention detects ground connection schematic diagram by exchange side ground insulation impedance detection network.
Fig. 8 is schematic diagram of the present invention by exchange side ground insulation impedance detection network detection ground connection.
Fig. 9 is the detection waveform of Fig. 8 exchange side under normal circumstances.
Figure 10 is that exchange side detection waveform after the cathode ground connection of the sides PV occurs.
Figure 11 is the DC component gone out to the waveform extracting of Figure 10.
Specific implementation mode
The invention will be further described with reference to the accompanying drawings and examples.
Embodiment one：
It is found by analysis circuit operation characteristic, after exchange side is grounded, the positive and negative voltage-to-ground detection waveform of DC side
It can occur to change accordingly, can AC earth insulation impedance be detected network completely removes, and is such as Fig. 2 institutes to simplify circuit
Show, passes through the square formation anode voltage-to-ground V to detectingPV+PEWith cathode voltage-to-ground VPV-PEWaveform accordingly divided
Analysis can be obtained by its fault message.
After earth fault occurs for the exchange side of system any one phase, as shown in figure 3, the square formation that DC side detects at this time
Positive voltage-to-ground VPV+PEWith cathode voltage-to-ground VPV-PEWaveform variation as shown in Figure 3 will occur, by original straight line,
Become the curve comprising output exchange side information (specific waveform is related to inverter hair wave).
So this method square formation anode voltage-to-ground V that it is only necessary to be detected to original DC sidePV+PEWith cathode pair
Ground voltage VPV-PEData carry out specifically analyze and extract, its alternating component is analyzed it may determine that go out inverter friendship
Whether stream side is grounded and its Grounding.
Specific judgment step is as follows.Y value is depending on actual battery plate voltage in Fig. 4~6.
1, under normal circumstances, abs (VPV+PE)=abs (VPV-PE)=VPV/ 2, VPVFor the electricity between DC side square formation positive and negative anodes
Pressure, i.e. detection waveform are DC quantity, as shown in Figure 4.VPV+PEAnd VPV-PENumerical value positive and negative detection and definition according to circuit
It determines, does not influence the judgement of failure.
2, after exchange side ground connection occurs, DC side detects at this time square formation anode voltage-to-ground VPV+PEOver the ground with cathode
Voltage VPV-PEWaveform variation as shown in Figure 5 will occur：By original serial 1 waveform, change as shown in series 2 or series 3
Waveform, specific waveform will see that inverter specifically sends out wave control method, and detected value will be changed to：abs(VPV+PE)=abs
(VPV-PE)=VPV/2+VINV-BUSN, wherein VINV-BUSNIt is exported to inverter busbar mid-point voltage for inversion.
3, square formation anode voltage-to-ground V at this time is sampledPV+PEWith cathode voltage-to-ground VPV-PEWaveform after, pass through number
According to processing, AC compounent V therein can be extractedacAs shown in Figure 6.
After obtaining above-mentioned data, it can be analyzed as follows：
If 1, Vac≈ 0, then exchange side earth fault does not occur.
If 2,0<Vac<Vout/ 1.732, wherein VoutFor inverter output line voltage virtual value, then exchange side generation impedance
(i.e. by certain impedance earth, value neglects greatly impedance ground and ground insulation impedance detection network impedance to ground connection for exchange side side
Value determines).
If 3, Vac≈Vout/ 1.732 (wherein VoutFor inverter output line voltage virtual value), then exchange side occurs complete
Earth fault.
The DC side Grounding of the above method judges that details are not described herein again not in this patent discussion range.
Embodiment two：
By the inspiration of above scheme, DC side ground connection can also be detected by exchange side impedance network.Pass through exchange side
The schematic diagram of ground insulation impedance detection network detection ground connection in exchange side A, B, C three-phase as shown in fig. 7, be separately added into ground connection absolutely
Edge impedance detection network, detection A phase-to-ground voltages VA-PE, B phase-to-ground voltages VB-PE, C phase-to-ground voltages VC-PEWaveform.Detection is former
Reason is as shown in figure 8, exchange side detection waveform occurs after there is a situation where solar panel positive/negative ground connection (being grounded for cathode in figure)
Variation.
Specific judgment step is as follows.Y value is depending on real voltage in Fig. 9~11.
1, under normal circumstances, VA-PE、VB-PE、VC-PEWaveform is as shown in figure 9, its detection waveform is of ac.What it was detected has
Depending on valid value neglects greatly inverter output, if inverter line voltage virtual value is 315V, then its exchange for detecting is effective over the ground
Value is 315/1.732=181.87V, other output systems and so on.
2, after the sides PV cathode ground connection occurs, the exchange side voltage-to-ground waveform that exchange side detects at this time will occur as schemed
Variation (if plus earth its change in the opposite direction) shown in 10：By 1 waveform of series of Fig. 9, change as series 2 or serial 3 institutes
Oscillography shape, specific waveform will see that inverter specifically sends out wave control method, and detection virtual value will be changed to：
Wherein VdcFor DC component ,-VPV/2≤Vdc≤VPV/ 2,
VINV-BUSNIt is exported to inverter busbar mid-point voltage for inversion.
3, therein in can extracting by data processing after the exchange side voltage-to-ground waveform after sampling cathode ground connection
DC component VdcAs shown in figure 11.VdcActual numerical value is related to PV voltages, plus earth its be negative value.
After obtaining above-mentioned data, it can be analyzed as follows：
If 1, Vdc≈ 0, then the sides PV earth fault does not occur.
If 2,0<abs(Vdc)<VPV/ 2, then the sides PV occur impedance earth (pass through certain impedance earth, concrete numerical value
Depending on impedance ground and ground insulation impedance detection network impedance value).
If 3, abs (Vdc)≈VPV/ 2, then DC side ground connection, V occursdcIt is worth just, to be then that the sides PV cathode is grounded, VdcValue
It is negative, then is the sides PV plus earth.
The exchange side Grounding of the above method judges that details are not described herein again not in this patent discussion range.
Claims (5)
1. the method that network detects inverter ac side ground connection is detected by single input grounding insulation impedance, it is characterized in that：Only
Ground insulation impedance detection network is added in solar battery input side, detects DC side solar battery anode voltage-to-ground
VPV+PEWith cathode voltage-to-ground VPV-PEWaveform；Under normal circumstances, detection waveform is DC quantity；After exchange side ground connection occurs,
The waveform that DC side detects at this time will be changed to：abs(VPV+PE)=abs (VPV-PE)=VPV/2+VINV-BUSN, wherein VPVIt is straight
Flow the voltage between the solar battery positive and negative anodes of side, VINV-BUSNIt is exported to inverter busbar mid-point voltage for inverter；Extract wave
AC compounent in shape judges exchange side Grounding.
2. detecting network by single input grounding insulation impedance as described in claim 1 detects inverter ac side ground connection
Method, characterized in that if extracting the AC compounent close to 0, judge that earth fault does not occur for exchange side, if
Close to Vout/ 1.732, VoutFor inverter output line voltage virtual value, then judge that dead ground failure occurs for exchange side, if
Between 0 and VoutBetween/1.732, then judge that impedance earth occurs for exchange side.
3. the method that network detects inverter direct-flow side ground connection is detected by single AC earth insulation impedance, it is characterized in that：Only
Ground insulation impedance detection network is added in inverter ac outlet side, ground insulation is separately added into exchange side A, B, C three-phase
Impedance detection network, detection A phase-to-ground voltages VA-PE, B phase-to-ground voltages VB-PE, C phase-to-ground voltages VC-PEWaveform；Normal condition
Under, detection waveform is of ac；After DC side cathode ground connection occurs, exchange side detects at this time exchange side voltage-to-ground wave
Shape will change, and detection virtual value will be changed to：VA-PE=VB-PE=VC-PE=Vdc+VINV-BUSN, wherein VdcFor direct current point
Amount ,-VPV/2≤Vdc≤VPV/ 2, VPVFor the voltage between DC side solar battery positive and negative anodes, VINV-BUSNFor inversion output pair
Inverter busbar mid-point voltage；Extract the DC component V in waveformdcTo judge DC side Grounding.
4. detecting network by single AC earth insulation impedance as claimed in claim 3 detects inverter direct-flow side ground connection
Method, characterized in that extract the DC component VdcIf close to 0, judge that earth fault does not occur for DC side；Such as
The absolute value of fruit DC component is close to VPV/ 2, then judge that dead ground failure occurs for DC side；If DC component is absolute
Value is between 0 and VPVBetween/2, then judge that impedance earth occurs for DC side.
5. detecting network by single AC earth insulation impedance as claimed in claim 3 detects inverter direct-flow side ground connection
Method, characterized in that the direct current component value is just, then it represents that DC side cathode is grounded, and it is negative to be worth, then it represents that DC side anode
Ground connection.
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| DE102016115295A1 (en) * | 2016-08-17 | 2018-02-22 | Sma Solar Technology Ag | Separator for a photovoltaic string |
| CN106301202A (en) * | 2016-08-28 | 2017-01-04 | 安徽普天电力科技有限公司 | A kind of solar photovoltaic inverter |
| JP6711462B2 (en) * | 2017-07-18 | 2020-06-17 | 東芝三菱電機産業システム株式会社 | Ground fault detector and power conditioner |
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| CN110708016B (en) * | 2019-10-22 | 2023-02-03 | 阳光电源股份有限公司 | Method and device for monitoring insulation performance of photovoltaic grid-connected power generation system |
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