CN103904994B - The detection method of a kind of leakage current and device - Google Patents
The detection method of a kind of leakage current and device Download PDFInfo
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- CN103904994B CN103904994B CN201410131465.0A CN201410131465A CN103904994B CN 103904994 B CN103904994 B CN 103904994B CN 201410131465 A CN201410131465 A CN 201410131465A CN 103904994 B CN103904994 B CN 103904994B
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Abstract
The invention discloses the detection method of a kind of leakage current and device, relate to current detection technology field, it is possible to solve the problem that the testing cost of common mode leakage current is high。Described method includes: the resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；The resistance of resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance obtains the capacitance of the parasitic capacitance over the ground of described target DC source；Derivative sampling circuit is utilized to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；Capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change obtains the Ground leakage current of described target DC source。The embodiment of the present invention is used for detecting common mode leakage current。
Description
Technical field
The present invention relates to current measurement techniques field, particularly relate to detection method and the device of a kind of leakage current。
Background technology
Solar energy refers to the emittance of sunlight, because its reserves are extremely abundant and cleanliness without any pollution, therefore becomes the first-selected alternative energy source of the fossil energy such as coal, oil。The ultimate principle of solar electrical energy generation includes: the emittance of sunlight is converted to low-voltage DC through photovoltaic cell, and the connection in series-parallel then through photovoltaic cell is converted to high voltage direct current, and converting to then through inverter can to the sinusoidal ac of public electric wire net conveying。In solar power system, owing to the DC voltage of monolithic photovoltaic battery panel output is relatively low, so it is generally required to polylith photovoltaic battery panel being carried out connection in series-parallel composition photovoltaic array to export high voltage direct current。The photovoltaic array formed through monolithic photovoltaic cell plate serioparallel needs to take very large-area soil, therefore can produce bigger parasitic capacitance over the ground between photovoltaic array and ground, and parasitic capacitance can be bigger over the ground in a humidity environment。Inverter is generally operational in high frequency state, it is possible to produce High-frequency Interference voltage on the DC voltage of photovoltaic array output。Under the combined effect of High-frequency Interference voltage and parasitic capacitance over the ground, solar power system can produce common mode leakage current over the ground。The personal safety of the properly functioning and operator of common mode leakage current serious threat generating equipment over the ground, it is therefore desirable to common mode leakage current over the ground is detected in real time。
The method detecting common mode leakage current over the ground in prior art includes: connects current sensor on generating equipment earth lead and detects common mode leakage current over the ground；The positive pole and negative pole of photovoltaic battery panel output connect current sensor and detects common mode leakage current over the ground；The AC line of generating equipment output connects current sensor and detects common mode leakage current over the ground。
But when stating method in realization, it is necessary to using current sensor, current sensor expensive, this has seriously raised the testing cost touching leakage current altogether。
Summary of the invention
The embodiment provides the detection method of a kind of leakage current and device, it is possible to solve the problem that the testing cost of common mode leakage current is high。
First aspect, it is provided that the detection method of a kind of leakage current, described method includes:
The resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；
The resistance of resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance obtains the capacitance of the parasitic capacitance over the ground of described target DC source；
Derivative sampling circuit is utilized to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；
Capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change obtains the Ground leakage current of described target DC source。
In conjunction with first aspect, in the first possible implementation of first aspect, the described resistance of positive pole insulation against ground resistance by measurement acquisition target DC source and the resistance of negative pole insulation against ground resistance include:
Obtained the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device；
Obtained the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
In conjunction with first aspect, in the implementation that the second of first aspect is possible, the capacitance of the parasitic capacitance over the ground that the resistance of the described resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance obtains described target DC source includes:
The positive pole parasitic capacitance over the ground of described target DC source is obtained according to described positive pole insulation against ground resistance；
The negative pole parasitic capacitance over the ground of described target DC source is obtained according to described negative pole insulation against ground resistance；
The parasitic capacitance over the ground of described target DC source is obtained in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
In conjunction with the implementation that the second of first aspect is possible, the third of first aspect be likely in implementation, positive pole parasitic capacitance over the ground described in described combination and described negative pole parasitic capacitance over the ground obtain the parasitic capacitance over the ground of described target DC source and include:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
In conjunction with first aspect, the 4th kind of first aspect be likely in implementation, the described capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change obtains the Ground leakage current of described target DC source and includes:
Capacitance according to described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the positive pole Ground leakage current of described target DC source, and described positive pole Ground leakage current is defined as described Ground leakage current；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
In conjunction with any one in the implementation first to fourth kind possible of first aspect or first aspect, the 5th kind of first aspect be likely in implementation, described target DC source includes photovoltaic cell。
Second aspect, it is provided that the detecting device of a kind of leakage current, described device includes:
Resistance acquiring unit, for the resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；
Electric capacity acquiring unit, is used for the capacitance of the parasitic capacitance over the ground of the resistance described target DC source of acquisition of the resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance；
Voltage sampling unit, for utilizing derivative sampling circuit to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；
Electric current acquiring unit, obtains the Ground leakage current of described target DC source for the capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change。
In conjunction with second aspect, in the first possible implementation of second aspect, described resistance acquiring unit specifically for:
Obtained the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device；
Obtained the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
In conjunction with second aspect, in the implementation that the second of second aspect is possible, described electric capacity acquiring unit specifically for:
The positive pole parasitic capacitance over the ground of described target DC source is obtained according to described positive pole insulation against ground resistance；
The negative pole parasitic capacitance over the ground of described target DC source is obtained according to described negative pole insulation against ground resistance；
The parasitic capacitance over the ground of described target DC source is obtained in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
In conjunction with the implementation that the second of second aspect is possible, in the third possible implementation of second aspect, described electric capacity acquiring unit is additionally operable to:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
In conjunction with second aspect, in the 4th kind of possible implementation of second aspect, described electric current acquiring unit specifically for:
Capacitance according to described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the positive pole Ground leakage current of described target DC source, and described positive pole Ground leakage current is defined as described Ground leakage current；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
In conjunction with any one in the implementation first to fourth kind possible of second aspect or second aspect, in the 5th kind of possible implementation of second aspect, described target DC source includes photovoltaic cell。
The embodiment of the present invention provides detection method and the device of a kind of leakage current, first passes through the resistance of resistance and the negative pole insulation against ground resistance measuring the positive pole insulation against ground resistance obtaining target DC source；The capacitance of the parasitic capacitance over the ground of target DC source is then obtained according to the resistance of the resistance of positive pole insulation against ground resistance and negative pole insulation against ground resistance；Recycling derivative sampling circuit obtains at least one in the positive pole voltage-to-ground rate of change of target DC source, negative pole voltage-to-ground rate of change；The Ground leakage current of target DC source is obtained finally according at least one and parasitic capacitance over the ground the capacitance in positive pole voltage-to-ground rate of change, negative pole voltage-to-ground rate of change。Visible, compared to existing technologies, the detection method of the leakage current that the embodiment of the present invention provides can realize the detection of common mode leakage current when not using current sensor such that it is able to reduces the testing cost of mode ship electric current。
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing used required in embodiment or description of the prior art will be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings。
Fig. 1 is the detection method flow chart of a kind of leakage current that the embodiment of the present invention provides；
Fig. 2 is the detection method flow chart of a kind of leakage current that the embodiment of the present invention provides；
Fig. 3 is the equivalent circuit diagram that the target DC source that the embodiment of the present invention provides produces Ground leakage current；
Fig. 4 is a kind of possible connected mode of the first measuring circuit that the embodiment of the present invention provides；
Fig. 5 is a kind of possible connected mode of the second measuring circuit that the embodiment of the present invention provides；
Fig. 6 is the derivative sampling circuit core element connection figure that the embodiment of the present invention provides；
Fig. 7 is a kind of possible connected mode of the derivative sampling circuit that the embodiment of the present invention provides；
Fig. 8 is the structural representation of the detecting device of a kind of leakage current that the embodiment of the present invention provides；
Fig. 9 is the structural representation of the detecting device of a kind of leakage current that the embodiment of the present invention provides。
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments。Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention。
Present embodiments providing the detection method of a kind of leakage current, referring to Fig. 1, the method flow that the present embodiment provides is specific as follows:
S101, the resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source。
S102, obtains the capacitance of the parasitic capacitance over the ground of target DC source according to the resistance of the resistance of positive pole insulation against ground resistance and negative pole insulation against ground resistance。
S103, utilizes derivative sampling circuit to obtain at least one in the positive pole voltage-to-ground rate of change of target DC source, negative pole voltage-to-ground rate of change。
S104, obtains the Ground leakage current of target DC source according at least one and parasitic capacitance over the ground the capacitance in positive pole voltage-to-ground rate of change, negative pole voltage-to-ground rate of change。
The embodiment of the present invention provides the detection method of a kind of leakage current, first passes through the resistance of resistance and the negative pole insulation against ground resistance measuring the positive pole insulation against ground resistance obtaining target DC source；The capacitance of the parasitic capacitance over the ground of target DC source is then obtained according to the resistance of the resistance of positive pole insulation against ground resistance and negative pole insulation against ground resistance；Recycling derivative sampling circuit obtains at least one in the positive pole voltage-to-ground rate of change of target DC source, negative pole voltage-to-ground rate of change；The Ground leakage current of target DC source is obtained finally according at least one and parasitic capacitance over the ground the capacitance in positive pole voltage-to-ground rate of change, negative pole voltage-to-ground rate of change。Visible, compared to existing technologies, the detection method of the leakage current that the embodiment of the present invention provides can realize the detection of common mode leakage current when not using current sensor such that it is able to reduces the testing cost of mode ship electric current。
In order to enable those skilled in the art to be more clearly understood that the technical scheme that the embodiment of the present invention provides, below by specific embodiment, the detection method of a kind of leakage current that the embodiment of the present invention provides is described in detail, as in figure 2 it is shown, the method includes:
S201, obtains the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, and described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device。
S202, obtains the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, and described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
Described target DC source refers to and is converted to, through inverter, the DC source powered to other equipment after alternating current。Preferably, described target DC source includes photovoltaic cell to the present embodiment。
Any equipment all can with megarelief parasitic capacitance in couples。In low frequency situation, the effect of parasitic capacitance is not as obvious over the ground, it is possible to ignore；And at high frequencies, parasitic capacitance can to the properly functioning generation large effect of equipment over the ground, it is impossible to ignore。
Described target DC source needs to be converted to through inverter to power to other equipment after alternating current, and inverter is usually operated at high frequency state, it is possible to produce High-frequency Interference voltage on the DC voltage of described target DC source output。Under the combined effect of High-frequency Interference voltage and parasitic capacitance over the ground, described target DC source can produce common mode leakage current (abbreviation Ground leakage current) over the ground。Fig. 3 is the equivalent circuit diagram that target DC source produces Ground leakage current。
Test between two conductors or a conductor is to the leakage current between the earth, to verify the reliability of the being not turned on property between them, be called megger test。Insulation resistance can be divided into insulation resistance between conductor (resistance as between the electric wire that wrapped up by insulated hull) and insulation against ground resistance (resistance as between the electric wire wrapped up by insulated hull and the earth)。
For the embodiment of the present invention, described positive pole insulation against ground resistance is the resistance between the positive pole of described target DC source and the earth, and described negative pole insulation against ground resistance is negative pole and the earth directly resistance of described target DC source。
Specifically, when measuring the positive pole insulation against ground resistance of target DC source, can applying a high-voltage dc voltage at the positive pole of described target DC source and earth lead two ends, the business then measuring corresponding electric current, described high-voltage dc voltage and electric current is described positive pole insulation against ground resistance。Same method can also be adopted to measure the negative pole insulation against ground resistance of described target DC source。
Described first measuring circuit is the loop of photovoltaic cell positive pole, photovoltaic cell earth terminal and default measurement device composition。
Described second measuring circuit is the loop of photovoltaic cell positive pole, photovoltaic cell earth terminal and default measurement device composition。
Described default measurement device is for providing the power supply of high direct voltage, and preferably, described default measurement device includes megameter to the present embodiment。
Fig. 4 illustrates a kind of possible connected mode of the first measuring circuit, and Fig. 5 illustrates a kind of possible connected mode of the second measuring circuit。
Described default measurement device applies DC voltage U to described first measuring circuit1While measure the electric current I of described first measuring circuit1, positive pole insulation against ground resistance R according to the known described photovoltaic cell of ohm law1For:
Described default measurement device applies DC voltage U to described second measuring circuit2While measure the electric current I of described second measuring circuit2, positive pole insulation against ground resistance R according to the known described photovoltaic cell of ohm law2For:
S203, obtains the positive pole parasitic capacitance over the ground of described target DC source according to described positive pole insulation against ground resistance。
S204, obtains the negative pole parasitic capacitance over the ground of described target DC source according to described negative pole insulation against ground resistance。
S205, obtains the parasitic capacitance over the ground of described target DC source in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
Preferably, positive pole parasitic capacitance over the ground described in described combination and described negative pole parasitic capacitance over the ground obtain the parasitic capacitance over the ground of described target DC source and include the present embodiment:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
S206, utilizes derivative sampling circuit to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change。
Physical property according to electric capacity is it can be seen that the electric current at electric capacity two ends is equal to the product of electric capacity and electric capacity both end voltage rate of change, it may be assumed that
Wherein, i is the electric current at electric capacity two ends, and u is the voltage at electric capacity two ends, and C is capacitance。
Through type (3) it can be seen that also need to before obtaining the Ground leakage current of described target DC source obtains the rate of change of voltage, i.e. positive pole voltage-to-ground rate of change or negative pole voltage-to-ground rate of change between negative or positive electrode and the earth terminal of described DC source。
Derivative sampling circuit can obtain the rate of change of target voltage。Fig. 6 illustrates the core element of derivative sampling circuit, including: capacitor C, resistance R and R ', operational amplifier A。Wherein, resistance R is connected to outfan and the negative input of operational amplifier A；The negative input of one end concatenation operation amplifier A of capacitor C, the other end connects input terminal voltage vs；The electrode input end of one end concatenation operation amplifier A of resistance R ', other end ground connection。
The output end voltage v of derivative sampling circuit shown in Fig. 60With input terminal voltage vsRelation be:
WhereinFor input terminal voltage vsRate of change。
The present embodiment preferably, adopts the derivative sampling circuit shown in Fig. 7 to obtain at least one in the positive pole voltage-to-ground rate of change of target DC source, negative pole voltage-to-ground rate of change。Derivative sampling circuit shown in Fig. 7 includes: operational amplifier A, B, C, resistance R1、R2、R3、R4、R5、R6、R7、R8、R9, electric capacity C1、C2、C3、C4、C5。Wherein, the outfan of operational amplifier C is connected with its negative input, the electrode input end of operational amplifier respectively with resistance R6、R7With electric capacity C5One end be connected；Resistance R7The other end and reference voltage VrefIt is connected；Resistance R6The other end be connected with the outfan of operational amplifier B；Electric capacity C5Other end ground connection；Resistance R5It is connected to outfan and the negative input of operational amplifier B；Electric capacity C4With resistance R5And even；The electrode input end of operational amplifier B and resistance R4One end be connected；Resistance R4Other end ground connection；The negative input of operational amplifier B and electric capacity C3One end be connected；Electric capacity C3The other end and resistance R3One end be connected；Resistance R3The other end be connected with the outfan of operational amplifier A；Resistance R2It is connected to outfan and the negative input of operational amplifier A；Electric capacity C2With resistance R2And even；The electrode input end of operational amplifier A is respectively at resistance R1And R8One end be connected；Resistance R1Other end ground connection；Resistance R8Other end PE ground connection；Electric capacity C1With resistance R1And even；The negative input of operational amplifier A and resistance R9One end be connected；The other end of resistance v connects voltage (negative pole for target DC source) to be detected。Resistance R8And R9Resistance equal, be all RD。
For circuit diagram shown in Fig. 7, if:
Wherein (PE-PV-) for target DC source negative pole and the earth between voltage difference。
Shown that the Vout (t) that rate of change sample circuit shown in Fig. 7 exports is by formula (4) and formula (5):
The negative pole voltage-to-ground rate of change that can be obtained target DC source by formula (6) is:
The positive pole voltage-to-ground rate of change of target DC source can adopt same method to obtain。
S207, obtains the positive pole Ground leakage current of described target DC source, described positive pole Ground leakage current is defined as described Ground leakage current according to the capacitance of described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
Can obtain according to formula (3), the Ground leakage current i of described target DC sourcecm(t) be:
Or
Wherein, negative pole voltage-to-ground rate of changeWith positive pole voltage-to-ground rate of changeObtain already by S206。With negative pole voltage-to-ground rate of changeCan obtain for example, convolution (7) and formula (8):
Calculating, with positive pole voltage-to-ground rate of change, the Ground leakage current obtained by negative pole voltage-to-ground rate of change in theory should be identical, but actually due to the existence of equipment error, the Ground leakage current obtained by negative pole voltage-to-ground rate of change is typically not equal to the Ground leakage current obtained by positive pole voltage-to-ground rate of change, therefore will can both calculate, take its meansigma methods end value as Ground leakage current。
Especially, described target DC source includes photovoltaic cell。
During existing use current sensor detection leakage current, it is necessary to by the detection hole of the earth lead of inverter traverse current sensor, and the earth lead of inverter is generally relatively thick, therefore that earth lead is very difficult through the operation in current sensor detection hole。Relative to prior art, the detection method that the embodiment of the present invention provides avoids the use of current sensor, and then reduces detection difficulty when detecting leakage current。
Further, the current range that current sensor can be measured is less, and the detection method that the embodiment of the present invention provides is not by the restriction of current range。Relative to the method that existing use current sensor detects leakage current, the method scope of application that the present embodiment provides is wider。
The embodiment of the present invention provides the detecting device 800 of a kind of leakage current, and referring to Fig. 8, described device 800 includes:
Resistance acquiring unit 801, for the resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；
Electric capacity acquiring unit 802, is used for the capacitance of the parasitic capacitance over the ground of the resistance described target DC source of acquisition of the resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance；
Voltage sampling unit 803, for utilizing derivative sampling circuit to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；
Electric current acquiring unit 804, obtains the Ground leakage current of described target DC source for the capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change。
Optionally, described resistance acquiring unit 801 specifically for:
Obtained the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device；
Obtained the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
Alternatively, described electric capacity acquiring unit 802 specifically for:
The positive pole parasitic capacitance over the ground of described target DC source is obtained according to described positive pole insulation against ground resistance；
The negative pole parasitic capacitance over the ground of described target DC source is obtained according to described negative pole insulation against ground resistance；
The parasitic capacitance over the ground of described target DC source is obtained in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
Alternatively, described electric capacity acquiring unit 802 is additionally operable to:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
Alternatively, described electric current acquiring unit 804 specifically for:
Capacitance according to described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the positive pole Ground leakage current of described target DC source, and described positive pole Ground leakage current is defined as described Ground leakage current；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
Especially, described target DC source includes photovoltaic cell。
The embodiment of the present invention provides the detecting device of a kind of leakage current, first passes through the resistance of resistance and the negative pole insulation against ground resistance measuring the positive pole insulation against ground resistance obtaining target DC source；The capacitance of the parasitic capacitance over the ground of target DC source is then obtained according to the resistance of the resistance of positive pole insulation against ground resistance and negative pole insulation against ground resistance；Recycling derivative sampling circuit obtains at least one in the positive pole voltage-to-ground rate of change of target DC source, negative pole voltage-to-ground rate of change；The Ground leakage current of target DC source is obtained finally according at least one and parasitic capacitance over the ground the capacitance in positive pole voltage-to-ground rate of change, negative pole voltage-to-ground rate of change。Visible, compared to existing technologies, the detection method of the leakage current that the embodiment of the present invention provides can realize the detection of common mode leakage current when not using current sensor such that it is able to reduces the testing cost of mode ship electric current。
The embodiment of the present invention provides the detecting device 900 of a kind of leakage current, and referring to Fig. 9, described device 900 includes: bus 901, and is connected to the interface 902 in bus 901, memorizer 903, processor 904；Wherein, interface 902 is for communicating with other equipment, and memorizer 903 is used for storing computer program 9031, and processor 904 is used for performing this computer program 9031 and is used for:
The resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；
The resistance of resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance obtains the capacitance of the parasitic capacitance over the ground of described target DC source；
Derivative sampling circuit is utilized to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；
Capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change obtains the Ground leakage current of described target DC source。
Optionally, processor 904 be used for performing this computer program 9031 specifically for:
Obtained the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device；
Obtained the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
Optionally, processor 904 be used for performing this computer program 9031 specifically for:
The positive pole parasitic capacitance over the ground of described target DC source is obtained according to described positive pole insulation against ground resistance；
The negative pole parasitic capacitance over the ground of described target DC source is obtained according to described negative pole insulation against ground resistance；
The parasitic capacitance over the ground of described target DC source is obtained in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
Optionally, processor 904 is used for performing this computer program 9031 and is additionally operable to:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
Optionally, processor 904 be used for performing this computer program 9031 specifically for:
Capacitance according to described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the positive pole Ground leakage current of described target DC source, and described positive pole Ground leakage current is defined as described Ground leakage current；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
The embodiment of the present invention provides the detecting device of a kind of leakage current, first passes through the resistance of resistance and the negative pole insulation against ground resistance measuring the positive pole insulation against ground resistance obtaining target DC source；The capacitance of the parasitic capacitance over the ground of target DC source is then obtained according to the resistance of the resistance of positive pole insulation against ground resistance and negative pole insulation against ground resistance；Recycling derivative sampling circuit obtains at least one in the positive pole voltage-to-ground rate of change of target DC source, negative pole voltage-to-ground rate of change；The Ground leakage current of target DC source is obtained finally according at least one and parasitic capacitance over the ground the capacitance in positive pole voltage-to-ground rate of change, negative pole voltage-to-ground rate of change。Visible, compared to existing technologies, the detection method of the leakage current that the embodiment of the present invention provides can realize the detection of common mode leakage current when not using current sensor such that it is able to reduces the testing cost of mode ship electric current。
In several embodiments provided herein, it should be understood that disclosed system, apparatus and method, it is possible to realize by another way。Such as, device embodiment described above is merely schematic, such as, the division of described unit, being only a kind of logic function to divide, actual can have other dividing mode when realizing, for instance multiple unit or assembly can in conjunction with or be desirably integrated into another system, or some features can ignore, or do not perform。Another point, shown or discussed coupling each other or direct-coupling or communication connection can be through INDIRECT COUPLING or the communication connection of some interfaces, device or unit, it is possible to be electrical, machinery or other form。
The described unit illustrated as separating component can be or may not be physically separate, and the parts shown as unit can be or may not be physical location, namely may be located at a place, or can also be distributed on multiple NE。Some or all of unit therein can be selected according to the actual needs to realize the purpose of the present embodiment scheme。
It addition, each functional unit in each embodiment of the present invention can be integrated in a processing unit, it is also possible to be that the independent physics of unit includes, it is also possible to two or more unit are integrated in a unit。Above-mentioned integrated unit both can adopt the form of hardware to realize, it would however also be possible to employ hardware adds the form of SFU software functional unit and realizes。
The above-mentioned integrated unit realized with the form of SFU software functional unit, it is possible to be stored in a computer read/write memory medium。Above-mentioned SFU software functional unit is stored in a storage medium, including some instructions with so that a computer equipment (can be personal computer, server, or the network equipment etc.) performs the part steps of method described in each embodiment of the present invention。And aforesaid storage medium includes: USB flash disk, portable hard drive, read only memory (Read-OnlyMemory, be called for short ROM), random access memory (RandomAccessMemory, be called for short RAM), the various media that can store program code such as magnetic disc or CD。
The above; being only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, any those familiar with the art is in the technical scope that the invention discloses; change can be readily occurred in or replace, all should be encompassed within protection scope of the present invention。Therefore, protection scope of the present invention should be as the criterion with described scope of the claims。
Claims (12)
1. the detection method of a leakage current, it is characterised in that described method includes:
The resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；
The resistance of resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance obtains the capacitance of the parasitic capacitance over the ground of described target DC source；
Derivative sampling circuit is utilized to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；
Capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change obtains the Ground leakage current of described target DC source。
2. the method for claim 1, it is characterised in that the described resistance of positive pole insulation against ground resistance by measurement acquisition target DC source and the resistance of negative pole insulation against ground resistance include:
Obtained the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device；
Obtained the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
3. the method for claim 1, it is characterised in that the capacitance of the parasitic capacitance over the ground that the resistance of the described resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance obtains described target DC source includes:
The positive pole parasitic capacitance over the ground of described target DC source is obtained according to described positive pole insulation against ground resistance；
The negative pole parasitic capacitance over the ground of described target DC source is obtained according to described negative pole insulation against ground resistance；
The parasitic capacitance over the ground of described target DC source is obtained in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
4. method as claimed in claim 3, it is characterised in that positive pole parasitic capacitance over the ground described in described combination and described negative pole parasitic capacitance over the ground obtain the parasitic capacitance over the ground of described target DC source and include:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
5. method according to claim 1, it is characterized in that, the described capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change obtains the Ground leakage current of described target DC source and includes:
Capacitance according to described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the positive pole Ground leakage current of described target DC source, and described positive pole Ground leakage current is defined as described Ground leakage current；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
6. the method as described in claim 1-5 any one, it is characterised in that described target DC source includes photovoltaic cell。
7. the detecting device of a leakage current, it is characterised in that described device includes:
Resistance acquiring unit, for the resistance of resistance and negative pole insulation against ground resistance by measuring the positive pole insulation against ground resistance obtaining target DC source；
Electric capacity acquiring unit, is used for the capacitance of the parasitic capacitance over the ground of the resistance described target DC source of acquisition of the resistance according to described positive pole insulation against ground resistance and described negative pole insulation against ground resistance；
Voltage sampling unit, for utilizing derivative sampling circuit to obtain at least one in the positive pole voltage-to-ground rate of change of described target DC source, negative pole voltage-to-ground rate of change；
Electric current acquiring unit, obtains the Ground leakage current of described target DC source for the capacitance according at least one and described parasitic capacitance over the ground in described positive pole voltage-to-ground rate of change, described negative pole voltage-to-ground rate of change。
8. device as claimed in claim 7, it is characterised in that described resistance acquiring unit specifically for:
Obtained the positive pole insulation against ground resistance of described target DC source by the first measuring circuit measurement, described first measuring circuit includes: the positive pole of described target DC source, earth terminal and default measurement device；
Obtained the negative pole insulation against ground resistance of described target DC source by the second measuring circuit measurement, described second measuring circuit includes: the negative pole of described target DC source, earth terminal and described default measurement device。
9. device as claimed in claim 7, it is characterised in that described electric capacity acquiring unit specifically for:
The positive pole parasitic capacitance over the ground of described target DC source is obtained according to described positive pole insulation against ground resistance；
The negative pole parasitic capacitance over the ground of described target DC source is obtained according to described negative pole insulation against ground resistance；
The parasitic capacitance over the ground of described target DC source is obtained in conjunction with described positive pole parasitic capacitance over the ground and described negative pole parasitic capacitance over the ground。
10. device as claimed in claim 9, it is characterised in that described electric capacity acquiring unit is additionally operable to:
Described positive pole parasitic capacitance over the ground is added with described negative pole parasitic capacitance over the ground described in obtaining parasitic capacitance over the ground。
11. device as claimed in claim 7, it is characterised in that described electric current acquiring unit specifically for:
Capacitance according to described positive pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the positive pole Ground leakage current of described target DC source, and described positive pole Ground leakage current is defined as described Ground leakage current；Or
Capacitance according to described negative pole voltage-to-ground rate of change and described parasitic capacitance over the ground obtains the negative pole Ground leakage current of described target DC source, and described negative pole Ground leakage current is defined as described Ground leakage current。
12. the device as described in claim 7-11 any one, it is characterised in that described target DC source includes photovoltaic cell。
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| EP3988947A4 (en) * | 2019-06-20 | 2022-08-31 | Goodwe Technologies Co., Ltd. | Circuit and method for detecting insulation resistance of photovoltaic array to ground, and photovoltaic inverter |
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| CN105790711A (en) * | 2014-12-26 | 2016-07-20 | 国家电网公司 | Detection method and system for silicon-based module defects of photovoltaic power station |
| CN104917458B (en) * | 2015-05-22 | 2017-12-15 | 江苏固德威电源科技股份有限公司 | A kind of method and its circuit of sensorless detection output current |
| MX2018011236A (en) * | 2016-03-15 | 2019-05-16 | Schlumberger Technology Bv | System and method for electric current leakage detection in a land seismic system. |
| CN108513616B (en) * | 2016-12-30 | 2020-03-10 | 华为技术有限公司 | Battery leakage current detection method, device and circuit |
| KR101960293B1 (en) * | 2017-02-14 | 2019-03-20 | 에스케이이노베이션 주식회사 | Insulation resistance measurement method and apparatus |
| CN107528296B (en) * | 2017-07-11 | 2019-04-23 | 江苏固德威电源科技股份有限公司 | Residual current protection method applied to photovoltaic DC-to-AC converter |
| JP7033102B2 (en) * | 2019-04-24 | 2022-03-09 | 株式会社デンソー | Leakage judgment device |
| CN111579877B (en) * | 2020-04-30 | 2022-11-18 | 厦门科华数能科技有限公司 | Parasitic capacitance detection circuit and detection method |
| CN111917127B (en) * | 2020-07-10 | 2022-05-03 | 爱士惟新能源技术(江苏)有限公司 | Control method and system for GFCI circuit of photovoltaic inverter |
| CN115629238A (en) * | 2022-11-29 | 2023-01-20 | 瑞浦兰钧能源股份有限公司 | Circuit and method for detecting parasitic capacitance of energy storage device |
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| AU655889B2 (en) * | 1992-06-24 | 1995-01-12 | Kabushiki Kaisha Toshiba | Inverter protection device |
| CN102255540B (en) * | 2011-07-06 | 2013-06-26 | 阳光电源股份有限公司 | Method, circuit and converter for converting DC voltage into AC voltage |
| US9048756B2 (en) * | 2012-03-07 | 2015-06-02 | Virginia Tech Intellectual Properties, Inc. | DC-side leakage current reduction for single phase full-bridge power converter/inverter |
| CN103048544B (en) * | 2012-12-13 | 2015-03-11 | 常熟开关制造有限公司(原常熟开关厂） | Insulation resistance monitoring method of photovoltaic power generation system |
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| EP3988947A4 (en) * | 2019-06-20 | 2022-08-31 | Goodwe Technologies Co., Ltd. | Circuit and method for detecting insulation resistance of photovoltaic array to ground, and photovoltaic inverter |
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