CN110346644A - A kind of double level ground insulation impedance detection circuits and its self checking method, measurement method - Google Patents
A kind of double level ground insulation impedance detection circuits and its self checking method, measurement method Download PDFInfo
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- CN110346644A CN110346644A CN201910671583.3A CN201910671583A CN110346644A CN 110346644 A CN110346644 A CN 110346644A CN 201910671583 A CN201910671583 A CN 201910671583A CN 110346644 A CN110346644 A CN 110346644A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/025—Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
- G01R27/18—Measuring resistance to earth, i.e. line to ground
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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
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/14—Circuits therefor, e.g. for generating test voltages, sensing circuits
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- H—ELECTRICITY
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- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
- H02S50/10—Testing of PV devices, e.g. of PV modules or single PV cells
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a kind of double level ground insulation impedance detection circuits and its self checking methods, measurement method, its circuit is simple, cost is relatively low, precision is higher, self-test is perfect, high reliablity, wider impedance measurement range may be implemented, and check frequency caused by can be avoided because of PV over the ground common-mode voltage.A kind of double level ground insulation impedance detection circuits, first resistor and second resistance connect to form the first branch, and the first branch connects BUS+ bus；3rd resistor and the 4th resistance connect to form second branch, and second branch connects BUS- bus；The first branch by third controllable switch is connected to casing or the earth after connecting with second branch；First partial pressure measurement resistance and the second partial pressure measurement resistance connect to form measurement pressure divider circuit；Bus Support Capacitor is parallel between BUS+ bus and BUS- bus；First controllable switch is parallel to first resistor, and the second controllable switch is parallel to 3rd resistor；5th resistance is connected to the casing of electric power energy equipment or the negative pole end of the earth and photovoltaic module.
Description
Technical field
The invention belongs to power electronics energy device field, be related to a kind of double level ground insulation impedance detection circuits and its
Self checking method, measurement method, and in particular to a kind of detection of double level ground insulation resistances of photovoltaic DC-to-AC converter or energy storage inverter
Circuit and its self checking method, measurement method.
Background technique
Ground insulation resistance detection module is that one kind is widely used in the power electronics energy such as photovoltaic DC-to-AC converter, energy storage inverter
Safety circuit module in source device.By taking photovoltaic DC-to-AC converter as an example, when photovoltaic DC-to-AC converter detects the input voltage of solar panel
And the output voltage of power grid will be ready for grid-connected when meeting service requirement.And be to meet safety requirement, photovoltaic DC-to-AC converter is simultaneously
Before net must insulation impedance between the energized circuit and inverter casing (casing connect the earth) to photovoltaic DC-to-AC converter into
Row detection, inverter can just start inversion when demanded and output power progress is grid-connected.Such operation can guarantee inverse
Become the electrical safety in the region that people can contact on device.
In in the industry cycle, basically by resistor network, relay or other switching devices, photovoltaic module anode (PV is constituted
+), the circuit of cathode (PV-) and casing.By the state of the switch elements such as relay in switched path, change the electricity of introducing
Network parameter is hindered, the different readings of somewhere measured value are obtained, then the method by solving circuit loop equation obtains insulation impedance
Measured value.Generally there are following a few class problems for such methods:
1, when there are the input of multichannel photovoltaic module, the switch element and resistor network being equal with input number are needed；Otherwise
The specific impedance that cannot obtain every road causes complicated circuit, higher cost, self-test difficulty, reliability lower；
2, use PV+ as the power supply source of resistor network, input voltage is unstable, significantly affects measurement accuracy, is protecting
It protects measured value at threshold value to obscure, cannot reliably guarantee safety or because the reason of measurement error causes to report Insulation monitoring mistake by mistake；
3, use PV+ as the power supply source of resistor network, resistor network input voltage variable is single, causes when multichannel light
Volt component generates measurement blind area when inputting the initial common-mode voltage in the road Zhong Mou close to PV+ input voltage, is unable to measure really to ground resistance
Anti- value, and because the difference of common-mode voltage generates different measurement errors, significantly affect measurement accuracy.
Summary of the invention
To solve problems recited above, an object of the present invention is to provide a kind of double level ground insulation resistances
Detection circuit, circuit is simple, cost is relatively low, precision is higher, self-test is perfect, high reliablity, wider impedance survey may be implemented
Range is measured, and check frequency caused by can be avoided because of PV over the ground common-mode voltage.
The second object of the present invention is to provide a kind of self checking method of double level ground insulation impedance detection circuits, self-test
Perfect, high reliablity.
The third object of the present invention is to provide a kind of measurement method of double level ground insulation impedance detection circuits, measurement
Precision is higher, and the impedance measurement range confused may be implemented.
In order to achieve the above objectives, a kind of technical solution that the present invention uses are as follows:
A kind of double level ground insulation impedance detection circuits, including first resistor, second resistance, 3rd resistor, the 4th electricity
Resistance, the 5th resistance, the first partial pressure measurement resistance, the second partial pressure measurement resistance, bus Support Capacitor, the first controllable switch, second
Controllable switch and third controllable switch；
The first resistor and the second resistance connect to form the first branch, the first end connection of the first branch
BUS+ bus；The 3rd resistor and the 4th resistance connect to form second branch, the first end connection of the second branch
BUS- bus；The second end of the first branch connected with the second end of the second branch after by the third controllable switch
It is connected to the casing or the earth of electric power energy equipment；
The first partial pressure measurement resistance and the second partial pressure measurement resistance connect to form measurement pressure divider circuit, the survey
Amount pressure divider circuit is connected between the tie point of the first branch and the second branch and the negative pole end of photovoltaic module；
The bus Support Capacitor is parallel between the BUS+ bus and the BUS- bus；
First controllable switch is parallel to the both ends of the first resistor, and second controllable switch is parallel to described
Three resistance；
5th resistance is connected to the casing of electric power energy equipment or the negative pole end of the earth and photovoltaic module.
Preferably, the BUS+ bus is connected with the BUS- bus with DC/DC booster circuit, to pass through the DC/DC
Booster circuit takes electricity to photovoltaic module.
Preferably, double level ground insulation impedance detection circuits further include for importing the second partial pressure measurement electricity
The amplifier circuit of the voltage at both ends is hindered, the impedance of the first partial pressure measurement resistance is greater than the resistance of the second partial pressure measurement resistance
It is anti-.
It is highly preferred that double level ground insulation impedance detection circuits further include DSP control device, the DSP control
Device is connected to the amplifier circuit by the AD conversion module of its own or the DSP control device passes through a/d conversion device
It is connected to the amplifier circuit.
Preferably, double level ground insulation impedance detection circuits further include be connected to electric power energy equipment casing or
The 5th resistance between the earth and the negative pole end of photovoltaic module.
Preferably, double level ground insulation impedance detection circuits further include controllably opening for controlling described first respectively
It closes, the control device of the on-off of second controllable switch and the third controllable switch.
It is highly preferred that first controllable switch, the second controllable switch and the third controllable switch are respectively relay.
Preferably, the BUS- busbar grounding.
The another technical solution that the present invention uses are as follows:
A kind of self checking method of double level ground insulation impedance detection circuits as described above, includes the following steps:
A, third controllable switch is kept to disconnect；
B, obtain respectively the first controllable switch and the second controllable switch when it is disconnected, the first controllable switch closure and the
The measurement voltage value at the second partial pressure measurement resistance both ends of two controllable switches when it is disconnected,
Or, obtaining the reality of three kinds in following four kinds of states or the partial pressure measurement of second under four kinds of states resistance both ends respectively
Survey voltage value: the first controllable switch and the second controllable switch disconnect, the first controllable switch closure and the disconnection of the second controllable switch,
First controllable beginning disconnected and the second controllable switch closure, the first controllable switch and the second controllable switch are closed；
C, judge whether the measurement voltage value under each state meets the second partial pressure measurement resistance both ends under corresponding states
Voltage calculated value, if result be it is yes, self-test passes through；If the result is negative, then double level ground insulation impedance detection circuits
Failure.
Preferably, the self checking method further includes third controllable switch detecting step, the third controllable switch detection step
Suddenly include: to keep third controllable switch closure, measure the first controllable switch closure respectively and the second controllable switch disconnect, first can
The voltage value at the second partial pressure measurement resistance both ends, establishes such as lower section under the disconnection of control switch and the second controllable switch closure two states
Journey,
Wherein:
R′xRefer to the parallel value of ground insulation resistance and the 5th resistance；
Uiso1Refer to that the first controllable switch is closed and the second partial pressure measurement of the second controllable switch when it is disconnected is ohmically
Voltage；
Uiso2Refer to that the first controllable switch disconnects and the second partial pressure under the second controllable switch closure two states measures resistance
On voltage；
U0For busbar voltage (voltage i.e. between BUS+ bus and BUS- bus), RisoFor the second partial pressure measurement resistance
Impedance, R0For the impedance of the first partial pressure measurement resistance；
Ra1=R2, Ra2=R2+R1；Rb1=R4+R3, Rb2=R4；R1、R2、R3、R4Respectively first resistor, second resistance,
The resistance value of three resistance, the 4th resistance；
Judge R 'xWhether be greater than the 5th resistance, if result be it is yes, third controllable switch is not closed, failure；If
As a result be it is no, then third controllable switch closure is normal.
The another technical solution that the present invention uses are as follows:
A kind of measurement method of double level ground insulation impedance detection circuits as described above, which is characterized in that including such as
Lower step: keeping third controllable switch closure, measure the first controllable switch closure respectively and the second controllable switch disconnect, first can
The voltage value at the second partial pressure measurement resistance both ends, establishes such as lower section under the disconnection of control switch and the second controllable switch closure two states
Journey solves ground insulation resistance Rx,
Wherein:
R′xRefer to the parallel value of ground insulation resistance and the 5th resistance；
Uiso1Refer to that the first controllable switch is closed and the second partial pressure measurement of the second controllable switch when it is disconnected is ohmically
Voltage；
Uiso2Refer to that the first controllable switch disconnects and the second partial pressure under the second controllable switch closure two states measures resistance
On voltage；
U0For busbar voltage (voltage i.e. between BUS+ bus and BUS- bus), RisoFor the second partial pressure measurement resistance
Impedance, R0For the impedance of the first partial pressure measurement resistance；
Ra1=R2, Ra2=R2+R1；Rb1=R4+R3, Rb2=R4；R1、R2、R3、R4Respectively first resistor, second resistance,
The resistance value of three resistance, the 4th resistance.
The present invention uses above scheme, has the advantages that compared with prior art
A kind of double level ground insulation impedance detection circuits provided by the invention, no matter the photovoltaic module number actually accessed,
Identical circuit is all used, due to using two kinds of level of BUS+, BUS-, the measurement blind area that common-mode voltage generates over the ground can be avoided,
And precision is higher；With rigorous self-test process, self-test is perfect, high reliablity；It is measured indirectly by parallel resistance over the ground, it can be with
Realize wider impedance measurement range.It is inverse that double level ground insulation impedance detection circuits can be applied to photovoltaic DC-to-AC converter, energy storage
Become the electric power energies equipment such as device, provide a kind of new topology and its self-test and measurement method, to realize to casing and equipment
The accurate measurement of the insulation impedance of an internal energized circuit, and circuit cost, complexity are reduced, improve measurement essence
Degree, measurement range, reliability, no measurement dead area, and can complete self-test.
Detailed description of the invention
It, below will be to attached drawing needed in embodiment description in order to illustrate more clearly of technical solution of the present invention
It is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, general for this field
For logical technical staff, without creative efforts, it is also possible to obtain other drawings based on these drawings.
Fig. 1 is a kind of circuit diagram of double level ground insulation impedance detection circuits of embodiment；
Fig. 2 is a kind of measurement flow chart of embodiment；
Fig. 3 is a kind of self-test flow chart of embodiment.
Specific embodiment
The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawing, so that advantages and features of the invention energy
It is easier to be understood by the person skilled in the art.It should be noted that the explanation for these embodiments is used to help
Understand the present invention, but and does not constitute a limitation of the invention.In addition, involved in the various embodiments of the present invention described below
And to technical characteristic can be combined with each other as long as they do not conflict with each other.
The present embodiment provides a kind of photovoltaic DC-to-AC converter or double level ground insulation impedance detection circuits of energy storage inverter.Ginseng
According to shown in Fig. 1, which is substantially examined by DC/DC booster circuit, bus Support Capacitor, impedance
Measuring resistance network, state switch, measurement pressure divider circuit, amplifier circuit and DSP composition.R in Fig. 1xWith UxIt takes out
The lumped parameter of ground insulation resistance and initial common-mode voltage over the ground, the two constitute earth impedance equivalent model.
It is specific as shown in Figure 1, double level ground insulation impedance detection circuits, including first resistor R1, second resistance R2,
Three resistance R3, the 4th resistance R4, first partial pressure measurement resistance R0, second partial pressure measurement resistance Riso, bus Support Capacitor, first can
Control switch, the second controllable switch and third controllable switch.In the present embodiment, first controllable switch, the second controllable switch and
The third controllable switch is respectively relay, is respectively labeled as relay K1, relay K2, relay K3.The first resistor
R1With the second resistance R2Series connection forms the first branch, and the first end of the first branch connects BUS+ bus；The third electricity
Hinder R3With the 4th resistance R4Series connection forms second branch, and the first end of the second branch connects BUS- bus；Described first
The second end of branch passes through relay K after connecting with the second end of the second branch3It is connected to photovoltaic DC-to-AC converter or energy storage is inverse
Become the casing of device, the casing connection the earth of photovoltaic DC-to-AC converter or energy storage inverter.The first partial pressure measurement resistance R0With it is described
Second partial pressure measurement resistance RisoSeries connection formed measurement pressure divider circuit, the measurement pressure divider circuit be connected to the first branch with
Between the tie point of the second branch and the negative pole end PV- of photovoltaic module, the first partial pressure measurement resistance R0Impedance be greater than the
Two partial pressure measurement resistance RisoImpedance, and first partial pressure measurement resistance R0For single resistance or for by the series-parallel shape of multiple resistance
At resistance string, first partial pressure measurement resistance R0One end be connected to the tie point and relay K of the first branch and second branch3
Between, one end of the second partial pressure measurement resistance is connected to the negative pole end PV- of photovoltaic module.The bus Support Capacitor is parallel to institute
It states between BUS+ bus and the BUS- bus.Relay K1It is parallel to the first resistor R1Both ends, relay K2It is parallel to
The 3rd resistor R3.The BUS- busbar grounding.
Double level ground insulation impedance detection circuits further include the machine for being connected to photovoltaic DC-to-AC converter or energy storage inverter
The 5th resistance R between shell and the negative pole end PV- of photovoltaic module1.It should also be noted that, the first resistor R that the present invention addresses1、
Second resistance R2, 3rd resistor R3, the 4th resistance R4, the 5th resistance R5It is single resistance or for by multiple electricity for equivalent circuit
Hinder the resistance string formed in series and parallel.5th resistance R5One end be specifically connected to relay K3Between casing, the other end is connected to
The negative pole end PV- of photovoltaic module.
Double level ground insulation impedance detection circuits further include for importing the second partial pressure measurement resistance RisoTwo
The amplifier circuit of the voltage at end, the first partial pressure measurement resistance R0Impedance be greater than it is described second partial pressure measurement resistance Riso's
Impedance.Double level ground insulation impedance detection circuits further include DSP control device, and the DSP control device passes through it certainly
The AD conversion module of body be connected to the amplifier circuit or the DSP control device be connected to by an a/d conversion device it is described
Amplifier circuit.In the present embodiment, DSP control device carries AD conversion module, and amplifier circuit is connected to AD conversion module, measurement
Voltage signal is sent into DSP control device and is AD converted.
The DSP control device is also used to control relay K respectively1, relay K2, relay K3On-off.DSP control
Device respectively with relay K1, relay K2, relay K3Control terminal be electrically connected.
The BUS+ bus is connected with the BUS- bus with DC/DC booster circuit, to pass through the DC/DC booster circuit
Electricity is taken to photovoltaic module.Entire double level ground insulation impedance detection circuits take electricity from the end photovoltaic module PV (PV+, PV-), to
The power supply of DC/DC booster circuit.It boosts by DC/DC booster circuit, forms bus (BUS) voltage BUS+ and BUS-, BUS+ bus
It has been sequentially connected in series R1、R2Two groups of resistance, BUS- bus have been sequentially connected in series R3、R4Two groups of resistance.The DC/DC booster circuit also and
The DSP control device is electrically connected.
The present embodiment also provides double level ground insulation impedance detection circuits of a kind of photovoltaic DC-to-AC converter or energy storage inverter
Measurement method.When a measurement is taken, BUS voltage stabilization is maintained still through DC/DC booster circuit.Then reset relay K1
Relay K2Original state (can customize), closing relay K3.By measuring relay K1Closing relay K2Disconnect, after
Electric appliance K1Disconnect relay K2The second partial pressure measurement resistance R being closed under two statesisoThe voltage value at both ends establishes equation counteracting
Common-mode voltage U over the groundxInfluence, solve actual ground insulation resistance value.Equation is specific as follows:
Wherein:
R′xRefer to ground insulation resistance RxWith the 5th resistance R5Parallel value；
Uiso1Refer to that the first controllable switch is closed and the second partial pressure of the second controllable switch when it is disconnected measures resistance RisoOn
Voltage；
Uiso2Refer to that the first controllable switch disconnects and the second partial pressure under the second controllable switch closed state measures resistance RisoOn
Voltage；
U0For busbar voltage, RisoFor the second partial pressure measurement resistance RisoImpedance, R0For the first partial pressure measurement resistance R0Resistance
It is anti-；
Ra1=R2, Ra2=R2+R1；Rb1=R4+R3, Rb2=R4；R1、R2、R3、R4Respectively first resistor R1, second resistance
R2, 3rd resistor R3, the 4th resistance R4Resistance value.
The measurement method can also detect relay K3Whether failure.Due to UisoThere are the precision upper limit, the R ' of return for measured valuex
There are an only related fixed upper limits with system parameter.Therefore the 5th resistance R of design5Less than this upper limit.Due to the 5th resistance R5
With insulation earth impedance RxAt parallel relationship, normal R 'xReturn value is necessarily smaller than R5.As the measured value R ' of returnxGreater than R5When, i.e.,
It can determine that relay K3It is not closed, breaks down.R in parallel simultaneously5Also by by R 'xIt is limited within certain value, passes through inverse
RxIt is exaggerated measurable RxRange, break through due to system generate the measurement upper limit.
Fig. 2 shows the present embodiment specifically used by measurement procedure.Referring to shown in Fig. 2, the measurement method of the present embodiment
Specifically comprise the following steps:
Start to detect；
Disconnect relay K1With relay K2, closing relay K3；
Calculate the second partial pressure measurement resistance RisoThe average value of the sampled voltage at both ends；
Closing relay K1, disconnect relay K2, closing relay K3；
Calculate the second partial pressure measurement resistance RisoThe average value of the sampled voltage at both ends；
Disconnect relay K1, closing relay K2, closing relay K3；
Calculate the second partial pressure measurement resistance RisoThe average value and busbar voltage of the sampled voltage at both ends；
Above-mentioned equation is constructed, R ' is calculatedx；
Judge R 'xWhether the 5th resistance R is greater than5If result is yes, relay K3It is not closed, breaks down；If knot
Fruit is no, then relay K3Closure is normal, calculates Rx；
Judge RxWhether threshold value is less than, if result is yes, photovoltaic DC-to-AC converter or energy storage inverter system insulation qualification；If
As a result be it is no, then photovoltaic DC-to-AC converter or energy storage inverter system insulation are unqualified.
The present embodiment further provides for double level ground insulation resistances detection of a kind of photovoltaic DC-to-AC converter or energy storage inverter
The self checking method of circuit.First passed through when work DC/DC booster circuit by bus (BUS) voltage rise to one be higher than photovoltaic module it is defeated
The stationary value of voltage out provides stable working voltage source.After detecting voltage within a certain period of time without fluctuation, start certainly
Inspection.Self-test has the optional mode of the following two kinds:
One, relay K is controlled when self-test first3, keep it in off-state.Then it is switched to following four kinds of shapes respectively
Three kinds or four kinds of state (relay K in state1Disconnect relay K2Off-state, relay K1Closing relay K2Off-state,
Relay K1Disconnect relay K2Closed state, relay K1Closing relay K2Closed state, no matter above four kinds of states are successive
Sequentially, wherein three kinds can also only be taken), measure the second partial pressure measurement resistance R respectively under each stateisoThe voltage U at both endsiso.Three
Three kinds or four kinds of circuit topologies are formed by the state of its switching device under kind or four kinds of states, every kind of circuit topology is all one corresponding
UisoCalculated value forms three or four UisoIndex.When measured in process of self-test three times or four UisoMeet all
(according to device property) when corresponding index, self-test passes through.
Two, relay K is controlled when self-test first3, keep it in off-state.Then it is switched to relay K respectively1It is disconnected
Open relay K2Off-state, relay K1Closing relay K2Off-state measures the second partial pressure measurement under two states respectively
Resistance RisoThe voltage U at both endsiso.Two kinds of circuit topologies are formed by the state of its switching device under two states, every kind of circuit is opened up
It flutters and all corresponds to a UisoCalculated value forms two UisoIndex.As the U twice measured in process of self-testisoMeet all
(according to device property) when corresponding index, self-test passes through.
Self-test process used by Fig. 3 shows the present embodiment specifically.From the figure 3, it may be seen that the present embodiment preferably the first side
Formula, when using which, every kind of Single Point of Faliure deviates smaller under certain single index, can not detect, pass through in error range
Three or four index amounts, can detect except relay K3The single-point open circuit and short trouble of outer all devices, guarantee insulation resistance
The reliability of anti-detection module measured value.Relay K3The self-test that failure can not be closed can be detected by subsequent operation.
The self checking method of the present embodiment further includes relay K3Detecting step, measure three times or four UisoMeet institute
When having corresponding index, i.e., respectively in range when, carry out relay K3Detecting step.Relay K3Detecting step detailed process is such as
Shown in Fig. 2, comprising:
Disconnect relay K1With relay K2, closing relay K3；
Calculate the second partial pressure measurement resistance RisoThe average value of the sampled voltage at both ends；
Closing relay K1, disconnect relay K2, closing relay K3；
Calculate the second partial pressure measurement resistance RisoThe average value of the sampled voltage at both ends；
Disconnect relay K1, closing relay K2, closing relay K3；
Calculate the second partial pressure measurement resistance RisoThe average value and busbar voltage of the sampled voltage at both ends；
Above-mentioned equation is constructed, R ' is calculatedx；
Judge R 'xWhether the 5th resistance R is greater than5If result is yes, relay K3It is not closed, breaks down；If knot
Fruit is no, then relay K3Closure is normal.
A kind of ground insulation impedance detection circuit is present embodiments provided, no matter the photovoltaic module number actually accessed, all makes
With identical circuit, and the DC/DC boosting inherently such as inverter can be used in the DC/DC module that stably measured power supply uses
Circuit, so that circuit is simple, cost is relatively low；Due to using two kinds of level of BUS+, BUS-, it can avoid what common-mode voltage over the ground generated
Measurement blind area, and precision is higher；With rigorous self-test process, self-test is perfect, high reliablity；It is indirect by parallel resistance over the ground
Measurement, may be implemented wider impedance measurement range.It can be applied to the electric power energies such as photovoltaic DC-to-AC converter, energy storage inverter and sets
It is standby, provide a kind of new topology and its self-test and measurement method.To realize to once charging back inside casing and equipment
The accurate measurement of the insulation impedance on road, and reduce circuit cost, complexity improves measurement accuracy, measurement range, reliable
Property, no measurement dead area, and can complete self-test.
The above embodiments merely illustrate the technical concept and features of the present invention, is a kind of preferred embodiment, and purpose exists
It cans understand the content of the present invention and implement it accordingly in person skilled in the art, protection of the invention can not be limited with this
Range.Equivalent transformation or modification made by all Spirit Essences according to the present invention, should all cover protection scope of the present invention it
It is interior.
Claims (10)
1. a kind of double level ground insulation impedance detection circuits, which is characterized in that including first resistor, second resistance, third electricity
Resistance, the 4th resistance, the 5th resistance, the first partial pressure measurement resistance, the second partial pressure measurement resistance, bus Support Capacitor, first are controllably
Switch, the second controllable switch and third controllable switch；
The first resistor and the second resistance connect to form the first branch, and the first end connection BUS+ of the first branch is female
Line；The 3rd resistor and the 4th resistance connect to form second branch, and the first end connection BUS- of the second branch is female
Line；The second end of the first branch is connected to after connecting with the second end of the second branch by the third controllable switch
The casing or the earth of electric power energy equipment；
The first partial pressure measurement resistance and the second partial pressure measurement resistance connect to form measurement pressure divider circuit, the measurement point
Road is pushed back to be connected between the tie point of the first branch and the second branch and the negative pole end of photovoltaic module；
The bus Support Capacitor is parallel between the BUS+ bus and the BUS- bus；
First controllable switch is parallel to the both ends of the first resistor, and second controllable switch is parallel to the third electricity
The both ends of resistance；
5th resistance is connected to the casing of electric power energy equipment or the negative pole end of the earth and photovoltaic module.
2. double level ground insulation impedance detection circuits according to claim 1, it is characterised in that: the BUS+ bus and
The BUS- bus is connected with DC/DC booster circuit, to take electricity to photovoltaic module by the DC/DC booster circuit.
3. double level ground insulation impedance detection circuits according to claim 1, it is characterised in that: double level are over the ground
Insulation resistance detection circuit further includes the amplifier circuit for importing the voltage at the second partial pressure measurement resistance both ends, and described the
The impedance of one partial pressure measurement resistance is greater than the impedance of the second partial pressure measurement resistance.
4. double level ground insulation impedance detection circuits according to claim 3, it is characterised in that: double level are over the ground
Insulation resistance detection circuit further includes DSP control device, and the DSP control device is connected to by the AD conversion module of its own
The amplifier circuit or the DSP control device are connected to the amplifier circuit by a/d conversion device.
5. double level ground insulation impedance detection circuits according to claim 1, it is characterised in that: double level are over the ground
Insulation resistance detection circuit further includes for controlling first controllable switch, second controllable switch and the third respectively
The control device of the on-off of controllable switch.
6. double level ground insulation impedance detection circuits according to claim 5, it is characterised in that: described first controllably opens
It closes, the second controllable switch and the third controllable switch are respectively relay.
7. double level ground insulation impedance detection circuits according to claim 1, it is characterised in that: the BUS- bus connects
Ground.
8. a kind of self checking method of such as described in any item double level ground insulation impedance detection circuits of claim 1-7, special
Sign is, includes the following steps:
A, third controllable switch is kept to disconnect；
B, obtain respectively the first controllable switch and the second controllable switch when it is disconnected, the first controllable switch closure and second can
The measurement voltage value at the second partial pressure measurement resistance both ends under switch off state is controlled,
Or, obtaining the actual measurement electricity of three kinds in following four kinds of states or the partial pressure measurement of second under four kinds of states resistance both ends respectively
Pressure value: the first controllable switch and the second controllable switch disconnect, the first controllable switch closure and the second controllable switch disconnect, first
The controllable beginning disconnects and the second controllable switch closure, the first controllable switch and the second controllable switch are closed；
C, judge whether the measurement voltage value under each state meets the voltage at the second partial pressure measurement resistance both ends under corresponding states
Calculated value, if result be it is yes, self-test passes through；If the result is negative, then double level ground insulation impedance detection circuit failures.
9. self checking method according to claim 8, which is characterized in that the self checking method further includes the inspection of third controllable switch
Step is surveyed, the third controllable switch detecting step includes: to keep third controllable switch closure, measures the first controllable switch respectively
The second partial pressure is surveyed under closure and the second controllable switch disconnect, the first controllable switch disconnects and the second controllable switch closure two states
The voltage value for measuring resistance both ends, establishes the following equation,
Wherein:
R′xRefer to the parallel value of ground insulation resistance and the 5th resistance；
Uiso1Refer to that the first controllable switch is closed and the second partial pressure of the second controllable switch when it is disconnected measures ohmically voltage；
Uiso2Refer to that the first controllable switch disconnects and the second partial pressure under the second controllable switch closure two states measures ohmically electricity
Pressure；
U0For busbar voltage, RisoFor the impedance of the second partial pressure measurement resistance, R0For the impedance of the first partial pressure measurement resistance；
Ra1=R2, Ra2=R2+R1；Rb1=R4+R3, Rb2=R4；R1、R2、R3、R4Respectively first resistor, second resistance, third electricity
It hinders, the resistance value of the 4th resistance；
Judge R 'xWhether be greater than the 5th resistance, if result be it is yes, third controllable switch is not closed, failure；If result
Be it is no, then third controllable switch closure is normal.
10. a kind of measurement method of such as described in any item double level ground insulation impedance detection circuits of claim 1-7, special
Sign is, includes the following steps: to keep third controllable switch closure, measures the first controllable switch closure respectively and second controllably opens
The voltage at the second partial pressure measurement resistance both ends under shutdown is opened, the first controllable switch disconnects and the second controllable switch closure two states
Value, establishes the following equation, solves ground insulation resistance Rx,
Wherein:
R′xRefer to the parallel value of ground insulation resistance and the 5th resistance；
Uiso1Refer to that the first controllable switch is closed and the second partial pressure of the second controllable switch when it is disconnected measures ohmically voltage；
Uiso2Refer to that the first controllable switch disconnects and the second partial pressure under the second controllable switch closure two states measures ohmically electricity
Pressure；
U0For busbar voltage, RisoFor the impedance of the second partial pressure measurement resistance, R0For the impedance of the first partial pressure measurement resistance；
Ra1=R2, Ra2=R2+R1；Rb1=R4+R3, Rb2=R4；R1、R2、R3、R4Respectively first resistor, second resistance, third electricity
It hinders, the resistance value of the 4th resistance.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111610411A (en) * | 2020-04-20 | 2020-09-01 | 华为技术有限公司 | Cable insulation impedance detection method and device |
| CN114966205A (en) * | 2021-02-19 | 2022-08-30 | 华为数字能源技术有限公司 | Insulation impedance detection method, device and system |
| CN117517906A (en) * | 2024-01-02 | 2024-02-06 | 博最科技(苏州)有限公司 | Insulation detection calculation method of self-adaptive Y capacitor |
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| CN103105537B (en) * | 2012-12-26 | 2015-08-12 | 深圳创动科技有限公司 | Battery panel ground insulation impedance detection circuit and method |
| US9621050B2 (en) * | 2013-05-31 | 2017-04-11 | Power Integrations, Inc. | Storage time control |
| WO2015069238A1 (en) * | 2013-11-06 | 2015-05-14 | Schneider Electric Solar Inverters Usa, Inc. | Systems and methods for insulation impedance monitoring |
| CN108427038A (en) * | 2017-12-22 | 2018-08-21 | 深圳市中兴昆腾有限公司 | A kind of multichannel input photovoltaic DC-to-AC converter ground insulation impedance detection |
| CN210487865U (en) * | 2019-07-24 | 2020-05-08 | 爱士惟新能源技术(扬中)有限公司 | Double-level ground insulation impedance detection circuit |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111610411A (en) * | 2020-04-20 | 2020-09-01 | 华为技术有限公司 | Cable insulation impedance detection method and device |
| CN114966205A (en) * | 2021-02-19 | 2022-08-30 | 华为数字能源技术有限公司 | Insulation impedance detection method, device and system |
| EP4057013A1 (en) * | 2021-02-19 | 2022-09-14 | Huawei Digital Power Technologies Co., Ltd. | Insulation impedance detection method, apparatus, and system |
| US11802897B2 (en) | 2021-02-19 | 2023-10-31 | Huawei Digital Power Technologies Co., Ltd. | Insulation impedance detection method, apparatus, and system |
| CN117517906A (en) * | 2024-01-02 | 2024-02-06 | 博最科技(苏州)有限公司 | Insulation detection calculation method of self-adaptive Y capacitor |
| CN117517906B (en) * | 2024-01-02 | 2024-03-22 | 博最科技(苏州)有限公司 | Insulation detection calculation method of self-adaptive Y capacitor |
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