CN207853843U - Photovoltaic array ground insulation impedance detection circuit, device and non-isolated photovoltaic DC-to-AC converter - Google Patents

Photovoltaic array ground insulation impedance detection circuit, device and non-isolated photovoltaic DC-to-AC converter Download PDF

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Publication number
CN207853843U
CN207853843U CN201721535810.2U CN201721535810U CN207853843U CN 207853843 U CN207853843 U CN 207853843U CN 201721535810 U CN201721535810 U CN 201721535810U CN 207853843 U CN207853843 U CN 207853843U
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voltage
terminal
detection
resistance
ground
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宋泽琳
雷龙
冯维雄
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Gree Electric Appliances Inc of Zhuhai
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Gree Electric Appliances Inc of Zhuhai
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy

Abstract

A kind of photovoltaic array ground insulation impedance detection circuit of the utility model offer, device and non-isolated photovoltaic DC-to-AC converter.Photovoltaic array ground insulation impedance detection circuit provided by the utility model includes:Signal ground terminal for accessing signal ground;The cathode voltage input terminal being connect for the positive electrode bus with photovoltaic array;The cathode voltage input terminal being connect for the negative busbar with photovoltaic array;Reference ground voltage input-terminal for the ground wire connection with photovoltaic array;First resistor, second resistance and the 3rd resistor being sequentially connected in series between the cathode voltage input terminal and the signal ground terminal;The reference ground voltage input-terminal is connect with the cathode of the first resistor;The first voltage detection terminal being connect with the cathode of the second resistance.Photovoltaic array ground insulation impedance detection circuit provided by the utility model is simple in structure, and by accurate sampling resistor, accurately continuously whether detection insulation impedance value meets grid-connected requirement, strong antijamming capability, reliability height.

Description

Photovoltaic array ground insulation impedance detection circuit, device and non-isolated photovoltaic DC-to-AC converter
Technical field
The utility model is related to photovoltaic arts, and in particular to a kind of photovoltaic array ground insulation impedance detection circuit, device And non-isolated photovoltaic DC-to-AC converter.
Background technology
Currently, when photovoltaic array and public electric wire net are grid-connected, the non-isolated photovoltaic DC-to-AC converter of generally use is directly accessed public Power grid.High frequency transformer or Industrial Frequency Transformer are eliminated in this circuit structure, are become to eliminate high frequency transformer or power frequency Electricity loss on depressor improves grid connection efficiency, and simplifies circuit structure, therefore, is largely pushed away in practical applications Extensively.
But since photovoltaic array is directly electrical connection in grid entry point and public electric wire net, therefore, it is necessary to using it is non-every Sufficient protection Design is carried out from the photovoltaic DC-to-AC converter of topological structure, it is ensured that photovoltaic array has before being incorporated into the power networks between the earth There is sufficiently large insulation impedance, avoids that grid-connected accident occurs, endanger Electrical Safety.
Currently, detection method of the generally use based on unbalanced bridge principle carries out insulation impedance detection both at home and abroad.Specifically Ground brings to form unbalanced bridge by the unbalanced resistance timing for cutting to positive and negative busbar, and is calculated based on the unbalanced bridge Obtain positive and negative busbar insulation against ground resistance value.Since it is desired that being switched over by the switch to two or more, grasp Make versus busy, and the frequency of system public electric wire net and voltage can be caused larger fluctuation occur.
In addition, balanced bridge method is able to detect that the case where positive and negative busbar insulating resistance simultaneously declines, but measurement accuracy is not It is high.
Utility model content
In view of this, one of the purpose of this utility model is that photovoltaic array positive and negative busbar can continuously be detected by providing one kind Whether ground insulation resistance value meets detection circuit, device and the non-isolated photovoltaic DC-to-AC converter of grid-connected requirement.
In order to achieve the above objectives, on the one hand, the utility model uses following technical scheme:
A kind of photovoltaic array ground insulation impedance detection circuit, including:
Signal ground terminal for accessing signal ground;
The cathode voltage input terminal being connect for the positive electrode bus with photovoltaic array;
The cathode voltage input terminal being connect for the negative busbar with photovoltaic array;
Reference ground voltage input-terminal for the ground wire connection with photovoltaic array;
First resistor, the second resistance being sequentially connected in series between the cathode voltage input terminal and the signal ground terminal And 3rd resistor;The reference ground voltage input-terminal is connect with the cathode of the first resistor;
The first voltage detection terminal being connect with the cathode of the second resistance.
Preferably, further include detection module;
The detection module by the first voltage detection terminal voltage value V3 and the first reference voltage V4, second ginseng It examines voltage V5 to be compared, the photovoltaic array ground insulation resistance situation is judged according to comparison result.
Preferably, the first reference voltage V4 and the second reference voltage V5 meet relational expression: V4>V3>V5, wherein V3 It is determined by the first formula, first formula is:
In formula, VpvFor the output voltage of photovoltaic array, Riso1For photovoltaic arrays anode insulation against ground resistance, it is more than or equal to Vmaxpv/30mA,VmaxpvFor photovoltaic arrays maximum output voltage, Riso2For photovoltaic arrays cathode insulation against ground resistance, it is more than or equal to Vmaxpv/30mA,VmaxpvFor photovoltaic arrays maximum output voltage, R1、R2、R3It is followed successively by and is determined according to the power of the detection circuit The first resistor, the resistance value of second resistance and 3rd resistor.
Preferably, further include:
The 4th resistance, the 5th resistance being sequentially connected in series between the cathode voltage input terminal and the signal ground terminal With the 6th resistance;
The second voltage detection terminal being connect with the cathode of the 4th resistance;
The tertiary voltage detection terminal being connect with the cathode of the 5th resistance.
Preferably, using the voltage at the second voltage detection terminal detected as the first reference voltage V4; And/or using the voltage at the tertiary voltage detection terminal detected as the second reference voltage V5.
Preferably, the detection module includes:
The reference anode of first comparator, the first comparator inputs the first reference voltage V4, first ratio Detection negative terminal compared with device inputs the voltage value V3 at the first voltage detection terminal;
The detection anode of second comparator, second comparator inputs the voltage value at the first voltage detection terminal The reference negative terminal of V3, second comparator input the second reference voltage V5;
The output valve of dsp processor module, the output valve of the first comparator and the second comparator inputs at the DSP Manage device.
Preferably, the dsp processor module samples the voltage at the first voltage detection terminal.
On the other hand, the utility model adopts the following technical solution:
A kind of photovoltaic array ground insulation resistance detection device, including above-mentioned photovoltaic array ground insulation resistance detection electricity Road.
In another aspect, the utility model adopts the following technical solution:
A kind of non-isolated photovoltaic DC-to-AC converter includes above-mentioned photovoltaic array ground insulation resistance detection device.
Photovoltaic array ground insulation impedance detection circuit in the application is simple in structure, passes through accurate sampling resistor high-precision Ground continuously detects whether insulation impedance value meets grid-connected requirement, strong antijamming capability, reliability height.
Photovoltaic array ground insulation resistance structure of the detecting device in the application is simple, passes through accurate sampling resistor high-precision Ground continuously detects insulation impedance value and whether meets grid-connected requirement, simplifies hardware design, further improves anti-interference ability and can By property.
Non-isolated photovoltaic DC-to-AC converter in the application is provided with whether continuous detection insulation impedance value meets grid-connected requirement Detection device, reliability protection Design to may insure that photovoltaic array has before being incorporated into the power networks between the earth sufficiently large exhausted Edge impedance simplifies the design of photovoltaic system, ensures grid connection security.
Description of the drawings
By referring to the drawings to the description of the utility model embodiment, the above-mentioned and other mesh of the utility model , feature and advantage will be apparent from, in the accompanying drawings:
Fig. 1 is shown provided with the photovoltaic array ground insulation resistance detection device of specific embodiment of the present invention offer Non-isolated photovoltaic DC-to-AC converter and photovoltaic array and public electric wire net attachment structure schematic diagram;
Fig. 2 shows the connections for the photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention provides Structural schematic diagram;
Fig. 3 shows the another of the photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention provides Kind attachment structure schematic diagram;
Fig. 4 shows the one kind for the photovoltaic array ground insulation resistance detection device that specific embodiment of the present invention provides Attachment structure schematic diagram;Wherein,
A, voltage detection terminal;
B, voltage detection terminal;
C, voltage detection terminal;
D, dsp processor.
Specific implementation mode
The utility model is described below based on embodiment, it should be understood by one skilled in the art that carrying herein The attached drawing of confession is provided to the purpose of explanation, and attached drawing is not necessarily drawn to scale.
Unless the context clearly requires otherwise, "include", "comprise" otherwise throughout the specification and claims etc. are similar Word should be construed as the meaning for including rather than exclusive or exhaustive meaning;That is, being containing for " including but not limited to " Justice.
It is comparator, non-isolated photovoltaic DC-to-AC converter, photovoltaic DC circuit, public it should be noted that in the art Alternating current circuit, grid-connected breaker etc. are components common in photovoltaic power system, where not being the improvements of the application yet, So no longer elaborating its concrete structure and operation principle in this application.Meanwhile in this application, other of use are common Device does not describe to its structure and function in detail generally.
In addition, it is those skilled in the art to be provided with signal ground and power supply access terminal in weak electric signal detection circuit It is known, therefore in description, the description that terminal is accessed to power supply is omitted;When drawing attached drawing, power supply incoming end Son is not shown.
This application provides a kind of photovoltaic array ground insulation impedance detection circuit and device, the photovoltaic array insulation against ground Impedance detection circuit and device, which are applied, to be incorporated to by non-isolated photovoltaic DC-to-AC converter in the photovoltaic array of public electric wire net, can be continued Whether the ground insulation resistance value of the positive and negative busbar of detection photovoltaic array output meets grid-connected requirement.
Fig. 1 shows the photovoltaic array ground insulation resistance detection dress for being provided with specific embodiment of the present invention offer The attachment structure schematic diagram of the non-isolated photovoltaic DC-to-AC converter set and photovoltaic array and public electric wire net.As shown in Figure 1, the utility model The photovoltaic array ground insulation resistance detection device that specific implementation mode provides is applied to be incorporated to by non-isolated photovoltaic DC-to-AC converter In the photovoltaic array of public electric wire net, specifically, the positive and negative anodes of photovoltaic array are directly connect with non-isolated photovoltaic DC-to-AC converter, and process is non- Be isolated photovoltaic DC-to-AC converter after, as a phase, two-phase or the three-phase of exchange, photovoltaic array output direct current energy it is grid-connected after, import Exchange public network.This photovoltaic array grid connected structure eliminates high frequency transformer or Industrial Frequency Transformer, to eliminate high frequency Electricity loss on transformer or Industrial Frequency Transformer improves grid connection efficiency, and simplifies circuit structure.
When it is implemented, the photovoltaic array ground insulation resistance detection device that specific embodiment of the present invention provides can With the photovoltaic array ground insulation impedance detection circuit that is provided including specific embodiment of the present invention as shown in Figure 2 or such as Another photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention shown in Fig. 3 provides.
As shown in Fig. 2, the photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention provides, packet It includes:
Signal ground terminal for accessing signal ground;
The cathode voltage input terminal PV being connect for the positive electrode bus with photovoltaic array+
The cathode voltage input terminal PV- being connect for the negative electrode bus with photovoltaic array;
Reference ground voltage input-terminal PE for the ground wire connection with photovoltaic array;
It is sequentially connected in series in the cathode voltage input terminal PV+With the first resistor R between the signal ground terminal1, second Resistance R2With 3rd resistor R3;Wherein, the reference ground voltage input-terminal PE is connect with the cathode of the first resistor;
The voltage detection terminal A being connect with the cathode of the second resistance.
By detecting the voltage value at voltage detection terminal A, and the range residing for the voltage value is judged to judge photovoltaic Whether the insulation impedance of array meets grid-connected requirement.
Preferably, the detection circuit further includes detection module;
The detection module by the voltage detection terminal A voltage value V3 and the first reference voltage V4, second reference Voltage V5 is compared, and judges the photovoltaic array ground insulation resistance situation according to comparison result.Wherein, first reference Voltage V4, the second reference voltage V5 can preset, such as specific numerical value are arranged by way of software;It can also pass through Circuit measures.
Specifically, the photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention provides is provided with Divider resistance R1And R2, sampling resistor R3;Wherein, the standard voltage value V3 of voltage detection terminal A is determined according to formula (1):
In formula, VpvFor the output voltage of photovoltaic array, Riso1For photovoltaic arrays anode insulation against ground resistance, it is more than or equal to Vmaxpv/30mA,VmaxpvFor photovoltaic arrays maximum output voltage, Riso2For photovoltaic arrays cathode insulation against ground resistance, it is more than or equal to Vmaxpv/ 30mA, VmaxpvFor photovoltaic arrays maximum output voltage, R1、R2、R3It is followed successively by and is determined according to the power of the detection circuit The first resistor, the resistance value of second resistance and 3rd resistor.
From formula (1) it is found that Riso1Terminal voltage with Riso1Reduce and reduces, and V3 increases at this time; Riso2Terminal voltage with Riso2Reduce and reduces, and V3 also reduces at this time.
Therefore, the positive bus-bar insulation resistance of the photovoltaic array can be continuously detected whether by detecting the increase tendency of V3 It is anti-to be less than grid-connected permission impedance value;Reduction trend by detecting V3 can continuously detect whether the negative mother of the photovoltaic array Line insulation impedance is less than grid-connected permission impedance value.
Specifically, when the first reference voltage V4, the second reference voltage V5 is arranged, can voltage first be determined according to above-mentioned formula The standard voltage value V3 of detection terminal A determines V4 and V5, wherein V4 then referring to the V3>V3>V5.
Handover operation detects ground insulation resistance not in turn with generally use list relay in the prior art or more relays Together, the photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention provides is simple in structure, passes through precision Accurately continuously whether detection insulation impedance value meets grid-connected requirement to sampling resistor, has been reduced as far as Insulation monitoring and has been fed back to To the voltage fluctuation of power grid, strong antijamming capability improves the stability and reliability of system operation.
In a preferred embodiment, the detection circuit further includes being sequentially connected in series in the cathode voltage input terminal PV+With the 4th resistance R between the signal ground terminals P E4, the 5th resistance R5With the 6th resistance R6
The voltage detection terminal B being connect with the cathode of the 4th resistance;
The voltage detection terminal C being connect with the cathode of the 5th resistance.
The photovoltaic array ground insulation impedance detection circuit that specific embodiment of the present invention provides is also provided with partial pressure Resistance R4, sampling resistor R5And R6, wherein the voltage value v of voltage detection terminal B4It is determined according to formula (2):
The voltage value v of voltage detection terminal C5It is determined according to formula (3):
By photovoltaic arrays anode insulation against ground resistance Riso1, photovoltaic arrays cathode insulation against ground resistance Riso2It is updated to Formula (1) can obtain the detection voltage reference value V3 at voltage detection terminal A;By selecting the 4th resistance, the 5th resistance R is selected with the resistance value of the 6th resistance4、R5And R6So that within the scope of the direct voltage output of the photovoltaic array, meet V5<V3 <V4。
In the ground insulation resistance value fluctuation of the positive and negative busbar of lasting detection photovoltaic array output, by detecting voltage inspection Real-time voltage output value V3 at terminal A is surveyed, and is respectively compared the relationship of V3 and V4 and V5, so that it may continuously to detect whether The positive bus-bar insulation impedance of the photovoltaic array is less than grid-connected permission impedance value and the negative busbar insulation impedance of the photovoltaic array is less than Grid-connected permission impedance value.
Specifically, by detecting the detection voltage value V3 at second resistance cathode, and with the 4th resistance cathode that detects The positive contrast potential value V4 at place compares, when the detection voltage value V3 is more than the anode contrast potential value V4, you can really The positive bus-bar insulation impedance of the fixed photovoltaic array is less than grid-connected permission impedance value;Or,
By detecting the detection voltage value V3 at second resistance cathode, and with the cathode at the 5th resistance cathode that detects Contrast potential value V5 compares, when the detection voltage value V3 is less than cathode contrast potential value V5, you can determine the photovoltaic array Negative busbar insulation impedance be less than grid-connected permission impedance value.
In this embodiment, the real-time voltage value V4 measured at the voltage detection terminal B is as the first reference voltage, institute The real-time voltage value V5 that is measured at voltage detection terminal C is stated as being measured at the second reference voltage and first voltage detection terminal A Real-time voltage value V3 be compared, to judge whether photovoltaic array ground insulation resistance meets grid-connected requirement.
The photovoltaic array ground insulation impedance detection circuit that the utility model specific implementation mode provides is simple in structure, leads to Crossing accurate sampling resistor, accurately continuously whether detection insulation impedance value meets grid-connected requirement, strong antijamming capability, reliability It is high.
In another specific embodiment, in order to realize to the voltage value V3 and at the first voltage detection terminal One reference voltage V4, the second reference voltage V5 are compared, as shown in figure 4, the detection module includes:First comparator Q1 and Second comparator Q2 and dsp processor D.
Specifically, the cathode of the 4th resistance is connect with the reference edge (+) of the first comparator Q1;
The cathode of the second resistance is connect with the test side (-) of the first comparator Q1;
The cathode of the second resistance is connect with the test side (+) of the second comparator Q2;
The cathode of 5th resistance is connect with the reference edge (-) of the second comparator Q2;
When the output valve for detecting the first voltage comparator Q1 is low level, you can determine the light currently detected The positive bus-bar insulation impedance of photovoltaic array is less than grid-connected permission impedance value;
When the output valve for detecting the second voltage comparator Q2 is low level, you can determine the light currently detected The negative busbar insulation impedance of photovoltaic array is less than grid-connected permission impedance value.
Dsp processor D is respectively connected to the output valve of first comparator Q1 and output valve and the progress of the second comparator Q2 Logic and operation is less than grid-connected permission impedance value in the positive bus-bar insulation impedance of the photovoltaic array currently detected or is currently examined The negative busbar insulation impedance of the photovoltaic array of survey exports the light currently detected when being less than grid-connected permission impedance value to processor The ground insulation resistance of photovoltaic array is less than the minimum grid-connected information for allowing impedance value, so that processor is generated for making and being somebody's turn to do The grid-connected switch of photovoltaic array connection disconnects so that the photovoltaic array stops grid-connected instruction.
The description of access way and dsp processor above in relation to comparator is only used as example.In those skilled in the art In known range, as long as the comparator connection type of detection logic described above can be realized with the specific choosing of processor Type and connection type belong to the technical solution being equal with the present embodiment, within the protection domain of the application.
On-site programmable gate array FPGA (FPGA may be used in detection module and detection circuit in above-described embodiment: Field-Programmable Gate Array) module or complex programmable logic device (CPLD) (CPLD:Complex Programmable Logic Device) module and necessary peripheral hardware circuit realize.
Power PC Processor, arm processor, DSP processors etc. can be used in detection module in above-described embodiment, In, voltage comparator circuit can be various comparator chips.Detection module may include that a variety of On-off signals and switching value are defeated Exit port.
In this embodiment, by reasonable preset first reference voltage V4 and the second reference voltage V5, make under normal circumstances Therebetween, first comparator and the second comparator export real-time voltage value V3 values at voltage detection terminal A at this time High level;Work as V3>V5 or V3<When V4, comparator exports low level.Therefore the output state of two comparators of detection is only needed, i.e., It can determine whether photovoltaic array positive and negative electrode ground insulation resistance situation.Photovoltaic generation voltage is variable quantity, therefore two voltages of V4 and V5 Preset value will change with the variation of input voltage, can be realized with software approach, can also be realized with hardware approach.
Specifically, the detection module may include above-mentioned voltage comparator circuit, processor, memory and interactive electricity Sub- device, by processor in the detection voltage value V3 for detecting second resistance cathode in real time, respectively with the anode that detects Contrast potential value V4 and cathode contrast potential value V5 are compared, and the positive bus-bar to judge the photovoltaic array currently detected is exhausted Whether edge impedance is less than grid-connected permission impedance value and whether the negative busbar insulation impedance of the photovoltaic array currently detected is less than simultaneously Net allows impedance value.
In another preferred embodiment, the photovoltaic array insulation against ground resistance that specific embodiment of the present invention provides When anti-detection devices is provided with photovoltaic array ground insulation impedance detection circuit shown in Fig. 2, specifically, the detection module can To include voltage detecting circuit, processor, memory and interactive electronic device, can be inputted from interactive electronic device The output voltage of the photovoltaic array currently detected, photovoltaic arrays anode insulation against ground resistance Riso1Over the ground with photovoltaic arrays cathode Insulation resistance Riso2, calculated with the voltage detection terminal A's of the photovoltaic array match parameters currently detected by processor Voltage reference value V3 and corresponding the first reference voltage V4 and the second reference voltage V5 are detected, and is stored in memory, and It by processor in the detection voltage value V3 for detecting second resistance cathode in real time, is compared, to judge currently to be detected Photovoltaic array positive bus-bar insulation impedance whether be less than it is grid-connected permission impedance value and the photovoltaic array currently detected negative mother Whether line insulation impedance is less than grid-connected permission impedance value.
Software can be used in the photovoltaic array ground insulation resistance detection device that specific embodiment of the present invention provides Mode realizes voltage comparing function and reference voltage setting function, adaptable, strong antijamming capability, reliability height.
The interactive electronic device can be setting value button or setting value panel.
The photovoltaic array ground insulation resistance detection device that specific embodiment of the present invention provides can also use hard The mode of part circuit realizes reference voltage setting function, can effectively inhibit temperature drift, adaptable, anti-interference ability By force, reliability is high.
Preferably, the photovoltaic array ground insulation resistance detection device that specific embodiment of the present invention provides includes control Molding block, it is described when the detection module determines that the positive bus-bar insulation impedance of the photovoltaic array is less than grid-connected permission impedance value Control module generate for make grid-connected switch connect with the photovoltaic array disconnection so that the photovoltaic array stop it is grid-connected Instruction;And/or
It is described when the detection module determines that the negative busbar insulation impedance of the photovoltaic array is less than grid-connected permission impedance value Control module generate for make grid-connected switch connect with the photovoltaic array disconnection so that the photovoltaic array stop it is grid-connected Instruction.
Specifically, the control module may include instruction output circuit, in the positive bus-bar insulation for determining the photovoltaic array When impedance is less than grid-connected permission impedance value, generates the grid-connected switch for making to connect with the photovoltaic array and disconnect so that the light Photovoltaic array stops grid-connected instruction.
Specific embodiment of the present invention provide photovoltaic array ground insulation resistance detection device detect it is discontented When sufficient grid-connected conditions, is actively disengaged from grid entry point, ensure that grid connection security.
Preferably, the photovoltaic array ground insulation resistance detection device that specific embodiment of the present invention provides, may be used also To include the human-computer interaction module being connect with the detection module;
Wherein, determine that the positive bus-bar insulation impedance of the photovoltaic array is less than grid-connected permission impedance value in the detection module When, generate the too small warning message of instruction positive bus-bar insulation impedance;The human-computer interaction module is shown or the voice broadcast alarm Information;And/or
When the detection module determines that the negative busbar insulation impedance of the photovoltaic array is less than grid-connected permission impedance value, generate Indicate the too small warning message of negative busbar insulation impedance;The human-computer interaction module is shown or the voice broadcast warning message.
Specific embodiment of the present invention provide photovoltaic array ground insulation resistance detection device detect it is discontented When sufficient grid-connected conditions, display or voice broadcast ground insulation resistance cross low state, to ensure that guarantee grid connection security.
The human-computer interaction module is also provided with status indicator lamp or buzzer, is used for the too low shape of ground insulation resistance State is alarmed or is prompted.
It should be appreciated that when it is implemented, above-mentioned resistance may each be a resistance or multiple resistance connection in series-parallel come in fact Existing required resistance value.
The non-isolated photovoltaic DC-to-AC converter that specific embodiment of the present invention provides, include above-mentioned photovoltaic array over the ground Insulation resistance detection device.Therefore there are above advantages, which is not described herein again.
Those skilled in the art will readily recognize that under the premise of not conflicting, above-mentioned each preferred embodiment can be free Ground combination, superposition.
The above is only the preferred embodiment of the present invention, is not intended to limit the utility model, for this field For technical staff, the utility model can have various modifications and changes.All institutes within the spirit and principle of the utility model Any modification, equivalent substitution, improvement and etc. of work, should be included within the scope of protection of this utility model.

Claims (9)

1. a kind of photovoltaic array ground insulation impedance detection circuit, which is characterized in that including:
Signal ground terminal for accessing signal ground;
The cathode voltage input terminal being connect for the positive electrode bus with photovoltaic array;
The cathode voltage input terminal being connect for the negative busbar with photovoltaic array;
Reference ground voltage input-terminal for the ground wire connection with photovoltaic array;
First resistor, the second resistance and being sequentially connected in series between the cathode voltage input terminal and the signal ground terminal Three resistance;The reference ground voltage input-terminal is connect with the cathode of the first resistor;
The first voltage detection terminal being connect with the cathode of the second resistance.
2. detection circuit as described in claim 1, which is characterized in that further include:
Detection module;
The detection module by the first voltage detection terminal voltage value V3 and the first reference voltage V4, second with reference to electricity Pressure V5 is compared, and judges the photovoltaic array ground insulation resistance situation according to comparison result.
3. detection circuit as claimed in claim 2, which is characterized in that the first reference voltage V4 and the second reference voltage V5 Meet relational expression:V4>V3>V5, wherein V3 determine that first formula is by the first formula:
In formula, VpvFor the output voltage of photovoltaic array, Riso1For photovoltaic arrays anode insulation against ground resistance, it is more than or equal to Vmaxpv/ 30mA,VmaxpvFor photovoltaic arrays maximum output voltage, Riso2For photovoltaic arrays cathode insulation against ground resistance, it is more than or equal to Vmaxpv/ 30mA,VmaxpvFor photovoltaic arrays maximum output voltage, R1、R2、R3It is followed successively by according to described in the determination of the power of the detection circuit The resistance value of first resistor, second resistance and 3rd resistor.
4. detection circuit as claimed in claim 2, which is characterized in that further include:
The 4th resistance, the 5th resistance and being sequentially connected in series between the cathode voltage input terminal and the signal ground terminal Six resistance;
The second voltage detection terminal being connect with the cathode of the 4th resistance;
The tertiary voltage detection terminal being connect with the cathode of the 5th resistance.
5. detection circuit according to claim 4, which is characterized in that at the second voltage detection terminal detected Voltage as the first reference voltage V4;And/or using the voltage at the tertiary voltage detection terminal detected as The second reference voltage V5.
6. detection circuit according to claim 5, which is characterized in that the detection module includes:
The reference anode of first comparator, the first comparator inputs the first reference voltage V4, the first comparator Detection negative terminal input the voltage value V3 at the first voltage detection terminal;
The detection anode of second comparator, second comparator inputs the voltage value V3 at the first voltage detection terminal, The reference negative terminal of second comparator inputs the second reference voltage V5;
The output valve of dsp processor, the output valve of the first comparator and the second comparator inputs the dsp processor.
7. detection circuit according to claim 6, which is characterized in that the dsp processor module is to the first voltage Voltage at detection terminal is sampled.
8. a kind of photovoltaic array ground insulation resistance detection device, which is characterized in that including the light described in one of claim 1-7 Photovoltaic array ground insulation impedance detection circuit.
9. a kind of non-isolated photovoltaic DC-to-AC converter, which is characterized in that include photovoltaic array insulation against ground as claimed in claim 8 Impedance detection device.
CN201721535810.2U 2017-11-14 2017-11-14 Photovoltaic array ground insulation impedance detection circuit, device and non-isolated photovoltaic DC-to-AC converter Active CN207853843U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110412352A (en) * 2019-06-20 2019-11-05 江苏固德威电源科技股份有限公司 Detection circuit, method and the photovoltaic DC-to-AC converter of photovoltaic array ground insulation resistance

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110412352A (en) * 2019-06-20 2019-11-05 江苏固德威电源科技股份有限公司 Detection circuit, method and the photovoltaic DC-to-AC converter of photovoltaic array ground insulation resistance
CN110412352B (en) * 2019-06-20 2021-09-07 江苏固德威电源科技股份有限公司 Detection circuit and method for ground insulation impedance of photovoltaic array and photovoltaic inverter

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