CN102279318B - Online detection system of insulating resistance to ground of photovoltaic grid-connected inverter - Google Patents
Online detection system of insulating resistance to ground of photovoltaic grid-connected inverter Download PDFInfo
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- CN102279318B CN102279318B CN 201110171262 CN201110171262A CN102279318B CN 102279318 B CN102279318 B CN 102279318B CN 201110171262 CN201110171262 CN 201110171262 CN 201110171262 A CN201110171262 A CN 201110171262A CN 102279318 B CN102279318 B CN 102279318B
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Abstract
The invention relates to the technology of photovoltaic grid-connected inverter, in particular to an online detection system of insulating resistance to ground of a photovoltaic grid-connected inverter. The system comprises an upper bridge arm, a lower bridge arm, a resistance switch circuit, a power frequency interference inhibiting circuit, a voltage following circuit, an isolating and amplifying circuit, a microprocessor, and a PV voltage detecting circuit for detecting output voltage of a photovoltaic cell; the microprocessor is provided with a detection result output port. With the system, the anode-to-ground resistance of the photovoltaic cell and the cathode-to-ground resistance of the photovoltaic cell can be online calculated in real-time and accurately and can be outputted to the relevant circuit and equipment by the detection result output port of the microprocessor, thus the photovoltaic grid-connected inverter is guaranteed to work safely and reliably.
Description
Technical field
The present invention relates to the photovoltaic combining inverter technology, relate in particular to a kind of insulation against ground resistance on-line detecting system of photovoltaic combining inverter.
Background technology
In photovoltaic combining inverter, the output voltage of photovoltaic cell is higher, and for example: powerful photovoltaic combining inverter, the output voltage of its photovoltaic cell can be up to more than the 600V.Simultaneously, because the photovoltaic battery panel of photovoltaic cell is open-air the placement, so the weather conditions such as dust, sleet, dense fog all can affect positive pole, the over the ground variation of (following alleged " over the ground " all refers on " for the earth ", i.e. Earth) insulation of negative pole of photovoltaic cell.As a kind of high-pressure system, a quality that key index is exactly the insulation degree of photovoltaic combining inverter safety, whether the state of insulation that the insulation measurement technology can be judged current system is good, and the situation of change of state of insulation.
At present, detect the insulation against ground resistance of photovoltaic combining inverter, usually adopt the detection method based on the bridge balance principle.Please refer to Fig. 1, be the insulation against ground resistance detecting circuit schematic diagram based on the bridge balance principle, the R+ of dotted portion is positive pole (PV+) insulation resistance over the ground of photovoltaic cell among Fig. 1, the R-of dotted portion is negative pole (PV-) insulation resistance over the ground of photovoltaic cell, wherein, between the positive pole and the earth of photovoltaic cell, all be connected to given resistance R between the negative pole of photovoltaic cell and the earth, when by detecting voltage U j and Um, in conjunction with given resistance R, can calculate R+ and R-again.But, when R+ and R-descend on an equal basis, this detection method based on the bridge balance principle, the anodal actual insulation resistance over the ground negative pole reality insulation resistance over the ground big or small and photovoltaic cell that can not accurately detect photovoltaic cell is big or small, namely can not accurately detect the positive pole of photovoltaic cell, the variation of negative pole insulation against ground.
Summary of the invention
The object of the invention is to provide for the deficiencies in the prior art a kind of insulation against ground resistance on-line detecting system of photovoltaic combining inverter, it can calculate positive pole insulation resistance and the negative pole insulation resistance over the ground over the ground of the photovoltaic cell of photovoltaic combining inverter online real-time and accurately.
Purpose of the present invention realizes by following technical measures: a kind of insulation against ground resistance on-line detecting system of photovoltaic combining inverter, and it includes brachium pontis, lower brachium pontis, resistance switch circuit, power frequency codan, voltage follower circuit, isolating amplifier circuit, microprocessor, for detection of the PV voltage detecting circuit of photovoltaic cell output voltage;
One end of described upper brachium pontis is connected with the positive pole of photovoltaic cell, another termination the earth of described upper brachium pontis, the first end of described resistance switch circuit is connected with the positive pole of photovoltaic cell, the second termination the earth of described resistance switch circuit, an I/O(I/O of the control end of described resistance switch circuit and described microprocessor) port is connected;
The first termination the earth of described lower brachium pontis, the second end of described lower brachium pontis is connected with the negative pole of photovoltaic cell, the dividing potential drop output terminal of described lower brachium pontis is connected with the input end of described power frequency codan, the output terminal of described power frequency codan is connected with the input end of described voltage follower circuit, the output terminal of described voltage follower circuit is connected with the input end of described isolating amplifier circuit, an A/D(analog-to-digital of the output terminal of described isolating amplifier circuit and described microprocessor) input port is connected;
The first test side of described PV voltage detecting circuit is connected with the positive pole of photovoltaic cell, the second test side of described PV voltage detecting circuit is connected with the negative pole of photovoltaic cell, and the output terminal of described PV voltage detecting circuit is connected with the 2nd A/D input port of described microprocessor; Wherein, described microprocessor is provided with the testing result output port.
The testing result output port of described microprocessor includes the 2nd I/O port, and described the 2nd I/O port is connected with warning circuit.
The testing result output port of described microprocessor also includes the pwm signal port, and described pwm signal port boosts with the Boost(of photovoltaic combining inverter) circuit and inverter circuit be connected.
The power supply of described voltage follower circuit and described isolating amplifier circuit all is the PWM(Pulse Width Modulation by the accessory power supply module of photovoltaic combining inverter, pulse-length modulation) power supply of control chip provides.
Be connected with filtering circuit between the output terminal of described power frequency codan and the input end of described voltage follower circuit, the input end of described filtering circuit is connected with the output terminal of described power frequency codan, and the output terminal of described filtering circuit is connected with the input end of described voltage follower circuit.
Described upper brachium pontis is made of one or more resistance, and described lower brachium pontis also is to be made of one or more resistance.
Described resistance switch circuit is made of resistance and switch series connection, and wherein, described switch is relay, switching tube or optocoupler.
Described isolating amplifier circuit adopts the isolating amplifier circuit that is made of linear optical coupling or isolation operational amplifier.
Described PV voltage detecting circuit adopts differential amplifier circuit or voltage sensor isolation sample circuit.
Described microprocessor adopts FIR(that limit for length's shock response is arranged) digital filtering algorithm, described microprocessor is made further digital filtering by the FIR digital filtering algorithm to the A/D sampled signal and is processed, and this microprocessor is DSP(digital signal processor) microprocessor.
Beneficial effect of the present invention is: the present invention includes upper brachium pontis, lower brachium pontis, resistance switch circuit, power frequency codan, voltage follower circuit, isolating amplifier circuit, microprocessor, for detection of the PV voltage detecting circuit of photovoltaic cell output voltage; Microprocessor is provided with the testing result output port; Microprocessor of the present invention can be by the output voltage of PV voltage detecting circuit sampling photovoltaic cell, simultaneously, microprocessor can send control signal, make the resistance switch circuit from upper brachium pontis, break away from or to access in the brachium pontis, the power frequency codan is eliminated the power frequency interference signals in the dividing potential drop output end voltage signal of lower brachium pontis, send microprocessor to carry out the A/D sampling through voltage follower circuit and isolating amplifier circuit again, the positive pole that so just obtains two groups of photovoltaic cells over the ground with the negative pole voltage ratio equation over the ground of photovoltaic cell, can calculate real-time and accurately online at last positive pole insulation resistance and the negative pole insulation resistance over the ground over the ground of the photovoltaic cell of photovoltaic combining inverter by the computing of microprocessor, and export to interlock circuit and equipment by the testing result output port of microprocessor, thereby guarantee that photovoltaic combining inverter works safely and reliably.
Description of drawings
Fig. 1 is existing insulation against ground resistance detecting circuit schematic diagram based on the bridge balance principle.
Fig. 2 is the block diagram of the insulation against ground resistance on-line detecting system of a kind of photovoltaic combining inverter of the present invention.
Fig. 3 is that the circuit of PV voltage detecting circuit of the insulation against ground resistance on-line detecting system of a kind of photovoltaic combining inverter of the present invention is realized schematic diagram.
Fig. 4 is that the circuit of upper brachium pontis, lower brachium pontis, resistance switch circuit, power frequency codan, filtering circuit, voltage follower circuit and isolating amplifier circuit of the insulation against ground resistance on-line detecting system of a kind of photovoltaic combining inverter of the present invention is realized schematic diagram.
In Fig. 2, Fig. 3 and Fig. 4, include:
1---upper brachium pontis 2---resistance switch circuit
3---PV voltage detecting circuit 4---warning circuit
The lower brachium pontis of 5---microprocessors 6---
7---power frequency codan 8---filtering circuit
9---voltage follower circuit 10---isolating amplifier circuit
11---Boost circuit and inverter circuit.
Embodiment
The present invention is further illustrated below in conjunction with accompanying drawing.
The insulation against ground resistance on-line detecting system of a kind of photovoltaic combining inverter of the present invention, shown in Fig. 2～4, it includes brachium pontis 1, lower brachium pontis 6, resistance switch circuit 2, power frequency codan 7, voltage follower circuit 9, isolating amplifier circuit 10, microprocessor 5, for detection of the output voltage (V of photovoltaic cell
PV) PV(be photovoltaic cell) voltage detecting circuit 3; Wherein, one end of upper brachium pontis 1 is connected with the positive pole (PV+) of photovoltaic cell, another termination the earth (Earth) of upper brachium pontis 1, the first end of resistance switch circuit 2 is connected with the positive pole of photovoltaic cell, the second termination the earth of resistance switch circuit 2, the control end of resistance switch circuit 2 is connected with an I/O port (I/O_1) of microprocessor 5, makes microprocessor 5 can send control signal and controlling resistance on-off circuit 2 breaks away from from upper brachium pontis 1 or access in the brachium pontis 1; The first termination the earth of lower brachium pontis 6, the second end of lower brachium pontis 6 is connected with the negative pole (PV-) of photovoltaic cell, the dividing potential drop output terminal of lower brachium pontis 6 is connected with the input end of power frequency codan 7, the output terminal of power frequency codan 7 is connected with the input end of voltage follower circuit 9, the output terminal of voltage follower circuit 9 is connected with the input end of isolating amplifier circuit 10, the output terminal of isolating amplifier circuit 10 is connected with an A/D input port (A/D_1) of microprocessor 5, and the voltage of the dividing potential drop output terminal that microprocessor 5 can be by 7 pairs of lower brachium pontis 6 of power frequency codan is sampled.Wherein, the R+ of dotted portion is the positive pole insulation resistance over the ground of photovoltaic cell among Fig. 2 and Fig. 4, and the R-of dotted portion is the negative pole insulation resistance over the ground of photovoltaic cell.
The first test side of PV voltage detecting circuit 3 is connected with the positive pole of photovoltaic cell, the second test side of PV voltage detecting circuit 3 is connected with the negative pole of photovoltaic cell, the output terminal of PV voltage detecting circuit 3 is connected with the 2nd A/D input port (A/D_2) of microprocessor 5, makes microprocessor 5 can pass through the output voltage of PV voltage detecting circuit 3 sampling photovoltaic cells; Wherein, microprocessor 5 is provided with the testing result output port, and the testing result output port is used for testing result is exported to interlock circuit and equipment, makes the user can watch intuitively testing result or directly drives relevant device.
The testing result output port of microprocessor 5 includes the 2nd I/O port (I/O_2), and the 2nd I/O port is connected with warning circuit 4, makes microprocessor 5 can drive warning circuit 4 and sends alerting signal.
The testing result output port of microprocessor 5 also includes the pwm signal port, the pwm signal port is connected with Boost circuit and the inverter circuit 11 of photovoltaic combining inverter, makes microprocessor 5 can forbid by pwm signal port (PWM) Boost circuit and the inverter circuit 11 startup work of photovoltaic combining inverter.
The power supply of voltage follower circuit 9 and isolating amplifier circuit 10 all be by the power supply of the pwm chip of the accessory power supply module of photovoltaic combining inverter (+VCCP) provide, because voltage follower circuit 9, isolating amplifier circuit 10 circuit such as grade need power supply, and do not have such power supply winding in the accessory power supply module of photovoltaic combining inverter the inside, so, generally needing increases by one group of independent winding and corresponding mu balanced circuit in the transformer of accessory power supply module of photovoltaic combining inverter again, produce one group of power supply, be voltage follower circuit 9, isolating amplifier circuit 10 circuit supplies such as grade, but so just increased the complexity of the accessory power supply module of photovoltaic combining inverter, ingenious part of the present invention be utilize photovoltaic combining inverter the accessory power supply module the power supply VCC of pwm chip (be exactly end) of pwm chip be voltage follower circuit 9, isolating amplifier circuit 10 circuit supplies such as grade, thus do not need to change the transformer of the accessory power supply module of photovoltaic combining inverter.
Be connected with filtering circuit 8 between the input end of the output terminal of power frequency codan 7 and voltage follower circuit 9, the input end of filtering circuit 8 is connected with the output terminal of power frequency codan 7, and the output terminal of filtering circuit 8 is connected with the input end of voltage follower circuit 9.In the present embodiment, described filtering circuit 8 adopts the RC filtering circuit, this RC filtering circuit comprises resistance R 6, capacitor C 2, one end of resistance R 6 is connected with the output terminal of power frequency codan 7, the other end of resistance R 6 is connected with the input end of voltage follower circuit 9, an end of capacitor C 2, and the other end of capacitor C 2 is connected with the negative pole of photovoltaic cell.Certainly, described filtering circuit 8 also can adopt the filtering circuit of other type, is not limited only to the RC filtering circuit that the present embodiment adopts.
For reduce disturbance, the control section of microprocessor 5 of the present invention and the power drive of photovoltaic combining inverter partly adopt not the altogether circuit structure on ground topology, isolating publicly of the negative pole of photovoltaic cell and microprocessor 5, therefore, be provided with isolating amplifier circuit 10 between power frequency codan 7 of the present invention and the microprocessor 5.The isolating amplifier circuit that isolating amplifier circuit 10 can adopt linear optical coupling to consist of namely adopts linear optical coupling to isolate, the impact that the isolating amplifier circuit that linear optical coupling consists of is simple in structure, the linearity of signal isolation amplification is good, be not subjected to electromagnetic interference (EMI).Certainly, described isolating amplifier circuit 10 also can be the isolating amplifier circuit of other type, for example: by the isolating amplifier circuit that consists of of isolation operational amplifier, the isolating amplifier circuit that is consisted of by linear optical coupling that is not limited only to that the present embodiment selects.
Specifically, in the present embodiment, isolating amplifier circuit 10 comprises resistance R 7, R8, R9, R10, capacitor C 3, C4, C5, C6, operational amplifier U1B, operational amplifier U2A, linear optical coupling U3; One end of resistance R 7 (being the input end of isolating amplifier circuit 10) is connected with the output terminal of voltage follower circuit 9, one end of the other end of resistance R 7 and capacitor C 3, the inverting input of operational amplifier U1B (being the pin 6 of operational amplifier U1B), one end of capacitor C 4,3 pin of linear optical coupling U3 connect, the other end of capacitor C 3, the in-phase input end of operational amplifier U1B (being the pin 5 of operational amplifier U1B), 4 pin of linear optical coupling U3 all are connected with the negative pole of photovoltaic cell, the output terminal of the other end of capacitor C 4 and operational amplifier U1B (being the pin 7 of operational amplifier U1B), one end of resistance R 8 connects, the other end of resistance R 8 is connected with 1 pin of linear light idol U3, the power supply of the pin two of linear optical coupling U3 and the pwm chip of the accessory power supply module of photovoltaic combining inverter (+VCCP) be connected, the pin 6 of linear optical coupling U3 and the inverting input (being the pin two of operational amplifier U2A) of operational amplifier U2A, one end of capacitor C 5, one end of resistance R 9 connects, the other end of capacitor C 5, the other end of resistance R 9, one end of resistance R 10 all is connected with the output terminal (being the pin one of operational amplifier U2A) of operational amplifier U2A, the other end of resistance R 10 is the output terminal of isolating amplifier circuit 10, one end of capacitor C 6 is connected with the output terminal of isolating amplifier circuit 10, the pin 5 of linear optical coupling U3, the in-phase input end of operational amplifier U2A (being the pin 3 of operational amplifier U2A), the other end of capacitor C 6 all connects simulation ground (AGND), the power supply of operational amplifier U2A anodal (being the pin 8 of operational amplifier U2A) is connected with the power supply+VCCA of photovoltaic combining inverter, and the power supply negative pole of operational amplifier U2A (being the pin 4 of operational amplifier U2A) is connected with the power supply-VCCA of photovoltaic combining inverter.
PV voltage detecting circuit 3 can adopt differential amplifier circuit, can isolate accurately sampling to the output voltage of photovoltaic cell by differential amplifier circuit.Certainly, described PV voltage detecting circuit 3 also can be the sample circuit of other type, and for example: voltage sensor isolation sample circuit is not limited only to the differential amplifier circuit that the present embodiment is selected.
Specifically, in the present embodiment, PV voltage detecting circuit 3 comprises resistance R 11, R12, R13, R14, R15, R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, capacitor C 7, C8, C9, operational amplifier U4A; Resistance R 11, R12, R13, R14, R15, after R16 connects successively, one end is connected with the negative pole of photovoltaic cell, the other end is connected with the inverting input (being the pin two of operational amplifier U4A) of operational amplifier U4A, an end that is resistance R 11 is the second test side of PV voltage detecting circuit 3, the other end of resistance R 11 is connected with an end of resistance R 12, the other end of resistance R 12 is connected with an end of resistance R 13, the other end of resistance R 13 is connected with an end of resistance R 14, the other end of resistance R 14 is connected with an end of resistance R 15, the other end of resistance R 15 is connected with an end of resistance R 16, and the other end of resistance R 16 is connected with the inverting input of operational amplifier U4A; Resistance R 18, R19, R20, R21, R22, after R23 connects successively, one end is connected with the positive pole of photovoltaic cell, the other end is connected with the in-phase input end (being the pin 3 of operational amplifier U4A) of operational amplifier U4A, an end that is resistance R 18 is the first test side of PV voltage detecting circuit 3, the other end of resistance R 18 is connected with an end of resistance R 19, the other end of resistance R 19 is connected with an end of resistance R 20, the other end of resistance R 20 is connected with an end of resistance R 21, the other end of resistance R 21 is connected with an end of resistance R 22, the other end of resistance R 22 is connected with an end of resistance R 23, and the other end of resistance R 23 is connected with the in-phase input end of operational amplifier U4A; After resistance R 17 and capacitor C 7 were in parallel, an end was connected with the inverting input of operational amplifier U4A, and the other end is connected with the output terminal (being the pin one of operational amplifier U4A) of operational amplifier U4A; After resistance R 24 and capacitor C 8 were in parallel, an end was connected with the in-phase input end of operational amplifier U4A, another termination simulation ground (AGND); One end of resistance R 25 is connected with the output terminal of operational amplifier U4A, and the other end of resistance R 25 is the output terminal of PV voltage detecting circuit 3; One end of capacitor C 9 is connected with the output terminal of PV voltage detecting circuit 3, another termination simulation ground of capacitor C 9; The power supply of operational amplifier U4A anodal (being the pin 8 of operational amplifier U4A) is connected with the power supply+VCCA of photovoltaic combining inverter, and the power supply negative pole of operational amplifier U4A (being the pin 4 of operational amplifier U4A) is connected with the power supply-VCCA of photovoltaic combining inverter.Wherein, circuit parameter satisfies following relation:
R11+R12+R13+R14+R15+R16= R18+R19+R20+R21+R22+R23；
R17=R24。
Microprocessor 5 adopts the FIR digital filtering algorithm, microprocessor 5 is made further digital filtering by the FIR digital filtering algorithm to the A/D sampled signal and is processed, effectively eliminate the electrical network power frequency component to impact of the present invention, and the computation process of FIR digital filtering algorithm is succinct, computational accuracy is high; This microprocessor 5 is the DSP microprocessor, and the DSP microprocessor has the advantages such as powerful data-handling capacity and high travelling speed.
In the present embodiment, power frequency codan 7 is made of bypass filter capacitor C1, and the end of bypass filter capacitor C1 is connected with the dividing potential drop output terminal of lower brachium pontis 6, and the other end of bypass filter capacitor C1 is connected with the negative pole of photovoltaic cell.Because photovoltaic combining inverter is connected with electrical network, and the distributed capacitance that photovoltaic combining inverter exists, the impact of distributed inductance, ground wire has been introduced the industrial frequency AC undesired signal, reality is tested and is shown, the amplitude of industrial frequency AC undesired signal is very large, and its peak-to-peak value can reach more than 20% of photovoltaic cell output voltage, therefore, in signal processing circuit, necessary filtering industrial frequency AC undesired signal, and bypass filter capacitor C1 is used for the filtering power frequency interference signals.Certainly, described power frequency codan 7 also can be the circuit of other filtering mode, such as: the filtering modes such as LC, CLC are not limited only to the bypass filtering mode that the present embodiment is selected.
In the present embodiment, described voltage follower circuit 9 is made of operational amplifier U1A, the in-phase input end of operational amplifier U1A (being the pin 3 of operational amplifier U1A) is the input end of voltage follower circuit 9, the inverting input of operational amplifier U1A (being the pin two of operational amplifier U1A) is connected with the output terminal (being the pin one of operational amplifier U1A) of operational amplifier U1A, the power supply of the power supply of operational amplifier U1A anodal (being the pin 8 of operational amplifier U1A) and the pwm chip of the accessory power supply module of photovoltaic combining inverter (+VCCP) being connected, the power supply negative pole of operational amplifier U1A (being the pin 4 of operational amplifier U1A) is connected with the negative pole of photovoltaic cell.
The model of above-mentioned operational amplifier U1A, operational amplifier U1B, operational amplifier U2A, operational amplifier U4A is LM258, and the model of linear optical coupling U3 is HCNR200.Certainly, model and the parameter value of above-mentioned electronic devices and components are only for reference, when the implementation the technical program, can make amendment according to actual environment.
The course of work of the present invention may further comprise the steps:
A: microprocessor 5 of the present invention (is V by the output voltage of PV voltage detecting circuit 3 sampling photovoltaic cells
PV);
B: microprocessor 5 sends control signal, make the switch S 1 in the resistance switch circuit 2 be in off-state, resistance R 5 is broken away from from upper brachium pontis 1, after then descending the processing of voltage signal (being Vo1) through power frequency codan 7, filtering circuit 8, voltage follower circuit 9 and isolating amplifier circuit 10 of the dividing potential drop output terminal of brachium pontis 6, deliver to microprocessor 5, adopt the FIR digital filtering algorithm that sampled signal is made further FIR digital filtering by microprocessor 5 and process;
Wherein, after the processing of voltage signal Vo1 through power frequency codan 7, filtering circuit 8, voltage follower circuit 9 and isolating amplifier circuit 10 of the resistance R 3 of lower brachium pontis 6, the output of R4 dividing potential drop, obtain output signal Vad1, the pass of Vad1 and Vo1 is:
(1)
According to the resistance R 3 of resistance R 1, R2 and the lower brachium pontis 6 of upper brachium pontis 1, the relation of R4 dividing potential drop, can obtain following formula:
C: microprocessor 5 sends control signal, make the switch S 1 in the resistance switch circuit 2 be in closure state, make in upper brachium pontis 1 circuit of resistance R 5 accesses, after then descending the processing of voltage signal (being Vo2) through power frequency codan 7, filtering circuit 8, voltage follower circuit 9 and isolating amplifier circuit 10 of the dividing potential drop output terminal of brachium pontis 6, deliver to microprocessor 5, adopt the FIR digital filtering algorithm that sampled signal is made further FIR digital filtering by microprocessor 5 and process;
Wherein, after the processing of voltage signal Vo2 through power frequency codan 7, filtering circuit 8, voltage follower circuit 9 and isolating amplifier circuit 10 of the resistance R 3 of lower brachium pontis 6, the output of R4 dividing potential drop, obtain output signal Vad2, the pass of Vad2 and Vo2 is:
According to the resistance R 3 of resistance R 1, R2 and the lower brachium pontis 6 of upper brachium pontis 1, the relation of R4 dividing potential drop, can obtain following formula:
(4)
D: the positive pole that can obtain two groups of photovoltaic cells by step B and C over the ground with the negative pole voltage ratio equation over the ground of photovoltaic cell, wherein unknown parameter is R+ and R-, microprocessor 5 carries out the resistance value that R+ and R-are tried to achieve in computing, process is derived as follows:
Can get formula (1) substitution formula (2), formula (3) substitution formula (4) respectively:
Because V
PV, Vad1, Vad2 be the numerical value that microprocessor 5 can be sampled and be obtained, order
(8)
Then can obtain:
By formula (7), (8), (9), (10), the computing by microprocessor 5 can calculate R+ and R-online real-time and accurately;
E: whether the resistance value of judging R+ and R-satisfies the safety requirement, insulation against ground safety requirement according to photovoltaic combining inverter, the positive pole of photovoltaic cell insulation resistance and negative pole insulation resistance over the ground over the ground will satisfy standard greater than 1K Ω/V, therefore, the resistance of R+ and R-will satisfy formula (11) and (12):
F: according to result of determination, carry out next step action of photovoltaic combining inverter, if the resistance of the R+ that microprocessor 5 is calculated and R-satisfies the safety requirement, then microprocessor 5 allows Boost circuit and the inverter circuit 11 startup work of photovoltaic combining inverters; If the R+ that microprocessor 5 is calculated and the resistance of R-do not satisfy the safety requirement, then microprocessor 5 can drive warning circuit 4 and send alerting signal, and passes through Boost circuit and the inverter circuit 11 startup work of pwm signal port blocking photovoltaic combining inverter.
In sum, computation process of the present invention is succinct, accuracy of detection is high, has realized that the online of negative pole insulation against ground resistance of the anodal insulation against ground resistance of photovoltaic cell and photovoltaic cell detects in real time, has guaranteed that photovoltaic combining inverter works safely and reliably.
Should be noted that at last; above embodiment is only in order to illustrate technical scheme of the present invention; but not limiting the scope of the invention; although with reference to preferred embodiment the present invention has been done to explain; those of ordinary skill in the art is to be understood that; can make amendment or be equal to replacement technical scheme of the present invention, and not break away from essence and the scope of technical solution of the present invention.
Claims (10)
1. the insulation against ground resistance on-line detecting system of a photovoltaic combining inverter is characterized in that: it includes brachium pontis, lower brachium pontis, resistance switch circuit, power frequency codan, voltage follower circuit, isolating amplifier circuit, microprocessor, for detection of the PV voltage detecting circuit of photovoltaic cell output voltage;
One end of described upper brachium pontis is connected with the positive pole of photovoltaic cell, another termination the earth of described upper brachium pontis, the first end of described resistance switch circuit is connected with the positive pole of photovoltaic cell, the second termination the earth of described resistance switch circuit, the control end of described resistance switch circuit is connected with an I/O port of described microprocessor;
The first termination the earth of described lower brachium pontis, the second end of described lower brachium pontis is connected with the negative pole of photovoltaic cell, the dividing potential drop output terminal of described lower brachium pontis is connected with the input end of described power frequency codan, the output terminal of described power frequency codan is connected with the input end of described voltage follower circuit, the output terminal of described voltage follower circuit is connected with the input end of described isolating amplifier circuit, and the output terminal of described isolating amplifier circuit is connected with an A/D input port of described microprocessor;
The first test side of described PV voltage detecting circuit is connected with the positive pole of photovoltaic cell, the second test side of described PV voltage detecting circuit is connected with the negative pole of photovoltaic cell, and the output terminal of described PV voltage detecting circuit is connected with the 2nd A/D input port of described microprocessor; Wherein, described microprocessor is provided with the testing result output port.
2. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 1, it is characterized in that: the testing result output port of described microprocessor includes the 2nd I/O port, and described the 2nd I/O port is connected with warning circuit.
3. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 1 and 2, it is characterized in that: the testing result output port of described microprocessor also includes the pwm signal port, and described pwm signal port is connected with Boost circuit and the inverter circuit of photovoltaic combining inverter.
4. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 1 and 2 is characterized in that: the power supply of described voltage follower circuit and described isolating amplifier circuit all is that the power supply by the pwm chip of the accessory power supply module of photovoltaic combining inverter provides.
5. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 1 and 2, it is characterized in that: be connected with filtering circuit between the output terminal of described power frequency codan and the input end of described voltage follower circuit, the input end of described filtering circuit is connected with the output terminal of described power frequency codan, and the output terminal of described filtering circuit is connected with the input end of described voltage follower circuit.
6. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 1 and 2, it is characterized in that: described upper brachium pontis is made of one or more resistance, and described lower brachium pontis also is to be made of one or more resistance.
7. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 6 is characterized in that: described resistance switch circuit is made of resistance and switch series connection, and wherein, described switch is relay, switching tube or optocoupler.
8. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 6 is characterized in that: the isolating amplifier circuit that described isolating amplifier circuit employing is made of linear optical coupling or isolation operational amplifier.
9. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 6 is characterized in that: described PV voltage detecting circuit employing differential amplifier circuit or voltage sensor isolation sample circuit.
10. the insulation against ground resistance on-line detecting system of photovoltaic combining inverter according to claim 6, it is characterized in that: described microprocessor adopts the FIR digital filtering algorithm, described microprocessor is made further digital filtering by the FIR digital filtering algorithm to the A/D sampled signal and is processed, and this microprocessor is the DSP microprocessor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110171262 CN102279318B (en) | 2011-06-23 | 2011-06-23 | Online detection system of insulating resistance to ground of photovoltaic grid-connected inverter |
Applications Claiming Priority (1)
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| CN102621394B (en) * | 2012-03-30 | 2014-07-09 | 广东易事特电源股份有限公司 | System and method for detecting insulation resistance to ground of dual-branch input photovoltaic grid-connected inverter |
| CN102830334B (en) * | 2012-08-12 | 2015-05-20 | 江苏旭源科技有限公司 | Novel photovoltaic grid-connected inverter insulation detection circuit and detection method thereof |
| CN103884911A (en) * | 2012-12-20 | 2014-06-25 | 北汽福田汽车股份有限公司 | Electric automobile high-voltage insulation monitoring device |
| CN104422825B (en) * | 2013-08-29 | 2017-10-27 | 浙江万向太阳能有限公司 | A kind of direct-current power ground insulation impedance detection apparatus and method |
| CN105891605A (en) * | 2014-11-04 | 2016-08-24 | 国电龙源电气有限公司 | Distribution transformer grounding resistor, current online measurement equipment and method thereof |
| CN104569597A (en) * | 2014-12-18 | 2015-04-29 | 北京新能源汽车股份有限公司 | Insulation resistance detecting method and device for power battery |
| CN106997008B (en) * | 2017-05-31 | 2020-11-10 | 阳光电源股份有限公司 | Insulation detection device and inverter |
| DE102017113192B3 (en) * | 2017-06-14 | 2018-07-12 | Sma Solar Technology Ag | Fail-safe insulation resistance determination in a photovoltaic system |
| CN108845186A (en) * | 2018-04-28 | 2018-11-20 | 歌尔股份有限公司 | The detection circuit and detection method of ground resistance |
| CN109142874B (en) * | 2018-09-27 | 2021-03-02 | 蔚来(安徽)控股有限公司 | Insulation detection circuit, insulation detection method and charging control method |
| CN112240954A (en) * | 2019-07-17 | 2021-01-19 | 上海海拉电子有限公司 | Insulation detection circuit and method |
| EP3879277A1 (en) * | 2020-03-11 | 2021-09-15 | FRONIUS INTERNATIONAL GmbH | Method and photovoltaic conversion device for determining the insulation resistance of a photovoltaic device against ground |
| EP3879283A1 (en) | 2020-03-11 | 2021-09-15 | FRONIUS INTERNATIONAL GmbH | Method and photovoltaic inverter for determining the capacity of a photovoltaic system against ground |
| CN112327055B (en) * | 2020-11-09 | 2024-05-14 | 爱士惟新能源技术(扬中)有限公司 | Insulation impedance detection circuit and method for photovoltaic inverter |
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| CN1687799A (en) * | 2005-04-06 | 2005-10-26 | 南京师范大学 | Combined detector and combined detecting method for switch state of DC ground resistance |
| US8488350B2 (en) * | 2009-09-25 | 2013-07-16 | Astec International Limited | DC-AC inverters |
| CN102097823B (en) * | 2010-12-21 | 2013-04-24 | 山东电力集团公司烟台供电公司 | Two-stage three-phase photovoltaic grid-connected system without direct-current (DC) voltage sensor and control method of system |
| CN202110220U (en) * | 2011-06-23 | 2012-01-11 | 广东易事特电源股份有限公司 | Ground insulation resistance online detecting system for photovoltaic grid-connected inverter |
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