CN104808037A - Photovoltaic inverter leakage current detecting device and method - Google Patents
Photovoltaic inverter leakage current detecting device and method Download PDFInfo
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- CN104808037A CN104808037A CN201510153034.9A CN201510153034A CN104808037A CN 104808037 A CN104808037 A CN 104808037A CN 201510153034 A CN201510153034 A CN 201510153034A CN 104808037 A CN104808037 A CN 104808037A
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Abstract
The invention discloses a photovoltaic inverter leakage current detecting device and method. The detecting device comprises a leakage current sampling module and a micro-controller module. The leakage current sampling module comprises a magnet ring, an oscillating circuit, a self-checking circuit, a filtering link and the like and is mainly responsible for sampling leakage current and filtering out interference of oscillation frequency, a microcontroller mainly comprises a small-size, low-price and all-functional STM32F030F4 and surrounding pin circuits thereof, and the microcontroller is responsible for controlling, calculating and correcting of detection of leakage current and information exchange with an external master controller. A whole detecting process is performed in a sequence of power-on handshaking, self-checking, circle detection, abnormal warning and the like. By means of the photovoltaic inverter leakage current detecting device, correcting of proportionality coefficient can be achieved, the same style of leakage current detecting device is applicable to inverters with different capacities, and conveniences are provided for united production of inverter leakage current detecting devices.
Description
Technical field
The present invention relates to power technique fields, particularly a kind of leak current detector for photovoltaic inverter and method.
Background technology
Not containing the non-isolated inverter of transformer (high frequency, low frequency), because it has obvious advantage on efficiency, volume, weight, cost, receive the attention of domestic and international scientific research people and pursue.But due to without transformer device structure, photovoltaic system and electrical network have had direct electrical connection, easily cause the significantly increase of leakage current and common mode current, cause serious potential safety hazard, therefore must introduce leakage current test.
Technical specifications specifies, when leakage current mean value is 30mA, 60mA, 100mA, the trip time of regulation is respectively 0.3s, 0.15s and 0.04s.Leak current detection device is in the market all the leakage current test for single product device, and each leak current detection device can only be applicable to a certain single paragraph type, is unfavorable for the unitized production of inverter.And unified modulesization can use problem to solve various capacity specifications inverter, this patent is improved on the leak current detection device of routine, increases zero offset capability.For the inverter of different size, pick-up unit can carry out adjustment and correct, and realizes unitized production.
Summary of the invention
Fundamental purpose of the present invention is, for above-mentioned deficiency of the prior art, leak current detector for photovoltaic inverter and method are provided, the stability of leakage current test can be improved, and realize the unitized production being applicable to the leak current detection device of different capabilities inverter, there is very high cost performance, be very suitable for extensively promoting and using.
A kind of leak current detector for photovoltaic inverter, comprise leakage current sample circuit and microcontroller composition, leakage current sample circuit comprises magnet ring, oscillatory circuit, filtering circuit and self-checking circuit, and leakage current sample circuit is responsible for the sampling of leakage current and filtering noise information and oscillation frequency interference; Microcontroller to the correction of the sampled value of leakage current sample circuit, and carries out signal transmission with external piloting control device;
Oscillatory circuit is connected with magnet ring, vibration environment is provided to magnet ring, magnet ring is also connected with filtering circuit, the leakage current that magnet ring detects circuit after filtering, filtering interference signals, and then the ADC (Analog-to-Digital Converter, analog to digital converter) passing to microcontroller carries out analog to digital conversion sampling; Self-checking circuit is connected with magnet ring with microcontroller, and the self-test signal by microcontroller controls to trigger, and the work of self-checking circuit can make magnet ring induce the current value of a quota, and circuit feeds back to microcontroller more after filtering;
Described magnet ring is operated in oscillatory regime, for detecting the leakage current in photovoltaic DC-to-AC converter;
Described oscillatory circuit makes magnet ring starting of oscillation, avoids magnet ring nonoscillatory and enters state of saturation, thus loses the measuring ability to photovoltaic inverter leakage current;
Described filtering circuit is used for the current increment that filtering oscillatory circuit causes, and guarantees the accurate and stable of sampling;
Described self-checking circuit, under the control of microcontroller triggers, can make magnet ring induce the electric current of a 50mA, then feed back to microcontroller, judge whether pick-up unit can normally work thus.
Further, described microcontroller adopts the STM32F030F4 having 20 pins, and this model microcontroller is small, low price, multiple functional, has promotional value.
The detection method of above-mentioned leak current detector for photovoltaic inverter, specifically comprises:
The first step, after pick-up unit powers on, first carries out initialization, reads correction coefficient, and correction coefficient stores in the microcontroller, and correction coefficient adjusts because of the difference of inverter capacity, guarantees that current sensing means can be applicable to the inverter of different capabilities;
Second step, sets up handshake between microcontroller and external piloting control device, and this dohandshake action is always carried out with the frequency f of setting, shake hands unsuccessful, restart leak current detection device, return the first step, external piloting control device N continuous time does not receive handshake, and N is setting value, then report an error, leak current detection device damages, if shake hands successfully, then enters the 3rd step, if there is no self-test signal, then enter the 4th step;
3rd step, pick-up unit is after initialization powers on and realizes normal handshake communication, and microcontroller provides a trigger pip to self-checking circuit, and whether testing fixture is normal, self-test signal only initialization power on Shi Caihui trigger, pick-up unit can not trigger self-test signal when normal work, if N continuous time fail self-test, microcontroller externally master controller reports an error, leak current detection device damages, if self-inspection success, then carry out next step, carry out normal leakage current test;
4th step; leakage current sample circuit starts the leakage current detecting photovoltaic DC-to-AC converter normally; the electric current that leakage current sample circuit detects passes to microcontroller; carry out correcting and judging; once occur that leakage current exceeds standard; microcontroller then externally master controller send warning information, trigger protection action.
Compared to prior art, it is simple that the present invention has structure, and the advantage easily realized, has coefficient correction function simultaneously, can according to different working environments, and resize ratio coefficient, meets the different needs.
Accompanying drawing explanation
Fig. 1 is the block diagram of inverter leakage current pick-up unit of the present invention.
Fig. 2 is the hardware circuit block scheme of inverter leakage current pick-up unit of the present invention.
Fig. 3 is the microprocessor controls algorithm block diagram of inverter leakage current pick-up unit of the present invention.
Fig. 4 is the simulated experiment block scheme of inverter leakage current pick-up unit of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described, but enforcement of the present invention and protection are not limited thereto, and do not describe part in detail especially if having below, is all that those skilled in the art can refer to existing techniques in realizing.
Fig. 1 is the block diagram of inverter leakage current pick-up unit in the embodiment of the present invention.
With reference to shown in Fig. 1, a kind of inverter leakage current pick-up unit, comprises sample circuit and microcontroller.
Further, described inverter leakage current pick-up unit, sample circuit is responsible for the collection of leakage current, filtering noise information and oscillation frequency interference.
Further, described inverter leakage current pick-up unit, microcontroller is responsible for control and the correction of whole leak current detection device.
Further, described inverter leakage current pick-up unit, microcontroller is responsible for carrying out signal transmission with peripheral control unit.
Fig. 2 is inverter leakage current pick-up unit hardware circuit block scheme of the present invention.
With reference to shown in Fig. 2, described hardware circuit comprises oscillatory circuit, self-checking circuit, filtering circuit.
Further, described oscillatory circuit is by the connection of signal at comparer 1 and comparer 2 in-phase end and end of oppisite phase, two comparers are made to be in different conditions all the time, different conditions the is corresponding again different working modes of comparer 3, finally form a degenerative working method, make circuit can keep the oscillatory work continued.Oscillatory circuit makes magnet ring be in oscillatory regime, makes it keep unsaturated state, ensures that it can normally to leakage current test.
Further, described self-checking circuit is by microprocessor controls, and mainly utilize the 2.5V accurate reference pin of stabilivolt as control signal in process of self-test, self-inspection can normally work in order to ensure hardware circuit.
Further, described wave filter adopts the voltage controlled voltage source type low-pass filter circuit design of two rank, this filtering circuit cutoff frequency f
c=1.2kHz, and collection signal is 50Hz, can guarantee normal sample.
Fig. 3 is the microprocessor controls method block scheme of inverter leakage current pick-up unit of the present invention.
Main MCU (Micro Control Unit in figure, microcontroller) represent external piloting control device, GFCI (Ground Fault Circuit, leakage current test), GFCI_MCU (Ground Fault CircuitInterrupter Micro Control Unit, leak current detection device microcontroller) represents the microcontroller that leak current detection device comprises.
With reference to shown in Fig. 3, microcontroller is responsible for control and the correction of whole leak current detection device.
The first step, after device powers on, first carries out initialization, reads correction coefficient, and correction coefficient stores in the microcontroller, and correction coefficient adjusts because of the difference of inverter capacity, guarantees that current sensing means can be applicable to the inverter of different capabilities;
Second step, set up handshake between microcontroller and external piloting control device, this dohandshake action is always carried out with certain frequency f, shakes hands unsuccessful, restarts leak current detection device, return the first step, external piloting control device does not receive handshake continuous 5 times, then report an error, and leak current detection device damages, if shake hands successfully, then enter the 3rd step, if there is no self-test signal, then enter the 4th step;
3rd step, device is after initialization powers on and realizes normal handshake communication, and microcontroller provides a trigger pip to self-checking circuit, and whether testing fixture is normal, self-test signal only initialization power on Shi Caihui trigger, device can not trigger self-test signal when normal work, if continuous 5 fail self-tests, microcontroller externally master controller reports an error, leak current detection device damages, if self-inspection success, then carry out next step, carry out normal leakage current test;
4th step; leakage current sample circuit starts the leakage current detecting photovoltaic DC-to-AC converter normally; the electric current that leakage current sample circuit detects passes to microcontroller; carry out correcting and judging; once occur that leakage current exceeds standard; microcontroller then externally master controller send warning information, trigger protection action.
Fig. 4 is the simulated experiment block scheme of inverter leakage current pick-up unit of the present invention.
With reference to shown in Fig. 4, application platform is hooked rifle (401,402), photovoltaic DC-to-AC converter 403, inverter leakage current pick-up unit, electrical network and monitoring software formed by direct supply 401, isolating switch (S1, S2), electric current.Close circuit breaker S1 can record positive pole leakage current over the ground, and close circuit breaker S2 can record negative pole leakage current over the ground.
Further, the working condition of system during test leakage current gradual change, test result is as shown in table 1.
Table 1 leakage current gradual change experimental data
Further, the working condition of system during the sudden change of test leakage current, test result is as shown in table 2.
Table 2 leakage current mutating experiment data
In sum, no matter be the leakage current of gradual change or the leakage current of sudden change, this inverter leakage current pick-up unit can be accomplished to sample accurately and make protection act accurately simultaneously, complex technique requirement actuation time.
The foregoing is only the preferred embodiments of the present invention; not thereby its scope of the claims is limited; every equivalent structure transformation utilizing instructions of the present invention and accompanying drawing content to do, is directly or indirectly used in the technical field that other are relevant, is all in like manner included in scope of patent protection of the present invention.
Claims (3)
1. a leak current detector for photovoltaic inverter, it is characterized in that comprising leakage current sample circuit and microcontroller composition, leakage current sample circuit comprises magnet ring, oscillatory circuit, filtering circuit and self-checking circuit, and leakage current sample circuit is responsible for the sampling of leakage current and filtering noise information and oscillation frequency interference; Microcontroller to the correction of the sampled value of leakage current sample circuit, and carries out signal transmission with external piloting control device;
Oscillatory circuit is connected with magnet ring, and provide vibration environment to magnet ring, magnet ring is also connected with filtering circuit, the leakage current that magnet ring detects circuit after filtering, filtering interference signals, and then passes to microcontroller and carry out the sampling of ADC modulus; Self-checking circuit is connected with magnet ring with microcontroller, and the self-test signal by microcontroller controls to trigger, and the work of self-checking circuit can make magnet ring induce the current value of a quota, and circuit feeds back to microcontroller more after filtering;
Described magnet ring is operated in oscillatory regime, for detecting the leakage current in photovoltaic DC-to-AC converter;
Described oscillatory circuit makes magnet ring starting of oscillation, avoids magnet ring nonoscillatory and enters state of saturation, thus loses the measuring ability to photovoltaic inverter leakage current;
Described filtering circuit is used for the current increment that filtering oscillatory circuit causes;
Described self-checking circuit, under the control of microcontroller triggers, can make magnet ring induce an electric current, then feed back to microcontroller, judge whether pick-up unit can normally work thus.
2. a kind of leak current detector for photovoltaic inverter according to claim 1, is characterized in that described microcontroller adopts the STM32F030F4 having 20 pins.
3. utilize the detection method of the leak current detector for photovoltaic inverter described in claim 1, it is characterized in that comprising the steps:
The first step, after pick-up unit powers on, first carries out initialization, reads correction coefficient, and correction coefficient stores in the microcontroller, and correction coefficient adjusts because of the difference of inverter capacity, guarantees that current sensing means can be applicable to the inverter of different capabilities;
Second step, sets up handshake between microcontroller and external piloting control device, and this dohandshake action is always carried out with the frequency f of setting, shake hands unsuccessful, restart leak current detection device, return the first step, external piloting control device N continuous time does not receive handshake, and N is setting value, then report an error, leak current detection device damages, if shake hands successfully, then enters the 3rd step, if there is no self-test signal, then enter the 4th step;
3rd step, pick-up unit is after initialization powers on and realizes normal handshake communication, and microcontroller provides a trigger pip to self-checking circuit, and whether testing fixture is normal, self-test signal only initialization power on Shi Caihui trigger, pick-up unit can not trigger self-test signal when normal work, if N continuous time fail self-test, microcontroller externally master controller reports an error, leak current detection device damages, if self-inspection success, then carry out next step, carry out normal leakage current test;
4th step; leakage current sample circuit starts the leakage current detecting photovoltaic DC-to-AC converter normally; the electric current that leakage current sample circuit detects passes to microcontroller; carry out correcting and judging; once occur that leakage current exceeds standard; microcontroller then externally master controller send warning information, trigger protection action.
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| CN104977494A (en) * | 2014-04-01 | 2015-10-14 | 青岛海信日立空调系统有限公司 | Method for detecting electric leakage of electric appliance, and electric appliance |
| CN105445590A (en) * | 2015-12-16 | 2016-03-30 | 中能易电新能源技术有限公司 | Photovoltaic inverter leakage current protection motion automatic testing device |
| CN106443124A (en) * | 2016-08-31 | 2017-02-22 | 阳光电源股份有限公司 | Current detection apparatus and method |
| CN110632366A (en) * | 2019-09-29 | 2019-12-31 | 浙江巨磁智能技术有限公司 | Leakage current sensor for low-power three-phase inverter |
| CN112285602A (en) * | 2020-10-20 | 2021-01-29 | 海光信息技术股份有限公司 | Leakage current detection circuit, leakage current processing circuit and processor system |
| CN113253152A (en) * | 2021-05-20 | 2021-08-13 | 青岛中科英泰商用系统股份有限公司 | Method and device for testing abnormal power failure of product |
| CN113759288A (en) * | 2021-11-08 | 2021-12-07 | 深圳市德兰明海科技有限公司 | Leakage current detection circuit and method and leakage current detector |
| CN116008863A (en) * | 2023-03-27 | 2023-04-25 | 云南华晟电力器材有限公司 | Electric iron tower electric leakage detection device with safeguard function |
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| CN113253152A (en) * | 2021-05-20 | 2021-08-13 | 青岛中科英泰商用系统股份有限公司 | Method and device for testing abnormal power failure of product |
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| CN113759288B (en) * | 2021-11-08 | 2022-03-11 | 深圳市德兰明海科技有限公司 | Leakage current detection circuit and method and leakage current detector |
| CN116008863A (en) * | 2023-03-27 | 2023-04-25 | 云南华晟电力器材有限公司 | Electric iron tower electric leakage detection device with safeguard function |
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