CN104009496A - Dual-threshold judgment switching circuit for micro grid backflow protection device - Google Patents
Dual-threshold judgment switching circuit for micro grid backflow protection device Download PDFInfo
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- CN104009496A CN104009496A CN201410261116.0A CN201410261116A CN104009496A CN 104009496 A CN104009496 A CN 104009496A CN 201410261116 A CN201410261116 A CN 201410261116A CN 104009496 A CN104009496 A CN 104009496A
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- comparison module
- voltage comparison
- switching circuit
- current sensor
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- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
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Abstract
The invention discloses a dual-threshold judgment switching circuit for a micro grid backflow protection device. The dual-threshold judgment switching circuit comprises a first voltage comparison module, a second voltage comparison module, a third voltage comparison module, a current sensor, an energy storage device and a direct current bus. The first voltage comparison module works in a two-way selection switching mode, and the second voltage comparison module and the third voltage comparison module work in a one-way comparison switching mode. The second voltage comparison module and the third voltage comparison module are connected in parallel and then connected with the first voltage comparison module in series, so that a switching circuit body is formed. The energy storage device, the current sensor and the switching circuit body are sequentially connected in series and then connected with the direct current bus, and a voltage signal output by the current sensor is transmitted to the first voltage comparison module. According to the dual-threshold judgment switching circuit, when a micro grid generates reverse power, the energy storage device is connected to the switching circuit to consume the reverse power, and the energy storage device is switched off after the reverse power is eliminated, so that renewable energy power generation is utilized to the maximum degree and meanwhile repeated switching-on and switching-off of the energy storage device is avoided.
Description
Technical field
The present invention relates to electrical engineering field, relate in particular to a kind of dual threshold for micro-electrical network anti-backflow device and judge switching circuit.
Background technology
Current, energy-saving and emission-reduction, green distributed energy become the focus that the whole world is paid close attention to.But, the features such as photovoltaic distributed power supply has intermittence, randomness, response speed is slow, inertia is little, grid-connected rear easily cause voltage fluctuation and flickering, especially in the time that large-capacity distributing power supply is incorporated to low and medium voltage distribution network, realize the power-balance of power distribution network, and ensure comparatively difficulty of power supply reliability and the quality of power supply.In order to reduce impact and the negative effect of large-scale distributed power grid to outside public electric wire net, carry out integrating distributed generation system by micro-electric power network technique, can solve well the technical barrier of the grid-connected existence of current distributed power generation.
Micro-electrical network according to and site power delivery direction be divided into " grid-connected do not surf the Net " and " grid-connected and surf the Net " two kinds of modes.Under " grid-connected do not surf the Net " mode, micro-electrical network site power can only be carried to micro-electrical network user load by public electric wire net; Under " grid-connected and online " mode, and site power can two-way flow, and the rich power of micro-electrical network can flow to public electric wire net.But for adopting " grid-connected and online " micro-electrical network that mode is moved, its power supply characteristic showing with respect to outside public electric wire net still can cause certain influence to the stable operation of electrical network, specifically mainly contains three aspects:
The first, the harmonic wave that in micro-electrical network, a large amount of power electronic equipments produces impacts the quality of power supply of public electric wire net.
The second, in the time that public electric wire net breaks down, the inverse probability that micro-electrical network produces can cause damage to machinery equipment, the personal safety that even jeopardizes maintainer when serious.
The 3rd, due to the power supply characteristic of micro-electrical network, change the feature of public electric wire net single supply, radial pattern, unidirectional trend, thereby made the existing current protection measure no longer applicable.
For the micro-electrical network that adopts " grid-connected do not surf the Net " mode to move; application number is that 201210173096.2 Chinese patent discloses a kind of grid-connected micro-grid system and control method thereof of not surfing the Net; preventing by micro-electrical network central controller and the reverse power protection device that is arranged on points of common connection place that inverse probability is counter send; ensure that whole micro-grid system is not only to public electric wire net power taking and to public electric wire net power transmission, thereby avoided micro-electrical network to impact public electric wire net.But there are following 2 deficiencies in this technology:
The first, the means that this technology is even excised distributed power source by the output of restriction distributed power source are eliminated inverse probability, do not make full use of the energy-storage system in micro-electrical network, have caused the waste of regenerative resource.
Second; the switch motion of this technology is judged to be traditional single threshold and judges; due to the fluctuation of photo-voltaic power supply, may cause in some cases the switch repeatedly of reverse power protection device, thereby shorten the useful life of installing the stability that has affected micro-operation of power networks.
For above policy and the state of the art, be necessary to propose a kind of switching circuit of judging based on dual threshold, be applied to the reverse power protection device of micro-electrical network, this becomes the applicant and is devoted to the direction of studying, thereby make photovoltaic power be greater than bearing power 105% time, energy storage device is accessed DC bus by switch closure, and inverse probability is carried to energy-storage system; And when photovoltaic power be less than bearing power 95% time, switch disconnect; Photovoltaic power is between 95% to 105% bearing power time, and the original state of holding circuit is failure to actuate.
Summary of the invention
The object of the present invention is to provide a kind of dual threshold for micro-electrical network anti-backflow device to judge switching circuit, do not excising under the prerequisite of distributed power source, the circuit that connects energy storage device is carried out to the control of dual threshold switch: in the time that micro-electrical network produces inverse probability, access energy storage device and consume inverse probability, thereby when inverse probability is eliminated, excise energy storage device in maximum using renewable energy power generation, avoided the switch repeatedly of energy storage device.
The technical scheme that realizes above-mentioned purpose is:
Dual threshold for micro-electrical network anti-backflow device is judged a switching circuit, comprising: the first voltage comparison module, second voltage comparison module, tertiary voltage comparison module, current sensor, energy storage device and DC bus, wherein:
Described the first voltage comparison module is operated in two-way selector switch pattern, and described second voltage comparison module and tertiary voltage comparison module are operated in relatively switching mode of single channel; After described second voltage comparison module and the parallel connection of tertiary voltage comparison module, connect with described the first voltage comparison module, form switching circuit;
Described energy storage device, current sensor and switching circuit access described DC bus after connecting successively, the voltage signal of described current sensor output is transferred to described the first voltage comparison module.
The above-mentioned dual threshold for micro-electrical network anti-backflow device is judged switching circuit, and the input variable of described the first voltage comparison module is: the output variable of described current sensor and 0 volt of voltage;
The input variable of described second voltage comparison module is: the output variable of photo-voltaic power supply current sensor and load current sensor output × 105%;
The input variable of described tertiary voltage comparison module is: the output variable of photo-voltaic power supply current sensor and load current sensor output × 95%.
The above-mentioned dual threshold for micro-electrical network anti-backflow device is judged switching circuit, and described the first voltage comparison module, second voltage comparison module and tertiary voltage comparison module comprise the two-way voltage comparable chip and the relay that are connected.
The above-mentioned dual threshold for micro-electrical network anti-backflow device is judged switching circuit, and described energy storage device comprises lead accumulator, lithium battery and super capacitor.
The above-mentioned dual threshold for micro-electrical network anti-backflow device is judged switching circuit, and described DC bus is connected with external communication electrical network by charging device.
The invention has the beneficial effects as follows: 1) the present invention has adopted two judgment thresholds in the control logic of switch: countercurrent prevention system starts threshold value and countercurrent prevention system is closed threshold value, two threshold values of operated by rotary motion are positive and negative 5 percent of current microgrid bearing power, thereby under the prerequisite that ensures the normal work of microgrid load, avoid micro-electrical network grid-connecting apparatus in critical point frequent movement and energy-storage system repeated charge, extended the micro-grid system life-span.2) the present invention adopted data integrated relatively and the voltage comparison module of relay switch as the critical piece of switching circuit, price, lower than conventional DSP, ARM development board, can be controlled the cost of product to a certain extent.3) the present invention, fully in conjunction with the feature of micro-electrical network, eliminates inverse probability by the controlled access energy-storage system of switching circuit, has effectively improved the utilance of renewable power supply and the validity of power supply in micro-electrical network.
Brief description of the drawings
Fig. 1 is the mode of operation schematic diagram of voltage comparison module in the present invention;
Fig. 2 is the structure chart that dual threshold of the present invention is judged switching circuit.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described.
Refer to Fig. 2, dual threshold of the present invention is judged switching circuit, comprises first, second, third voltage comparison module A, B, C, current sensor 11, and energy storage device 12 and DC bus 13, wherein:
Three voltage comparison module A, B, C are by two-way voltage comparable chip LM393n and the integrated control module of relay moduleization, and the size by relatively input voltage and reference voltage is cut-off with high/low level control relay, is ripe prior art.Voltage comparator module has two kinds of mode of operations: single channel is switching mode and two-way selector switch pattern relatively, as shown in Figure 1.
The first voltage comparison module A is operated in two-way selector switch pattern (that is: two-way selector switch), and second, third voltage comparison module B, C are operated in relatively switching mode (that is: relatively switch of single channel) of single channel.After second, third voltage comparison module B, C parallel connection, connect with the first voltage comparison module A (that is: after the switch in parallel of second, third voltage comparison module B, C, connecting with the switch of the first voltage comparison module A) form switching circuit, as shown in Figure 2.
Energy storage device 12, current sensor 11 and switching circuit access DC bus 13 after connecting successively, and DC bus 13 is connected with external communication electrical network by charging device; The voltage signal that current sensor 11 is exported is transferred to the first voltage comparison module A.
Energy storage device 12 comprises lead accumulator, lithium battery, super capacitor etc.
The function of judging in order to complete dual threshold, need to be used the connection in series-parallel of three voltage comparator modules to be used in combination, as shown in Figure 2: the first voltage comparison module A adopts two-way selector pattern, is chosen between control circuit 1 and 2 and switches according to input voltage size; Second, third voltage comparison module B, C adopt relatively switching mode of single channel; Use this control loop to carry out switch control to the energy storage device in micro-electrical network or micro-power supply.Following table has been listed input variable and the action logic of three voltage comparator modules:
In conjunction with input variable and the action logic of three voltage comparator modules described in upper table, below by the correctness of structure shown in example key diagram 2.
It is P that micro-electric network source generate output is set
s, micro-electrical network user load capacity is P
l, it is P that countercurrent prevention system starts threshold value
a, it is P that countercurrent prevention system is closed threshold value
b, operated by rotary motion P
a=P
b=0.05 × P
l.By P
sand P
lbe separately converted to voltage signal input voltage comparison module by current sensor, as input variable and comparison signal;
Initial condition circuit 2 closures, now photovoltaic output gross power P
srise to and exceed inverse probability upper bound threshold value, i.e. P
l× 105%, switch B, C are all closed, and the current sensor output that control loop conducting is connected is on the line greater than zero, and circuit 2 is still closed, and now micro-electrical network power more than needed is carried to energy storage device;
Work as P
sdrop to P
l× 95%～P
lbetween × 105% time, switch B disconnects and C is still closed, so the state that disconnects switch B due to circuit 1 does not affect control loop;
Work as P
scontinue to drop to P
lbelow × 95% time, during lower than inverse probability lower bound threshold value, switch C disconnects and causes control loop open circuit, and current sensor is output as zero and causes circuit 1 closed circuit 2 to disconnect, now switch B still remains open, and has excised energy storage device so control loop is still opened a way;
Work as P
srise to P
l× 95%%P
lbetween × 105% time, switch B is cut-off switch C closure still, so but the state that disconnects switch C due to circuit 2 does not affect control loop;
Work as P
scontinue to rise to P
l× 105% when above, and, higher than when the threshold value of the inverse probability upper bound, switch B Closing Switch C still remains closed, and causes circuit 2 closed circuits 1 to disconnect because current sensor output is greater than zero, and control loop conducting power more than needed is carried to energy storage device.
Visible by above-mentioned analysis, the combinational circuit structure of the voltage comparison module shown in Fig. 2 can realize the function that dual threshold is judged, when photovoltaic power be greater than bearing power 105% time, energy storage device is accessed DC bus by switch closure, inverse probability is carried to energy-storage system; And when photovoltaic power be less than bearing power 95% time, switch disconnect; Photovoltaic power is between 95% to 105% bearing power time, and the original state of holding circuit is failure to actuate.
Above embodiment is used for illustrative purposes only, but not limitation of the present invention, person skilled in the relevant technique, without departing from the spirit and scope of the present invention, can also make various conversion or modification, therefore all technical schemes that are equal to also should belong to category of the present invention, should be limited by each claim.
Claims (5)
1. judge a switching circuit for the dual threshold of micro-electrical network anti-backflow device, it is characterized in that, comprising: the first voltage comparison module, second voltage comparison module, tertiary voltage comparison module, current sensor, energy storage device and DC bus, wherein:
Described the first voltage comparison module is operated in two-way selector switch pattern, and described second voltage comparison module and tertiary voltage comparison module are operated in relatively switching mode of single channel; After described second voltage comparison module and the parallel connection of tertiary voltage comparison module, connect with described the first voltage comparison module, form switching circuit;
Described energy storage device, current sensor and switching circuit access described DC bus after connecting successively, the voltage signal of described current sensor output is transferred to described the first voltage comparison module.
2. the dual threshold for micro-electrical network anti-backflow device according to claim 1 is judged switching circuit, it is characterized in that,
The input variable of described the first voltage comparison module is: the output variable of described current sensor and 0 volt of voltage;
The input variable of described second voltage comparison module is: the output variable of photo-voltaic power supply current sensor and load current sensor output × 105%;
The input variable of described tertiary voltage comparison module is: the output variable of photo-voltaic power supply current sensor and load current sensor output × 95%.
3. the dual threshold for micro-electrical network anti-backflow device according to claim 1 and 2 is judged switching circuit, it is characterized in that, described the first voltage comparison module, second voltage comparison module and tertiary voltage comparison module comprise the two-way voltage comparable chip and the relay that are connected.
4. the dual threshold for micro-electrical network anti-backflow device according to claim 1 is judged switching circuit, it is characterized in that, described energy storage device comprises lead accumulator, lithium battery and super capacitor.
5. the dual threshold for micro-electrical network anti-backflow device according to claim 1 is judged switching circuit, it is characterized in that, described DC bus is connected with external communication electrical network by charging device.
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| CN201410261116.0A CN104009496B (en) | 2014-06-12 | 2014-06-12 | A kind of dual threshold for micro-capacitance sensor anti-backflow device judges switching circuit |
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|---|---|---|---|
| CN201410261116.0A CN104009496B (en) | 2014-06-12 | 2014-06-12 | A kind of dual threshold for micro-capacitance sensor anti-backflow device judges switching circuit |
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| CN104009496A true CN104009496A (en) | 2014-08-27 |
| CN104009496B CN104009496B (en) | 2016-01-06 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117977588A (en) * | 2024-04-02 | 2024-05-03 | 杭州微慕科技有限公司 | Energy distribution method, control device and energy distribution equipment of micro-grid |
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| US5642030A (en) * | 1995-06-30 | 1997-06-24 | Seelye Equipment Specialists | Charge control circuit |
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| CN101841163A (en) * | 2010-03-15 | 2010-09-22 | 三一电气有限责任公司 | Grid-connected wind-light combined power generation system and power generation method thereof |
| CN103683466A (en) * | 2012-09-17 | 2014-03-26 | 周锡卫 | Emergent direct supply off-grid photovoltaic power supply system based on existing photovoltaic controller |
| CN203883494U (en) * | 2014-06-12 | 2014-10-15 | 国网上海市电力公司 | Double-threshold determination switch circuit for micro-grid anti-reflux device |
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2014
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Patent Citations (6)
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|---|---|---|---|---|
| US4401935A (en) * | 1982-03-04 | 1983-08-30 | Atlantic Richfield Company | Charge control apparatus and method |
| US5642030A (en) * | 1995-06-30 | 1997-06-24 | Seelye Equipment Specialists | Charge control circuit |
| JP2002058174A (en) * | 2000-08-08 | 2002-02-22 | Nippon Telegr & Teleph Corp <Ntt> | Independent solar generation system and its control method |
| CN101841163A (en) * | 2010-03-15 | 2010-09-22 | 三一电气有限责任公司 | Grid-connected wind-light combined power generation system and power generation method thereof |
| CN103683466A (en) * | 2012-09-17 | 2014-03-26 | 周锡卫 | Emergent direct supply off-grid photovoltaic power supply system based on existing photovoltaic controller |
| CN203883494U (en) * | 2014-06-12 | 2014-10-15 | 国网上海市电力公司 | Double-threshold determination switch circuit for micro-grid anti-reflux device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117977588A (en) * | 2024-04-02 | 2024-05-03 | 杭州微慕科技有限公司 | Energy distribution method, control device and energy distribution equipment of micro-grid |
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