CN103326400A - Countercurrent-preventing protection and control method for microgrid - Google Patents
Countercurrent-preventing protection and control method for microgrid Download PDFInfo
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- CN103326400A CN103326400A CN2013102526159A CN201310252615A CN103326400A CN 103326400 A CN103326400 A CN 103326400A CN 2013102526159 A CN2013102526159 A CN 2013102526159A CN 201310252615 A CN201310252615 A CN 201310252615A CN 103326400 A CN103326400 A CN 103326400A
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Abstract
The invention relates to a countercurrent-preventing protection and control method for a microgrid. The method comprises the following steps that (1) when Ps-P1>Pa, the method turns to a step (2); when P1-Ps>Pb, the method turns to a step (3); when -Pb<=Ps-P1<=Pa, the current state of the microgrid is kept unchanged; (2) the current capacity of an energy storage system is detected, and if the current capacity of the energy storage system does not reach the upper energy limit of the energy storage system, the method turns to a step (4); if the current capacity of the energy storage system reaches the upper energy limit of the energy storage system, the method turns to a step (5); (3) the microgrid is switched to be in a grid-connection mode, and the load gap of the microgrid is supplemented through a public supply network and the energy storage system; (4) the microgrid is switched to be in an island mode, and the energy storage system absorbs redundant distributed power generation capacity in a charging mode; (5) the microgrid is switched to be in the island mode, a controllable switch on a line connected between an additional load and an alternating current bus is powered off, and redundant power sent by the microgrid is absorbed through the additional load.
Description
Technical field
The present invention relates to a kind of counterflow-preventing protection control method for little electrical network, belong to the distributed power generation field.
Background technology
Current, energy-saving and emission-reduction and green energy resource become the focus that the whole world is paid close attention to, and also are one of construction objects of China's intelligent grid simultaneously.As intelligent grid, require its access that can adapt to large power supply, also to support regenerative resource with the friendly access of the mode of distributed power generation, satisfy the requirement of electric power and natural environment, social economy's harmonious development.
But, the characteristics such as photovoltaic distributed power supply has intermittence, randomness, response speed is slow, inertia is little, be incorporated into the power networks rear easily cause voltage fluctuation and flickering, especially when the large-capacity distributing power supply is incorporated low and medium voltage distribution network into, realize the power-balance of power distribution network, and guarantee comparatively difficulty of power supply reliability and the quality of power supply.In order to reduce large-scale distributed power grid to impact and the negative effect of outside public electric wire net, come the integrating distributed generation system by little electric power network technique, can solve well the technical barrier that present distributed power generation is incorporated into the power networks and exists.
Little electrical network according to and site power delivery direction be divided into " be incorporated into the power networks and do not surf the Net " and " be incorporated into the power networks and surf the Net " dual mode.Under " be incorporated into the power networks and do not surf the Net " mode, little electrical network and site power can only be carried to little electrical network user load by public electric wire net; " be incorporated into the power networks and surf the Net " under the mode, and site power can two-way flow, the rich power of little electrical network can flow to public electric wire net.Yet for little electrical network that " be incorporated into the power networks and the surf the Net " mode of employing is moved, it still can cause certain influence to the stable operation of electrical network with respect to the power supply characteristic that outside public electric wire net shows, and specifically mainly contains three aspects:
The first, the harmonic wave that a large amount of power electronic equipments produces in little electrical network impacts the quality of power supply of public electric wire net.
The second, when public electric wire net broke down, the inverse probability that little electrical network produces can cause damage to machinery equipment, when serious even the personal safety that jeopardizes the maintainer.
The 3rd, because the power supply characteristic of little electrical network, changed the characteristics of public electric wire net single supply, radial pattern, unidirectional trend, thereby so that existing current protection measure is no longer applicable.
For the little electrical network that adopts " be incorporated into the power networks and do not surf the Net " mode to move; application number is that 201210173096.2 Chinese patent discloses a kind of micro-grid system and control method thereof of not surfing the Net that be incorporated into the power networks; preventing by little electrical network central controller and the reverse power protection device that is installed in the points of common connection place that inverse probability is counter send; guarantee that whole micro-grid system does not only send electricity to public electric wire net to the public electric wire net power taking, thereby avoided little electrical network that public electric wire net is impacted.But this technology mainly is to eliminate inverse probability by the means of the output of restriction distributed power source even excision distributed power source, this had not both met the policy of the remaining electricity online of national requirements, also be unfavorable for the normal operation of distributed power source, simultaneously do not take full advantage of new forms of energy yet, caused the waste of regenerative resource.
For above policy and the state of the art; be necessary to propose a kind of counterflow-preventing protection control method for little electrical network; under the prerequisite of not excising distributed power source; by reasonably microgrid energy being managed; realize the counterflow-preventing control of micro-grid system; thereby avoid public electric wire net is impacted, simultaneously the maximum using renewable energy power generation.
Summary of the invention
Technical problem to be solved by this invention is to overcome deficiency of the prior art and a kind of counterflow-preventing protection control method that is used for little electrical network reasonable in design is provided; under the prerequisite of not excising distributed power source; by reasonably microgrid energy being managed; realize the counterflow-preventing control of micro-grid system; thereby avoid public electric wire net is impacted, simultaneously the maximum using renewable energy power generation.
The technical scheme that the present invention solves the problems of the technologies described above employing is: a kind of counterflow-preventing protection control method for little electrical network, and described little electrical network comprises distributed power source, energy-storage system, user load; Described distributed power source and energy-storage system pass through energy converter incoming transport bus separately; User load is with the mode incoming transport bus of grouping; Ac bus accesses public electric wire net by points of common connection; Also be provided with counterflow-preventing control in little electrical network; It is characterized in that: described little electrical network also disposes extra load, this extra load is connected with ac bus by gate-controlled switch, and this extra load is connected with public electric wire net, and the power of described extra load is greater than the rich power of little electrical network;
It is Ps that the distributed power source generate output is set, and little electrical network user load capacity is Pl, and it is Pa that counterflow-preventing control starts threshold value, and it is Pb that threshold value is closed in counterflow-preventing control;
This counterflow-preventing protection control method is further comprising the steps of:
(1) when Ps-Pl＞Pa, turns step (2);
When Pl-Ps＞Pb, turn step (3);
When-Pb≤Ps-Pl≤Pa, little electrical network keeps standing state constant;
(2) detect the current capacity of energy-storage system;
The current capacity of energy-storage system does not reach its upper energy limit, turns step (4);
The current capacity of energy-storage system has reached its upper energy limit, turns step (5);
(3) little electrical network switches to the pattern of being incorporated into the power networks, and replenishes little network load breach by public electric wire net and energy-storage system;
(4) little electrical network switches to island mode, and the energy-storage system charging absorbs unnecessary distributed power source generate output;
(5) little electrical network switches to island mode, and the gate-controlled switch on closed extra load and the circuit that ac bus is connected is by the extra load rich power that little electrical network sends of dissolving.
When distributed power source power output in little electrical network had reached upper energy limit greater than user load and energy-storage system, the rich power of little electrical network was consumed by this extra load, thereby does not need to excise distributed power source.
Be provided with the inverse probability checkout gear on extra load of the present invention and the circuit that public electric wire net is connected; In step (5), little electrical network switches to island mode, the gate-controlled switch that closed extra load is connected with ac bus, by the extra load rich power that little electrical network sends of dissolving, at this moment, when the inverse probability checkout gear detects inverse probability at this connection line place, when namely public electric wire net breaks down, disconnect the gate-controlled switch on extra load and the circuit that ac bus is connected, and little electrical network is switched to island mode.
The present invention arranges Pa=Pb=0.05 * Pl.
Also be provided with the unidirectional electric energy metering device on extra load of the present invention and the circuit that ac bus is connected.The effect of unidirectional electric energy metering device is the remaining electric electricity volume of measuring little electrical network, thereby can provide electricity charge subsidy for little electrical network user according to policy and the standard that country formulates.
Extra load of the present invention comprises electric automobile charging station or public place lighting apparatus.When planning little electrical network, can select the so round-the-clock load of electric automobile charging station, public place lighting apparatus as the extra load of little electrical network, so that can be at any time and the rich power of little electrical network of all dissolving.
Distributed power source of the present invention comprises wind generator system, photovoltaic generating system, biomass power generation system.
The present invention compared with prior art has following advantage and effect:
(1) for little electrical network problem that is incorporated into the power networks, by little electrical network being carried out counterflow-preventing protection control, eliminated the power supply characteristic of little electrical network, thereby so that little electrical network the impact of the public electric wire net quality of power supply, relaying protection, electricity consumption reliability, fail safe is reduced greatly.
(2) for the policy requirements of electricity online more than the national requirements distributed generation system, existing counterflow-preventing control technology is made improvement, by little electrical network is configured extra load so that the rich electric weight of little electrical network can be sold to electrical network under the prerequisite that power distribution network is not produced adverse current, do not need to excise distributed power source, further improved the renewable energy utilization rate.
(3) the present invention has adopted two judgment thresholds in control logic: counterflow-preventing control starts threshold value Pa and threshold value Pb is closed in counterflow-preventing control, it is 5 percent of current little electrical network user load capacity that two threshold values are set, thereby under the prerequisite that guarantees little electrical network load normal operation, avoided little electrical network grid-connecting apparatus in critical point frequent movement and energy-storage system repeated charge, prolonged the micro-grid system life-span.
Description of drawings
Fig. 1 is the major loop schematic diagram of the embodiment of the invention.
Fig. 2 is the control flow chart of counterflow-preventing protection control method of the present invention.
Embodiment
The invention will be further described below in conjunction with accompanying drawing and by embodiment.
Referring to Fig. 1 and Fig. 2, little electrical network of the embodiment of the invention comprises distributed power source, energy-storage system BAT, user load LOAD1～LOADn.Distributed power source comprises wind generator system PW, photovoltaic generating system PV, the PB of biomass power generation system etc.Energy-storage system BAT comprises lead accumulator, lithium battery, super capacitor etc.
Distributed power source and energy-storage system BAT access the ac bus of 400V by energy converter separately.User load LOAD1～LOADn accesses the ac bus of 400V in the mode of grouping.Ac bus is by points of common connection PCC access public electric wire net.
Extra load LOAD is connected with ac bus by gate-controlled switch K, closed gate-controlled switch K, and extra load LOAD and ac bus are connected, and disconnect gate-controlled switch K, and extra load LOAD and ac bus disconnect.Be provided with unidirectional electric energy metering device W on extra load LOAD and the circuit that ac bus is connected.
Extra load LOAD also is connected with public electric wire net, and the circuit that is connected with public electric wire net at extra load LOAD is provided with inverse probability checkout gear N.Jointly extra load LOAD is powered by little electrical network and public electric wire net.
The power of extra load LOAD is greater than the rich power of little electrical network, and the rich power that sends of little electrical network of dissolving at any time.
The points of common connection PCC place of little electrical network and public electric wire net is provided with static switch, and the Main Function of static switch is when little electrical network produces inverse probability and inverse probability disappearance, and the operational mode (being incorporated into the power networks/isolated island) of little electrical network is switched.In addition, when outside public electric wire net breaks down, can make little electrical network withdraw from rapidly public electric wire net, enter the island mode operation.
When planning little electrical network, can select the round-the-clock loads such as electric automobile charging station, public place lighting apparatus as the extra load LOAD of little electrical network, so that can be at any time and the rich power of little electrical network of all dissolving.
It is Ps that the distributed power source generate output is set, and little electrical network user load capacity is Pl, and it is Pa that counterflow-preventing control starts threshold value, and it is Pb that threshold value is closed in counterflow-preventing control; Ps is the total power generating capacity of the power supplys such as wind generator system PW, photovoltaic generating system PV, the PB of biomass power generation system of access; Pl is the total capacity of the user load LOAD1～LOADn of access.Pa and Pb arrange Pa=Pb=0.05 * Pl for to adopt in control logic.
This counterflow-preventing protection control method of the present invention is further comprising the steps of:
(1) detects behind the system initialization, when Ps-Pl＞Pa, turn step (2);
When Pl-Ps＞Pb, turn step (3);
When-Pb≤Ps-Pl≤Pa, little electrical network keeps standing state constant, repeats to begin step (1);
(2) detect the current capacity of energy-storage system BAT;
The current capacity of energy-storage system BAT does not reach its upper energy limit, turns step (4);
The current capacity of energy-storage system BAT has reached its upper energy limit, turns step (5);
(3) little electrical network switches to the pattern of being incorporated into the power networks, and replenishes little network load breach by public electric wire net and energy-storage system BAT, and little electrical network keeps the existing mode state that is incorporated into the power networks constant, repeats to begin step (1);
(4) little electrical network switches to island mode, and energy-storage system BAT charging absorbs unnecessary distributed power source generate output, and little electrical network keeps existing island mode state constant, repeats to begin step (1);
(5) little electrical network switches to island mode, the gate-controlled switch K on closed extra load LOAD and the circuit that ac bus is connected, and extra load LOAD and ac bus are connected, by the extra load LOAD rich power that little electrical network sends of dissolving; At this moment, when inverse probability checkout gear N detects inverse probability at this connection line place, be that public electric wire net is when breaking down, disconnect the gate-controlled switch K on extra load LOAD and the circuit that ac bus is connected, extra load LOAD and ac bus disconnect, and little electrical network switched to island mode, little electrical network keeps existing island mode state constant, repeats to begin step (1); When inverse probability checkout gear N does not detect inverse probability at this connection line place, when namely public electric wire net does not break down, repeat to begin step (1).
Although the present invention with embodiment openly as above; but it is not to limit protection scope of the present invention; any technical staff who is familiar with this technology not breaking away from change and the retouching of doing in the spirit and scope of the present invention, all should belong to protection scope of the present invention.
Claims (6)
1. a counterflow-preventing that is used for little electrical network is protected control method, and described little electrical network comprises distributed power source, energy-storage system, user load; Described distributed power source and energy-storage system pass through energy converter incoming transport bus separately; User load is with the mode incoming transport bus of grouping; Ac bus accesses public electric wire net by points of common connection; Also be provided with counterflow-preventing control in little electrical network; It is characterized in that: described little electrical network also disposes extra load, this extra load is connected with ac bus by gate-controlled switch, and this extra load is connected with public electric wire net, and the power of described extra load is greater than the rich power of little electrical network;
It is Ps that the distributed power source generate output is set, and little electrical network user load capacity is Pl, and it is Pa that counterflow-preventing control starts threshold value, and it is Pb that threshold value is closed in counterflow-preventing control;
This counterflow-preventing protection control method is further comprising the steps of:
(1) when Ps-Pl＞Pa, turns step (2);
When Pl-Ps＞Pb, turn step (3);
When-Pb≤Ps-Pl≤Pa, little electrical network keeps standing state constant;
(2) detect the current capacity of energy-storage system;
The current capacity of energy-storage system does not reach its upper energy limit, turns step (4);
The current capacity of energy-storage system has reached its upper energy limit, turns step (5);
(3) little electrical network switches to the pattern of being incorporated into the power networks, and replenishes little network load breach by public electric wire net and energy-storage system;
(4) little electrical network switches to island mode, and the energy-storage system charging absorbs unnecessary distributed power source generate output;
(5) little electrical network switches to island mode, and the gate-controlled switch on closed extra load and the circuit that ac bus is connected is by the extra load rich power that little electrical network sends of dissolving.
2. the counterflow-preventing protection control method for little electrical network according to claim 1 is characterized in that: be provided with the inverse probability checkout gear on described extra load and the circuit that public electric wire net is connected; In step (5), little electrical network switches to island mode, the gate-controlled switch that closed extra load is connected with ac bus, by the extra load rich power that little electrical network sends of dissolving, at this moment, when the inverse probability checkout gear detects inverse probability at this connection line place, when namely public electric wire net breaks down, disconnect the gate-controlled switch on extra load and the circuit that ac bus is connected, and little electrical network is switched to island mode.
3. the counterflow-preventing protection control method for little electrical network according to claim 1 is characterized in that: Pa=Pb=0.05 * Pl is set.
4. the counterflow-preventing protection control method for little electrical network according to claim 1 is characterized in that: also be provided with the unidirectional electric energy metering device on described extra load and the circuit that ac bus is connected.
5. the counterflow-preventing for little electrical network according to claim 1 is protected control method, and it is characterized in that: described extra load comprises electric automobile charging station or public place lighting apparatus.
6. the counterflow-preventing for little electrical network according to claim 1 is protected control method, and it is characterized in that: described distributed power source comprises wind generator system, photovoltaic generating system, biomass power generation system.
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| CN201310252615.9A CN103326400B (en) | 2013-06-24 | 2013-06-24 | Countercurrent-preventing protection and control method for microgrid |
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| CN201310252615.9A CN103326400B (en) | 2013-06-24 | 2013-06-24 | Countercurrent-preventing protection and control method for microgrid |
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| CN103326400A true CN103326400A (en) | 2013-09-25 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104899790A (en) * | 2014-03-07 | 2015-09-09 | 国网上海市电力公司 | Energy management method in energy storage system in micro-grid |
| CN106301156A (en) * | 2016-08-28 | 2017-01-04 | 刘建林 | The dynamic energy storage method of solar panel and system |
| CN109802432A (en) * | 2019-01-04 | 2019-05-24 | 浙江联盛合众新能源有限公司 | A kind of anti-reverse flow control device of photovoltaic plant and its control method |
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|---|---|---|---|---|
| US20070129110A1 (en) * | 2005-11-04 | 2007-06-07 | Wisconsin Alumni Research Foundation | Interface switch for distributed energy resources |
| CN102664415A (en) * | 2012-04-27 | 2012-09-12 | 湖北省电力公司电力试验研究院 | Classified microgrid networking system based on terminal users |
| CN102664429A (en) * | 2012-05-29 | 2012-09-12 | 国电联合动力技术有限公司 | Grid-connected non-networking micro-grid system and control protection method thereof |
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- 2013-06-24 CN CN201310252615.9A patent/CN103326400B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070129110A1 (en) * | 2005-11-04 | 2007-06-07 | Wisconsin Alumni Research Foundation | Interface switch for distributed energy resources |
| CN102664415A (en) * | 2012-04-27 | 2012-09-12 | 湖北省电力公司电力试验研究院 | Classified microgrid networking system based on terminal users |
| CN102664429A (en) * | 2012-05-29 | 2012-09-12 | 国电联合动力技术有限公司 | Grid-connected non-networking micro-grid system and control protection method thereof |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104899790A (en) * | 2014-03-07 | 2015-09-09 | 国网上海市电力公司 | Energy management method in energy storage system in micro-grid |
| CN106301156A (en) * | 2016-08-28 | 2017-01-04 | 刘建林 | The dynamic energy storage method of solar panel and system |
| CN109802432A (en) * | 2019-01-04 | 2019-05-24 | 浙江联盛合众新能源有限公司 | A kind of anti-reverse flow control device of photovoltaic plant and its control method |
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| CN103326400B (en) | 2015-07-15 |
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