CN102510124A - Mode switching method for switching micro power grid from islanding mode to grid-connected mode - Google Patents

Mode switching method for switching micro power grid from islanding mode to grid-connected mode Download PDF

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Publication number
CN102510124A
CN102510124A CN2011103826062A CN201110382606A CN102510124A CN 102510124 A CN102510124 A CN 102510124A CN 2011103826062 A CN2011103826062 A CN 2011103826062A CN 201110382606 A CN201110382606 A CN 201110382606A CN 102510124 A CN102510124 A CN 102510124A
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China
Prior art keywords
microgrid
power
distributed power
power source
switch
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CN2011103826062A
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Inventor
舒鹏
谷延辉
张毅
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Beijing Goldwind Science and Creation Windpower Equipment Co Ltd
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Beijing Goldwind Science and Creation Windpower Equipment Co Ltd
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Priority to CN2011103826062A priority Critical patent/CN102510124A/en
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00Integration of renewable energy sources in buildings
    • Y02B10/70Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

Abstract

The invention provides a mode switching method of a micro power grid from an islanding mode to a grid-connected mode. The mode switching method comprises the steps of: stopping operation of all distributive power supplies in the micro power grid; cutting off all switches of operating loads in the micro power grid; closing a grid-connected switch; closing all switches of loads when the bus voltage of the micro power grid is greater than a predetermined voltage; respectively feeding an energy storage distributive power supply, a photovoltaic distributive power supply and a fan distributive power supply and enabling the distributive power supplies to work in a control mode that output active power and inactive power equal to a reference power. A mode switching safe terminating mechanism is additionally arranged to better protect equipment. All the distributive power supplies are ensured to stop operating, thus asynchronous grid-connected problem cannot happen, and the grid-connected impact current is reduced to the minimum extent.

Description

The mode switching method that is used for microgrid from the isolated island mode switch to the pattern of being incorporated into the power networks
Technical field
The present invention relates to the mode switch of microgrid, specifically, relate to the mode switching method of microgrid from the isolated island mode switch to the pattern of being incorporated into the power networks.
Background technology
Along with petering out of conventional energy resource, and serious environmental is polluted day by day, has obtained increasing attention and development in regenerative resource and the distributed power generation technology world in recent years scope.At present, distributed power generation generally be meant generated output at thousands of watts of miniaturizations, modularization, distributing to 50 megawatts, be arranged near the user the small power generation system that is connected to distribution system for user's power supply.Present existing research and practice show; With the distributed power generation energy supplying system with micro power network (MicroGrid; Below it is called microgrid) form insert big electrical network and be incorporated into the power networks, support each other with big electrical network, be the effective means of performance distributed power generation energy supplying system usefulness.
As one of important composition form of distributed power generation; Microgrid normally compiles the small-sized electric system of being transported to that forms by distributed power source (DG), energy storage device, energy converter, relevant load, supervisory control system, protection system, power transmitting device etc., is an autonomous system that can realize oneself's control, protection and management.Because; Microgrid both can be through power distribution network and big electrical network parallel running; Form the combined operation system of a large-scale power grid and small grids, also can be independently for local load provides electricity needs, its flexibly operational mode improved the power supply reliability of load side greatly; Simultaneously, microgrid inserts big electrical network through single-point, can reduce a large amount of small-power distributed power sources and insert behind the big electrical network influence to big electrical network.In addition, microgrid small power generations that will disperse, dissimilar sources (distributed power source) power supply that combines can make Miniature Power Unit obtain higher utilization ratio.Under big electrical network normal condition, microgrid needs operation steady in a long-term; And when big electrical network was interfered, microgrid must break away from big electrical network fast, got into and remain in the islet operation state, treat big electric network fault get rid of after auto-parallel operation again.Above-mentioned functions is summarized as: peak load shifting, power are level and smooth, mode switch etc.Realizing the control strategy that these functions are required, is the difficult point of microgrid technology, and various countries research team is just continually developing more excellent control method and hardware is formed.
In recent years; The development of wind power generation, solar photovoltaic technology makes renewable energy power generation obtain increasing utilization, the technology that renewable energy power generation is combined with the microgrid form; Be the boundless technology of application prospect, become the frontier of electric power system research.Because microgrid is a kind of novel power grid, its system complex degree is much higher than General Electric Network, and this has caused the control strategy of microgrid and the relative General Electric Network of complexity of control method also to promote greatly.
Mode switch is to best embody one of function that microgrid is worth, and can be summarized as three kinds of behaviors under the different operating modes: when big electrical network normal power supply, microgrid is with the mode operation that is incorporated into the power networks (1); (2) when big electrical network appearance interference caused supplying power, microgrid need be from the mode switch that is incorporated into the power networks to the isolated island pattern; (3) after big electric network fault is got rid of, service restoration, microgrid need be from the isolated island mode switch to the pattern of being incorporated into the power networks.
The mode switch technology has experienced operates the automatically evolution of operation of machine manually, focuses on the opportunity how preference pattern is switched, and the engagement process of each equipment when switching.
At present, existing microgrid system simply is made up of the distributed power source of single kind, load, power transmitting device etc. usually.Distributed power source is the power supply type of traditional energy normally, for example is the energy type energy storage device of representative with lead-acid batteries, lithium battery group, the combustion machine of an also configurable constant volume.
Fig. 1 shows microgrid topological structure of the prior art.In microgrid system shown in Figure 1, the microgrid distributed power source often is combustion machine/energy-storage system, inserts bus BUS1, and the microgrid load also inserts this bus BUS1.BUS1 is the low-voltage alternating-current bus, and voltage links to each other with BUS2 through transformer between 220V~35KV.BUS2 is the high-voltage alternating bus, can be considered big electrical network, and voltage is between 10KV~220KV.Circuit breaker shown in the PCC is the tie point between microgrid and the big electrical network.
When big electrical network normal power supply, the generation outage of microgrid distributed power source, PCC is in closure state, and microgrid is loaded fully by big mains supply; When big electric network fault, PCC is in off-state, and the microgrid distributed power source starts generating, is the power supply of microgrid load.This technology is this control purpose of mode switch in order to realize microgrid mainly.Usually control logic is implemented in the controller of current transformer of microgrid distributed power source.
But existing microgrid is that the mode switch of isolated island pattern exists the shortcoming be described below from the mode switch that is incorporated into the power networks: (1) can only adapt to the microgrid system simple structure under, the impulse current height during control; (2) when in the microgrid system being the distributed power generation type such as wind power generation, photovoltaic generation, prior art can't adapt to the coordination control of regenerative resource and energy storage; (3) poor with the conformability of big electrical network, there is the possibility that influences big electric network protection, automation equipment.
Summary of the invention
When microgrid is incorporated into the power networks, has increased mode switch safety and stopped mechanism, in isolated island commentaries on classics and network process, better protection equipment; Guarantee that all distributed power sources are out of service, non-simultaneous interconnecting problem can not occur, it is minimum that the impulse current that will be incorporated into the power networks reduces to.In addition, according to exemplary embodiment of the present invention, drop into distributed power source successively by the order of energy storage distributed power source, photovoltaic distributed power source and blower fan distributed power source, thereby can carry out better protection equipment.
According to an aspect of the present invention, a kind of mode switching method from the isolated island mode switch to the pattern of being incorporated into the power networks when big power system restoration normal power supply that is used for microgrid is provided, said method comprises: all distributed power sources in the microgrid out of service; Break off the switch of all operating loads in the microgrid; The closure switch that is incorporated into the power networks; In the busbar voltage of microgrid during greater than predetermined voltage, the switch of closed all loads; Drop into the energy storage distributed power source and make this energy storage distributed power source be operated in the control model that equals reference power from the active power and the reactive power of this energy storage distributed power source output; Drop into the photovoltaic distributed power source and make this photovoltaic distributed power source be operated in the control model that equals reference power from the active power and the reactive power of this photovoltaic distributed power source output; Drop into the blower fan distributed power source and make this blower fan distributed power source be operated in the control model that equals its reference power from the active power and the reactive power of this blower fan distributed power source output.
According to a further aspect in the invention; After all distributed power sources in microgrid out of service; Also can comprise the step that all distributed power sources of judging in the microgrid are whether out of service,, then carry out the step of the switch that breaks off all operating loads in the microgrid if all distributed power sources in the microgrid all are stopped operation; Otherwise, stop switching from the isolated island pattern to the pattern of being incorporated into the power networks.
According to a further aspect in the invention; After the switch of all operating loads in breaking off microgrid; Also can comprise the step whether switch of judging all operating loads in the microgrid has all broken off,, then carry out the step of the closed switch that is incorporated into the power networks if all operating loads in the microgrid all break off; Otherwise, stop switching from the isolated island pattern to the pattern of being incorporated into the power networks.
According to a further aspect in the invention, after closure is incorporated into the power networks the step of switch, during smaller or equal to predetermined voltage, can stop switching from the isolated island pattern to the pattern of being incorporated into the power networks in the busbar voltage of microgrid.
According to a further aspect in the invention, the step of all distributed power sources in the microgrid out of service can comprise: the main distributed power source in the microgrid at first out of service; Other distributed power source in the microgrid is out of service after detecting microgrid and site decompression.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is done further explain.
Fig. 1 shows the topological structure of microgrid of the prior art.
Fig. 2 is according to an exemplary embodiment of the present invention with the flow chart of microgrid from the isolated island mode switch to the pattern of being incorporated into the power networks.
Embodiment
Fig. 2 shows the control flow chart from the isolated island mode switch to the pattern of being incorporated into the power networks according to an exemplary embodiment of the present invention.
The topological structure of microgrid is with the different of maximum of the topological structure of prior art according to an exemplary embodiment of the present invention, and the microgrid power supply is made up of blower fan distributed power source, photovoltaic distributed power source and various energy storage distributed power source according to an exemplary embodiment of the present invention.
Microgrid is when islet operation; The voltage recovery situation of the supply line of the big electrical network of monitoring disappears when judging big electric network fault in real time, after date when voltage recovers to stablize a section; To start " isolated island pattern " incision " pattern is incorporated into the power networks " function; Will be in order microgrid equipment out of service, the closure switch that is incorporated into the power networks is incorporated into big electrical network with microgrid equipment more in order.If meet accident in the process, launch mode switch safety and stop mechanism, each device security is isolated.Wherein, the foundation of microgrid from the isolated island mode switch to the pattern of being incorporated into the power networks is to detect big power system restoration normal power supply.At this moment, the main distributed power source in the microgrid is at first out of service and cause the microgrid decompression, the load short supply interruption, and other distributed power source is out of service after detecting microgrid and site decompression.The closed then microgrid switch that is incorporated into the power networks, the load restoration power supply, through certain hour at interval after, all distributed power sources in the microgrid are incorporated into the power networks again.
According to an exemplary embodiment of the present, detect big power system restoration normal after, at step S200, all distributed power sources in the microgrid out of service.
At step S210, all distributed power sources have been judged whether out of service.If all distributed power sources out of service, then execution in step S220; Otherwise execution in step S300 stops the switching from the isolated island pattern to the pattern of being incorporated into the power networks.
At step S220, break off the switch of all operating loads.
At step S230, judge whether that the switch of all operating loads all breaks off.If the switch of all operating loads has all broken off, then carry out step S240, otherwise execution in step S300.
At step S240, the closure switch that is incorporated into the power networks.
At step S250, whether the busbar voltage of judging microgrid is greater than predetermined voltage U1.If the busbar voltage of microgrid is greater than said predetermined voltage, execution in step S260 then, otherwise, execution in step S300.
At step S260, the switch of closed all loads.
At step S270, drop into the energy storage distributed power source, and make it be operated in the PQ control model that equals its reference power respectively from the active power and the reactive power of the output of energy storage distributed power source.
At step S280, drop into the photovoltaic distributed power source and make it be operated in the PQ control model that equals its reference power respectively from the active power and the reactive power of the output of photovoltaic distributed power source.
At step S290, drop into the blower fan distributed power source and make it be operated in the PQ control model that equals its reference power respectively from the active power and the reactive power of the output of blower fan distributed power source.
According to another exemplary embodiment of the present invention; After the supply line's voltage that detects big electric network fault elimination and big electrical network is stable; Stop all equipment that moving in the microgrid, break off the switch that is incorporated into the power networks, manually or automatically drop into the switch that is incorporated into the power networks, microgrid load, microgrid distributed power source simultaneously.
According to an exemplary embodiment of the present, compare, when microgrid is incorporated into the power networks again, has increased mode switch safety and stopped mechanism with existing mode switch from the isolated island mode switch to the pattern of being incorporated into the power networks, in isolated island commentaries on classics and network process, better protection equipment; Guarantee that all distributed power sources are out of service, non-simultaneous interconnecting problem can not occur, it is minimum that the impulse current that will be incorporated into the power networks reduces to.

Claims (5)

1. mode switching method when big power system restoration normal power supply that is used for microgrid from the isolated island mode switch to the pattern of being incorporated into the power networks, said method comprises:
All distributed power sources in the microgrid out of service;
Break off the switch of all operating loads in the microgrid;
The closure switch that is incorporated into the power networks;
In the busbar voltage of microgrid during greater than predetermined voltage, the switch of closed all loads;
Drop into the energy storage distributed power source and make this energy storage distributed power source be operated in the control model that equals reference power from the active power and the reactive power of this energy storage distributed power source output;
Drop into the photovoltaic distributed power source and make this photovoltaic distributed power source be operated in the control model that equals reference power from the active power and the reactive power of this photovoltaic distributed power source output;
Drop into the blower fan distributed power source and make this blower fan distributed power source be operated in the control model that equals its reference power from the active power and the reactive power of this blower fan distributed power source output.
2. mode switching method as claimed in claim 1; Wherein, after all distributed power sources in microgrid out of service, also comprise the step that all distributed power sources of judging in the microgrid are whether out of service; If all distributed power sources in the microgrid all are stopped operation; Then carry out the step of the switch that breaks off all operating loads in the microgrid, otherwise, switching stopped from the isolated island pattern to the pattern of being incorporated into the power networks.
3. mode switching method as claimed in claim 2; Wherein, after the switch of all operating loads in breaking off microgrid, also comprise the step whether switch of all operating loads of judging that microgrid is interior has all broken off; If all operating loads in the microgrid all break off; Then carry out the step of the closed switch that is incorporated into the power networks, otherwise, switching stopped from the isolated island pattern to the pattern of being incorporated into the power networks.
4. method as claimed in claim 2 wherein, after closure is incorporated into the power networks the step of switch, during smaller or equal to predetermined voltage, stops the switching from the isolated island pattern to the pattern of being incorporated into the power networks in the busbar voltage of microgrid.
5. the step of all distributed power sources in the microgrid the method for claim 1, wherein out of service comprises:
Main distributed power source in the microgrid at first out of service;
Other distributed power source in the microgrid is out of service after detecting microgrid and site decompression.
CN2011103826062A 2011-11-25 2011-11-25 Mode switching method for switching micro power grid from islanding mode to grid-connected mode Pending CN102510124A (en)

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CN103475023A (en) * 2013-09-09 2013-12-25 国家电网公司 On/off-grid control method for microgrid with a plurality of distributed power supplies
CN104242340A (en) * 2014-09-10 2014-12-24 南京磐能电力科技股份有限公司 Stable control method in switching process from micro-grid non-planned grid connection operation mode to isolated island operation mode
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Cited By (15)

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Publication number Priority date Publication date Assignee Title
CN103346586B (en) * 2013-07-08 2015-11-04 中国科学院电工研究所 The method for handover control of double-mode converter in a kind of three-phase microgrid
CN103346586A (en) * 2013-07-08 2013-10-09 中国科学院电工研究所 Switching control method for double-mode converter in three-phase microgrid
CN103475023A (en) * 2013-09-09 2013-12-25 国家电网公司 On/off-grid control method for microgrid with a plurality of distributed power supplies
CN103475023B (en) * 2013-09-09 2014-09-03 国家电网公司 On/off-grid control method for microgrid with a plurality of distributed power supplies
US9620960B2 (en) 2014-01-13 2017-04-11 Abb Schweiz Ag Control of a stabilizing energy storage in a microgrid
CN104242340B (en) * 2014-09-10 2016-07-27 南京磐能电力科技股份有限公司 The unplanned grid-connected stable control method turned when islet operation pattern switches of micro-capacitance sensor
CN104242340A (en) * 2014-09-10 2014-12-24 南京磐能电力科技股份有限公司 Stable control method in switching process from micro-grid non-planned grid connection operation mode to isolated island operation mode
WO2016101787A1 (en) * 2014-12-23 2016-06-30 南京南瑞继保电气有限公司 Island-to-network switching method
CN104485683A (en) * 2014-12-23 2015-04-01 南京南瑞继保电气有限公司 Island-to-network switching method
CN104485683B (en) * 2014-12-23 2018-07-06 南京南瑞继保电气有限公司 A kind of isolated island turns networking method
US10418816B2 (en) 2014-12-23 2019-09-17 Nr Electric Co., Ltd. Passive islanding-to-grid-connected switch method
US10965153B2 (en) 2016-02-05 2021-03-30 Duke Energy Corporation Methods of microgrid communications and connection transitions
CN111095718A (en) * 2017-08-02 2020-05-01 Go电子有限公司 Microgrid controller and related methods
CN110212577A (en) * 2019-06-17 2019-09-06 南通国轩新能源科技有限公司 A kind of energy resource system self-balancing control method
US20220261026A1 (en) * 2021-02-12 2022-08-18 Landis+Gyr Innovations, Inc. Islanding control using multi-port meters

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Application publication date: 20120620