WO2015161881A1 - Commande d'un miniréseau - Google Patents

Commande d'un miniréseau Download PDF

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Publication number
WO2015161881A1
WO2015161881A1 PCT/EP2014/058360 EP2014058360W WO2015161881A1 WO 2015161881 A1 WO2015161881 A1 WO 2015161881A1 EP 2014058360 W EP2014058360 W EP 2014058360W WO 2015161881 A1 WO2015161881 A1 WO 2015161881A1
Authority
WO
WIPO (PCT)
Prior art keywords
bus
power
converter
microgrid
controller
Prior art date
Application number
PCT/EP2014/058360
Other languages
English (en)
Inventor
Ritwik MAJUMDER
Original Assignee
Abb Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Technology Ltd filed Critical Abb Technology Ltd
Priority to PCT/EP2014/058360 priority Critical patent/WO2015161881A1/fr
Publication of WO2015161881A1 publication Critical patent/WO2015161881A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J5/00—Circuit arrangements for transfer of electric power between ac networks and dc networks
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P80/00—Climate change mitigation technologies for sector-wide applications
    • Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
    • Y02P80/14—District level solutions, i.e. local energy networks

Definitions

  • the present disclosure relates to methods and devices for controlling a microgrid comprising at least one distributed generator (DG) which is connected in said microgrid via at least one direct current (DC) to alternating current (AC) converter.
  • DG distributed generator
  • DC direct current
  • AC alternating current
  • a microgrid is a localized grouping of electricity generation, energy storage, and loads that normally operates connected to a traditional centralized grid (macrogrid) via a point of common coupling (PCC). This single point of common coupling with the macrogrid can be disconnected, islanding the microgrid.
  • Microgrids are part of a structure aiming at producing electrical power locally from many small energy sources, DGs.
  • a DG is connected via a converter which controls the output of the DG, i.e. the power injected into the microgrid.
  • a microgrid in grid connected mode, i.e. connected to the macrogrid
  • the microgrid is connected to the macrogrid at a PCC through a controllable switch. This grid connection is lost during grid fault and the microgrid is islanded.
  • the change in control mode of the DGs is from current control to voltage control operation and is initiated to create the voltage and frequency reference for the microgrid without presence of the macrogrid. This switchover from one mode to another is initiated by island detection and thus the set point tracking of the converters depend on the island detection time, mode change signal and settling time of the primary control loop.
  • a microgrid may be an AC microgrid with an AC bus connected to the different DGs and loads, or a DC microgrid with a DC bus.
  • Hybrid microgrids with both an AC bus and a DC bus are known.
  • US 8,183,714 discloses DGs connected via a DC bus to an AC side via converters.
  • a microgrid comprising at least a first distributed generator (DG); a direct current (DC) bus; an alternating current (AC) bus; a switch arranged for connecting the AC bus to a power grid when in a closed position and for disconnecting the AC bus from the power grid when in an open position; a DC to AC converter for connecting the first DG to the AC bus; a first power controller for controlling power exchange between the first DG and the DC bus; and a converter controller of the DC to AC converter for controlling an output of the first DG to the AC bus.
  • DG distributed generator
  • DC direct current
  • AC alternating current
  • the converter controller is configured for controlling the DC to AC converter in a first mode when the first power controller is configured not to allow any power exchange between the first DG and the DC bus, and in a second mode when the first power controller is configured to allow power exchange between the first DG and the DC bus.
  • a method performed in a microgrid comprising at least one distributed generator (DG).
  • DG distributed generator
  • the method comprises exchanging power between the DG and an AC bus via a first DC to AC converter, when a power controller is configured not to allow any power exchange between the DG and the DC bus; detecting an event in the microgrid; and in response to the detected event, exchanging power with the DC bus when the power controller is configured to allow power exchange between the DG and the DC bus, thereby allowing the first DC to AC converter to control an output of the DG to the AC bus, e.g. an output voltage or power factor.
  • the DC to AC converter is able to limit and control the amount of power exchanged with (e.g. injected into or extracted from) the AC bus from the DG, without having to shut down or reduce the power production of the DG.
  • the converter controller may conveniently change mode to the second mode, in which some power is allowed to be injected into the DC bus.
  • power may be extracted from the DC bus, albeit injection into the DC bus may be most common.
  • the converter controller may in its second mode control the voltage of the AC bus, i.e. act as a voltage controlling source, e.g.
  • the power controller e.g. a switch or a DC to DC converter, allows exchange of power with the DC bus when the converter controller is in the second mode, and does not allow it, e.g. switch is open, when the converter controller is in the first mode.
  • the power controller e.g. a switch or a DC to DC converter
  • the power controller is controlled by the converter controller, while in other embodiments, the power controller is controlled by a central control unit.
  • Fig l is a schematic circuit diagram of an embodiment of a microgrid in accordance with the present invention.
  • Fig 2 is a schematic circuit diagram of another embodiment of a microgrid in accordance with the present invention.
  • Fig 3 a schematic circuit diagram of another embodiment of a microgrid in accordance with the present invention.
  • Fig 4 is a schematic block diagram illustrating embodiments of a control method in accordance with the present invention.
  • Fig 5 is a schematic block diagram illustrating an example embodiment of a control method in accordance with the present invention.
  • Fig 6 is a schematic flow chart of an embodiment of a method of the present invention.
  • FIG. l schematically illustrates an embodiment of a microgrid l of the present invention.
  • the microgrid l is connected to a power grid (macrogrid) 2 via a circuit breaker or other switch 3.
  • the microgrid comprises a plurality of distributed generators (DG) 4, here a first DG 4a, a second DG 4b and a third DG 4c, e.g. wind turbines or solar power arrangements each producing a DC power output Pdcdg.
  • DG 4 is connected to a DC bus 6, typically via a respective DC to DC power converter for controlling the DC output of the DG 4.
  • Each DG 4 is also associated with a respective power controller 8, i.e.
  • a first power controller 8a associated with the first DG 4a a second power controller 8b associated with the second DG 4b and a third power controller 8c associated with the second DG 4c.
  • These power controllers 8 are configured for controlling how much power Pdc, if any, is injected into or extracted from the DC bus 6 from the respective DG 4.
  • Each DG 4 is also connected to an AC bus 5, via a DC to AC power converter 7 for controlling the power P ac and/or voltage V ac outputted to the AC bus 5 having the voltage Vgrid.
  • the DG 4a may e.g.
  • the first power controller 8a allows power from the first DG 4a to be exchanged with the DC bus 6
  • power from the first DG 4a may additionally or alternatively be exchanged with the AC bus 5 via the second DC to AC converter 7b and the DC bus 6.
  • An energy storage 11, e.g. a battery or flywheel, is connected to the DC bus 6, allowing power injected by any of the DGs 4 into the DC bus 6 to be stored in the energy storage.
  • power may be extracted from the DC bus 6 by discharging the energy storage 11.
  • each converter 7 and 10 has its own control unit 9.
  • FIG 1 only the converter controller 9 of the first DC to AC controller 7a is schematically shown.
  • This converter controller 9 is in accordance with the present invention configured to control the amount of power exchanged between the AC bus 5 and the first DG 4a, e.g. injected by the DG 4a.
  • a first control mode when no power from the first DG 4a is exchanged with the DC bus 6 (e.g.
  • the converter controller 9 may typically control the converter 7a to inject all power outputted by the DG 4a (and any other power from other DGs which reach the converter 7a).
  • the first power controller 8a is controlled (e.g.
  • the converter controller 9 switches to a second control mode wherein the amount of power P ac exchanged with the AC grid is regulated/limited and any excess power Pdc is instead injected into the DC bus and e.g. stored in the energy storage 11.
  • the second control mode may conveniently be a voltage control mode for controlling the voltage V gr id in the AC bus 5 in absence of the voltage controlling influence of the power grid 2.
  • power exchange with the DC bus 6, when allowed by the power controller 8, may in some cases include extraction of power from the DC bus 6, e.g. by discharging the energy storage 11 or by extracting power which is injected into the DC bus 6 by another DG 4, e.g. the second DG 4b.
  • the power exchange with the AC bus may be in either direction, both when the converter controller 9 is in its first mode and/or in its second mode, although power may usually be injected into the DC bus, especially in the first mode.
  • power and/or voltage outputted to the AC bus 5 may be positive or negative power or voltage, especially in the second mode.
  • FIG. 2 schematically shows another embodiment of a microgrid 1 of the present invention.
  • the power controller 8a which controls the injection of power into the DC bus 6 from the DG 4a is a switch.
  • the switch 8a When the converter controller 9 is running in its first mode, the switch 8a is open whereby no power is allowed to be injected into the DC bus 6, i.e. all power is injected into the AC bus 5.
  • FIG. 3 schematically shows another embodiment of a microgrid 1 of the present invention.
  • the power controller 8a which controls the injection of power into the DC bus 6 from the DG 4a is a DC to DC converter, which may or may not be complemented by a switch.
  • the converter 8a controls the power exchange with the DC bus 6 such that no power is allowed to be injected into the DC bus 6, i.e. all power is injected into the AC bus 5.
  • the converter 8a controls the power exchange with the DC bus 6 such that power is allowed to be injected into the DC bus 6 as needed depending on how much power, if any, the DC to AC converter 7a injects into the AC bus 5.
  • Using a DC to DC converter as the power controller 8 may offer more flexibility than a switch (which on the other hand is less complex), since the power controller 8 may then regulate how much power is injected into the DC bus 6 and is not only an on-off switch.
  • Figure 4 schematically illustrates an embodiment of a control system for controlling the microgrid 1.
  • the converter controller 9 may comprise a DG controller 42 and may be configured to control, in addition to the operation of the DC to AC converter 7, also the operation of the power controller 8.
  • the converter controller 9 may be viewed as separate from or comprised in the DG controller 42.
  • a central microgrid controller 41 cooperates with the converter controller 9/DG controller 42.
  • a decentralised control without a central microgrid controller 41 may used, e.g. with cooperating local DG controllers 42 (one for each DG 4).
  • the microgrid controller 41 obtains voltage (v) and/or frequency (f) measurements.
  • Local measurements from where the DG 4 injects power into the AC bus 5 may be obtained from the DG controller 42 and global measurements may be obtained from elsewhere in the microgrid 1 (typically from the AC side of the microgrid).
  • Voltage and frequency regulation control functions in the microgrid controller 41 analyses the measurements and draws the conclusion that the power voltage and/or frequency of the AC bus 5 needs to be regulated.
  • a function in the microgrid controller 41 selects which one or several DG 4 should be used for said regulation and communicates this to the DG controller 42 of the selected DG.
  • the DG controller steers the operation of the power controller 8 such that power exchange with the DC bus 6 is allowed.
  • the DG controller 42/converter controller 9 changes the control mode to the second mode for the control of the DC to AC converter 7.
  • the microgrid controller 41 may additionally (separately) activate change of mode to the second mode for other converter controllers 9 of other DGs 4.
  • Figure 5 illustrates an example embodiment of control of a microgrid 1 when using a DC bus 6 connected to the DG 4.
  • AC side regulations of voltage and frequency of the AC bus 5 are maintained with DC side maximum power point tracking (MPPT) and connection with DC bus 6 (switch 8 is closed). It can be seen that separate power or voltage control in the AC side is possible with DC bus voltage control while maintaining maximum power extraction from the DG 4.
  • Figure 6 is a flow chart of an embodiment of a method of the present invention. The method may be performed by the converter controller 9 or by a control system of the microgrid 1 comprising the converter controller 9.
  • Power from the DG 4 is injected Si into the AC bus 5 via the first DC to AC converter 7a, when the power controller 8 is configured not to allow any power exchange between the DG 4 and the DC bus 6. Then, an event is detected S2 in the microgrid 1. In response to the detected S2 event, power from the DG 4 is injected S3 into the DC bus 6 when the power controller 8 is configured to allow power exchange between the DG 4 and the DC bus 6, thereby allowing the first DC to AC converter 7a to control an output of the DG 4 to the AC bus 5.
  • the converter controller 9 in the first mode is configured for controlling the DC to AC converter 7a to inject all power (except any losses) outputted from the first DG 4a into AC bus 5.
  • the converter controller 9 is configured for controlling the DC to AC converter 7a to inject less than all power outputted from the first DG 4a into AC bus 5 thereby allowing a part of the power outputted from the first DG 4a to be injected into DC bus 6.
  • the converter controller 9 is, in its second mode, configured for injecting more than all power outputted from the first DG 4a into the AC bus 5 by extracting power from the DC bus 6.
  • the first power controller 8a is a switch or a DC to DC converter.
  • the controlled output is a voltage output and/or a power output.
  • the voltage and/or frequency of the AC bus 5 can be controlled.
  • the microgrid 1 also comprises a second DG 4b, and a second power controller 8b for controlling power exchange between the second DG 4b and the DC bus 6.
  • the second DG 4b may also be connected to the AC bus 5 via a second DC to AC converter 7b.
  • the control system of the microgrid 1 may also control the second DC to AC converter 7b to regulate the amount of power/voltage outputted into the AC bus 5 from the second DG (when the second power controller 8b allows power exchange with the DC bus 6) and/or from the first DG 4a (when the first power controller 8b allows power exchange with the DC bus 6).
  • the microgrid 1 also comprises an energy storage 11 connected to the DC bus 6 and arranged for storing or discharging at least some of the power injected into or extracted from the DC bus by the first and/or any second or further DG:s 4.
  • the detected S2 event is any of an indication that the microgrid 1 has lost its connection to the power grid 2, an indication that the power import to the microgrid 1 from a power grid 2 is below a predetermined threshold and/or an indication that there is a voltage drop in the microgrid 1.
  • the microgrid may need to switch to voltage control, by a converter controller 9 running in its second mode.
  • all available power from the DG 4 is injected Si into the AC bus 5, before detecting S2 the event.
  • At least a part of the power exchanged S3 with the DC bus 6 is stored in or discharged from an energy storage 11 connected to the DC bus, and/or is exchanged with the AC bus 5 via a second DC to AC converter 7b.
  • a second DC to AC converter 7b are examples of how to take care of the power injected into or extracted from the DC bus 6, i.e. excess power produced by the DG 4 which may currently not be injected into the AC bus 5, at least not via the first DC to AC converter 7a.
  • the stability of the microgrid 1 may be improved with DC bus 6 voltage control and interlink connection between the different DGs 4. Multiple DGs and common storage 11 connections at DC bus 6 may reduce DC voltage fluctuations.
  • the stability aspect of parallel converter controllers 9 in the AC side is determined by the controller parameters and control structure which may remains unchanged (the DC voltage may be taken as input and relate the switching functions to the system states).
  • the control scheme is modular in structure and an individual DG 4 failure may only lead to non-participation of that particular DG.
  • the microgrid controller (centralized or decentralized) may be updated based on operating DGs.
  • Advantages of embodiments of the present invention include: - Selective participation of the DGs 4 in microgrid 1 AC side regulation while outputting maximum available power without individual storages.
  • Controllable connection 8 at DC bus 6 provides possibility in decoupling of DC and AC side power.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

La présente invention concerne un miniréseau électrique (1) comprenant au moins un premier générateur réparti (DG) (4a); un bus pour courant continu (c.c.) (6); un bus pour courant alternatif (c.a.); un commutateur (3) conçu pour relier le bus c.a. à un réseau électrique (2); un convertisseur c.c./c.a. (7) pour connecter le premier DG au bus c.a.; un premier organe de commande de puissance (8a) pour commander l'échange de puissance entre le premier DG et le bus c.c.; et un dispositif de commande de convertisseur (9) du convertisseur c.c./c.a. pour commander une sortie du premier DG vers le bus c.a. L'organe de commande de convertisseur est configuré pour commander le convertisseur c.c./c.a. dans un premier mode lorsque le premier organe de commande de puissance est configuré pour ne pas permettre d'échange de puissance entre le premier DG et le bus c.c./c.c., et dans un second mode lorsque le premier organe de commande de puissance est configuré pour permettre un échange de puissance entre le premier DG et le bus c.c.
PCT/EP2014/058360 2014-04-24 2014-04-24 Commande d'un miniréseau WO2015161881A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2014/058360 WO2015161881A1 (fr) 2014-04-24 2014-04-24 Commande d'un miniréseau

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2014/058360 WO2015161881A1 (fr) 2014-04-24 2014-04-24 Commande d'un miniréseau

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WO2015161881A1 true WO2015161881A1 (fr) 2015-10-29

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108695895A (zh) * 2018-06-26 2018-10-23 山西清新新能源科技有限公司 一种基于微电网的综合能源开发系统及方法
CN113938084A (zh) * 2021-09-30 2022-01-14 西北工业大学 一种利用电机驱动器实现直流微网功率迁移的拓扑及方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010088545A2 (fr) * 2009-01-30 2010-08-05 Board Of Regents, The University Of Texas System Procédés et appareils pour la conception et la gestion d'une interface électronique de puissance multiport pour des sources d'énergie renouvelables
EP2325970A2 (fr) * 2009-11-19 2011-05-25 Samsung SDI Co., Ltd. Système de gestion d'énergie et système de stockage d'énergie raccordée au réseau incluant le système de gestion d'énergie
US20110148198A1 (en) * 2010-12-28 2011-06-23 Vestas Wind Systems A/S Power conversion system and method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010088545A2 (fr) * 2009-01-30 2010-08-05 Board Of Regents, The University Of Texas System Procédés et appareils pour la conception et la gestion d'une interface électronique de puissance multiport pour des sources d'énergie renouvelables
EP2325970A2 (fr) * 2009-11-19 2011-05-25 Samsung SDI Co., Ltd. Système de gestion d'énergie et système de stockage d'énergie raccordée au réseau incluant le système de gestion d'énergie
US20110148198A1 (en) * 2010-12-28 2011-06-23 Vestas Wind Systems A/S Power conversion system and method

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Title
WANG Y ET AL: "Coordinated control of battery energy storage system in a microgrid", 2013 IEEE PES ASIA-PACIFIC POWER AND ENERGY ENGINEERING CONFERENCE (APPEEC), IEEE, 8 December 2013 (2013-12-08), pages 1 - 6, XP032606936, DOI: 10.1109/APPEEC.2013.6837211 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108695895A (zh) * 2018-06-26 2018-10-23 山西清新新能源科技有限公司 一种基于微电网的综合能源开发系统及方法
CN113938084A (zh) * 2021-09-30 2022-01-14 西北工业大学 一种利用电机驱动器实现直流微网功率迁移的拓扑及方法

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