aggregation of microgrids: cluster-oriented network · output of pv + battery the amount of pv that...
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Aggregation of Microgrids: Cluster-oriented network
November 19, 2014
Osaka Gas Co., Ltd.
Engineering Department
Kunihiro Nakao
１. Background of Japan’s energy industry
２．Technical development of proposed system
∇Overview of technical feature
∇Laboratory test
∇Demonstration in Osaka Gas’s apartment
３．As a key solution for installing large amount of
renewable energy
∇For frequency fluctuation
∇For voltage rising
Contents of Today’s Presentation
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Due to the shut down of nuclear power plants after the earthquake disasters and the introduction of Feed-in Tariff system, the various problems of power system in Japan are becoming obvious.
What happens around power grid？
Reference: Material by the 2nd New and Renewable Energy Subcommittee, the Federation of Electric Power Companies of Japan (August 8, 2014)
Reference: Material by the 1st New and Renewable Energy Subcommittee, METI (June 17, 2014)
Transition of installed capacity of renewable energies Problems of power system
Some power utilities have already suspended acceptance of interconnection.
Annual averaged increase 5%
Annual averaged increase 9%
32% increase over the previous year
RPS systemExcess electricity purchasing scheme
Feed-in Tariffs
Fiscal year
■PV■Wind■Mid-/small-scale
hydraulic power■Geothermal heat■Biomass
10 thousand kW
Excess power generation
Totaldemand
Adjustable amount
Basic supply amount(including minimum output* from thermal power generation)
Renewable energy
Output adjustment
Basic supply amount
Expanding PV and Wind power* Minimum output by ensuring the power for adjustment capability for demand change and backups
Excess power3000
2000
1000
0
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A new type of Micro-grids; that confines the effect of renewable energy within a local area by “clustering and autonomous distributed controlling.”
How to manage a large amount of renewable energy ?
Transmission Substations
Poletransformers
Present S
ystemP
roposed system
[Features]
・Local generation for local consumption
・Excess & shortfall accommodation
Power Stations
DistributionSubstations
loose coupling,best mix
ECO Network
Ref.)Analogy of the Development of Mobile Phone Technology
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Development of Telecommunication
<radio communication/ubiquitous ><cable communications/landline>
Development of Electricity Network
Jumping Technology
Jumping Technology
ECO NetworkAggregation of microgrids
１. Background of Japan’s energy industry
２．Technical development of proposed system
∇Overview of technical feature
∇Laboratory test
∇Demonstration in Osaka Gas’s apartment
３．As a key solution for installing large amount of
renewable energy
∇For frequency fluctuation
∇For voltage rising
Contents of Today’s Presentation
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7
The structure of “Clustering and Autonomous distributed controlling”
・・・・・
・・・・・
・・・
Cluster N
Stand-alone inverter for power supplyInterconnection inverter for power interchange
I : flexible power supply from power source and battery in the cluster
II : flexible power supply from power source and battery in the cluster
To the grid or the other clusters
SW
SW
Cluster 1
Cluster 2
Depending on the power situation, the switching system select the power from the grid or from ECO network.
While a conventional system is operated by “large-scale power source and integrated controlling”, the proposed system is an autonomous distribution energy system that reduces the dependency on the grid as much as possible by “clustering and autonomous distributed controlling”.
Realizing auto-control by a new approach
combining 2 types of inverters
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“Clustering + Self-distribution control by 2 types of inverters” realizes autonomous power interchange. By this, combination system with storage and PV will be more easy to build.
Charging rate of battery (SOC.%)Fre
quency in
a c
luste
r
60.0
60.2
59.8
50 8020
Conventionalcontrol
Newcontrol
Control by stand-alone inverterControl by stand-alone inverter
Power interchange is automatically done from larger to smaller remaining amount.
Ｐ
Ｖ
Stand-alone inverterHigh-freq.
Cluster B
・ ・ ・
Interconnection inverter
Ｐ
Ｖ
Low freq. Cluster AStand-alone inverter
Charging rate of battery
0％
100％
Cluster A Cluster B
Automatic power interchange by detecting both frequencies
Control by interconnection inverterControl by interconnection inverter
How to realize the control?
・ ・ ・
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SOC is reflected to frequency setting
Technical point (Detailed)
Power Router
SOCReference
+-
Calculationof SOC
FrequencyController
DC
AC
DC
AC
Controllerfor Tie-linePower Flow
Inverter for stand-alone operation
(CVCF Operation)
Frequency in Cluster A
Frequency in Cluster B
Cluster1
Cluster2Inverter for
Interconnection(APR Operation)
Battery
The control of frequency, and power transfer between clusters leads to synchronization of SOC in all clusters
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Development and demonstration
-420
-360
-300
-240
-180
-120
-60
0
60
120
180
18:57:36 19:12:00 19:26:24 19:40:48 19:55:12 20:09:36
Time
OUTPUT[W
]
58.6
58.8
59
59.2
59.4
59.6
59.8
60
60.2
60.4
60.6
Frequency[Hz]
STEP① Lab. Test :Theoretical verification STEP② Field Test : Real load test
The proposal system has already demonstrated at an apartment in Osaka.
10,000
5,000
0
‐5000
‐10,000
‐15,0002:000:00 4:00 6:00 8:00 10:00 12:00
Time
OUTPUT[W
]
15,000
Lab. at Osaka
Apartment “NEXT21”
Verifying a fully new approach “automatic power interchange control” that using the variable frequency as a signal for control
Under the actual loading condition having precipitous fluctuations, verifying the
continuous power supply without trip and effect on load side
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Outline of actual-load demonstration test at NEXT21
For verification of technical issues that are detected only under the condition of actual-load operation, the demonstration test will be conducted at NEXT21 from June by using 2 clusters consisting of 9 and 6 residences.
601 502 603 604 605
GE FC FC
FCFCFCFC
FC FC FC
FC FC
FC
501 503 504
402 403 404 405301
302 303 304 305
202
3F
Backup
PV Battery
Apartment NEXT21
4F
5F
6F
2F
B1F
Battery
Interconnectioninverter
Stand-alone inverter
Stand-alone inverter
Backup inverter
-15
-10
-5
0
5
10
15
20
59
59.5
60
60.5
61
9:00 11:00 13:00 15:00 17:00 19:00
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Test dataPower supply from Aggregation of Microgrids was verified under the actual demand condition.
Cluster ①Residential loads and FC
Cluster ②Residential loads and FC, PV
SOC of Batt.② > ① Charge ② to ①by Interconnection inverter
SOC of Batt. ② got low.Back-up inverter started to charge Batt. ②
Cluster① ②
6 Houses 9 Houses
※with PV and FC
Composition Test Result
Stand-aloneInverter①
Stand-aloneInverter②
Back-upInverter
InterconnectionInverter
Backup
Cluster ①
Cluster ②
Batt.1
Batt.2
Stand-alone inverter ①Inter connection inverterFrequency ①
Stand-alone inverter ②Back-up inverterFrequency ②
POW
ER [kW
]Frequency [H
z]
SOC of Batt. ②= F② got low.Back-up inverter started.
Difference of F ② and F①is reflected to the power of Interconnection inverter
１. Background of Japan’s energy industry
２．Technical development of proposed system
∇Overview of technical feature
∇Laboratory test
∇Demonstration in Osaka Gas’s apartment
３．As a key solution for installing large amount of
renewable energy
∇For frequency fluctuation
∇For voltage rising
Contents of Today’s Presentation
13
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Many issues related Renewable Energy Sources, RES, can be solved easily & economically by the proposal system.
As a key solution for installing large amount of RE
Easy to solve underAggregation of Microgrids
No problems under Aggregation of Microgrids
Easy to handle with Aggregation of Microgrids
No problems under Aggregation of
Microgridsis considered as an critical issue.*
[Reference] The Institute of Applied Energy: Seasonal report Vol29 No.2 “Total study about network technology of power system”
Voltage stabilityVoltage regulator problemsInstantaneous voltage fluctuation
Frequency fluctuation
Load flow managementVoltage management
Difficulty in capacity management, lower capacity utilization
Huge counter measure costComplicated regulatory work
(Main) (Sub) (Sub-sub)
Operation
Voltage
FrequencyHarmonicsHigh-freq.
DCStabilized sys.
Sys. management
Equip. managementSys. operation
Facility planning
FlickerImbalance
Voltage/Current DistortionNoise
OutflowRotary actuator
Voltage regulator managementSystem switching
Power loss
Power quality
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In remote area, the cost of power supply is expensive. So there is an incentive for installing renewable energy. But large amount of renewable energy causes fluctuation of frequency.
So, we recommend the installation of proposed system for confining bad effect of renewables.
As a solution for remote area
Battery and Inverter
Battery and Inverter
Diesel power plant (backup power source)
Diesel power plant (backup power source)
Cluster 1Cluster 1
PVPV
Cluster 2Cluster 2
Cluster 3Cluster 3
Aggregation of Microgridsin remote island
The same control system can be applied to other remote areas. It can reduce the installation costs.
The same control system can be applied to other remote areas. It can reduce the installation costs.
Segmented autonomous units realize the improved secure power system.Segmented autonomous units realize the improved secure power system.Fluctuation suppression
and countermeasures against voltage rises are simultaneously achieved.
Fluctuation suppression and countermeasures against voltage rises are simultaneously achieved.
Clusters can be extended gradually.Clusters can be extended gradually.
Autonomous power interchange between clusters depending on the amount of charge in batteries.
Autonomous power interchange between clusters depending on the amount of charge in batteries.
We have conducted a detailed feasibility study jointly with utility company in Japan.
Output of PV + battery
The amount of PV that can be integrated is limited due to its unstable, fluctuating voltage and/or frequency. Fuel saving is limited, and the power quality is not as good
PV + Small generator
・ ・ ・ ・ ・ ・
[Conventional Systems]
Output of PVPV + Small generator
Gensets mitigate fluctuation of PV
but not completely
Limited PV allowance・ Gen response not 100%
(load rate cannot be too low)・ PV output fluctuation is a
burden to gensets
Diesel might not be able to completely compensate PV fluctuation
Problem of PV installation into conventional system
Output of generator
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Generator GeneratorOutput of generator
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Aggregation of Microgrids is superior to the conventional solution in cost and extensibility.
So that it will be a good solution for installing massive amount of renewable energy in remote.
Comparison with conventional solution
・ ・ ・
[ Proposed method (Aggregation of Microgrids) ]
・ ・ ・
Aggregation of Microgrids
Output of PVOutput of PV +
stand-alone system
Output of stand-alone system
PV + Small generator
Suppressing the
fluctuation of
renewable energy
PV + Small generator
Generator Output of generator
The fluctuation of renewable energy doesn’t effect to the
generator.
U
V
W
House
House
SW
BATT
1φINV
House
HouseBATT
1φINV
1φINV
1φINV
1φINV
BATT
1φINV
3φLoad
BATT
3φINV
6.6kV
House
House
House
House
1φTr.
In Japanese distribution line, there are high voltage lines(6.6kV) and then step down to low voltage by pole transformer. These are the design method for clustering of secondary of pole transformer.
1φINV
【Clustering for single phase line】
3φLoad
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3φINV
Inverter & battery
Detailed clustering design for actual distribution line
【Clustering for three phase line】
1φTr. 1φTr.
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Field investigationCandidate place for installing PV① Candidate place for installing PV②
Candidate place for installing Batt & Inverter①
Candidate place for installing Batt & Inverter②
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Many issues related Renewable Energy Sources, RES, can be solved easily & economically by the proposal system.
As a key solution for installing large amount of RE
Easy to solve underAggregation of Microgrids
No problems under Aggregation of Microgrids
Easy to handle with Aggregation of Microgrids
No problems under Aggregation of
Microgridsis considered as an critical issue.*
[Reference] The Institute of Applied Energy: Seasonal report Vol29 No.2 “Total study about network technology of power system”
Voltage stabilityVoltage regulator problemsInstantaneous voltage fluctuation
Frequency fluctuation
Load flow managementVoltage management
Difficulty in capacity management, lower capacity utilization
Huge counter measure costComplicated regulatory work
(Main) (Sub) (Sub-sub)
Operation
Voltage
FrequencyHarmonicsHigh-freq.
DCStabilized sys.
Sys. management
Equip. managementSys. operation
Facility planning
FlickerImbalance
Voltage/Current DistortionNoise
OutflowRotary actuator
Voltage regulator managementSystem switching
Power loss
Power quality
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Countermeasure for voltage rises by Aggregation of Microgrids
Distribution Voltage
MAXVoltage
MINIVoltage When PV output exceeds the load[kW], this
becomes a disturbance to the network .
Stand-alone inverter
Grid connected PV
PV with “Aggrigation of Microgrids”
Distribution Voltage
MAXVoltage
MINIVoltage Stand-alone inverter can control distribution voltage to
reduce the voltage rise, and support installing PV generation.
Interconnection inverter
Both the system structure and action enables the suppressive effect for voltage rises.In addition, ingenious inverter control can realize more effective measures.
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Aggregation of Microgrids ScorecardConvetional System vs. Aggregation of Microgrids : Aggregation of Microgrids can allow massive RES into the system. More fuel saving, and higher grid reliability.Micro Grid vs. Aggregation of Microgrids : Aggregation of Microgrids has cost advantages because of built-in control function, and does not require complex external control stations.
Aggregation of
Microgrids
Conventional system
[ Diesel + PV ]
Micro Grid System[ Diesel + PV +
Large Scale Battery]
System Capability Excellent Fair Excellent
Fuel saving Excellent Fair ExcellentQuality of power Excellent Fair GoodSecurity Excellent Fair FairCost of Initial investment Fair Excellent FairCost of Control System Good Excellent Fair
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Concluding remarks
Osaka Gas has been working on the research and development of a new type micro grid jointly with VPEC Inc. (currently, WINDEC Corp.) as a cooperative partner and Waseda University.
The new system has already demonstrated under the actual loading condition. And we have conducted a detailed feasibility study jointly with utility company in Japan. The technologies of this system has been proven.
We are expecting to develop the field of application by taking advantages of characteristics of this proposed system.
Now, we are searching for various partners domestically and internationally in the field of inverter and battery manufacturers, engineering companies and utilities as our strong partners in expanding the businesses.
