Demonstration Project utilizingHybrid Storage Battery System

in the Oki-islands

June 16, 2016Power System Division

The Chugoku Electric Power Co., Inc.

Subsidized project of Ministry of the Environment

1

１．Overview of the Oki-Islands

2Overview of the Oki-islands The Oki-islands are located in the Sea of Japan, about 50km to the north of

Shimane Peninsula. Composed of the “Dozen” and “Dogo” and about 180 small islands. The total area is about 350km2. A population is about 21,100 (Dozen: about

6,100, Dogo: about 15,000). Fisheries, agriculture and forestry, tourism are their major industries.

September 2013Certified as Global GeoparksNovember 2015

Global Geoparks confirmed as UNESCO Global Geoparks

Matengai（Nishinoshima）

Nishinoshima（Nishinoshima）

Nakanoshima（Ama）Chiburijima

（Chibu）

Dogo（Okinoshima）

【Dogo】【Dozen】

Rousokuiwa（Dogo）

The Oki-Islands

Oki-Islands UNESCO Global Geopark

(Source: Wikipedia, Japan natural location map with side map of the Ryukyu Islands.jpg)

3Electrical power supply facilities and demand in the Oki-Islands (Before start of project)

Dozen

Dogo

Saigo-Kuroki submarine power cable (22kV,18km)

Oki IslandsTotal capacity: 32.70MW+ wind, hydromaximum demand during 2012: 24.1 MW

DozenTotal capacity: 7.38 MWMaximum demand during 2012: 7.3 MW

DogoTotal capacity: 25.32 MW+ Wind, HydroMaximum demand during 2012: 16.8 MW

Kuroki Plant(internal combustion)

(7.38 MW)

2 internal combustion power plants(heavy oil diesel) “Saigo” and “Kuroki”, supply almost all the electricity with 22kV tie line.

Maximum Power demand is about 24ＭＷ，minimum is about 10ＭＷ.

Yui Plant (hydroelectric dam)

(0.2 MW)

Prefectural Ohmineyama Plant (wind)(Three 600-kW towers for 1.8 MW total)

Minamitani Plant(hydroelectric run-of-river)

(0.1MW)

Saigo Plant(internal combustion)

(25.32 MW)

4Renewable energy in the Oki-Islands（Before start of the project）

10.0

12.0

14.0

16.0

18.0

20.0

22.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

春（５月）夏（８月）秋（１０月）冬（１月）

（MW）

wind power plant（1.8 ＭＷ）

Shimane PrefecturalBureau of Enterprise

hydroelectric plant（0.3 ＭＷ）

The Chugoku Electric Power

residential PV（about 0.8 MW)

(As of Jan. 2014）

Large fluctuations between seasons

（Surplus power generation will

occur during light-load seasons）

DemandCharacteristic

Large-scale introduction of renewable energy used to be difficult

(Hours)

Seasonal typical demand-curves in 2012Spring(May)

Summer(August)

Autumn(October)

Winter(January)

5

２．Overview of demonstration Project utilizing

Hybrid Storage Battery System

6Challenges for large renewable energy

penetration in the Oki-Islands

6 129 15 18 21 243

Photovoltaic

Increase of Renewable energy〔MW〕

Use of surplus powerat night time

demand

Base-load generation

〔Hours〕

Renewable energy output fluctuation

Lack of frequency regulation capacity

Surplus power generated

Output fluctuation of REdue to such as a change in the

position of the sun

Output fluctuation of REdue to such as transit of cloud

Short term fluctuation Long term fluctuation

7Concept of Hybrid Storage Battery System

Problem

Simultaneous solution

Hybrid Storage Battery System

Coordination

Increase of Renewable energy

Output

TimeBase-load generation

Demandcurve

Renewable energy(existing)

[Fast and small fluctuation]ex.)Fluctuation

by passing cloud

[Slow and large fluctuation] → use PV output at night

ex.)Fluctuation by locating sun

Fast and small fluctuation↓

Small capacity and high-output

Lithium ion battery（Li-ion)

Slow and large fluctuation↓

Large capacity

Sodium-sulfur battery（NAS)

Sodium-sulfur battery(NAS)Lithium ion battery(Li-ion)

Countermeasure of short term fluctuation

Countermeasure of long term fluctuation

8

西ノ島変電所

Period : From September 2015 to March 2019 （3.5 years） Items: ① Coordinated control between storage battery and diesel generation

② Charge/discharge control technology in order to take full advantage of the storage battery capacity

③ Output allocation of the lithium-ion and the NAS batteries

Dozen

Dogo

西ノ島変電所

Hybrid Storage Battery SystemType Output Capacity

NAS 4,200kW 25,200kWh

Li-ion 2,000kW 700kWh

Nishinoshimasubstation

Hybrid StorageBattery System

6,200kW

Large-scale PV Plant 2,000kW

NEW

NEW

NEW

NEW

NEW

Outline of the Demonstration Project

Prefectural Ohmineyama Plant (wind)(Three 600-kW towers for 1.8 MW total)

Minamintani Plant(hydroelectric run-of-river)

(0.1MW)

Saigo Plant(internal combustion)

(25.32 MW)

Yui Plant(hydroelectric dam)

(0.2 MW)Kuroki Plant(internal combustion)

(7.38 MW)

AmaPlant(wind)2,000kW

residential PV

500kW

Saigo-Kuroki submarine power cable (22kV,18km)

Large-scale PV Plants 3,000kW

9

Aiming at 11MW of total renewable, by newly introducing 8.0MW in addition to the existing 3.0MW, by utilizing the storage battery system.

Renewable energy introduction plan

10

11

Demand Power supply

（M

W）

Minimum demand

Renewable energy

Operational required minimum

output of the internal-combustion

power

Supply and demand image at the time of the minimum demand

Storage battery absorb the surplus power generated by renewable energy

Renewable energy

facilities

Plan

〔MW〕

Record〔MW〕

As of March 31,

2016

Before the start

of the

demonstration

project

Wind power 1.8 1.8

Residential PVAbout

0.8About

0.8

Hydroelectric power 0.3 0.3

SubtotalAbout

3.0About

3.0

After the start

of the

demonstration

project

Large scale PVAbout

5.03.0

Wind power plant 2.0 0.0

Residential PVAbout

0.5About0.

3

SubtotalAbout

8.0About

3.3

TotalAbout

11.0

About

6.3

10

Site area：about 2,400㎡

Grid-connection equipmentTransformers 7,500kVA

NAS batteries4,200kW25,200kWh

PCS for NaS batteries

Control room

NaS batteries

Lithium-ion batteries

PCS for Lithium-ion

batteries

Grid-connection equipment

Installed facilities and equipments

The Nishinoshimasubstation

Lithium-ion batteries2,000kW700kWh

NaS batteries

NaS batteries

NaS batteries

Designed as compact as possible, considering safety measures for NAS characteristics and noise mitigation for neighbor residences.

11Benefits of hybrid scheme for storage battery system

Combination of different types of storage battery system

Initial cost reduction

about 30%

Improvement of charge/discharge management of NAS batteries

Improvement of system efficiency

Cost reduction

■In hybrid storage battery system, the frequency of SOC reset can be increased by sharing the absorbing capacity for RE output fluctuation between NAS and Li-ion battery, and SOC operational range is possible to expand.

■Reduction of auxiliary power consumption can be achieved by reducing the capacity of NAS battery, that improves the system efficiency of storage battery system.

■Combination of Li-ion and NAS battery can decrease construction cost, because ¥/kW of Li-ion and ¥/kWh of NAS are economical.

SOC Operational range

(NAS only : SOC reset once a week)

SOC Operational range

(Hybrid storage battery system: SOC reset twice a week)

Discharge end Charge end

Expandable Expandable

12

Amount of acceptable renewable energy and the required power output and capacity of storage battery system have been determined by simulation.

Alternative No. 2 in following table was selected.

Optimal combination of the storage battery capacity

Alternatives

Output [MW] Simulation result

CostLi-ionBattery

NASBattery

Capacity of tie-line

Charging/Discharging fluctuation

Frequency deviation

No. 1 1.5 4.8

No. 2 2.0 4.2

No. 3 2.5 3.6

Battery Capacity within the range

Battery Capacity within the range

NAS Battery Capacity over the range

13Hybrid system configuration diagram

300V

290V

The PCS converts betweenDC and AC as well asprotects the facilities frompossible malfunctions ofthe power system.

DC/ACInverter(PCS)

DC AC

DC/ACInverter(PCS)

transmissionlines

Breaker

Switch gearMain transformer

Boost transformer

Lithium-ionbatteries

NaSbatteries

Li-ion (2,000kW) batteries are composed of 500kW unit × 5 set. NAS (4,200kW) batteries are composed of 1,200kW unit × 2 set

and 1,800kW unit 1 set.

14

３．Balancing operation utilizing hybrid Storage Battery System

15

EMS equipped in “Nishinoshima substation” performs centralized control through the telecommunication network.- Main function - ・Forecast of renewable generation and demand

・Charge/discharge control

・Mitigation control of short and long term fluctuation

・Diesel power generation control

Demand and supply control system- ＥＭＳ(Energy Management System) Network -

Power Managementoffice

Control Center

Network

Wind power generation

(new)

PrefecturalOhmineyamawind powergeneration

EMS(terminal)

EMS(terminal)

EMS(terminal)

EMS(main)

Saigo power station

Kuroki power station

Nishinoshimasubstation

Control system

StorageBatteries Photo voltaic

generation(new)

：Tie line：EMS information：Control system information

Legend

16

By means of unmanned automatic operation, coordinated control between storage battery and internal-combustion power is executed.

EMS operation control mechanism

Long term controlShort term control

Renewable generation forecasting

Supply and demand plan（long-term control）

Demand forecast

Li-ion batteryInternal

combustionNAS Battery

・Weather Forecast Data・Historical Data

EMS

⊿P+⊿f Control

Internal combustion output

Frequency

Allocation of control demand

The short-term control demand

Command the number of operating units and the output

Feedback control

Economical load dispatchingor Priority List Method

Supply and demand control（middle-term control）

17Operational performance of the storage battery

Currently, coordinated control performance is generally satisfactory.

(MW)

(Hz)

Example of Coordinated control performance (April 26, 2016)

Total output of Renewable energy

Total output of Internal-combustion

Total demand

NAS battery output

Frequency management value (upper limit)

Frequency management value (lower limit)

Frequency

Lithium ion battery output

Lithium ion batteryAbsorb small fluctuation

NAS batteryDischarge the surplus power during the daytime to peak load

0

60

18

４．Effect and future prospects by the demonstration project

19Expected benefits

②Reduction of environmental impact

By reducing fossil fuel diesel power generation consumption, We can reduce CO2 emissions

③Activation of the local community

Hybrid storage battery is the first challenge in Japan.

Expect an increase of visitors

④Development and application of new technology

Accumulate technical knowledge such as the EMS control logic

Contribute to the solution of global challenges

①Improvement of the power supply stability

Introduction of renewable energy and storage battery system improves the stability of power supply in isolated power system

Verification being continued aiming further penetration of renewables

About 10 thousand tons CO2 reduction per year

20

Acknowledgements

This project was realized with great support of the Ministry of the Environment, through the adoption of the “Storage battery demonstration project for promoting the introduction of renewable energy for remote islands“, subsidized by the ministry.

Also, we have received great cooperation from each municipals of Nishinoshima Town, Oki-Islands, and Shimane Prefecture, in the process of the construction of the substation, and the introduction of renewable energy.

We would like to express our sincere appreciation for the efforts of those concerned.

21

Nakanoshima (Ama)Nishinoshima (Nishinoshima)

chiburijima (Chibu) Dogo (Okinoshima)

＜Demonstration project website (Oki hybrid Daisakusen )＞http://www.energia.co.jp/okihybrid/index.html