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Opportunities for Battery Storage and Australian Energy Storage Knowledge Bank Test System for Microgrid Applications

Nesimi Ertugrul, Graeme Bell, Gabriel G. Haines and Qing Fang

University of Adelaide School of Electrical and Electronic Engineering nesimi.ertugrul@adelaide.edu.au

• Distributed generation (embedded generation) include various sources (biomass-based

generators , combustion turbines, concentrating solar power and photovoltaic systems, fuel cells, wind turbines, microturbines, engine/ generator sets) and storage and control technologies.

• They are usually modular (allowing for easy deployment) or may have storage located

near the point of use.

• They can be grid-connected (by interfacing at the distribution system) or operated

independently of the grid.

• Provides secure uninterrupted power supply
• More choice in fuel supply options
• Can be quieter and less polluting
• Can help reduce the load on distribution and transmission systems : reduction of line

losses and helping increase reliability of the electric system

• Flexible electric power: on-/off-grid reducing dependence on centralized power plants.
• Can meet base load/peak-shaving/backup/remote/grid support power needs.
• Can help reduce the cost of distribution system maintenance and operation which

account for half of the retail price of electric service.

Distributed Power Generation/Battery Storage Features of Distributed Power Generation

Distributed Power Generation/Battery Storage Issues

• Demand is unpredictable, generation (predictable !) must meet demand
• Renewable energy (generation !) is also unpredictable
• Australian Network:
• Is weak, long and thin (rural farming and community loads)
• Have limited import/export opportunities (between the states)
• Have large load variations (associated with heat waves, or mining loads)
• Have low power system inertia (due to decommissioning old power stations)
• In Australia:
• Fringe-of-grid areas, isolated or islanded systems, and remote/very remote areas

(mining sites) are likely to experience reliability and power quality issues.

• The battery storage can also offer significant savings in off-grid applications.
• Voltage fluctuations are the major issues with the integration of renewable energy
• The randomness of the mining loads and their co-incident simultaneous operation

the demand cycle of the multiple loads might have a very large short term power variation incidentally.

• Steep ramps: Lower base load and relatively unchanged peak demand means that

utilities would need to increase or decrease baseload generation capacity (large coal or nuclear power plants), or diesel or natural gasfired ramping generators.

• Hence utility and industry scale battery storage applications can be utilized
• However, careful management is required !
• It is predicted that (Navigant Research) 11 GW of energy storage capacity will be

installed annually by 2020 in 22 countries (1/3 is in Asia and Oceania).

Distributed Power Generation/Battery Storage A forthcoming issue: Duck Curve/ Steep ramps

Distributed Power Generation/Battery Storage Utility scale battery storage applications

Generation Level Transmission Level Distribution Level

 Fast-response

frequency regulation

 Black start  Spinning

reserve

 Back-up and

mission critical power

 Power plant

hybridization

 Ramp rate

management

 Peak demand

management

 Mitigating

intermittency (firming)

 Dynamic line

rating support

 Dynamic stability

support

 Reducing

interconnection cost

 Voltage support of

long radial circuits

 Energy storage for

utilities

 Facilitating high PV

penetration embedded microgrids

 Energy arbitrage  Ramp-Rate control

• f PV inputs

 Increase asset efficiency and utilization and

ancillary services

 Loss reduction  Voltage support  Peak-shaving, load and time shifting  Power quality improvement  Power reduction in curtailment events to shut

down to mitigate issues associated with generator loading, export to the grid, or certain planning conditions.

 Renewable integration

(wind and solar)

 Asset deferral 

Reactive power control

Distributed Power Generation/Battery Storage Technical characteristics of battery storage applications

Technical Characteristics Common Storage Applications Power (MW) Backup Time Cycles /Year Storage Response Time Spinning reserve ~100 hours 20-50 sec to min Load levelling ~100 hours 250 minutes Black start ~100 hours seldom <1 min Investment deferral ~100 hours >100 minutes Power regulation with intermittent sources <10 min 1000s <1 min Integration of non- predictable sources ~10 min frequent <min Power quality <1 min <100 10s - 1 min Line stability ~100 sec 100 ~ cycles Power oscillation damping <1 sec 100 ~ cycles

Power versus Energy !

Australian Battery Storage Test System ARENA Project/University of Adelaide

Aim: “Accelerate growth of energy storage industry in Australia by real tests on system components and applications, knowledge sharing and training. Australian Energy Storage Knowledge Bank (AESKB)

• Central Repository will include:

Case studies, trial / test data, network performance outcomes, storage system level, environmental data, battery level data, link with other databases / projects around Australia and the world, reports, research publications.

Australian Battery Storage Test System Test System Architecture

• Extended version of a modern energy storage system !
• Standard termination arrangements for interconnecting cables from battery, smaller

distributed controllers facilitate customisation at BMS interface, access to software by the university facilitates delivery of custom interfaces at the BMS interface, and Internet

• f Things controller architecture.
• Initial and Final battery capacity, Charge / Discharge profiles and Battery Cell / Module

Characteristics / Tests, Power Quality

Diesel Gen Solar PV DUT (Spare) 3 x PCS100 ABB Inverter Modules 270kW

Isolating Transformer (360 kVA) MV Distribution Line (or microgrid) Container

Local LV load (Embedded Microgrid)

Load bank (200kW)

Safety Interlock

Normal Duty Battery

(LG Chem, 273 kWh, 3 strings, 820V dc)

Battery (DUT)

Features of Battery Storage Systems

CONVERTER: Bidirectional DC SIDE : DC protections, DC voltage ranges, DC current ripple, keep safe operating conditions AC SIDE: System operator related : flexible, ancillary, reactive support, black start, ramp rate control PERFORMANCE: Harmonics, time response, cooling, efficiency, power deratings CONTROL AND COMMUNICATIONS: Frequency, power input/output in MV, the state of charge, the control mode by BMS, historical view of data, alarms EPC (ENGINEERING, PROCUREMENT, CONSTRUCTION) AND INTEGRATION : Companies doing EPC: Such ABB, Siemens, AES, ABENGOA and also locals (Magellan, ZEN) GRID INTERCONNECTION: Interconnection point (distribution line , transmission line, suburb, urban/ rural, safety, noise, location, lightning , grounding etc., Communication/protection requirements by the T/D providers Ability and cost of interconnecting, Size of the distributed generation system, Voltage considerations

Diesel Gen Solar PV DUT (Spare) 3 x PCS100 ABB Inverter Modules 270kW

Isolating Transformer (360 kVA) MV Distribution Line (or microgrid) Container

Local LV load (Embedded Microgrid)

Load bank (200kW)

Safety Interlock

Normal Duty Battery

(LG Chem, 273 kWh, 3 strings, 820V dc)

Battery (DUT)

Sizing and design is all around the storage technology !

• 1. Parallel to Mains only, No Islanding

OR

Australian Battery Storage Test System Operational Modes of the Test System

• 2. Parallel to grid / with islanding of MV tail section

Australian Battery Storage Test System Operational Modes of the Test System

• 3. Parallel to Mains with islanding of LV network section

Australian Battery Storage Test System Operational Modes of the Test System

• 4. Embedded LV Microgrid

*

Australian Battery Storage Test System Operational Modes of the Test System

• 5. Isolated diesel-dominant microgrid (PV integration and load

threshold support only):

*

Australian Battery Storage Test System Operational Modes of the Test System

Test Set points

• 6. Testing other energy storage installations

Example 1 (Absorb excess PV + Evening Assist)

Australian Battery Storage Test System Operational Modes of the Test System

Test Set points

• 6. Testing other energy storage installations

Example 2 (Ramp Rate Control)

Australian Battery Storage Test System Operational Modes of the Test System

Australian Battery Storage Test System Hardware System

• Custom container to accommodate switchgear,

control, battery systems and measurement hardware

• The weather station (with pyranometer), both 4G

antennas, and the GPS antenna and lightning protection system are located outside of the energy storage enclosure

• Physical layout of the data logging system

Australian Battery Storage Test System Data Logging System Diagram

Australian Battery Storage Test System Network Plan

The 4G router/VPN gateway allows for remote monitoring of the data acquisition system

Australian Battery Storage Test System Data Handling Process

Australian Battery Storage Test System Web Site Summary

Conclusions

DGT’11 #22

• Distributed generation systems issues
• Battery storage applications
• Australian Energy Storage Knowledge Bank
• Description
• Capabilities

What defines the performance and overall efficiency of BSS ?

• Battery technology
• Converter
• Protection and cabling
• Isolation transformer (at the output of the converter) and/or D/T

transformer

• Point of common connection (to GRID: includes all the stages, to the

OFF-GRID: after the converter stage hence the efficiency of protection and cabling and transformer is not counted!)

Features of Battery Storage Systems

Features of Battery Storage Systems Battery packaging and Balancing

Battery packaging: Cell Module/Rack Bank Section Rack Balancing Unbalance occurs among the racks (due to initial installation or rack replacement) The rack voltages can be synchronized in the connecting sequence. The battery modules can be grouped together in a parallel or serial combination to achieve desired voltage/current output.

Features of Battery Storage Systems Data Points in Battery Management System (BMS) Protocol

• Status
• Final charge/discharge info
• Overcharge/over discharge/over temperature info
• Unit SOC
• Max voltage value of cells in the unit
• Minimum voltage of cells in the unit
• Max temperature value of each cell
• Average temperature value of each cell
• Min temperature value of each cell
• Max cell voltage value of the modules
• Min cell voltage of the module
• Max. cell temperature value
• Min. cell temperature value
• Unit charge current
• Unit discharge current
• Unit voltage
• Unit SOC (%)
• Cell failures in the modules
• Cell balance status in the modules
• Cell voltages
• Cell Temperatures

Battery Safety Standards

 There are no mandatory requirements for lithium battery safety testing !  Since product safety is important, certifications are a means of demonstrating product safety as raising brand image and liability. Three questions about Lithium Battery Safety in practice:  Does self-certify or use an independent third-party testing needed ? Prefer the lab is ISO/IEC 17025 accredited, and approved by nationally recognised testing laboratories and safety institutions (as Nationally Recognized Testing Laboratory (NRTL) and OSHA (Occupational Safety and Health Administration).  Is cell testing necessary ? Note that new cell designs are generally certified by the cell manufacturer and battery (module) certification is the responsibility of the end-user / application device manufacturer  Does battery certification needed ? Depending on your market needs, one of the following should be considered: UL 2054 (for general battery safety certification; global recognition and acceptance) IEC 62133 (for Europe and CB Scheme certification) SAE J2464 / J2929 (for Electric and Hybrid Vehicles; other standards for Light Electric  Standards primarily include abuse tests, transport and recycling …..

Standards Battery safety standards related matrix

Distributed Power Generation/Battery Storage Technical characteristics of battery storage applications

Distributed Power Generation/Battery Storage Energy Storage Technologies and Batteries

CAPACITY/LIFE/CRITICAL VALUES

• Battery Capacity (C Rate)
• Battery Capacity/Temperature
• Open-Circuit Voltage
• Cut-off voltage (threshold voltage)
• Resting time
• Cycle life
• Calendar life
• State of Health (SoH)
• The beginning-of-life (energy) (BOL)
• The end-of-life (energy) (EOL)
• Cycle pattern

EFFICIENCY

• Energy efficiency =

Voltage efficiency x Coulomb efficiency

Battery terminology/definitions

CHARGE/DISCHARGE

• State of Charge (SoC)
• State of Discharge (SoD)
• Depth of Discharge (DoD)
• Discharge Rate

ENERGY

• Battery Energy
• Specific Energy (Energy Density)

POWER

• Battery Power
• Specific Power (Power Density)
• Maximum Battery Power
• Ragone Plots (Power density versus

Energy Density)

DGT’11 #32

Life time-analysis model uses three primary components of batteries:

 Electrical model

• Energy accounting model (It requires specification of available battery energy,

maximum power limits, and direct current efficiency then battery SOC is calculated by integrating power flows. Allowable power is calculated from the specified power limits and SOC, and heat generation is computed using the DC efficiency value.)

• Equivalent circuit model (It calculates battery voltage and heat generation as a

function of current)  Thermal model (Used to simulate battery temperature, using the generated heat value from the electrical model, the thermal mass of the battery, thermal connections to a system container and the ambient environment, and consideration of active cooling and heating systems)  Degradation (wear) model The model captures sensitivity to voltage, SOC, temperature, depth of discharge, and cycling frequency to forecast irreversible reductions in battery capacity and increases in battery resistance due to loss of active sites, solid electrolyte interface layer growth, and other electrochemical degradation processes that occur within Li- ion batteries.

Battery terminology/definitions, battery technologies

Life time-analysis model

Battery technologies A comparison between different battery chemistries

UL Underwriters Laboratories, an independent safety science company IEC The International Electrotechnical Commission (IEC), writes international standards NEMA National Electric Manufactures Association SAE Society of Automotive & Aerospace Engineers UN United Nations IEEE The Institute of Electrical and Electronics Engineers JIS Japanese Standards Association BATSO Battery Safety Organization CTIA The Cellular Telephone Industries Association UN/DOT United Nations/Department of Transport BMS Battery Management System BMU Battery Management Unit DSC Differential Scanning Calorimetry PHS: Pumped hydroelectric storage CAES: Compressed Air Energy Storage Zebra Zero Emissions Batteries Research Activity

Appendix Acronyms