1. Energy Storage Systems For Advanced Power Applications
Paulo F. Ribeiro, Ph.D., MBA
Calvin College
 Grand Rapids, Michigan, USA

2. Energy Storage Energy is a Life Sustainable Business Sustainability
Efficiency
Performance
Conservation
Renewable Sources
Present socio-economic realities – limits developments
Better Understanding of Performance Issues is Needed

3. Abstract Energy storage technologies do not represent energy sources
Energy storage technologies do not represent energy sources
Provide valuable added benefits to improve:
stability, power quality and security of supply.
Battery Technologies
Flywheel Technologies
Advanced / Super Capacitors
Superconducting Energy Storage Systems

4. Introduction Electric Power Systems - Experiencing Dramatic Changes
Electric load growth and higher regional power transfers in a largely interconnected network: >>complex and less secure power system operation.
Power generation and transmission facilities - unable to meet these new demands
Growth of electronic loads has made the quality of power supply a critical issue.
Power system engineers facing these challenges - operate the system in more a flexible.
In face of disturbances - generators unable to keep the system stable.
High speed reactive power control is possible through the use of flexible ac transmission systems (FACTS) devices.
Better solution: rapidly vary real power without impacting the system through power circulation.
Recent developments and advances in energy storage and power electronics technologies

5. Energy Storage Systems for Advanced Transmission and Distribution Applications
Energy Storage Technology – Power Convert
Factors:
The amount of energy that can be stored in the device.
The rate at which energy can be transferred into or out of the storage device.
Power/Energy ranges for near to mid-term technology have projected
Integration of energy storage technologies with Flexible AC Transmission Systems (FACTS) and custom power devices are among the possible advanced power applications utilizing energy storage.

6. for Near to Midterm Technology
Power vs. Energy Ranges
for Near to Midterm Technology
SMES
100 10
Power (MW)
Flywheel
Batteries
Capacitor 1 1 10
100
1000
Energy
(MWsec)
Benefits: transmission enhancement, power oscillation damping, dynamic voltage stability, tie line control, short-term spinning reserve, load leveling, under-frequency load shedding reduction, circuit break reclosing, sub-synchronous resonance damping, and power quality improvement.

7. Source ASA

8. A. Superconducting Magnetic Energy Storage (SMES)

9. A. Superconducting Magnetic Energy Storage (SMES)

10. Solenoid Configuration
A. Superconducting Magnetic Energy Storage (SMES)
Solenoid Configuration
(100 MJ – 4kA - 96MW System)

11. A. Superconducting Magnetic Energy Storage (SMES)
SMES’ efficiency and fast response capability (MW/millisecond) have been, and can be further exploited in applications at all levels of electric power systems. Potential applications have been studied since 1970’s.
load leveling,
frequency support (spinning reserve) during loss of generation,
enhancing transient and dynamic stability,
dynamic voltage support (VAR compensation),
improving power quality,
increasing transmission line capacity, thus enhancing overall security and reliability of power systems.
Further development continues in power conversion systems and control schemes, evaluation of design and cost factors, and analyses for various SMES system applications..
[iii] D. Lieurance, F. Kimball, C. Rix, C. Luongo, ”Design and Cost Studies for Small Scale Superconducting Magnetic Energy Storage Systems,” IEEE Transactions on Applied Superconductivity, vol. 5, no. 2, June 1995, pp
S.M. Schoenung, W.R. Meier, R. L. Fagaly, M. Heiberger, R.B. Stephens, J.A. Leuer, R.A. Guzman, ”Design, Performance, and Cost Characteristics of High Temperature Superconducting Magnetic Energy Storage,” IEEE Transactions on Energy Conversion, vol. 8, no. 1, March 1993, pp

12. A. Superconducting Magnetic Energy Storage (SMES)
Energy-power characteristics for potential SMES applications for generation, transmission, and distribution.

13. B. Battery Energy Storage Systems (BESS)
B. Battery Energy Storage Systems (BESS)
Batteries are one of the most cost-effective energy storage technologies available, with energy stored electrochemically.
Key factors in battery for storage applications include: high energy density, high energy capability, round trip efficiency, cycling capability, life span, and initial cost.
Battery technologies under consideration for large-scale energy storage.
Lead-acid batteries can be designed for bulk energy storage or for rapid charge/discharge.
Mobile applications are favoring sealed lead-acid battery technologies for safety and ease of maintenance.
Valve regulated lead-acid (VRLA) batteries have better cost and performance characteristics for stationary applications.
Photo Source: UP Networks

14. BESS Example – Transmission/Distribution Application
Lead-acid batteries, have been used in a few commercial and large-scale energy management applications.
The largest one is a 40 MWh system in Chino, California, built in The table below lists and compares the lead-acid storage systems that are larger than 1MWh.

15. C. Advanced / Super / Capacitors
The amount of energy a capacitor is capable of storing can be increased by either increasing the capacitance or the voltage stored on the capacitor.
The stored voltage is limited by the voltage withstand strength of the dielectric.
As with batteries, the turn around efficiency when charging/discharging capacitors is also an important consideration, as is response time.
The effective series resistance of the capacitor has a significant impact on both. The total voltage change when charging or discharging capacitors is shown in equation 2 1 CV E = CV q = d A C e =
tot R i C dt dV * + =

16. C. Advanced / Super / Capacitors
                                                                                                                                                                                                                                                         
NESSCAP 10F/2.3V

17. Advantages Disadvantage
C. Advanced Capacitors
Advantages Disadvantage
Power (higher density) Energy Density
Energy Efficiency (higher)
Maintenance
Discharge
Parameters Electrostatic Cap Ultra-Cap Battery
Discharge 10E-3-6 sec sec hours
Charge 10E-3-6 sec sec 1-5 hours
Energy Density <0.1 Wh/kg 1-10Wh/kg Wh/kg
Power Density >10E4Wh/kg E4Wh/kg 5-200Wh/kg
Charge Eff. ~
Cycle life infinite >500,
Ness Caps

18. E = I D. Flywheel Energy Storage (FES) 1 2 2
Flywheels can be used to store energy for power systems when the flywheel is coupled to an electric machine.
Stored energy depends on the moment of inertia of the rotor and the square of the rotational velocity of the flywheel.. Energy is transferred to the flywheel when the machine operates as a motor (the flywheel accelerates), charging the energy storage device. The flywheel is discharged when the electric machine regenerates through the drive (slowing the flywheel).
Active Power, Inc. 1 2 E = I
The moment of inertia (I) depends on the radius, mass, and height (length) of the rotor 2
The energy storage capability of flywheels can be improved either by increasing the moment of inertia of the flywheel or by turning it at higher rotational velocities, or both.

19. D. Flywheel Energy Storage (FES)
Flywheel energy storage coupled to a dynamic voltage restorer.

20. Example – End-User Application Energy Storage / UPS Systems
Manufacturer
Technology
Capacity (kW)
Capacity (time) A
Flywheel
120 kW
20 sec B
Flywheel/Battery
160 kW
15-30 min C
Battery
kVA
15 min
kVA
10 min
kVA
13 min
kVA
17 min D
1250 kVA
700 kW E
kVA
6-12 min F
kVA
5-60 min G
kVA
5-59 min H
kVA
Source: EPRI

21. Advanced Power Systems Applications
SMES can inject and absorb power rapidly, but battery and flywheel systems are modular and more cost effective. Advanced flywheels and advanced capacitor technologies are still being developed and are emerging as promising storage technologies as well.
Performance \ ESS
SMES
BESS
FES
Advanced
capacitor
Dynamic Stability
Needs to be explored
Transient Stability
Voltage Support
Area Control/ Frequency Regulation
Transmission Capability Improvement
Power Quality Improvement

22. A. Integration of Energy Storage Systems into FACTS Devices
FACTS controllers are power electronics based devices that can rapidly influence the transmission system parameters such as impedance, voltage, and phase to provide fast control of transmission or distribution system behavior.
FACTS controllers that can benefit the most from energy storage are those that utilize a voltage source converter interface to the power system with a capacitor on a dc bus. This class of FACTS controllers can be connected to the transmission system in parallel (STATCOM), series (SSSC) or combined (UPFC) form, and they can utilize or redirect the available power and energy from the ac system.
Without energy storage, FACTS devices are limited in the degree of freedom and sustained action

23. A. Integration of Energy Storage Systems into FACTS Devices
Steady State
Issues
Voltage Limits
Thermal Limits
Angular Stability Limits
Loop Flows
Dynamic
Issues
Transient Stability
Damping Power Swings
Post-Contingency Voltage Control
Voltage Stability
Subsynchronous Res.
Traditional Solutions
Breaking Resistors Load Shedding
Advanced Solutions
FACTS
Energy Storage
Fixed Compensation
Transmission Link
Enhanced Power Transfer and Stability
Line Reconfiguration
Better Protection
SVC
STATCOM
TCSC, SSSC
UPFC
FACTS
Devices
Increased Inertia

24. A. Integration of Energy Storage Systems
Energy Storage for
Generation
Transmission
Distribution
End-User
Functions
Spinning Reserve
Load Leveling
Transmission Cap.
Reliability
Stability
Continuity
Reliability
Power Quality
Power Quality
Configurations
Shunt Comp.
Shunt / Series Comp.
Shunt / Series Comp.
Shunt Comp.
Applications
FACTS Devices
Statcom
PQ Parks
Arc Furnace

25. STATCOM with SMES

26. STATCOM with SMES
The performance of a power-electronics -energy-storage-enhanced device is very sensitive to the location with regard to generation and loads, topology of the supply system, and configuration and combination of the compensation device.
STATCOM/SMES dynamic response to ac system oscillations

27. Enhanced Voltage and Stability Control
STATCOM with SMES
Location and Configuration Type Sensitivity
2 STATCOMs
1 STATCOM + SMES
Voltage and Stability Control
Enhanced Voltage and Stability Control
System Frequency
(Hz)
60.8
59.2
time (sec)
(2 x 80 MVA Inverters)
( 80 MVA Inverter + 100Mjs SMES)
No Compensation

28. FACTS with BESS

29. FACTS with BESS Predicted and experimental response of the SSSC/BESS
FACTS with BESS
(b) reactive power from 755Var to 355Var
(a) active power from 50W to 400 W
Predicted and experimental response of the SSSC/BESS

30. FACTS with BESS Active power flow between areas
FACTS with BESS
(a) STATCOM vs STATCOM/BESS
(b) SSSC vs SSSC/BESS
(c) STATCOM/BESS vs SSSC/BESS vs UPFC
Active power flow between areas

31. FACTS with BESS Voltage at Area 2 bus (a) STATCOM vs STATCOM/BESS
FACTS with BESS
(a) STATCOM vs STATCOM/BESS
(b) SSSC vs SSSC/BESS
(c) STATCOM/BESS vs SSSC/BESS vs UPFC
Voltage at Area 2 bus

32. B. Advanced HVDC Transmission and Distribution
Improvements in power electronic device technologies have led to significant improvements in the flexibility of dc transmission systems through the ability to use voltage source converters.
Traditional direct current systems see limited use as high power, high voltage dc (HVdc) transmission systems.
Advanced dc systems allows lower voltage dc transmission system capable of supporting a large number of standard “off the shelf” inverters.
Energy storage can be added to the dc system, providing improved response to fast load changes drawn by the inverters.
DC system with capacitive energy storage added to the dc system through a dc to dc converter.

33. C. Power Quality Enhancement with Energy Storage
Custom power devices address problems found at distribution level, such as voltage sags, voltage swells, voltage transients and momentary interruptions.
The most common approaches to mitigate these problems focus on customer side solutions such as Uninterruptible Power Supply (UPS) systems based on battery energy storage.
Alternative UPS systems based on SMES and FESS are also available.
Dynamic voltage restorer (DVR) with capacitor storage

34. Q FACTS + Energy Storage P
The Role of Energy Storage: real power compensation can increase operating control and reduce capital costs
STATCOM
Reactive Power Only
Operates in the vertical axis only P
MVA Reduction
P - Active Power
Q - Reactive Power
The Combination or Real and Reactive Power will typically reduce the Rating of the Power Electronics front end interface.
Real Power takes care of power oscillation, whereas reactive power controls voltage.
STATCOM + SMES
Real and Reactive Power
Operates anywhere within the
PQ Plane / Circle (4-Quadrant)

35. Power Electronics - Semiconductor Devices
Decision-Making Matrix

36. Universal Topology + Energy Storage Implementation E2 / 2 E1 / 1 P&Q X
Regulating Bus Voltage + Injected Voltage + Energy Storage
Can Control Power Flow Continuously, and Support Operation Under Severe Fault Conditions (enhanced performance)
Plus Energy Storage

37. Cost Considerations
Energy storage system costs for a transmission application are driven by the operational requirements.
The costs of the system can be broken into three main components:
The energy storage system,
The supporting systems (refrigeration for SMES is a big item) and
The Power Conversion System.
The cost of the energy storage system is primarily determined by the amount of energy to be stored. The configuration and the size of the power conversion system may become a dominant component for the high-power low-energy storage applications. For the utility applications under consideration, estimates are in the range of $10-100K per MJ for the storage system.  

38. Cost Considerations
In order to establish a realistic cost estimate, the following steps are suggested:
·  identify the system issue(s) to be addressed;
·   select preliminary system characteristics:
·  define basic energy storage, power, voltage and current requirements;
·  model system performance in response to system demands to establish effectiveness of the device;
·  optimize system specification and determine system cost;
·  determine utility financial benefits from operation;
·  compare system’s cost and utility financial benefits to determine adequacy of utility’s return on investment,
·  compare different energy storage systems performance and costs

39. Technology & Cost TrendsI
$$$ $
additional cost savings possible

40. Conclusions
Potential performance benefits produced by advanced energy storage applications:
improved system reliability
dynamic stability
enhanced power quality
transmission capacity enhancement
area protection, etc..
FACTS (Flexible AC Transmission Systems) devices which handle both real and reactive power to achieve improved transmission system performance are multi-MW proven electronic devices now being introduced in the utility industry. In this environment, energy storage is a logical addition to the expanding family of FACTS devices.

41. Conclusions
As deregulation takes place, generation and transmission resources will be utilized at higher efficiency rates leading to tighter and moment-by-moment control of the spare capacities.
Energy storage devices can facilitate this process, allowing the utility maximum utilization of utility resources.
The new power electronics controller devices will enable increased utilization of transmission and distribution systems with increased reliability.
This increased reliance will result in increased investment in devices that make this asset more productive.
Energy storage technology fits very well within the new environment by enhancing the potential application of FACTS, Custom Power and Power Quality devices.