1. Franz Frank (ABB Switzerland Ltd) – PowerGen Europe 2010
Significant energy savings and reduced emissions in power plants through variable speed drives
© ABB Group
April 15, 2017 | Slide 1

2. Agenda Savings potential by using variable speed drives
What is a Variable Speed Drive (VSD) system ?
Variable speed drive applications in power stations
Comparison of process control methods with respect to efficiency
References
Payback calculation – case example
ABB medium voltage drives portfolio
© ABB Group
April 15, 2017 | Slide 2

3. Savings potential by using variable speed drives Electrical aux
Savings potential by using variable speed drives Electrical aux. consumption in a coal fired power plant
Auxiliary consumption
5-10% of the produced power dedicated to electrical auxiliary consumption in the power plant (i.e. “losses”)
Processes driven by electric motors consume ~80 % of this electricity
By applying electrical variable speed drives (VSDs), total losses can be reduced by >20 %
In an 800 MW power plant there exists a reduction potential of >8 MW (mounting up to 8 – 12 MEUR capital costs)
Electric Motors
Others (HVAC, lighting, etc.)
© ABB Group
April 15, 2017 | Slide 3

4. What is a Variable Speed Drive (VSD) System ?
Input Frequency Motor Transformer Converter
Usual scope of a VSD system
Consisting of input transformer, frequency converter (also called ‘drive’) and motor
Controlling motor speed, torque and power
On process level control of flow, pressure, level, etc.
always with best possible efficiency !
© ABB Group
April 15, 2017 | Slide 4

5. Main components of a VSD system Input transformer
Main purpose
Voltage matching
Galvanic isolation of the VSD system from the medium voltage mains supply
Possible designs
Dry type transformers
Oil immersed transformers
Efficiencies >99 % possible today, e.g. using ABB EcoDry99plus design
© ABB Group
April 15, 2017 | Slide 5

6. Main components of a VSD system Frequency converter
Main purpose
Continuous adjustment of output voltage and frequency
Benefits
Permanent operation of the motor at its optimum duty point  best possible efficiency
Heavy duty start without overcurrent  no more network dips
Increased system lifetime due to reduced mechanical and thermal stress of the driven equipment
Types of design
Air cooled (up to ~7 MVA)
Water cooled (from ~2 MVA on)
Efficiency typically >98 %
© ABB Group
April 15, 2017 | Slide 6

7. Main components of a VSD system Medium voltage motor
Types of design
Air and water cooled
Forced or self ventilated
Induction motors
Power range: up to ~22 MW
Efficiencies of >97 % possible today
Synchronous motors
Power range: >100 MW
Efficiencies >98 % possible
Efficiency optimization
Minimized air gap
Low loss bearings
High quality material
Optimized air flow
 increased lifetime expectancy M
3 ~
© ABB Group
April 15, 2017 | Slide 7

8. Agenda Savings potential by using variable speed drives
What is a Variable Speed Drive (VSD) system ?
Variable speed drive applications in power stations
Comparison of process control methods with respect to efficiency
References
Payback calculation – case example
ABB medium voltage drives portfolio
© ABB Group
April 15, 2017 | Slide 8

9. Thermal power plant Pump applications
Boiler recirc. pump kW
Cooling water pump kW
Booster Pumps: Creates a high suction head for the Boiler Feed Pump. Usually moved by a common drive with the Boiler Feed Pump.
Boiler Feed Pumps: Pumps the water into the boiler. Due to the high pressure, the mass flow rate must be performed by variation of speed. Most commonly used are fluid coupling, steam turbine and distribution gear from main turbine shaft. But VFD is gaining interest due to (amongst others) higher efficiency and less maintenance.
Boiler circulation pumps: Increases the fluid velocity in the internal water circuit to ensure a sufficient heat exchange. Operate at high pressure, single speed.
Cooling Water Pumps: Several pumps are normally connected to operate in parallel. Certain control can be achieved by putting pumps in or out of service. VFDs are generally not seen on this application.
Condensate Extraction Pumps: Pump the condensate from the condenser through a series of feedwater heaters. Flow control is performed either with by-pass or throttle control. However speed control is emerging, possibly VFD application.
Condensate pump kW
Feed water booster pump
Boiler feed pump kW
© ABB Group
April 15, 2017 | Slide 9

10. Thermal power plant Fan applications
Coal pulverizer fan kW
Gas recirc. fan kW
Induced draft fan (booster) kW
See notes for add’l info
Primary/Secondary Air Fans: Provide air to the preheater, coal mills and consequently to the burners. These are usually centrifugal fans with large diameters and operated at high speeds, which can reach 1800 rpm. Normally not controlled by VFD.
Forced Draft Fans: Supplies combustion or secondary air to the steam generator. For efficient burning of the fuel, speed control with VFD is the state of the art design.
Induced Draft Fans: Discharges the combustion products from the steam generator and control furnace pressure. On plants where SCR (selective catalytic reduction) are installed the ID fan might require operation at several speeds. VFD is an high performance solution for ID fans. In combination with VFD on the FD fan a very high efficient burning of the fuel can be achieved.
Flue Gas Recirculation Fans: Serve to control the temperature of the furnace. Normally not controlled by VFD.
Force draft fan kW
Primary air fan
secondary air fan kW
Induced draft fan kW
© ABB Group
April 15, 2017 | Slide 10

11. Power demand of centrifugal pumpsH
 · g · Q · H
Pump Curve
P = 
Process
Curve
P  k · Q · H
 P
P: Pump shaft power
Q: Quantity of flow
H: Height / pressure
: Density of flowing medium
: Pump efficiency
g: Gravitation acceleration Q
© ABB Group
April 15, 2017 | Slide 11

12. Power demand Throttling control versus VSD control
Q2 = 0,7
H2 = 1,27
H1 = 1
H1 = 1
Design Point
H2 = 0,64
Q2 = 0,7
Design Point
Q1 = 1
Q1 = 1 Q Q
© ABB Group
April 15, 2017 | Slide 12

13. Energy Efficiency of Pump Control Methods
These curves show the reason for using the AC drive for flow control of the centrifugal pump.
The lowest curve is the actual power required to run the pump. The different control methods need more power from the line:
The lowest power requirement has the AC drive, which has the best efficiency. The highest power is required for recirculation, which has the lowest efficiency. The most usual control method in the existing systems is the throttling by a valve. Its power requirement is quite high also, which means that the efficiency is poor especially in the lower flow range.
% of industrial electrical energy is consumed by electric motors
For each 1 USD spent to purchase a motor, 100 USD are spent for energy cost during its lifetime
Today, only 5% of these motors are controlled by variable speed drives
30% of existing motors can be retrofitted with variable speed drives
The installed base of ABB drives saves more than 120 TWh of energy per year, the equivalent of 15 nuclear power plants.
ABB drives reduce CO2 emissions by approx. 60 million tons per year.
Energy savings potential of VSD Control versus
Throttling Control
© ABB Group
April 15, 2017 | Slide 13

14. Energy Efficiency of Fan Control Methods
These curves show the reason for using the AC drive for flow control of the centrifugal pump.
The lowest curve is the actual power required to run the pump. The different control methods need more power from the line:
The lowest power requirement has the AC drive, which has the best efficiency. The highest power is required for recirculation, which has the lowest efficiency. The most usual control method in the existing systems is the throttling by a valve. Its power requirement is quite high also, which means that the efficiency is poor especially in the lower flow range.
% of industrial electrical energy is consumed by electric motors
For each 1 USD spent to purchase a motor, 100 USD are spent for energy cost during its lifetime
Today, only 5% of these motors are controlled by variable speed drives
30% of existing motors can be retrofitted with variable speed drives
The installed base of ABB drives saves more than 120 TWh of energy per year, the equivalent of 15 nuclear power plants.
ABB drives reduce CO2 emissions by approx. 60 million tons per year.
Energy savings potential of VSD Control versus
Damper Control
© ABB Group
April 15, 2017 | Slide 14

15. Agenda Savings potential by using variable speed drives
What is a Variable Speed Drive (VSD) system ?
Variable speed drive applications in power stations
Comparison of process control methods with respect to efficiency
References
Payback calculation – case example
ABB medium voltage drives portfolio
© ABB Group
April 15, 2017 | Slide 15

16. Case example Helsinki Energy, Finland
Retrofit of fixed-speed motors with ACS 1000 VSDs, operating four boiler feedwater pumps (FWPs), each 4500 kW
Benefits
Improved power plant efficiency (as FWPs are one of the biggest energy consumers in a power plant)
Reduced maintenance costs
© ABB Group
April 15, 2017 | Slide 16

17. Case example University of Illinois power plant, USA
An US university power plant installed a 1,000 hp ACS 1000 MV drive for its scrubber booster fan
Energy efficiency improved by 25% against that of inlet vanes
Energy savings: about 1’460’000 kWh / year
Reduction of CO2 Emissions: 730’000 kg / year
Other benefits
Better process controllability
Less maintenance by soft starting
No more start-up problems
© ABB Group
April 15, 2017 | Slide 17

18. Case example Grosskraftwerke Mannheim, Germany
Refurbishment of the 280 MW boiler at block 6 of the GKM power plant
Retrofitting 2 of 3 boiler feedwater pumps with ACS 1000 VSDs, by replacing the old hydraulic couplings (with poor efficiency)
ABB scope of supply:
2 x water cooled ACS 1000 VSD incl. dry type transformers, 4000 kW
General overhaul and star-delta reconnection of the 6 kV motors
Benefits
20 – 25 percent energy savings: around 12’000 MWh / year
Reduction of CO2 emissions: 10’000 t / year
Container Solution
© ABB Group
April 15, 2017 | Slide 18

19. Payback of applying electrical variable speed drives Case example
Feedwater pump, average operating time / year = 8’000 h
Average electrical power consumption = 4’000kW
Resulting electrical energy demand = 32’000 MWh
Energy savings due to applying VSD = 20%
Resulting energy savings per year = 6’400 MWh
Energy cost savings = 320’000 EUR based on el. energy costs of 5 ct / kWh
resulting in a payback time of only two years
total savings over 20 years lifetime = 5’760’000 EUR
Additionally !
Reduction of CO2 emissions of ~5’000 t / year
© ABB Group
April 15, 2017 | Slide 19

20. Lifetime costs of a VSD system
20 years total lifetime costs
Total investment costs < 6 % of the total lifetime costs
Customer benefit: Big savings on energy consumption, not on investment costs
Energy costs
Investment costs
Maintenance and overhaul
costs
© ABB Group
April 15, 2017 | Slide 20

21. Agenda Savings potential by using variable speed drives
What is a Variable Speed Drive (VSD) system ?
Variable speed drive applications in power stations
Comparison of process control methods with respect to efficiency
References
Payback calculation – case example
ABB medium voltage drives portfolio
© ABB Group
April 15, 2017 | Slide 21

22. Product portfolio ABB Medium voltage drives
Motor [MW]
100 50 20 10 5 2 1
0.315
1.8
2.3
3.3
4.0
4.16
6.0
6.9
10.0
Motor [kV]
LCI
6.6
ACS 1000
ACS 5000
ACS 6000
ACS 2000
LCI
ACS 2000
© ABB Group
April 15, 2017 | Slide 22

23. ACS 1000, ACS 1000i 3-Level Voltage Source Inverter (VSI)
Air and water cooling
Power range: 315 kW – 5 MW
Output voltage range: 2.3 – 4.16 kV
ACS 1000-Air optionally with integrated input transformer and feeding contactor
ACS 1000
Water cooled
Portfolio
© ABB Group
April 15, 2017 | Slide 23

24. ACS 1000 topology VSI with 3-level Inverter
ACS 1000 MV variable speed drive
Rectifier
DC link &
prot IGCTs
Inverter
Output sine
filter
MV AC
induction
motor MV
supply
I>> Prot
Main feeder
breaker
& protection
Converter input
transformer
Transformer
3-winding (12-pulse) or optionally 5-winding (24-pulse) type
Optionally integrated dry type transformer
12 / 24-pulse diode rectifier
DC-link with protection-IGCTs (fuseless design)
3-level inverter
Output voltage 2.3 kV, 3.3 kV 4.16 kV
Output sine filter as standard
For operation of induction motors
Portfolio
© ABB Group
April 15, 2017 | Slide 24

25. ACS 1000 topology Output sine filter
Inverter output voltage
Drive output voltage to the motor
Output sine filter
Motor
side
Inverter
Actively controlled LC low pass filter
Eliminates virtually all inverter switching harmonics to the motor (THD < 2%)
Keeps motor and bearings common mode voltage free
Return
© ABB Group
April 15, 2017 | Slide 25

26. ACS 5000 5-Level Voltage Source Inverter (VSI) Air and water cooled
Air cooled
5-Level Voltage Source Inverter (VSI)
Air and water cooled
Power range: 2 MW – 22 MW (up to 30 MW on request)
Output voltage range: 6.0 – 6.9 kV
ACS 5000-Air optionally with integrated input transformer
ACS 5000
Water cooled
Portfolio
© ABB Group
April 15, 2017 | Slide 26

27. ACS 5000 converter topology VSI with 5-level inverter
Transformer
2 x 4-winding or 1 x 7-winding
36-pulse diode rectifier
3 x 12-pulse bridges
DC link (in triplicate)
5-level-Inverter (in triplicate)
H-bridge configuration
Output voltage up to 6.9 kV
EMC-filter (dv/dt limitation at output) as standard
Motor types
Asynchronous
Synchronous
Permanent magnet
The drive is an MV ac-ac drive with DC link, a so called voltage source inverter. It is a non-regenerative system with a braking option. Two inverter units can be combined in parallel operated from a common DC bus to increase the output power.
The system is based on three floating DC-link system which can be combined via the inverter output bridge in series. Therefore without putting semiconductor devices active in series a higher output voltage can be reached with the existing devices.
A similar connection trick is already known from the old cycloconverters
The drive is equipped with a 36pulse diode rectifier capable to fulfil the most demanding harmonic standards.
Common DC bus for power increase means minimized foot print and cost efficient design. We will see this on a later slide.
The converters are principally very steep voltage sources for the loading machines. Installation of a Sinus-Filter is problematic from the cost point of view and in our case means overdesign. In Titlis we reuse the idea of an EMC+CM topology from ACS 6000 together with the 5-level topology approach. This will fulfil the requirements for DOL motors.
Portfolio
© ABB Group
April 15, 2017 | Slide 27

28. ACS 5000 converter topology How to reach the 6.9 kV?
3-level
4.16kV =
Delta Configuration
 4.16kVAC
5-level
6.9kV
4.16kV
Star Configuration
 6.9kVAC =
Function principle
Use the existing 3-level platform and put the converter phases in Y-connection instead of D-connection
Portfolio
© ABB Group
April 15, 2017 | Slide 28

29. ACS 5000 converter topology Motor friendliness
Motor Voltage Phase – Phase
Motor Current
Typical example:
6.6kV induction motor
7.2MW shaft power
60Hz
Motor Current THD = 4.6 %
Return
© ABB Group
April 15, 2017 | Slide 29

30. ACS 6000 and MEGADRIVE-LCI 3-level Voltage Source Inverter (VSI)
Water cooled
Power range: 3 – 27 MW
Motor voltage range: 3.0 – 3.3 kV
Configurable as single and multi-drive
MEGADRIVE
LCI
Current Source Inverter in 6- and 12-pulse configuration (motor and network side)
Air and water cooled
Power range : 2 – 72 MW (higher on request)
Motor voltage range: 2.1 – 10 kV
Portfolio
© ABB Group
April 15, 2017 | Slide 30

31. MEGADRIVE-LCI Typical configurations (1)
LCI.ST – Gas Turbine Starter
CSI in 6 / 6-pulse configuration
Usually air cooled
Start-Up Excitation
Rectifier
Inverter
DC-Link Reactor
Control
Unit
Portfolio
© ABB Group
April 15, 2017 | Slide 31

32. MEGADRIVE-LCI Typical configurations (2)
LCI.DR - MegaDrive
CSI in 12 / 12-pulse configuration
Air and water cooled
Water Cooling Unit
Rectifier
Inverter
DC-Link Reactor
Control Unit
Return
© ABB Group
April 15, 2017 | Slide 32

33. ACS 2000 ABB’s new member of the ACS family
5-level VSI with Active Front End
Available for operation with or without input transformer
Air cooled
Power range: 400 kVA – 1 MVA (higher power to follow)
Motor voltage range: 6.0 – 6.9 kV
Portfolio
© ABB Group
April 15, 2017 | Slide 33

34. ACS 2000 converter topology Line supply connection flexibility
Direct to Line Configuration
Lower investment costs
Less space required
Quick installation and commissioning
Connection to external transformer
For matching supply line to VSD voltage
Galvanic isolation from supply line
Motor friendly Output
Portfolio
© ABB Group
April 15, 2017 | Slide 34

35. ACS 2000 converter topology Motor friendly output
Line current & voltage
Line side harmonics
Low harmonic signature due to its Active Front End
Harmonic emissions are compliant with all relevant standards
Motor current & voltage
Motor side harmonics
ACS 2000 provides near sinusoidal current and voltage to the motor
Compatible for use with standard motors and cables
Return
© ABB Group
April 15, 2017 | Slide 35

36. © ABB Group
April 15, 2017 | Slide 36