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

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

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

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

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

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

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

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

Thermal power plant Pump applications Boiler recirc. pump 100-400 kW Cooling water pump 300-2300 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 100-1200 kW Feed water booster pump Boiler feed pump 2000-20000 kW © ABB Group April 15, 2017 | Slide 9

Thermal power plant Fan applications Coal pulverizer fan 100-400 kW Gas recirc. fan 400-1500 kW Induced draft fan (booster) 400-9000 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 400-4500 kW Primary air fan secondary air fan 400-4000 kW Induced draft fan 400-9000 kW © ABB Group April 15, 2017 | Slide 10

Power demand of centrifugal pumps H  · 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

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

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. 60 - 65% 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

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. 60 - 65% 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

© ABB Group April 15, 2017 | Slide 36