A new static DC drive system with AFE for mining excavators W.M.E.A. Conference in Edmonton, Alberta, Canada June 12 th, 2003 Walter Koellner Siemens Energy & Automation, Alpharetta, USA
Requirements for Electric Excavator Drives Siemens Energy && Automation The drives must be able to handle the peak HP requirements to allow fast cycle times. Control must be extremely dynamic to handle severe impact loads. The power converters must allow four quadrant operation with electric braking. The converters must be capable of handling momentary line voltage fluctuations of +10% and -30% without shutdowns and/or component failures.
Requirements for Electric Excavator Drives Siemens Energy && Automation The drives must operate with unity or leading power factor and produce low current harmonics to meet the electrical utility standards. The drive system must be reliable, using few components with the highest quality. Converters must be dust and shock protected and able to handle ambient / altitude requirements. The drive system must be easy to troubleshoot to keep downtime to a minimum.
Requirements for Electric Shovel Drives Siemens Energy && Automation Power Factor PF is a measure of usable power transmitted by the power company Uncompensated DC static excavator drives had only 0.3 average power factor Then the distribution system must be rated for 3x current Increased voltage fluctuation in distribution systems creates unacceptable voltage flicker
Requirements for Electric Shovel Drives Siemens Energy && Automation Harmonics All normal SCR machines create harmonics (THD 6-pulse > 40%, THD 6-pulse with harmonic filter > 10%) Harmonics create additional losses which heat up equipment and can produce failures of other equipment on the distribution system
Traditional Solutions DC Rotating DC motors powered by DC generators driven by AC induction or synchronous motor Good power factor and low harmonic distortion Bad efficiency (12 % worse than static) Outdated technology, difficult to procure spare parts
Traditional Solutions DC Static Conventional DC motors powered by SCR rectifiers with antiparallel bridges in 6 configuration Harmonic filters tuned to 5th and 7th harmonic RPC (Reactive Power Compensation) with switched capacitors and phase-controlled reactors The Result: PF of approx. 0.93 lagging, THD of approx.11% (with harmonic filter) Conversion fault when line voltage dips during regeneration (results in blown rectifier fuses)
New Solutions AC Static AFE AC motors powered by AFE s and PWM inverters Power Factor = 1 Harmonic Distortion THD < 5% Present standard equipment on all Bucyrus 495 B shovels ctive ront nd
New Solutions DC Static AFE DC motors powered by AFE s and DC choppers Power Factor = 1 Harmonic Distortion THD < 5% Uses same IGBT power electronics as AC shovel drive only different software ctive ront nd
Key Data Comparison DC Rotating DC Static AC and DC IGBT AFE Power Factor 1.0 0.93 lag 0.8 lead 1.0 Input Voltage +10, -30% +10, -20% +10, -30% THD < 5 % 11% < 5 % RPC No Yes No Efficiency 80% 90% 92 / 89%
DC Static AFE - Single Line Diagram AFE 1-90 O AFE 2-270 O AFE 3-360 O AFE 4-180 O
DC Static AFE - Single Line Diagram Detail for 1 AFE AFE 1-90 O Transformer Line Reactors AFE DC Link ctive ront nd
AFE Advantages Reduced Harmonic Current Distortion THDi from more than 40% to less than 5% Adjustable Power Factor between 0.8 leading and 1.0 Improved dynamic performance High tolerance for line voltage fluctuations Full regenerative operation Result: Higher availability and productivity of the excavator
AFE Advantages Better Dynamic Response No current free safety time required to switch from forward bridge (motoring) to reverse bridge (regeneration) Better DC bus voltage control Fewer DC bus capacitors required ctive ront nd
DC Static AFE - DC Chopper Chopper Applications - DC Traction (North America) San Diego Denver Salt Lake City 54 trains 57 trains 24 trains
DC Static AFE - DC Chopper Dragline Single Line AFE's AFE's DC Link Hoist Swing Drag Pre-Charge
DC Static AFE - DC Chopper Chopper Single Line Detail for Hoist Transformer AFE's DC Link IGBT Choppers Inter-phase Reactors Hoist Motors
DC Static AFE - DC Chopper Chopper Single Line 4 Chopper Detail T + Chopper 1 Chopper 2 Chopper 3 Chopper 4 M * Field Supply Field Supply - Inter-Phase Reactors M Hoist Motors
DC Static AFE - DC Chopper Chopper Principle IGBT choppers switch ( chop ) a constant DC input voltage into a variable DC output voltage for high performance torque and speed control of DC motors 2 Choppers provide bi-directional connection for motoring and regeneration DC motor voltage and speed are independent of DC link voltage. Inter-phase reactors combine voltage pulses from several parallel choppers and create a smooth motor voltage waveform
DC Static AFE - DC Chopper Chopper Advantages Inter-phase reactors reduce dv/dt seen by DC motors (without reactor the motor would see the full DC bus voltage) Low motor dv/dt means: Easy on insulation - motors do not need to be rewound, no dv/dt filters are required Less risk for flashover at high speed Small bearing currents IGBT Choppers are well suited for high torque operation at standstill AFE DC chopper can be used as a retrofit on machines with rotating and static DC
DC Static AFE - IGBT Advantages IGBT's utilize reliable, low cost control circuits (gate drives) without snubber/reactor circuits IGBT's can safely turn-off overload currents without damage (GTO's fail if overloaded even momentarily) High switching frequency means smoother currents Air cooled design Fuseless design 10 inch IGBT Double Phase Module (AFE or Chopper) 18 inch 25 inch Weight : 130lbs
DC Static AFE - Remote Diagnostics The drive system can be monitored from the site office, Siemens office, or any Internet connection (password protected) The factory expert sees exactly what the local electrician sees and can directly diagnose problems - Full 2 way communication Radio Tower Software can be accessed and upgraded Advanced diagnostic aids for preventative maintenance To Mine Network Booster Access Point Various service packages
Basic SiRAS Operation - Shovel Side Hardware: upgraded, standard HMI computer on board the shovel, an Ethernet radio link HMI Touch screen Display Remote I/O on Shovel connected via Profibus Wireless Ethernet Station PC RACK Ethernet card MIDAS SLOT PLC S7 Ethernet Wireless Ethernet Shovel Access Point Ethernet transmitter Shovel Maintenance Computer Connected via internal bus Software allows to run all functions of the Shovel Maintenance PC remotely by remapping the I/O vectors Processor Local Processor Executes Diagnostics Second Static Hard Disk w/ Diagnostic Application Programs & Diagnostic Cache SiBAS Control Rack Connected via monitor interface (serial link)
Basic SiRAS Operation - Mine Office and Internet Siemens Energy && Automation. Secondary Tower - for Direct LOS, if required. - can be moved around - can be Solar powered Radio tower Access Point Wireless Ethernet Station / repeater Hardware: a standard PC with modem or Internet access at the mine Main Tower (Range 20 km) Radio tower The Mine Host Provides the connection to the outside world and is also available as a monitoring station. Software Hub Ethernet Mine Connection to Internet Firewall Internet ISP Any PC with Internet connection can access the shovel Main Tower Booster Mine Host Computer with Internet address Access Point Ethernet Mine Computer on LAN Shovel Wireless Ethernet Station Access Point Mine Wireless Ethernet Station Telephone Dial up is also possible Any PC on the Mine Network can access the shovel
SiRAS not tied to Siemens Equipment Simoreg Exciter or Drill Drive Dragline Simoverts Other Manufacturer PLC or Discreet Logic. Profibus Real Time Data Gathering Diagnostic Computer Logic Data Gathering
What is SiRAS? (Remote Diagnostics) Keep the factory on your machine SiRAS / AccessDirect connects the drive system to the Internet. Factory experts can log on to the drive systems from around the world for monitoring, troubleshooting and maintenance. On line monitoring Monitor during normal operation. Plan for preventive maintenance. Software updates Download software during operation. Install during lunch break. PM aids Advanced software can monitor electrical AND mechanical systems.
What is MIDAS? (Operation Analysis) MIDAS provides enhanced software tools for machine analysis. 50 Million bytes of data are collected for a 24 hour period. These data are analyzed using custom tailored interfaces to generate reports for: Basic Digging Statistics Machine Health Data Machine Environment Data Miscellaneous Machine Statistics Etc. The data can also be used to link back to actual events, faults, etc. \Seamlessly integrates with Microsoft Office
Siemens SiemensEnergy Energy&&Automation Automation MIDAS Operation Analysis Screen
Summary DC Static AFE drives are an exciting alternative for new and retrofit DC excavators Inherently excellent Power Factor, THD Fuse less design Chopper technology has been extensively used in traction Same control and power hardware as in AC shovel drives SiRAS Remote Diagnostics with direct access to the factory experts and MIDAS Production Analysis tools