Diesel Power Station (DG Set)

Diesel Power Station (DG Set)

• A generating station that uses a diesel engine as the prime mover for generating electrical energy.
• The diesel engine drives an alternator, which converts mechanical energy into electrical energy.
• Advantages:
  • Simple design and layout
  • Occupies less space
  • Can be located anywhere
  • Quick start-up and load pick-up
  • No standby losses
  • Less water required for cooling
  • Lower overall cost compared to a steam power station of the same capacity
  • Higher thermal efficiency
  • Requires less operating staff
• Disadvantages:
  • High running charges due to costly fuel (diesel)
  • Unsatisfactory performance under overload conditions for a long period
  • Limited to generating small power
  • High cost of lubrication
  • High maintenance charges

Schematic Arrangement of Diesel Power Station

• Auxiliaries:
  • Fuel supply system
  • Air intake system
  • Exhaust system
  • Cooling system
  • Lubricating system
  • Engine starting system
• Diesel generator set: a salient pole type synchronous generator, self-excited and self-regulated by an excitation unit

Uninterruptible Power Supply (UPS)

• A device that maintains a continuous supply of electrical power, even in the event of a mains (utility) supply failure.
• Installed between the mains supply and the equipment to be protected.
• Uses: safeguarding computers, data centers, and critical equipment in large organizations.
• Working principle:
  • Converts mains AC supply to DC voltage
  • Charges batteries during normal operation
  • Uses DC voltage from batteries to supply power during a mains failure
  • Converts DC voltage back to AC voltage using an inverter
• Advantages: immediate protection against input power interruptions, short battery run time, and safe shutdown of connected equipment

Types of UPS

• Off-line UPS (Standby UPS system):
  • Primary source is the filtered AC mains
  • Transfer switch selects the backup source during a power breakage
  • Least expensive UPS system, provides surge protection and backup
• On-line UPS:
  • Double conversion method: AC input is converted to DC for storage, and then converted back to AC for the load
  • Used where electrical isolation is mandatory
  • More expensive due to the design of constantly running converters and cooling systems
• Line Interactive UPS:
  • Used for small business and departmental servers
  • Similar to off-line UPS, but with the addition of a tap-changing transformer for voltage regulation
  • Provides additional filtering and lower transient loss

Battery Types

• Lead Acid/Plante Battery
• Lead Acid/Antimony Battery
• Lead Acid/Calcium Battery
• Lead Acid/Calcium, Maintenance-free Liquid Electrolyte Battery
• Lead Acid/Calcium, Maintenance-free Gelled Electrolyte, Sealed Battery
• Lead Acid (Special Alloy), Suspended Electrolyte, Maintenance-free, Sealed Battery
• Nickel Cadmium, Pocket Plate Liquid Electrolyte Battery

Battery Sizing

• Manufacturers provide sizing information for their batteries
• Battery sizing is typically done using watts per cell or amperes per cell
• Watts per cell method: uses kilowatts per cell tabulated for various backup times
• Amperes per cell method: uses charts expressed in available amps for specified periods of time

Selection of UPS and Battery Banks

• Key considerations:
  • Power capacity (kVA or kW)
  • Topology (Online Double Conversion, Line Interactive, Standby)
  • Redundancy
  • Scalability
  • Efficiency
  • Compatibility
  • Monitoring and management
  • Form factor
  • Battery type (VRLA, lithium-ion)
  • Capacity and autonomy
  • Charging time
  • Temperature considerations
  • Maintenance requirements
  • Footprint
  • Monitoring system
  • Warranty
  • Integration and compatibility
  • Safety
  • Testing and maintenance schedule

A generating station that uses a diesel engine as the prime mover for generating electrical energy, offering advantages like simple design, quick start-up, and lower costs.