Poor power quality leads to improper functioning of the system and in some cases it may cause hazardous problems. The steadfastness of the system depends on the amount of electricity it receives to perform its action. In order to safeguard the system from power anomalies, it is necessary to detect these problems with appropriate instruments.
This course, gives students a wide idea on power quality indicators, improvement methods and selection of UPS, batteries and semiconductor devices.
After completion of this course, students will know about the need of power quality improvement and need of uninterrupted power supply.
WHO SHOULD COMPLETE THIS COURSE?
- Electronics engineers
- Power system analysts
- Instrumentation engineers/ technicians
- Electricians/Operators
- Electrical engineers
- Maintenance Engineers/technicians
- Protection and control engineers
- University Power System educators
- Safety Facilitators
COURSE OUTLINE
POWER QUALITY & INDICATORS
- Note carefully
- Power quality – definition
- Important aspects
- Power quality attributers
- Why are limits specified?
- Typical power quality problems
- Power quality indicators
- Sag, swell, surges and interruption
- Frequency disturbance
- Importance of maintaining frequency
- Mitigation frequency disturbances
- Waveform asymmetry
POWER QUALITY IMPROVEMENT
- Need for power quality improvement
- Continuity-Equipment needs
- Understand failures
- Effect of interruptions
- Production behavior after power failure
- Safety hazards – Examples
- Equipment damage – Examples
- Hazards conditions
- Direct & indirect costs of interruption
- Minimizing failures
- Minimize duration of interruption
- Consider non-electrical solutions
- Redundancy approach
UPS TYPES & VOLTAGE VARIATIONS
- UPS – types
- Static UPS systems
- General configuration –Static UPS
- System components
- Static & passive UPS
- Line interactive UPS
- Double conversion UPS
- Rotary & hybrid UPS system
- Voltage variation, sage reasons
- Factors determine sag vales
- Voltage sag during a fault
- Effects of sag & swell
- Equipment sensitivity
- CBEMA sensitivity curve
- Handling voltage variations
- Control improvements – Examples
- Voltage regulators
- Improvement by system change
- Summary
TYPES OF BATTERY & CHARGING
- Need for uninterrupted power supply
- What is a battery?
- Typical cell
- Primary & secondary battery
- General operation cycle
- Types of battery construction
- General features – lead acid cells & Ni Cd cells
- Need for charging
- Types of charging
- Trickle, float and boost charging
- Battery discharge characteristics
- Charging equipment
- Configuration
- UPS battery charging
SEMICONDUCTORS AS RECTIFIERS & INVERTERS
- Common solid state devices
- Diode, N-P-N Transistor, Thyristor (SCR), GTO Thyristor, IGBT
- Rectifiers – basics
- Rectifier single & three phase configurations
- Inverters – Principle of operation
- Synthesized AC waveform – PWM
- Why PWM
BATTERY SELECTION, SIZING & INSTALLATION
- Battery selection
- Sizing of batteries
- DC system battery sizing
- Sizing process for DC systems
- Calculating number of cells
- Computing duty cycle & load
- A typical load cycle
IEEE method & alternative method
- Correction factor for sizing
- UPS battery sizing
- Batter kW calculation
- Handling the cells
- Safety during installation
- Failure by sulphation
- Excessive discharging – Hydration
- Mechanical failures
- Is battery room classified as hazardous location?
- Disposal of cells
SURGES – CAUSES, MITIGATION & PROTECTION
- Surges, causes and mitigation
- Surge coupling
- Surge mitigation approach
- Lightning – the external sources
- Lightning multiple waves
- Resistive & inductive capacitive coupling
- Types of grounding systems
- Isolated grounding systems
- Multiple grounding points – bonding
- Surges and surge protection
- Basic principle of surge protection
- Surge Protection Devices (SPD)
SURGE – SUPPRESSORS & PROTECTION
- Type of surge suppressors
- Voltage limiting & switching type
- Metal Oxide Varistors (MOV)
- Gas arrestors
- Spark gaps & gas discharge tubes
- Surge protection of electronic equipment
- Lightning surge in sensitive equipment
- Surge protection zones
- Zoned protection approach
- Selection criteria of SPD
- Positioning of a lightning arrestors
- Supplementary surge protection
- Practical view of surge protection
- SPD’s for special applications
- Protection of C&I equipment
- Crucial factors
- Protection of transmitters
- Loop protection
- Protection at field end
- Comprehensive protection
- Motor temperature sensors
- Data communication devices
- Hazardous areas – special features
- Grounding of IS circuits
HARMONICS
- What are harmonics?
- Linear loads
- Non-linear load (Saturation)
- Non-linear load (Electronics switches)
- SMPS waveform
- Non-linear load (Arc furnace)
- Non-linear load (Arc welders)
- Harmonic characteristics
- Effect of third harmonic component
- Detecting & analyzing the cause
- Harmonic components – SMPS
- Non-linear loads are harmonic sources
HARMONICS – PROBLEMS
- Problems – neutral overload
- Overloading due to 3rd harmonics
- Solutions for neutral overloading
- Overheating of transformers
- False tripping of circuit breakers
- Capacitor failures due to harmonics
- Harmonic currents
- Skin effect
- Electromagnetic interference
- Voltage distortion due to harmonic current
- Reduce distortion by segregation
- Harmonic effects on rotating machine
- Interference with zero crossing
- Limits of harmonics
- Harmonic components
HARMONIC CONTROL METHODS
- Harmonic control methods
- Rectifier configuration
- Single phase rectifier
- Passive filters for harmonic control
- Shunt filter
- Isolation by transformer delta winding
- Active filters
- Harmonic content before & after filtering
- Active filter advantages
- Linear and non-linear loads & harmonics
NOISE IN ELECTRICAL CIRCUITS
- Noise fundamentals
- Typical sources of noise
- Principles of dealing with noise
- How does noise affect circuits
- Common & transverse mode noise
- Noise coupling
- Galvanic coupling
- Capacitive or electrostatic coupling
- Capacitive coupling
- Shield minimizes capacitive coupling
- Electromagnetic coupling
- Twisted pair principle
- Separation in cabling avoids induction
- Electromagnetic shield
- Opto-coupling for noise mitigation
- Transformer coupling
- Measures to avoid noise coupling
POWER FACTOR ANALYSIS
- Power flow
- Power triangle
- Power factor correction
- Effect of reactive loads
- Shunt capacitance
- Effect of shunt capacitance on current phase & voltage phase
- Voltage regulation using shunt capacitors
- Use & Effects of series capacitors
- Series compensation (SC)
- Shunt reactors
- Synchronous compensators
- Dynamic compensation
- Static VAR compensators
- Effect of capacitors on induction motor torque
POWER QUALITY ISSUES AND STUDIES
- Power quality problems
- Common power quality problems
- What is a separately derived source?
- Power quality related problems -1
- Power supply system’s TN-C vs. TN-S
- FPSO power distribution – cyclone, vessel A
- Power quality related problems -2, 3 & 4
- Solutions normally adopted
- Common solutions
- Defining the problem
- Site coordination agencies
- Conducting the study
- Building service entrance
- Distribution system checking
- Branch circuits for sensitive loads
- Separately derived systems
- Connection integrity
- Isolated ground systems
- Neutral & ground conductors
- Surge protection checklist
- Specialized instruments
