Electrical Engineering: Power Systems

• Electrical engineering focuses on the study and practical application of electricity, electronics, and electromagnetism.
• Its sub-disciplines include power systems, control systems, signal processing, telecommunications, and electronics.

Power Systems

• Power systems encompass electrical power generation, transmission, distribution, and utilization.
• They ensure electricity is delivered reliably and efficiently from power plants to end-users.

Components of a Power System

• Generation: Power plants use generators to convert energy from sources like fossil fuels, nuclear, hydro, solar, and wind into electrical energy.
• Transmission: High-voltage transmission lines transport electricity from power plants to substations across long distances.
• Distribution: Distribution networks deliver electricity from substations to end-users through lower voltage lines.
• Substations: Substations utilize transformers, circuit breakers, as well as other equipment to step down voltage levels and protect the power system.

Power System Analysis

• Load Flow Analysis: Determines steady-state voltage, current, and power flow under specific operating conditions.
• Short Circuit Analysis: Calculates fault current magnitude during short circuits and other abnormal conditions to facilitate protective device design.
• Stability Analysis: Assesses the power system's ability to maintain synchronism and equilibrium after a disturbance.

Power System Protection

• Protective Relays: Detect faults/abnormal conditions and trigger circuit breakers to isolate faulty sections.
• Circuit Breakers: Interrupt fault currents to safeguard equipment and prevent cascading failures.
• Instrument Transformers: (CTs and PTs) scaled-down replicas of currents and voltages for measurement and protection.

Power System Operation and Control

• Economic Dispatch: Optimizes power plant output to minimize electricity production costs while meeting demand.
• Automatic Generation Control (AGC): Automatically adjusts generation to maintain system frequency and tie-line power flows within limits.
• Voltage Control: Regulates voltage levels to ensure reliable operation and prevent voltage collapse.

Power System Stability

• Transient Stability: The ability to maintain synchronism after large disturbances like faults or generation loss.
• Small Signal Stability: The ability to maintain synchronism following small disturbances like gradual load changes.
• Voltage Stability: Ability to maintain acceptable voltage levels under varying load conditions.

Power System Transients

• Switching Transients: Voltage and current surges from switching actions like energizing/de-energizing lines/transformers.
• Lightning Transients: Voltage surges from lightning strikes on equipment or transmission lines.
• Temporary Overvoltages (TOV): Sustained voltage increases due to load rejection, faults, or other abnormal conditions.

Power System Harmonics

• Harmonic Distortion: Voltage and current harmonics that can cause overheating, protective device maloperation, and reduced power quality.
• Harmonic Mitigation: Uses filters, reactors, and other devices to reduce harmonic distortion.

Power System Reliability

• Reliability Assessment: Evaluates the probability of system failure and expected consequences like load loss or service interruption.
• N-1 Criterion: The power system must withstand the loss of any single component (e.g., generator, transmission line) without widespread outage.

Smart Grids

• Smart grids use smart meters, sensors, and communication networks to improve efficiency, reliability, and security.
• Advanced Metering Infrastructure (AMI): It allows two-way communication between utilities and customers for real-time monitoring and remote control.
• Demand Response: Programs that incentivize customers to reduce electricity use during peak demand to balance the grid.

Renewable Energy Integration

• Solar, wind, and hydro energy sources are integrated to reduce reliance on fossil fuels and mitigate climate change.
• Intermittency: Renewable energy sources are variable and unpredictable, challenging grid operators.
• Energy Storage: Technologies like batteries and pumped hydro store excess energy to mitigate intermittency.

Power Quality

• It refers to the characteristics of voltage and current waveforms. It should supply power to electrical equipment without causing damage or malfunction.
• Voltage Sags: Temporary voltage reductions can cause equipment trips or malfunctions.
• Voltage Swells: Temporary voltage increases can damage electrical equipment.
• Transients: Short-duration voltage or current spikes can disrupt sensitive equipment.
• Harmonics: Voltage or current waveforms are integer multiples of the fundamental frequency, potentially overheating equipment and reducing power quality.

High Voltage Direct Current (HVDC) Transmission

• HVDC transmission transmits large amounts of power over long distances with lower losses than AC transmission.
• HVDC systems convert AC to DC for transmission, then back to AC at the receiving end.
• HVDC is useful for connecting asynchronous AC systems and for transmitting power through underground/submarine cables.

Flexible AC Transmission Systems (FACTS)

• FACTS devices improve the stability, controllability, and power transfer capability of AC transmission systems.
• FACTS devices include Static VAR Compensators (SVCs), Thyristor Controlled Series Compensators (TCSCs), and Static Synchronous Compensators (STATCOMs).
• SVCs provide dynamic reactive power compensation to regulate voltage levels and improve system stability.
• TCSCs control transmission line impedance to improve power flow control and enhance system stability.
• STATCOMs use solid-state electronics to provide dynamic reactive power compensation and voltage support.