Why Faults Matter in Power Systems
Faults create abnormal low-impedance paths that can drive severe current and voltage disturbances, making fault studies essential for protection design and system security.
Articles
Technical deep-dives into power systems engineering topics.
Symmetrical Components: Decomposing and Reconstructing Three-Phase Systems
Symmetrical components decompose unbalanced three-phase systems into positive, negative, and zero-sequence sets, then reconstruct the original system exactly.
Zero Sequence Component
The zero-sequence component consists of equal phasors moving together with no 120 degree phase separation, capturing common-mode behaviour linked to neutral and ground-return paths.
Negative Sequence Component
The negative-sequence component is the balanced reverse-rotating part of an unbalanced three-phase system and helps explain behaviour that positive sequence cannot capture alone.
Positive Sequence Component
The positive-sequence component is the balanced forward-rotating part of an unbalanced three-phase system and represents behaviour closest to normal operation.
Why Three-Phase Systems Become Difficult When Unbalanced
Balanced systems are easy because symmetry reduces the problem; unbalanced systems lose that symmetry, which motivates sequence-component decomposition.
Phase-Locked Loop (PLL)
The Phase-Locked Loop continuously aligns the rotating reference frame with the space vector by monitoring the q-component and adjusting the observer's angle and frequency estimates.
When the Reference Frame Is Wrong
The synchronous reference frame produces constant dq quantities only when the observer has both the correct speed and the correct angle. This article examines what happens when either condition fails.
Synchronous Reference Frame (dq)
When the observer rotates at the same speed as the space vector, balanced steady-state quantities become constant. The synchronous dq reference frame exploits this property through the Park transformation.
Stationary Reference Frame (αβ)
The Clarke transformation maps balanced three-phase systems into a two-dimensional stationary reference frame, representing oscillating quantities as a single rotating space vector.
From Sinusoids to Rotating Vectors
Understanding how sinusoidal waveforms relate to rotating vectors and reference frames—the foundation for multi-dimensional power system analysis.
Per-Unit System: Common Mistakes in EMT and RMS Studies
Identifying and preventing common per-unit mistakes in RMS and EMT power system simulations.
Per-Unit System: Changing Base Across Transformers and Networks
Understanding when and how to change base quantities in per-unit systems, particularly across transformers and multi-voltage networks.
Per-Unit System: Base Quantities and Their Relationships
How base quantities are defined, how they relate to each other, and how they propagate through a power system model.
Per-Unit Impedance from Physical Parameters
Converting physical resistance, inductance, and capacitance into per-unit values for RMS and EMT studies.
Per-Unit System in Power Systems: Concept and Why It Works
Understanding the conceptual foundation of the per-unit system—why normalisation is necessary, why it works, and what it does not do.
Transmission Line Behaviour: Inductive or Capacitive
A practical framework for understanding when transmission lines behave inductively or capacitively, based on surge impedance loading and characteristic impedance.