When discussing electricity usage, people often prioritize safety while overlooking a critical factor: power quality.
In reality, stable, high-quality power is a cornerstone for safe and efficient industrial production and a fundamental requirement for the reliable operation of critical facilities such as hospitals, data centers, and research institutions. It also directly impacts the daily electricity experience of commercial complexes and households alike.
Simply put, power quality refers to the "quality" of the electricity itself. Much like the vital signs of the human body—such as blood pressure, lipid levels, and blood sugar—must be within normal ranges for the body to function healthily, parameters like voltage and frequency must meet standards for the power system to deliver "healthy" electricity to equipment.
If power quality falls short, equipment may suffer from reduced operating efficiency or, in severe cases, damage and downtime—ultimately compromising actual production output and the quality of daily life.
The following power quality issues are the most common in everyday electricity usage:
1. Harmonics: These occur when current or voltage waveforms become distorted and deviate from the standard sine wave. Such distortions are primarily caused by non-linear equipment like variable frequency drives (VFDs), rectifiers, and uninterruptible power supplies (UPS). Harmonics act like "impurities" in the power system, causing abnormal transformer heating, increased motor vibration and noise, and malfunctions in protective relays, while also interfering with communication systems.
2. Three-phase imbalance: This occurs when the amplitudes of three-phase voltages or currents are unequal, or when the phase difference deviates from the standard 120°. It is mainly caused by the uneven distribution of single-phase loads. Imbalance leads to excessive zero-sequence current and increased losses in transformers and power lines; in severe cases, it can burn out neutral wires and damage equipment.
3. Reactive power and power factor: Reactive power is not "useless" power; equipment such as motors requires it to generate the magnetic fields necessary for operation. However, excessive reactive current consumes distribution capacity and increases line losses, leading to voltage drops and insufficient equipment output. Users may also incur additional electricity charges based on power factor adjustments. Proper reactive power compensation can effectively improve voltage quality and reduce electricity costs.
4. Voltage deviation: This occurs when the actual voltage deviates from the rated voltage. The adverse effects of voltage deviation work in both directions: excessively high voltage places increased stress on equipment insulation, accelerating aging and shortening service life—or even causing immediate burnout in severe cases. Conversely, excessively low voltage results in insufficient motor torque, potentially making equipment difficult to start or causing sluggish operation and reduced lighting brightness, thereby disrupting normal production and daily life. Even more critically, under-voltage conditions cause equipment current to rise, which in turn exacerbates heat generation and power losses in the electrical lines.
5. Voltage sags and short-duration interruptions: These occur when the voltage suddenly drops to between 10% and 90% of its rated value, lasting anywhere from half a cycle to several seconds. This is the power quality issue with the most severe impact on industrial users; a single voltage sag can halt entire production lines in sectors such as precision manufacturing, semiconductors, and pharmaceuticals, resulting in losses amounting to millions or even tens of millions of yuan.
How can power quality be improved?
Harmonic control ：Adopt APF (Active Power Filter) to filter out each order of harmonics; series reactors are used to suppress harmonic amplification.
Reactive power compensation ：SVG (Static Var Generator) / capacitor banks provide dynamic reactive power compensation, improve power factor and stabilize voltage.
Three‑phase unbalance control ：SVG / unbalance regulation modules balance three‑phase currents and eliminate negative‑sequence currents
