Harmonic Study and Analysis

Harmonics are unwanted electric voltages and currents within an electrical power system that can lead to serious power quality issues. When harmonic distortion levels rise, equipment and machinery may malfunction, overheat, or fail completely. As industries increasingly rely on automation and sensitive electronic systems, harmonic distortion has become a major concern for engineers, maintenance teams, and facility managers.

Why Perform Harmonic Study and Analysis?

Harmonic studies are essential to identify, evaluate, and mitigate harmonic distortion that can impact the reliability and efficiency of electrical systems. Though harmonic issues may seem minor initially, they can cause significant operational and financial losses if left unresolved.

According to IEEE Std. 519-1992, harmonic distortion must remain within acceptable limits at the point where the power system serves multiple customers. A harmonic analysis becomes necessary when nonlinear loads (like VFDs, rectifiers, or UPS systems) exceed 16–25% of the total connected load, as this can lead to resonance, voltage distortion, and reduced system performance.

Common Effects of Harmonics

Circulating currents and overvoltages caused by resonance

Equipment malfunction and false tripping

Transformer and motor overheating

Reduced system power factor and increased losses

Metering errors and nuisance breaker trips

Fire hazards in wiring and distribution networks

When is a Harmonic Study Required?

A detailed harmonic study should be conducted:

During design, if nonlinear loads exceed 25% of total connected load

When adding capacitor banks or expanding facilities

To resolve existing harmonic-related equipment failures

Before commissioning new industrial systems or modifying electrical networks

What is Done During Harmonic Study and Analysis?

A harmonic analysis involves mathematical modeling of the electrical system to predict resonance conditions and distortion levels. This is typically done using advanced software such as ETAP. System components (transformers, cables, capacitors, and nonlinear loads) are modeled to simulate real-world performance under different scenarios.

Two main types of analyses are performed:

Current and Voltage Distortion Analysis – Measures individual and total harmonic distortion (THD) levels.

Impedance vs. Frequency Analysis – Determines resonant frequencies and system impedance characteristics.

Corrective Actions for Harmonic Distortion

If the study detects excessive harmonics or resonance issues, mitigation methods may include:

Installing harmonic filters (active or passive)

Using higher-pulse rectifiers

Relocating or resizing capacitor banks

Implementing PWM rectifiers or VFDs with harmonic mitigation features

How Harmonic Study and Analysis is Performed

The process typically includes:

Reviewing system one-line diagrams and identifying nonlinear loads

Determining the point of common coupling (PCC)

Collecting harmonic data from equipment and utilities

Modeling the system in software (e.g., ETAP)

Simulating various operating conditions

Verifying compliance with IEEE 519 or utility limits

Implementing and validating corrective measures

ETC is an authorized provider of Electrical Installation Study, Analysis, Inspection, and Certification services in the UAE, offering comprehensive Harmonic Study and Analysis solutions. Our engineers utilize advanced analytical tools and international standards to ensure system reliability, safety, and compliance.