Power Quality AnalysisHigh-precision power quality measurement and analysis

What is power quality?

Power quality refers to the stability and consistency of electrical power supplied to equipment. It encompasses various parameters, including voltage, frequency, and waveform characteristics, that ensure electrical devices operate efficiently and reliably. High power quality means that the power supply is free from interruptions, fluctuations, and distortions, which can otherwise lead to equipment malfunctions, reduced efficiency, or even damage.

Why do we need power quality analyzers?

Power quality analyzers (PQAs) are essential tools for assessing and maintaining the quality of electrical power. Here’s why they are important:

1. Identifying Power Issues: PQAs help in detecting power disturbances such as voltage sags, swells, transients, and harmonics that can negatively affect equipment performance.

2. Preventing Equipment Damage: By monitoring power quality, PQAs can prevent damage to sensitive electronic equipment caused by poor power conditions, thus prolonging the lifespan of the equipment.

3. Improving Energy Efficiency: Analyzing power quality helps in identifying inefficiencies and losses in the power system, allowing for corrective measures to improve overall energy efficiency.

4. Ensuring Compliance: Many industries are required to comply with specific power quality standards. PQAs ensure that power systems meet these regulatory requirements, avoiding potential fines and penalties.

5. Enhancing Reliability and Performance: Consistent power quality is crucial for the reliable operation of industrial processes, data centers, healthcare facilities, and other critical infrastructure. PQAs help maintain the performance and reliability of these systems.

6. Data-Driven Decision Making: PQAs provide detailed data and insights into power quality, enabling informed decision-making for maintenance, upgrades, and optimization of power systems.

In summary, power quality analyzers are vital for maintaining the integrity and efficiency of electrical systems, protecting equipment, and ensuring regulatory compliance. They play a crucial role in modern power management and system reliability. Dewesoft power quality analyzers can be used in all the mentioned steps, providing the most flexible power quality analysis solution on the market today.

Advanced data analysis

The Dewesoft Power Quality Analyzer is a highly flexible data acquisition (DAQ) solution that integrates power and energy logging with several other measurement instruments into a single device. This integration offers numerous advantages for the measurement process:

1. Data Synchronization: Fully synchronized data ensures compatibility and ease of comparison.

2. Raw Data Logging: Raw data is always stored, allowing for detailed analysis at any time during post-processing.

3. User-Friendly: Intuitive software simplifies measurement and analysis tasks, making it easy to learn and use.

4. Cost-Effective: A single instrument that can measure and analyze power parameters, which would typically require multiple devices, saving space, time, and money.

Comprehensive Measurement Capabilities

The Dewesoft Power Quality Analyzer combines several features and offers advanced data analysis capabilities:

• Harmonics and THD up to 150 kHz

• Interharmonics and higher frequencies

• Flicker, Flicker Emissions, and RVCs

• FFT and waterfall FFTs

• Scopre and vectorscope

• Extended symmetrical components

• Power, efficiency, energy, period values, power of harmonics calculations

FFT harmonics analysis

Harmonics are integer multiples of the fundamental frequency (e.g., 50 Hz) that distort the voltage and current waveforms. These distortions, caused by non-sinusoidal loads, can negatively impact the operation and lifespan of electrical equipment and devices.

Effects on Motors and Generators:

• Increased Heating: Harmonic frequencies cause iron and copper losses, leading to excessive heating.

• Torque Issues: Harmonics can cause pulsating or reduced torque.

• Mechanical Problems: They create mechanical oscillations and higher audible noise, which accelerate the aging of shafts, insulation, and mechanical parts, reducing efficiency.

Effects on Transformers:

• Current Harmonics: Increase copper and stray flux losses.

• Voltage Harmonics: Increase iron losses.

• Frequency Dependency: Losses are directly proportional to frequency, making higher frequency harmonics more significant.

• Additional Issues: Harmonics can cause vibrations and increased noise.

Effects on General Electrical Equipment:

• Reduced Efficiency and Lifespan

• Increased Heating

• Malfunctions or Unpredictable Behavior

In summary, harmonics can cause significant issues such as reduced efficiency, increased heating, and potential malfunctions in various electrical equipment and devices. Understanding and analyzing these harmonics is crucial for maintaining optimal performance and longevity.

Harmonics, Interharmonics and THD

Dewesoft power quality meters can measure harmonics for voltage, current, and additional active and reactive power up to the 3000th order, with calculations following the IEC 61000-4-7 standard.

You can customize the number of sidebands and half-bands for harmonic order calculation. Higher frequency components can be grouped in 200 Hz bands up to 150 kHz.

The system also calculates Total Harmonic Distortion (THD) for voltage and current up to the 3000th order and includes interharmonics to provide comprehensive analysis functionalities.

These advanced harmonic calculation features enable thorough analysis for all types of electrical equipment and devices.

Harmonics calculations

• U, I, P, Q, and impedance

• Individual setup of the number of harmonics, including DC component (Example: 20 kHz sampling rate = 200 harmonics @ 50 Hz)

• Harmonics up to 3000th order (@50 Hz)

• Variable sidebands and half sidebands for Harmonics

• Higher Frequencies up to 150 kHz in 200 Hz bands

• Interharmonics, groups or single values

• According to EN 61000-4-7

• Calculation corrected to the actual real frequency

• THD, THD even, THD odd

• Trigger on each parameter

• Background harmonics subtraction

2D and 3D FFT waterfall analysis

In addition to standard FFT and harmonic FFT analysis, the Power Quality Analyzer also offers 2D and 3D FFT waterfall analysis.

This visualization technique is particularly useful for analyzing variable drives. For instance, when examining the run-up of an inverter, the harmonic sidebands become clearly visible as the frequency increases. The image shows the run-up of an inverter for a traction drive from 0 to 150 Hz.

The FFT waterfall display can be configured to be linear or logarithmic, in 2D or 3D, and sorted by harmonic order or frequency.

Rapid voltage changes (RVCs)

Rapid Voltage Changes (RVCs) are additional parameters supplementing the flicker standard. Dewesoft X data acquisition software calculates these parameters according to the IEC 61000-4-15 standard.

RVCs describe any voltage fluctuations where the voltage amplitude changes by more than 3% between two steady states within a certain time interval. These voltage changes can be analyzed in post-processing using various parameters, including:

• Depth of voltage change

• dU, dMax, dUduration

• Steady-state deviation

• And more

Frequency deviations

The Dewesoft Power Analyzers are ideal for frequency monitoring and testing the frequency behavior of power generation units in the developmental stage (see renewable energy testing).

High-frequency deviations from the fundamental frequency in public grids can have severe consequences. Excessive frequency drops or rises can risk a total power system collapse, potentially causing a blackout.

Frequency deviations in power grids are typically caused by the connection or disconnection of power generation plants or large loads. The grid becomes unstable if there is any deviation from the nominal operating frequency. An excessively high frequency indicates an oversupply of power in the grid, while an excessively low frequency indicates an undersupply of power.

With the growing popularity of renewable energy sources, such as wind and solar, grid stability is more at risk. Wind does not always blow at constant speeds, and solar energy is affected by clouds, shadows, and fluctuations in radiation intensity. These factors lead to abrupt deviations in the frequency at which power is delivered to the grid.