Electrical Power Quality Services: A Comprehensive Overview

Introduction

Various quality indicators of electrical power are crucial for the optimal performance of electrical equipment. Kimiagaran Energy Company, with years of experience in the field of electrical power quality, is prepared to provide services to units with power quality problems. The power quality indicators examined by this company include voltage sags and swells, frequency fluctuations, voltage and current harmonics, voltage fluctuations, transients, noise, flicker, and unbalance. After an initial assessment of the existing situation, the company measures the power quality indicators and provides a technical report that not only describes the current situation but also offers practical solutions for improvement.

Services Offered

• Measurement of power quality indicators
• Monitoring and analysis of power quality
• Inspection and identification of power quality problems
• Standardization of electrical power quality
• Identification and elimination of harmonic loads
• Design and implementation of active filters
• Design and implementation of passive filters
• Design and implementation of capacitor banks
• Design, implementation, and improvement of earthing pits

Harmonics

Any distorted waveform can be represented as a combination of sinusoidal waves with different frequencies and amplitudes. These sinusoidal waves, whose frequencies are integer multiples of the fundamental frequency (50 Hz), are called harmonics of the fundamental component. If their frequencies are not integer multiples of the fundamental frequency (50 Hz), they are called interharmonics.

Importance of Electrical Power Quality

Power quality is one of the critical parameters for evaluating power networks. Various studies in the electrical energy consumption sectors have shown that the lack of standard power quality indicators can cause severe problems for equipment. These problems include safety hazards for personnel and equipment, reduced lifespan, equipment burnout, increased losses, and more. The first step in solving such problems is to use power quality analysis equipment.

Power Quality Indicators

Several indicators are defined for power quality. Some of the most important power quality indicators include voltage and frequency fluctuations, voltage sags and swells, voltage interruptions, unbalance, transients, voltage and current harmonics, noise, and flicker. Non-standard values of any of these indicators can lead to poor and incorrect performance of various equipment.

Definitions and Units of Power Quality

Signs of Decreased Power Quality

• Reduced production speed
• Increased energy consumption
• Reactive energy costs
• Production stoppages
• Damaged or destroyed equipment
• Production line stoppages
• Reduced equipment life
• Data loss

In addition to the direct impacts above, poor power quality often also has a negative impact on business costs, such as:

• Rework and repetition of previous work
• Increased start-up costs
• Delayed revenue
• Reduced cash flow
• Poor reputation among customers
• Loss of market share

Details of Power Quality Indicators

Each of the various power quality indicators has its own characteristics, which are explained below. These explanations demonstrate the importance of power quality in industrial, commercial, and agricultural units.

Causes of Harmonics

Advances in semiconductor technology (such as diodes, thyristors or SCRs, IGBTs, and GTOs) have led to the use of semiconductor controllers instead of contactors and relays in automation processes. These components are also commonly used in uninterruptible power supplies used in hospitals, banks, security centers, and more. The main feature of these components is the ability to change the shape and form of the current and convert it into waves that are not sinusoidal but have periodicities. In the alternating current and normal power grids, the sinusoidal voltage at a specific frequency, usually 50 or 60 Hz, is When a linear load is connected to the system, a sinusoidal current with the same frequency as the voltage is formed. When a nonlinear load such as a rectifier is connected to the power system, it creates a current that is not exactly sinusoidal.

Sources of Harmonics

• Electric arc and induction furnaces (iron melting)
• Rectifiers and electronic power converters (electroplating)
• Speed controllers of electric machines (metro and drives)
• Switching power supplies
• Welding machines
• Synchronous machines due to slots
• Transformer magnetic flux
• HVDC systems
• Fluorescent lamps (ferromagnetic equipment) and energy-saving lamps

Harmonic Filters

Harmonic filters use an arrangement of capacitors, inductors, and resistors to direct harmonic currents to ground. Each harmonic filter can be composed of many elements, each of which is used to transmit one of the harmonic multiples to ground.

How to Choose the Right Harmonic Reactor

It is necessary to install a reactor in networks whose current THD is more than 10% or voltage THD is more than 3% (without capacitor). In such cases, the following points must be observed: 1-If the amplitude of the third harmonic current is more than 20% of the fifth harmonic current, third harmonic reactors (P=14%) are used. Otherwise, fifth harmonic reactors (P=7