Harmonic analysis involves identifying harmonic distortions in an electrical distribution system. Combined with load flow analysis, harmonic analysis is used in power systems to calculate linear and nonlinear loads connected to distribution networks. From the source of power to all load areas, harmonic analysis services can cover all major parts of the electrical distribution system. The studies are conducted assuming the worst-case scenario of operation, which results in harmonic distortions that exceed the standards.
Harmonic distortions are one of the most common and vexing issues in the industrial setting. Therefore industries must identify the source of harmonics and suppress them in order to ensure a reliable power supply. These harmonics must be measured at various points throughout the system and conduct proper scientific analysis in accordance with international standards.
A voltage or current waveform in an electric power system is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency. Harmonic frequencies are generated by nonlinear loads such as rectifiers, discharge lighting, SMPS loads, or saturated electric machines. They are a common source of power quality issues, causing increased equipment and conductor heating, misfiring in variable speed drives, and torque pulsations in motors and generators.
Different classes of Harmonics in electrical systems:
There are two ways to classify harmonics: the type of signal (voltage or current) and harmonic order (even, odd, triplen, or non-triplen odd). In a three-phase system, they can also be classified based on their phase sequence (positive, negative, zero).
Non-linear loads cause current harmonics. When a non-linear load, such as a rectifier, is connected to the system, it draws a non-sinusoidal current. Current waveform distortion can be quite complicated depending on the load and its interaction with other system components. Regardless of how complex the current waveform becomes, the Fourier series transform allows it to be deconstructed into a series of simple sinusoids that begin at the fundamental frequency of the power system and occur at integer multiples of the fundamental frequency. The positive integer multiple of the fundamental frequency in power systems is named harmonics.
The current in a typical alternating current power system varies sinusoidally at a specific frequency, usually 50 or 60 hertz. When a linear time-invariant electrical load is connected to the system, a sinusoidal current with the same frequency as the voltage is drawn (though usually not in phase with the voltage).
Harmonics occur when the loads in a power system are non-linear. Normally, harmonic generation is not a significant component of electric motors. When motors or transformers are over-fluxed or saturated, they emit harmonics.
Harmonics in current are the primary cause of harmonics in voltage. The voltage provided by the voltage source will be distorted by current harmonics due to the source impedance. If the source impedance of the voltage source is low, current harmonics will lead to only relatively insignificant voltage harmonics. Harmonics in voltage are usually small compared to those in current. Due to this, the voltage waveform is typically approximated by its fundamental frequency.
Current sounds have no effect on the actual control sent to the stack if this estimation is used. A simple way to illustrate this is to draw the voltage wave at the fundamental frequency and overlay the resulting current harmonic without shifting the phase (to observe the following phenomenon more easily). As can be seen, there is an equal amount of region above the horizontal axis and just below the current harmonic wave for each period of voltage as there is below the axis and above the current harmonic wave. As a result, current harmonics contribute zero real power on average. Current harmonics contribute to the real power transferred to the load when higher voltage harmonics are considered.
Consequences of Harmonic Distortion:
Electrical equipment can be damaged by harmonic distortion. When there is a distortion in a power system, the current can increase, causing the temperatures of neutral conductors and distribution transformers to rise.
The Harmonic distortion at the dc link is controlled by IEEE 519 (2014), which specifies the THD and TDD levels of Harmonic distortion that a facility must maintain. ISC/ IL defines the distortion limit, and the standard includes a table of harmonic distortion limits for various ISC/ IL ratios. Harmonic distortion in the PCC sub-distribution is not governed by any standard. Utility companies are aware of the IEEE 519 standard and expect their industrial customers to follow it.
Here are a few renowned outcomes of excessive harmonic distortion in electricity grids:
- Elevated implementation and overhead charges
- Components overheating
- Device misfire
- Circuit breaker nuisance tripping
- Incorrect measurements of the sensor
- Interference in communications
Harmonics and their effects on different components
While electrical harmonics are not responsible for all electrical quality problems in an installation, they are usually the most common and significant factors.
When harmonics exist in electrical systems, current and voltage are distorted and deviate from sinusoidal waveforms.
Designers are being asked to pay increasing attention to energy savings and improved electricity availability. This is why harmonics are a growing concern in electrical system management today.
Harmonics have existed since the dawn of time and were (and continue to be) caused by the non-linear magnetizing impedance of transformers, reactors, fluorescent lamp ballasts, and so on. Furthermore, because of their capabilities for precise process control and energy savings, power electronic devices have become abundant today. However, they do bring some downfalls into electrical distribution systems harmonics.
Overheating of transformers, motors, and cables, thermal tripping of protective devices, and logic faults in digital devices are all symptoms of high harmonic levels. Furthermore, elevated operating temperatures shorten the life of many devices.
Because capacitive reactance decreases with frequency, capacitors are especially sensitive to harmonic components of the supply voltage. In practice, this means that a small percentage of harmonic voltage can cause a significant current to flow through the capacitor circuit.
The most common effects of voltage and current harmonics in a power system are:
- Parallel and series resonances may amplify certain harmonics
- Decreased performance of energy generation, transportation, and utilisation systems
- The premature deterioration of insulation on grid components, resulting in energy savings.
- Inadequate operation of the system or any of its components
What is the purpose of Harmonic Analysis Services?
When harmonic distortion enters a power system, its ability to perform at peak levels is jeopardized. The increased demand for power, it causes inefficiencies in equipment operation. Increased overall current requirements result in higher installation and utility costs, heating, and decreased profitability. Harmonic distortion in a power system’s current and voltage can cause unnecessary stress on your installation and lead to performance issues in critical system components.
Harmonic analysis services provide in-depth analytical studies that are required for compliance as well as to improve the reliability of your power system. Multiple Power Analyzers are used in these studies to check distortion at various levels at the same timestamp.
Harmonics cancel each other out as they move upstream, so the distortion measured at the load end is always greater than the distortion measured at a point further upstream. Failures caused by harmonics result in production losses as well as lost man-hours and machine hours. It may occasionally result in the failure of critical components, necessitating the replacement of costly components.
Because the power of harmonic analysis services lies in providing solutions to various problems as an infinite series of basic functions, it is necessary to understand how these series came about and how these series converge in order to produce algorithms for FFT boxes.
Harmonic distortion costs utility companies worldwide, and utility companies in India are now transitioning to kVAH billing. Higher harmonics can thus directly increase your utility bills while also causing direct losses in addition to indirect losses.
The following are the benefits of using Harmonic Analysis Services:
- Increased system efficiency.
- Reduce the magnitude and frequency of power variations.
- Include a solution to the power quality issues.
- Harmonics protection measures.
- Reduce the liability associated with electrical equipment failure.
- Prevents line loading and loss.
We can now predict the harmonics in the system and their distortion levels within the power distribution system using Electrical System simulation software in the Harmonic analysis services. This predictive study aids in the selection of appropriate equipment as well as the design of the mitigation system prior to project execution. SASPPL has been providing Harmonic Analysis services to its clients across various verticals in India & South East Asia Region. We are known for sharing findings transparently & unbiased reporting. The Harmonic Analysis services and solutions suggested by us are the most economical and have helped clients achieve predicted results.