The quality of the electrical supply and energy efficiency have recently become major issues due to the growing usage of power electronics, and firm energy managers are becoming more and more aware of the advantages of paying attention to that. The primary indicator of power quality is harmonic analysis services distortion, which shows the difference between the actual network voltage or load current and the desired sinusoidal waveform. The following are some of the effects the harmonic may have on the installation, the equipment, or both:
- Increased efficiency losses in the electrical installation and equipment-based system.
- Surprising resonances.
- Electronic equipment malfunctions that result in “logical” errors in digital circuits
- Unwanted overload (or requirement for oversize) for wirings and transformers.
- Problems with generators and motors.
- Unwanted tripping of circuit breakers or blowing of fuses.
The reduction of harmonics can provide industry-critical processes, IT systems, data centers, etc. with tangible benefits in terms of lower installation costs, lower energy costs, and protection from equipment failures and process interruptions.
What are harmonics, and how are they produced?
The “non-linear” loads are the primary reason for the harmonics creation. Therefore, before discussing harmonics, it is necessary to clarify the differences between “linear” and “non-linear” loads.
Linear load:
It is a load with an instantaneous current draw that is inversely proportional to the applied voltage, meaning that its impedance remains constant throughout the entire alternating period.
This also refers to a pure sinusoidal current for the public energy supply at 50 or 60 Hz.
Electric heaters and incandescent light bulbs are examples of resistive loads. Transformers and motors are examples of inductive loads. Linear loads can also be classed as resistive, capacitive, or combinations of these.
Non-Linear Load:
As opposed to linear loads, non-linear loads change their impedance in response to the instantaneous applied voltage, which results in a non-sinusoidal current draw when that is the case. In other words, the relationship between current and voltage for this type of load is not constant over the course of the alternating period. A diode-rectifier, with its several variations (full-wave diode rectifier, half-wave diode rectifier, single-phase, or three-phase), is the simplest circuit to represent a non-linear load.
Industrial equipment (welding, arc furnace), variable frequency drives (VFD), line-switched rectifiers, switch-mode power supplies, and lighting ballasts are a few examples of non-linear loads that have the ability to introduce harmonics into an electrical distribution. contemporary electronic devices can even be made to maximize efficiency at low load levels relative to their rated functioning point. All of these circuits may use semiconductor power components like transistors, diodes, thyristors (SCRs), and/or switches for loads or circuits.
It is vital to introduce the notion of Point of Common Coupling in order to comprehend how distortion is converted from the injection of current harmonics into harmonic voltage distortion (PCC). It is described as the location where specific loads will be connected when the distribution line, which is often public, reaches the end customer.
Therefore, this point could be “serviced” for industrial or commercial users by a distribution transformer (for instance, an MV to LV transformer), a lengthy distribution line, or a combination of the two. The corresponding distribution circuit between the “ideal” power source and this PCC can be summarised as a series impedance.
Additional results effects of the harmonics:
- Due to greater voltage peaks, unexpected zero-crossing, effects on protection circuits, etc., electronic equipment may be sensitive to the voltage distortion providing it.
- When there are harmonics present, incorrect logical value interpretation might have an impact on digital circuits.
- Components and machinery have a shorter lifespan when the supply voltage is continuously distorted.
- Impact on IT equipment, including memory loss and shutdowns.
- The UPS may need to handle highly distorted loads, meaning that high current peaks may exceed the UPS’s crest factor capabilities. If the UPS’s inverter is inadequate in this situation, the voltage distortion may further worsen.
Effects of harmony on various components:
Transformers:
The iron and copper losses in transformers rise as a result of harmonics. Voltage distortion puts the utilized insulation material under too much stress and increases losses from hysteresis and eddy currents. The increased heat produced is the main result of power line harmonics in transformers. Other issues could be a resonance between the system capacitance and the transformer’s inductance, thermal wear from temperature cycling, and potential core vibrations.
Generators and Motors:
Due to greater iron and copper losses at harmonic frequencies, harmonic voltage and current increase heating in rotating machinery. This reduces the machine’s efficiency and has an impact on the torque produced. Current flow in the rotor is caused by harmonic currents flowing in the stator. This causes the rotor to heat up and pulse, as well as reduce torque. While pulsing or low torque causes mechanical oscillation that increases shaft stress and accelerates the aging of mechanical parts, rotor heating affects the efficiency and life of the machinery.
Thyristor drives:
When used at slow speeds, AC variable frequency drives with thyristor converters typically produce poor power factors. Normal levels of harmonic currents in power cables heat the cables. However, under conditions of system resonance, cables involved may be exposed to corona and voltage stress, which can cause insulation breakdown.
Metering devices:
Generally speaking, harmonics flowing in induction-type metering devices will provide more coupling routes, increasing the speed of the disc and resulting in an apparent rise in costs.
Switchgear and relay:
Harmonics current causes switchgear to heat up more and lose more heat, which reduces the switchgear’s typical current capacity and shortens its lifespan under voltage stress. As a result, fuses need to be derated.
Earthing system and computer performance:
In a three-phase and neutral system, the neutral conductor size should match the phase conductor size when third harmonics and multiples are anticipated.
A computer hanging up, losing commands or data, or acting abnormally can all be attributable to low power quality. Computer equipment should be independently earthed and connected to the main earthing at just one location, ideally the entry point. Coupling to several additional pieces of equipment is introduced through multipoint earthing.
Communication network:
The induction coupling between the nearby communication network and the AC power transmission cables carrying harmonics results in excessive noise levels.
What Is the Purpose of Services For Harmonic Analysis?
Harmonic distortion compromises a power system’s capacity to operate at peak efficiency. Inefficient equipment operation is a result of the rising demand for power. Higher installation and utility expenses increased heating costs, and decreased profitability are the results of increased overall current demand. Harmonic distortion in the current and voltage of a power system can put additional strain on your installation and cause problems with key system components’ functionality.
Conclusion:
Using the electrical system modeling software in the harmonic analysis services, we can now forecast the harmonics in the system and their distortion levels inside the power distribution system. Prior to project execution, this predictive research helps with the selection of the proper equipment and the design of the mitigation system. SASPPL has been offering Harmonic Analysis services to its clients in South East Asia and India across a variety of industries. We have a reputation for reporting findings objectively and transparently. Our proposed Harmonic Analysis services and solutions are the most affordable and have aided clients in achieving expected results.
