Power quality is a crucial issue in modern electrical applications.
With the increasing deployment of advanced electronic devices, the power grid faces new challenges to ensure stability, efficiency and safety. This article explores the main issues related to Power Quality, analyses their causes and describes innovative solutions to mitigate the negative effects on the grid and connected devices.
THE IMPORTANCE OF POWER QUALITY
In the past, the electricity grid mainly supplied power to linear loads, such as motors and resistive loads, which absorbed power in a predictable manner and without generating significant disturbances.
However, with the spread of modern technologies such as computers and servers, power converters (e.g. inverters for solar panels), LED lighting systems and other advanced electronic technologies, the nature of power consumption has changed dramatically. These devices, often based on power electronics, introduce disturbances into the grid, altering the quality of the energy supplied.
These problems not only reduce energy efficiency but can also damage sensitive devices and increase maintenance and repair costs.
In industrial and IT environments, where business continuity is essential, poor power quality can result in significant economic losses.
THE MAIN POWER QUALITY PROBLEMS
Voltage fluctuations. Voltage fluctuations can be caused by heavy loads suddenly turning on or off, causing a momentary drop or rise in voltage. These phenomena can affect the operation of sensitive electronic equipment.
Power supply interruptions. Interruption can be for a short duration (milliseconds or seconds) or longer (minutes or hours). Even a short interruption can cause critical equipment, such as servers and industrial machinery, to restart, with serious operational consequences.
Harmonics. Harmonics are voltage and current waveform distortions caused by non-linear loads such as inverters and variable speed motors. The presence of harmonics can lead to overheating of transformers and motors, as well as reducing the overall efficiency of the electrical system.
Flicker. Flicker is a rapid voltage fluctuation that manifests itself as a change in the brightness of lights. It can be caused by variable loads such as electric welders or by changes in the distribution network. Flickers not only accelerate the wear and tear of LED lamps but also cause problems with sensitive industrial devices (PLCs, medical equipment and automation systems).
Power factor problems. A low power factor indicates that electrical energy is being used inefficiently. This problem can lead to additional costs for companies and require compensating equipment, such as capacitor power factor correction systems.
Electromagnetic disturbances and transients. Electromagnetic disturbances occur in the form of high-frequency interference and are generally caused by atmospheric discharges, power electronics, welders and induction furnaces. Transients are sudden voltage and current peaks that last from a few microseconds to milliseconds. Generally, they are caused by atmospheric discharges, heavy load drives and power grid interruptions and resets.
SOLUTIONS TO MAJOR POWER QUALITY PROBLEMS
To tackle Power Quality problems, several technological solutions have been developed.
Voltage variations
- Voltage stabilisers (Automatic Voltage Regulators): compensate for sudden variations to keep the voltage constant.
- Automatically switching transformers: adjust the voltage level by adapting to changes in the network.
- UPS (Uninterruptible Power Supply): provide instant power in the event of surges or short interruptions.
Power supply interruptions
- UPS (Uninterruptible Power Supplies): provide power in the event of short interruptions, allowing critical devices to be switched off correctly.
- Voltage sag/dip compensators: guarantee power in the event of voltage drops lasting up to 1 second.
- Micro-interruption compensators: guarantee power in the event of very short interruptions, in the order of microseconds.
- Emergency generators: provide power during prolonged blackouts.
- Battery Energy Storage Systems (BESS): stabilise the energy supply in case of interruptions.
- Microgrids with renewable sources: can operate in island mode during grid outages.
Harmonics
- Active filters: detect and compensate harmonics in real time.
- Passive filters: use electrical components (inductors, capacitors and resistors) to attenuate harmonics.
- Special transformers (K-rated transformers): designed to consider the effects of harmonics in terms of losses and efficiency.
Flicker
- Static reactive power compensators (Static Var Compensators): quickly adjust the voltage to reduce flicker.
- Active Fast Compensation Filters: eliminate rapid voltage fluctuations.
- Improved electrical infrastructure: stronger cables and suitable transformers can reduce flickers.
Power factor problems (low power factor)
- Capacitor banks: correct the power factor by compensating reactive power.
- Static reactive power compensators (Static Var Compensators): correct the power factor electronically.
Electromagnetic and transient disturbances
- Surge Protection Devices (SPD): protect equipment from sudden voltage spikes.
- EMI/RFI (Electromagnetic and Radio Frequency) filters: reduce electromagnetic interference.
- Shielded wiring and proper earthing: help reduce electromagnetic noise.
Each power quality problem has specific solutions that can be adopted individually or in combination to ensure a stable, efficient and reliable power supply.
POWER QUALITY: A CRUCIAL ASPECT
Power Quality has become a crucial issue in the age of advanced electronics. Power Quality problems not only reduce the efficiency of electrical systems but can have significant economic and operational impacts.
Fortunately, with innovative solutions, it is possible to mitigate these problems and ensure a more stable and reliable power supply.
Adopting prevention strategies and advanced technologies to improve power quality, reduce operating costs and increase the safety of electrical systems is becoming an increasingly important factor today.
