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- What is a Smart Grid?
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- Advanced Metering Infrastructure
- Smart Meters - Introduction
- Smart Meters - AMI
- Smart Meters - AMIS
- Communication Architecture
- Drivers & Benefits
- Phasor Measurement Unit
- Intelligent Electronic Devices
- Power Quality Management
- Power Quality in Smart Grid
- Power Quality Issues
- Power Quality Monitoring Techniques
- Power Quality Conditioners
- Electromagnetic Compatibility (EMC)
- Power Quality Audit
- Smart Grid Communication
- Smart Grid Communication
- Communication Network
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Power Quality Issues in Smart Grid
A smart grid is an evolved version of the traditional electric grid that is primarily meant for enhanced efficiency, reliability, and sustainability of the electric grid. However, with the technological advancement in the smart grid, we are facing several power quality issues coming into picture. All these power quality issues can significantly affect the reliability, efficiency, and overall performance our power delivery system.
In this chapter, we will understand try to the major power quality issues in smart grid and will also see their possible impacts and remedies.
What is a Power Quality Issue in Smart Grid?
Power quality issue issue can be defined as a problem associated with the operation and performance of the power system. It can deviate the operation of electrical system from its normal operating condition and can result in poor efficiency, reliability and safety.
In smart grid systems, these issues can be determined in various forms like voltage fluctuations, power surges, harmonics, interruptions, and more. Power quality issues increase the operational cost of power system and reduce efficiency and lifespan.
The sources of power quality issues can be external or internal. Some of the common examples of external sources of power quality issues are lightning and switching surges, natural disasters, etc. Similarly, examples of internal sources of power quality issues include non-linear loads, power electronic components, operation of heavy industrial machinery and more.
At the end, it is very essential to effectively detect the power quality issues and reduce their impact on the performance and efficiency of the power system.
Let us now discuss about different major power quality issues in smart grid along with their impact and remedies.
Power Quality Issues in Smart Grid
Some of very common and major power quality issues in smart grids are listed below −
- Power Frequency Disturbance
- Electromagnetic Interferences
- Power System Transients
- Power System Harmonics
- Electrostatic Discharge (ESD)
- Low Power Factor
- Waveform Distortion
Let us now discuss each of these issues in detail.
Power Frequency Disturbance
In power system, when the frequency of the power supply deflects from its rated value (like from 50 Hz in India), then this condition is referred to as power frequency disturbance. The main causes of the frequency disturbance can be sudden variation in power generation or load conditions in the system.
The power frequency disturbances impact the power system in the following ways −
- It can disturb the operation of sensitive electronic devices due to which they may malfunction or get damaged.
- If frequency variations stay for a long period, then they can lead to stability issues in the power system.
We can address this power quality issue i.e., frequency disturbance through the following practices −
- Power frequency disturbances can be minimized by regulating generator speed through automatic generation control systems.
- This power quality issue can also be eliminated by using energy storage systems to balance the supply and demand.
Electromagnetic Interferences (EMI)
Electromagnetic interference or EMI is a disturbance in the power system that is caused by external sources of electromagnetic fields. It negatively affects the operation of sensitive electronic devices or electrical equipment.
The following are some major impacts of the electromagnetic interference in smart grids −
- EMI affects the communication systems or may destroy the communication signals.
- EMI can interfere with the operation of sensitive electronic devices or can cause their malfunctioning.
This power quality issue in smart grid can be addressed by taking the following steps −
- EMI can be reduced in power system by providing some physical barriers (shielding) to block the external electromagnetic fields.
- Different types of line filters can be used to remove unwanted communication signals from power lines.
Power System Transients
In power system, transients are the short-term voltage or current spikes or dips that are characterized by their very high or low amplitudes. Thus, power system transients result in poor power quality. The power system transients are mainly caused by faults, switching operations, or lightning surges.
Power system transients impact the power quality in smart grid in the following ways −
- Transients can cause breakdown of insulation of electrical components and result in faults or short-circuits.
- Transients can permanently damage the sensitive electronic systems like data centers.
Here are some remedies to solve the power quality issues due to power system transients −
- We can use surge protectors to protect equipment from high-voltage transients.
- In highly sensitive electronic devices, a device called transient voltage suppression diode can be used to limit the transients within a safe limit.
Power System Harmonics
In a power system, those voltage or current components that have frequencies multiples of fundamental frequency are called harmonics. The main causes of harmonics in smart grid systems are non-linear loads and power electronic converters.
The power system harmonics have the following impacts on the power quality in smart grid −
- Harmonics cause vibrations and overheating of power system equipment and conductors.
- Harmonics increase energy losses and reduce the efficiency of the power system.
The following are some key steps that can be taken to solve the power quality issues due harmonics −
- Harmonics can be reduced or removed from the power supply by using harmonic filters.
- The impact of harmonics can also be reduced by improving the power factor, as the power factor correction reduce the harmonic distortions in power supply.
Electrostatic Discharge (ESD)
In smart grid systems, electrostatic discharges (ESDs) are unwanted conditions. ESD is nothing but an abrupt transfer of electrical charge between two bodies having different electrical potentials. In power system, electrostatic discharge can occur due to contact or short circuit or dielectric breakdown between two charged bodies.
In a smart grid, the electrostatic discharge can result in the following consequences −
- It can damage the electronic devices and components.
- It can cause malfunctioning of sensitive electronic systems and devices.
- It can cause fires and explosions in the presence of combustible gases.
We can avoid the impacts of electrostatic discharge on power quality in smart grid as follows −
- The impacts of electrostatic discharges can be reduced by properly grounding the equipment.
- ESD can also be managed by using ESD tools likes mats, wrist straps, or tables for safely grounding the static electricity.
Low Power Factor
In electrical systems, power factor is the measure of useful power in the total power delivered to the load. It indicates the efficiency of the electrical system or load.
In a smart grid, low power factor is not desirable, but it is caused due to inductive effect of motors, transformers, and other electrical equipment. However, we cannot completely eliminate the low power factor in a power system, but we can make it better as much as possible.
The following are some major impacts of the low power factor in smart grid systems −
- Low power factor increases the energy losses in power distribution.
- Low power factor causes energy wastages within the system and hence poses penalties on utility companies.
- It also degrades the performance of the transmission and distribution systems.
The following steps can be taken to address the power quality issues in smart grid due to low power factor −
- We can use power factor correction equipment like capacitor banks and synchronous condensers to improve the power factor through reactive power compensation.
Waveform Distortion
Any deviation in the shape of waveform of voltage or current from its standard shape (like sinusoidal shape) is referred to as waveform distortion. The waveform distortion is a serious issue in power quality. The main causes of waveform distortions include harmonics, voltage notching, electrical noise, etc.
Here are some key impacts of the waveform distortion on power quality in smart grid −
- Waveform distortion affects the operation of equipment and poses additional electrical stress that degrades the performance and life of the equipment.
- Waveform distortion can cause temperature rise of distribution transformer and neutral conductor.
In order to solve the power quality issues due to waveform distortion, we can take the following actions −
- Waveform distortion can be minimized by reducing the harmonics in power system. For this, we have to use harmonic filters and power conditioning devices.
- Waveform distortion can also be prevented through continuous monitoring of the waveform quality and taking appropriate action when needed.
Conclusion
For reliable operation of the modern smart grid, we need to keep the parameters of power supply within a specified limit. Otherwise, the deviation of supply parameters from their standard values can result in poor power quality, malfunctioning and damages to equipment.
Overall, the performance and reliability of smart grid significantly depend on the power quality delivered to the consumers. Also, the increasing demand of electricity and advancement in technology are making the power quality a challenge that has to be addressed for providing a stable and efficient power supply.