This document discusses power quality and defines it as any deviation from the normal sinusoidal voltage or current waveform. It covers various power quality issues like voltage sags, swells, fluctuations, harmonics, interruptions and more. It explains the causes and impacts of different power quality problems. The document also discusses classification of issues, measurement and evaluation of power quality as well as relevant standards from organizations like IEEE.
Loading Capability Limits of Transmission LinesRaja Adapa
This document discusses the four main loading capability limits of transmission lines: thermal, voltage, dielectric, and stability limits. The thermal limit depends on ambient temperature, wind conditions, conductor size and is usually the main limiting factor. Voltage limits require the transmission voltage to be maintained within a specified range, like plus/minus 5% of nominal. The dielectric limit concerns insulation and allows for some increase in normal operating voltage. Stability limits involve ensuring the power system remains stable after the loss of a single element to prevent cascading outages. FACTS technology can help utilize more of the thermal limits and improve stability.
this is useful for peoples interested in power quality problems and their mitigation. it provides causes, effects of voltage sag and their mitigation techniques.
This project presentation discusses the design of an automatic power factor correction system. The system uses a microcontroller to measure the power factor and control relays that switch capacitor banks in and out of the circuit to maintain a set power factor. When the measured power factor deviates from the set point, the microcontroller activates a relay connecting additional capacitors in parallel to improve the power factor. The system provides an economical way to automatically correct power factor using static capacitors.
The electricity supply industry is undergoing a profound transformation worldwide. Market forces, scarcer natural resources, and an ever-increasing demand for electricity are some of the drivers responsible for such unprecedented change. Against this background of rapid evolution, the expansion programs of many utilities are being thwarted by a variety of well-founded, environment, land-use, and regulatory pressures that prevent the licensing and building of new transmission lines and electricity generating plants.
This document provides an overview of power factor, including basics, causes of low power factor, disadvantages, correction methods, and advantages of correction. It defines power factor as the ratio of true power to apparent power. Induction motors, transformers, and other inductive loads cause low power factors. Correcting power factor reduces equipment sizes and losses, improves voltage regulation, and avoids penalties under power factor tariffs. Static capacitors and synchronous condensers are common correction methods.
EHV (extra high voltage) AC transmission refers to equipment designed for voltages greater than 345 kV. Higher transmission voltages increase efficiency by reducing transmission losses and current, decrease infrastructure costs, and increase transmission capacity. However, they also present safety and interference risks. New technologies like FACTS (flexible AC transmission systems) help maximize the benefits of EHV transmission by enabling voltage control and power flow management. There is growing support for expanding national EHV transmission grids to facilitate large-scale renewable energy integration and inter-regional power sharing.
The document discusses capacitive voltage transformers (CVTs). It describes CVTs as devices that step down extra high voltage signals for metering and protection purposes. CVTs consist of capacitors that divide the transmission line voltage, with an inductive element to tune the device to line frequency and a voltage transformer to further step down the voltage. CVTs are more economical than wound transformers for voltages over 100kV. CVTs can also be used for power line carrier communications and provide insulation between high and low voltage circuits.
Loading Capability Limits of Transmission LinesRaja Adapa
This document discusses the four main loading capability limits of transmission lines: thermal, voltage, dielectric, and stability limits. The thermal limit depends on ambient temperature, wind conditions, conductor size and is usually the main limiting factor. Voltage limits require the transmission voltage to be maintained within a specified range, like plus/minus 5% of nominal. The dielectric limit concerns insulation and allows for some increase in normal operating voltage. Stability limits involve ensuring the power system remains stable after the loss of a single element to prevent cascading outages. FACTS technology can help utilize more of the thermal limits and improve stability.
this is useful for peoples interested in power quality problems and their mitigation. it provides causes, effects of voltage sag and their mitigation techniques.
This project presentation discusses the design of an automatic power factor correction system. The system uses a microcontroller to measure the power factor and control relays that switch capacitor banks in and out of the circuit to maintain a set power factor. When the measured power factor deviates from the set point, the microcontroller activates a relay connecting additional capacitors in parallel to improve the power factor. The system provides an economical way to automatically correct power factor using static capacitors.
The electricity supply industry is undergoing a profound transformation worldwide. Market forces, scarcer natural resources, and an ever-increasing demand for electricity are some of the drivers responsible for such unprecedented change. Against this background of rapid evolution, the expansion programs of many utilities are being thwarted by a variety of well-founded, environment, land-use, and regulatory pressures that prevent the licensing and building of new transmission lines and electricity generating plants.
This document provides an overview of power factor, including basics, causes of low power factor, disadvantages, correction methods, and advantages of correction. It defines power factor as the ratio of true power to apparent power. Induction motors, transformers, and other inductive loads cause low power factors. Correcting power factor reduces equipment sizes and losses, improves voltage regulation, and avoids penalties under power factor tariffs. Static capacitors and synchronous condensers are common correction methods.
EHV (extra high voltage) AC transmission refers to equipment designed for voltages greater than 345 kV. Higher transmission voltages increase efficiency by reducing transmission losses and current, decrease infrastructure costs, and increase transmission capacity. However, they also present safety and interference risks. New technologies like FACTS (flexible AC transmission systems) help maximize the benefits of EHV transmission by enabling voltage control and power flow management. There is growing support for expanding national EHV transmission grids to facilitate large-scale renewable energy integration and inter-regional power sharing.
The document discusses capacitive voltage transformers (CVTs). It describes CVTs as devices that step down extra high voltage signals for metering and protection purposes. CVTs consist of capacitors that divide the transmission line voltage, with an inductive element to tune the device to line frequency and a voltage transformer to further step down the voltage. CVTs are more economical than wound transformers for voltages over 100kV. CVTs can also be used for power line carrier communications and provide insulation between high and low voltage circuits.
The document discusses various objectives and applications of static shunt compensation on transmission lines. Shunt compensation can increase steady-state transmittable power, control voltage profiles, minimize line overvoltage under light loads using shunt reactors, and maintain voltage levels under heavy loads using shunt capacitors. Midpoint shunt compensation significantly increases transmitted power and is best located at the midpoint where voltage sag is maximum. End of line shunt compensation effectively increases voltage stability limits and regulates terminal voltages to prevent voltage instability. Shunt compensation can also improve transient stability and damp power oscillations on transmission lines.
Generation of High D.C. Voltage (HVDC generation)RP6997
Generation of high dc voltage using different methods like half wave and full wave rectifier, voltage doubler circuits, voltage multiplier circuits, cockcroft-walton circuits and van de graaff generators.
Power Factor Correction Methods
Fixed Capcitors
Synchronous Condensors
Phase Advancers
Switch Capacitors
Static Var Compensator(SVC)
Static Synchronous Compensator(STATCOM)
Modulated power filter capacitor compensator
Economics of power factor improvement
Economical comparison of increasing the power supply
This presentation provides an overview of power quality, including definitions of power quality, common power quality disturbances like sags, swells, harmonics and interruptions. It discusses the increased sensitivity of modern electronic equipment to power quality issues. Real-time power quality monitoring systems are described that can identify issues, locate their sources, and help utilities and customers mitigate problems to reduce costs and equipment damage. The benefits of power quality monitoring include improved reliability, preventative maintenance, and identification of sensitive equipment needing protection.
Disadvantages of corona, radio interference, inductive interference between p...vishalgohel12195
Disadvantages of corona, radio interference, inductive interference between power and communication lines
Introduction
Disadvantages of corona.
Radio interference.
Inductive interference between power and communication lines
This document discusses power factor, causes of low power factor, disadvantages of low power factor, and methods for improving power factor. It begins by defining power factor as the ratio of active power to apparent power. Inductive loads like transformers and motors cause low power factors by introducing reactive power. Low power factor results in larger equipment sizes, greater losses, and reduced system capacity. Methods for improving power factor include installing capacitors to offset reactive power and replacing standard motors with high efficiency models. The document concludes with a case study where installing capacitors at a factory's main board improved the average power factor from 0.75 to 0.95.
The document discusses various power quality problems such as harmonic distortion, voltage sags, swells, and interruptions. It then discusses solutions for power quality problems including maintaining grid adequacy, using distributed resources like distributed generation and energy storage, and implementing enhanced interface devices. The document also describes the operation of the Merus A-series Active Filter, which can be used to compensate for harmonics and reactive power in an electrical system.
This document discusses the history and development of high voltage engineering. It begins with early experiments with static electricity by ancient Greeks. Key figures who contributed include Franklin, Faraday, Tesla, and Edison. Faraday's law established that a magnetic field can induce current in a wire. Advances allowed longer distance power transmission. Challenges included developing high voltage insulation. Numerical methods like finite element analysis are now used to model electric field distributions in complex high voltage components.
This document discusses Flexible AC Transmission Systems (FACTS) controllers. It defines FACTS controllers as power electronic devices that control parameters of AC transmission systems. The document describes several types of FACTS controllers including STATCOM, SVC, TCSC, SSSC, and UPFC. It explains how each type of controller works and its benefits such as increasing power transfer capability and network reliability.
Series & shunt compensation and FACTs Deviceskhemraj298
Series compensation is used to improve the performance of extra high voltage transmission lines by connecting capacitors in series with the line. It allows for increased transmission capacity and improved system stability by reducing the phase angle between sending and receiving end voltages for the same power transfer. Shunt compensation controls the receiving end voltage by connecting shunt capacitors or reactors to meet reactive power demand and prevent voltage drops or rises. Flexible AC transmission systems use high-speed thyristors to switch transmission line components like capacitors and reactors to control parameters like voltages and reactances to optimize power transfer.
This document presents information on HVDC transmission and FACTS technology. It discusses the advantages and disadvantages of HVDC transmission, including its ability to transmit power over long distances with lower losses compared to AC transmission. It also introduces various FACTS controllers and their advantages in enhancing power flow control and transmission capacity. While FACTS can improve AC system utilization, HVDC may be less expensive for long distance overhead transmission or submarine cables. Both technologies are complementary with HVDC suitable for interconnecting unsynchronized AC systems and FACTS providing added benefits within AC networks.
This document discusses active and reactive power flow control using a Static Synchronous Series Compensator (SSSC). The SSSC injects a controllable voltage in series with a transmission line to regulate power flow. It can control both real and reactive power flow to improve transmission efficiency. The SSSC consists of a voltage source converter connected to the line via a transformer. It provides advantages like power factor correction, load balancing, and reducing harmonic distortion.
This document discusses power quality and defines it as the ability of a power system to supply voltage continuously within tolerances. It outlines various power quality events like sags, swells, interruptions, harmonics, and their causes and effects. It then describes various techniques to mitigate power quality issues, including dynamic voltage restorers, harmonic filters, static VAR compensators, and unified power quality conditioners. Maintaining high power quality improves system efficiency and equipment lifespan while eliminating problems like voltage fluctuations, harmonics, and reactive power issues.
This document discusses different methods for generating high voltages and currents, including cascade transformers, resonant transformers, and Tesla coils for AC voltages, and single-stage and Marx generators for impulse voltages. It also covers impulse current generation using a bank of parallel capacitors discharged through an R-L circuit. Cascade transformers consist of multiple transformer stages connected in series to achieve high voltages. Resonant transformers use tuning of the secondary circuit. Tesla coils produce high frequency AC through magnetic coupling of primary and secondary air-core coils.
The document provides information about a PowerPoint presentation on Distributed Static Compensator (D-STATCOM) given by Sheikh Mohammad Sajid. It introduces D-STATCOM as a device used to mitigate current-based power quality problems at the distributed level. It discusses various classifications, topologies, components, control strategies and objectives of D-STATCOM, including reactive power compensation, load balancing and harmonic suppression. The key principles of operation involve injecting compensating currents from a voltage source converter to regulate voltage at the point of common coupling.
This document discusses power quality and power quality disturbances. It defines power quality as the set of parameters defining the properties of power supply in normal operating conditions. Common power quality disturbances include steady-state variations like voltage fluctuations, harmonics, and high frequency noise as well as events like interruptions, sags, swells, and transients. Solutions to power quality problems include distributed generation, energy storage systems, codes and standards, interface devices, and making equipment less sensitive.
Extra high voltage long ac transmission linesShivagee Raj
From economical point of view designing of transmission line system is very important in the electricity supply system. Extra High Voltage Transmission Lines are best suited for transmission of bulk power.
It is based on current transformer description
It's working and applications are present in it ,it also includes videos of it's windings and it's inrush ability of transformer, and also about instrument transformer and it's working with applications.Current transformers are used-in measuring high currents and connected with it in parallel to it
The document summarizes a seminar presentation on HVDC (high voltage direct current) transmission. Some key points:
- HVDC transmission has advantages over HVAC like lower transmission losses over long distances. The first HVDC link was between Gotland and mainland Sweden in 1954.
- HVDC uses direct current instead of alternating current to transmit electricity over long distances. It requires only two conductors instead of three. Losses are also lower compared to HVAC.
- HVDC transmission can be classified as homopolar, monopolar or bipolar depending on the conductor configuration. Early HVDC projects in India included the Rihand-Delhi and Chandrapur-Padghe lines which helped transmit
seminar report on power quality monitoring khemraj298
The document discusses power quality monitoring and its importance for sustainable energy systems like solar power in India. It provides context on increased sensitivity of modern equipment to power quality issues and defines different types of steady state variations and events that impact power quality. Monitoring objectives include proactive and reactive approaches to characterize system performance and identify specific problems. The development of an intelligent power quality monitoring system using LabVIEW and sensors is described to efficiently monitor power quality in sustainable energy systems.
1. The document discusses power quality and its importance in reliable power supply as the sensitivity of equipment has increased. It defines power quality as the set of parameters defining the properties of power supply during normal operation in terms of voltage continuity and characteristics.
2. Power quality problems can have internal causes like equipment start/stop or external causes like weather or utility issues. Disturbances are categorized as steady state variations like voltage fluctuations or events which are sudden deviations. Common steady state variations discussed are voltage/current unbalance and harmonic distortion.
3. Power quality monitoring is important to identify causes of problems before interruptions and helps improve power quality with suitable solutions. It is a critical step in ensuring reliability of sustainable energy sources and reducing
The document discusses various objectives and applications of static shunt compensation on transmission lines. Shunt compensation can increase steady-state transmittable power, control voltage profiles, minimize line overvoltage under light loads using shunt reactors, and maintain voltage levels under heavy loads using shunt capacitors. Midpoint shunt compensation significantly increases transmitted power and is best located at the midpoint where voltage sag is maximum. End of line shunt compensation effectively increases voltage stability limits and regulates terminal voltages to prevent voltage instability. Shunt compensation can also improve transient stability and damp power oscillations on transmission lines.
Generation of High D.C. Voltage (HVDC generation)RP6997
Generation of high dc voltage using different methods like half wave and full wave rectifier, voltage doubler circuits, voltage multiplier circuits, cockcroft-walton circuits and van de graaff generators.
Power Factor Correction Methods
Fixed Capcitors
Synchronous Condensors
Phase Advancers
Switch Capacitors
Static Var Compensator(SVC)
Static Synchronous Compensator(STATCOM)
Modulated power filter capacitor compensator
Economics of power factor improvement
Economical comparison of increasing the power supply
This presentation provides an overview of power quality, including definitions of power quality, common power quality disturbances like sags, swells, harmonics and interruptions. It discusses the increased sensitivity of modern electronic equipment to power quality issues. Real-time power quality monitoring systems are described that can identify issues, locate their sources, and help utilities and customers mitigate problems to reduce costs and equipment damage. The benefits of power quality monitoring include improved reliability, preventative maintenance, and identification of sensitive equipment needing protection.
Disadvantages of corona, radio interference, inductive interference between p...vishalgohel12195
Disadvantages of corona, radio interference, inductive interference between power and communication lines
Introduction
Disadvantages of corona.
Radio interference.
Inductive interference between power and communication lines
This document discusses power factor, causes of low power factor, disadvantages of low power factor, and methods for improving power factor. It begins by defining power factor as the ratio of active power to apparent power. Inductive loads like transformers and motors cause low power factors by introducing reactive power. Low power factor results in larger equipment sizes, greater losses, and reduced system capacity. Methods for improving power factor include installing capacitors to offset reactive power and replacing standard motors with high efficiency models. The document concludes with a case study where installing capacitors at a factory's main board improved the average power factor from 0.75 to 0.95.
The document discusses various power quality problems such as harmonic distortion, voltage sags, swells, and interruptions. It then discusses solutions for power quality problems including maintaining grid adequacy, using distributed resources like distributed generation and energy storage, and implementing enhanced interface devices. The document also describes the operation of the Merus A-series Active Filter, which can be used to compensate for harmonics and reactive power in an electrical system.
This document discusses the history and development of high voltage engineering. It begins with early experiments with static electricity by ancient Greeks. Key figures who contributed include Franklin, Faraday, Tesla, and Edison. Faraday's law established that a magnetic field can induce current in a wire. Advances allowed longer distance power transmission. Challenges included developing high voltage insulation. Numerical methods like finite element analysis are now used to model electric field distributions in complex high voltage components.
This document discusses Flexible AC Transmission Systems (FACTS) controllers. It defines FACTS controllers as power electronic devices that control parameters of AC transmission systems. The document describes several types of FACTS controllers including STATCOM, SVC, TCSC, SSSC, and UPFC. It explains how each type of controller works and its benefits such as increasing power transfer capability and network reliability.
Series & shunt compensation and FACTs Deviceskhemraj298
Series compensation is used to improve the performance of extra high voltage transmission lines by connecting capacitors in series with the line. It allows for increased transmission capacity and improved system stability by reducing the phase angle between sending and receiving end voltages for the same power transfer. Shunt compensation controls the receiving end voltage by connecting shunt capacitors or reactors to meet reactive power demand and prevent voltage drops or rises. Flexible AC transmission systems use high-speed thyristors to switch transmission line components like capacitors and reactors to control parameters like voltages and reactances to optimize power transfer.
This document presents information on HVDC transmission and FACTS technology. It discusses the advantages and disadvantages of HVDC transmission, including its ability to transmit power over long distances with lower losses compared to AC transmission. It also introduces various FACTS controllers and their advantages in enhancing power flow control and transmission capacity. While FACTS can improve AC system utilization, HVDC may be less expensive for long distance overhead transmission or submarine cables. Both technologies are complementary with HVDC suitable for interconnecting unsynchronized AC systems and FACTS providing added benefits within AC networks.
This document discusses active and reactive power flow control using a Static Synchronous Series Compensator (SSSC). The SSSC injects a controllable voltage in series with a transmission line to regulate power flow. It can control both real and reactive power flow to improve transmission efficiency. The SSSC consists of a voltage source converter connected to the line via a transformer. It provides advantages like power factor correction, load balancing, and reducing harmonic distortion.
This document discusses power quality and defines it as the ability of a power system to supply voltage continuously within tolerances. It outlines various power quality events like sags, swells, interruptions, harmonics, and their causes and effects. It then describes various techniques to mitigate power quality issues, including dynamic voltage restorers, harmonic filters, static VAR compensators, and unified power quality conditioners. Maintaining high power quality improves system efficiency and equipment lifespan while eliminating problems like voltage fluctuations, harmonics, and reactive power issues.
This document discusses different methods for generating high voltages and currents, including cascade transformers, resonant transformers, and Tesla coils for AC voltages, and single-stage and Marx generators for impulse voltages. It also covers impulse current generation using a bank of parallel capacitors discharged through an R-L circuit. Cascade transformers consist of multiple transformer stages connected in series to achieve high voltages. Resonant transformers use tuning of the secondary circuit. Tesla coils produce high frequency AC through magnetic coupling of primary and secondary air-core coils.
The document provides information about a PowerPoint presentation on Distributed Static Compensator (D-STATCOM) given by Sheikh Mohammad Sajid. It introduces D-STATCOM as a device used to mitigate current-based power quality problems at the distributed level. It discusses various classifications, topologies, components, control strategies and objectives of D-STATCOM, including reactive power compensation, load balancing and harmonic suppression. The key principles of operation involve injecting compensating currents from a voltage source converter to regulate voltage at the point of common coupling.
This document discusses power quality and power quality disturbances. It defines power quality as the set of parameters defining the properties of power supply in normal operating conditions. Common power quality disturbances include steady-state variations like voltage fluctuations, harmonics, and high frequency noise as well as events like interruptions, sags, swells, and transients. Solutions to power quality problems include distributed generation, energy storage systems, codes and standards, interface devices, and making equipment less sensitive.
Extra high voltage long ac transmission linesShivagee Raj
From economical point of view designing of transmission line system is very important in the electricity supply system. Extra High Voltage Transmission Lines are best suited for transmission of bulk power.
It is based on current transformer description
It's working and applications are present in it ,it also includes videos of it's windings and it's inrush ability of transformer, and also about instrument transformer and it's working with applications.Current transformers are used-in measuring high currents and connected with it in parallel to it
The document summarizes a seminar presentation on HVDC (high voltage direct current) transmission. Some key points:
- HVDC transmission has advantages over HVAC like lower transmission losses over long distances. The first HVDC link was between Gotland and mainland Sweden in 1954.
- HVDC uses direct current instead of alternating current to transmit electricity over long distances. It requires only two conductors instead of three. Losses are also lower compared to HVAC.
- HVDC transmission can be classified as homopolar, monopolar or bipolar depending on the conductor configuration. Early HVDC projects in India included the Rihand-Delhi and Chandrapur-Padghe lines which helped transmit
seminar report on power quality monitoring khemraj298
The document discusses power quality monitoring and its importance for sustainable energy systems like solar power in India. It provides context on increased sensitivity of modern equipment to power quality issues and defines different types of steady state variations and events that impact power quality. Monitoring objectives include proactive and reactive approaches to characterize system performance and identify specific problems. The development of an intelligent power quality monitoring system using LabVIEW and sensors is described to efficiently monitor power quality in sustainable energy systems.
1. The document discusses power quality and its importance in reliable power supply as the sensitivity of equipment has increased. It defines power quality as the set of parameters defining the properties of power supply during normal operation in terms of voltage continuity and characteristics.
2. Power quality problems can have internal causes like equipment start/stop or external causes like weather or utility issues. Disturbances are categorized as steady state variations like voltage fluctuations or events which are sudden deviations. Common steady state variations discussed are voltage/current unbalance and harmonic distortion.
3. Power quality monitoring is important to identify causes of problems before interruptions and helps improve power quality with suitable solutions. It is a critical step in ensuring reliability of sustainable energy sources and reducing
Electric powerWords: 3005 Pages: 11
International Business Environment: Coca-Cola Company
Introduction A firm’s international business environment, commonly abbreviated as IBE, is a crucial multidimensional component of multinational corporations. It encompasses four major aspects: the socio-cultural, geographic, economic, technological, political environment of a company. According to Grgić (2020), the global business environment allows companies to expand their operations and increase their...
Topic: Coca Cola
Words: 3005 Pages: 10
Analysis of Amazon Go’s Expansion Into the European Market
Introduction Amazon is a global corporation headquartered in Seattle, United States. It is principally an online retailer and technology company based on cloud computing, artificial intelligence, digital streaming, and e-commerce. Amazon is, therefore, renowned for its technological prowess including the revolutionary development of the Amazon Go shopping experience. Amazon Go...
Topic: Amazon
Words: 3005 Pages: 11
Harvard Business School’s Partnership Opportunities
Introduction The modern era learning institutions are taking school partnerships a notch higher by leveraging technology on global connectivity where partnership activities occur over digital platforms. School partnerships denote the strong alliances and affiliations between two or more learning institutions to improve service quality delivery to the learners. Historically, alliances...
Topic: School
Words: 3005 Pages: 10
Female Patient With Hypotension and Alzheimer’s Disease
Introduction The case study analysis a female patient with hypotension and Alzheimer’s disease who recently suffered a fall. The Nursing and Midwifery Council (NMC) code 2018 and Data Protection Act (DPA) 2018 require nurse-patient confidentiality. Therefore, in the analysis of this case, I will refer to the female patient as...
Topic: Alzheimer’s Disease
Words: 3005 Pages: 11
The Role of Technology in Architecture
Introduction Technology has become of the fundamental vital aspects in the modern world since it has affected many social, economic and political undertakings. In this regard, it has become a pertinent component of the architectural profession. In the past, architecture was limited to physical conceptualization and actualization of ideas to...
Topic: Architecture
Words: 3006 Pages: 11
Lab Experiment on Photovoltaics
The abstract With regard to the theories of Photovoltaics physics learned in the course, this report is an attempt to support and rationalize their implications in actuality. The experiment was done specifically to ascertain how various connected units could be coordinated to give a more reliable and controllable functioning. It...
Topic: Experiment
Words: 3007 Pages: 10
Duty and Standard of Care Concepts
Introduction The legal framework of business is the structure by which commercial decision is made. Basic knowledge is that legal issues are important in forming a solid foundation for the study
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...IRJET Journal
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
This document provides an introduction to power quality, including definitions, concepts, and classifications of various power quality disturbances. It defines power quality as the characteristics of voltage and current in a power system that allow equipment to function properly. Power quality issues are deviations from the ideal voltage and current sine waves, including transients, sags, swells, interruptions, harmonics, and voltage imbalance. These issues are characterized and classified based on duration, magnitude, frequency content, and causes. International standards for measuring and monitoring power quality are also mentioned.
The document summarizes power quality issues including defects like under voltage, over voltage, dips, surges, blackouts, harmonics, and transients. It discusses who is responsible for ensuring power quality and some typical problems caused by defects. Solutions mentioned include surge protection, UPS systems, generators, filters, proper wiring, and load zoning. Assuring high quality power is challenging as electricity must flow continuously from generators to consumers via a shared infrastructure.
Power quality is important for reliable operations and avoiding downtime. It refers to maintaining steady voltage and frequency levels. Poor power quality can cause equipment damage and failure through issues like harmonics, sags, swells, transients, unbalance, and flicker. Power quality monitoring involves continuous measurement and analysis to diagnose problems, improve reliability, and optimize maintenance. Janitza offers complete solutions for power quality monitoring and energy management that help facilities meet standards, protect assets, and reduce costs.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
1) The document discusses various power quality problems faced in power systems such as voltage sags, interruptions, flicker, surges, spikes, and harmonics.
2) It describes different types of active power filters that can be used to solve power quality issues, including shunt active filters that inject compensating current, and series active filters that inject compensating voltage.
3) The unified power quality conditioner is introduced, which uses both series and shunt active filters to improve both voltage and current quality by controlling series injected voltage and shunt injected current.
IRJET- Study on Power Quality Problem and its Mitigation Techniques in Electr...IRJET Journal
This document discusses power quality problems in electrical power systems and techniques to mitigate them. It begins by defining power quality and listing some common power quality issues like voltage sags, swells, interruptions, harmonics, and waveform distortions. Potential causes of these issues are also provided. The document then discusses various techniques that can be used to improve power quality, including surge protection devices, UPS systems, filters, custom devices like DVRs, STATCOMs and UPQC. It concludes by stating that power quality must be maintained as power needs increase and sensitive loads become more common, and discusses the need for mitigation techniques to address issues like voltage sags and harmonics.
IRJET- Investigation of Various Power Quality Issues & its Solution in Gr...IRJET Journal
This document discusses various power quality issues that can occur in grid-connected distributed power systems and their potential solutions. It defines power quality and lists several common power quality issues including voltage sags, swells, fluctuations, interruptions, harmonics, flicker, and unbalances. For each issue, it provides a definition and description of the potential causes and impacts. The goal of the paper is to investigate these power quality problems and discuss their possible solutions to help suppliers, distributors and consumers of electricity maintain a clean and stable power supply.
This document discusses a study analyzing and simulating a Dynamic Voltage Restorer (DVR) to compensate for power quality issues like voltage sags and swells. A DVR is a custom power device that injects voltage into the distribution system to regulate the load voltage. It monitors the load voltage and injects or absorbs any imbalance to maintain the load voltage within tolerance limits. The document outlines different power quality problems caused by faults and equipment, and introduces DVRs and other custom power devices as effective solutions to mitigate issues like voltage sags and harmonics.
Power quality issues arise from disturbances in the electric power supply that can negatively impact equipment. Common issues include voltage sags, swells, interruptions, harmonics, and spikes. Around 80% of problems originate from within industrial facilities due to large loads or improper wiring, while 20% come from external utility issues like weather events. Poor power quality can increase energy costs and cause equipment failures. Monitoring power quality helps identify disturbances and their sources to improve reliability and reduce costs. Various devices like filters, regulators, and compensators can help mitigate different power quality issues. Maintaining high power quality supports the economic operation of power systems and equipment.
This document discusses power quality and issues that can arise such as voltage variations, frequency variations, and waveform distortions. It defines key power quality terms like sags, swells, flicker, harmonics, and describes how loads and generation sources can impact power quality. Active power filters are presented as a solution to power quality problems in electric rail systems by compensating for unbalance, harmonic distortion, and low power factor. Compression algorithms are also discussed to efficiently store and analyze large power quality data sets.
The quality of power supply is very important in any power network particularly to electricity consumers. Power quality encompasses availability of supply, frequency and voltage magnitude as well as waveform characteristics of the power supply.
Power Quality Improvement by UPQC based on Voltage Source ConvertersIJRST Journal
In modern power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment’s are nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale. Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like Unified Power Quality Conditioner (UPQC) which aims at achieving a low cost under highly effective control. The UPQC device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics and voltage sags. The simulation results are compared without and with UPQC for the verification of results.
IRJET- Improvement of Power Quality using Active FiltersIRJET Journal
This document discusses improving power quality using active filters. It provides an overview of various power quality issues caused by harmonic pollution and reactive power in distribution systems. Active filters are presented as an effective solution to power quality problems. The document describes different types of active filters, including shunt and series active filters, and their applications in compensating for issues like harmonics, reactive power, voltage fluctuations, and unbalanced currents. Control strategies for active filters are also discussed. The document aims to give researchers and engineers an understanding of active filter technology and its role in addressing common power quality problems.
Control of Dvr with Battery Energy Storage System Using Srf TheoryIJERA Editor
One of the best solutions to improve power quality is the dynamic voltage restorer (DVR). DVR is a kind of
custom power devices that can inject active/reactive power to the power grids. This can protect loads from
disturbances such as sag and swell. Usually DVR installed between sensitive loads feeder and source in
distribution system. Its features include lower cost, smaller size, and its fast dynamic response to the
disturbance. In this project SRF technique is used for conversion of voltage from rotating vectors to the
stationary frame. SRF technique is also referred as park’s transformation. In this the reference load voltage is
estimated using the unit vectors. The real power exchanged at the DVR output ac terminal is provided by the
DVR input dc terminal by an external energy source or energy storage system. In this project three phase
parallel or series load may be used along with SRF technique to compensate voltage sag and voltage swell. And
also wind generator is also used as a load. This project presents the simulation of DVR system using
MATLAB/SIMULINK.
1. The document describes a simulation of a Dynamic Voltage Restorer (DVR) for mitigating voltage sags in a distribution system. A DVR injects voltage in series with the distribution feeder using a voltage source inverter, injection transformer, and energy storage device.
2. The performance of three control techniques for the DVR's inverter - PI controller, hysteresis current control, and hysteresis voltage control - were compared through MATLAB simulation. Hysteresis voltage control was able to fully compensate a three-phase fault that caused a 17% voltage sag.
3. By injecting the appropriate compensating voltage, a DVR can restore the load voltage to its rated value during faults or disturbances
Better Builder Magazine brings together premium product manufactures and leading builders to create better differentiated homes and buildings that use less energy, save water and reduce our impact on the environment. The magazine is published four times a year.
Covid Management System Project Report.pdfKamal Acharya
CoVID-19 sprang up in Wuhan China in November 2019 and was declared a pandemic by the in January 2020 World Health Organization (WHO). Like the Spanish flu of 1918 that claimed millions of lives, the COVID-19 has caused the demise of thousands with China, Italy, Spain, USA and India having the highest statistics on infection and mortality rates. Regardless of existing sophisticated technologies and medical science, the spread has continued to surge high. With this COVID-19 Management System, organizations can respond virtually to the COVID-19 pandemic and protect, educate and care for citizens in the community in a quick and effective manner. This comprehensive solution not only helps in containing the virus but also proactively empowers both citizens and care providers to minimize the spread of the virus through targeted strategies and education.
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
Sri Guru Hargobind Ji - Bandi Chor Guru.pdfBalvir Singh
Sri Guru Hargobind Ji (19 June 1595 - 3 March 1644) is revered as the Sixth Nanak.
• On 25 May 1606 Guru Arjan nominated his son Sri Hargobind Ji as his successor. Shortly
afterwards, Guru Arjan was arrested, tortured and killed by order of the Mogul Emperor
Jahangir.
• Guru Hargobind's succession ceremony took place on 24 June 1606. He was barely
eleven years old when he became 6th Guru.
• As ordered by Guru Arjan Dev Ji, he put on two swords, one indicated his spiritual
authority (PIRI) and the other, his temporal authority (MIRI). He thus for the first time
initiated military tradition in the Sikh faith to resist religious persecution, protect
people’s freedom and independence to practice religion by choice. He transformed
Sikhs to be Saints and Soldier.
• He had a long tenure as Guru, lasting 37 years, 9 months and 3 days
1. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 1
Power Quality
Unit -1
Syllabus
Definition of Power Quality- Power Quality Terminology – Classification of Power Quality
Issues-Magnitude Versus Duration Plot - Power Quality Standards - Responsibilities of The
Suppliers and Users of Electric Power-CBEMA and ITIC Curves.
Introduction:
Development of any country’s economy depends on power production and power
consumption. Power consumption is an index of growth and development, with rapid growth
of industrialization manufacturers want faster, more productive, more efficient machinery.
Utilities encourage this effort because it helps their customers become more profitable and
also helps to put off large investments in substations and generation by using more efficient
load equipment. Interestingly, the equipment installed to increase the productivity is also
often the equipment that suffers the most from common power disruptions. And the
equipment is sometimes the source of additional power quality problems. When entire
processes are automated, the efficient operation of machines and their controls becomes
increasingly dependent on quality power
Electric power is the most essential raw material. It is unusual commodity as it
requires continuous flow and can not be conveniently stored. It is a typical example of “Just
in Time” philosophy – Components are delivered to the production line at the point and time
of use by a trusted supplier with no requirement of “goods in” inspection.
Power quality is any abnormal behaviour on a power system arising in the form of
voltage or current, which affects the normal operation of electrical or electronic equipment.
Power quality is any deviation of the voltage or current waveform from its normal sinusoidal
wave shape.
Power quality has been defined as the parameters of the voltage that affect the customer’s
supersensitive equipment.
The IEEE defines POWER QUALITY as
“The ability of a system or an equipment to function satisfactorily in its
electromagnetic environment without introducing intolerable electromagnetic
disturbances to anything in that environment”.
Power Quality can also be defined as
“Any power problem manifested in voltage, current, or frequency deviations that
results in failure or misoperation of customer equipment”
2. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 2
Power Quality = Voltage Quality
The common term for describing the power quality is actually the quality of the
voltage that is being supplied. Power is the rate of energy delivery and is proportional to the
product of the voltage and current. It would be difficult to define the quality of this quantity
in any meaningful manner. The power supply system can only control the quality of the
voltage; it has no control over the currents that particular loads might draw. Therefore, the
standards in the power quality area are devoted to maintaining the supply voltage within
certain limits.
AC power systems are designed to operate at a sinusoidal voltage of a given
frequency [typically 50 or 60 hertz (Hz)] and magnitude. Any significant deviation in the
waveform magnitude, frequency, or purity is a potential power quality problem. Of course,
there is always a close relationship between voltage and current in any practical power
system. Although the generators may provide a near-perfect sine-wave voltage, the current
passing through the impedance of the system can cause a variety of disturbances to the
voltage. For example,
1. The current resulting from a short circuit causes the voltage to sag or disappear
completely, as the case may be.
2. Currents from lightning strokes passing through the power system cause high-
impulse voltages that frequently flash over insulation and lead to other phenomena,
such as short circuits.
3. Distorted currents from harmonic-producing loads also distort the voltage as they
pass through the system impedance. Thus a distorted voltage is presented to other end
users.
Therefore, while it is the voltage with which we are ultimately concerned, we must also
address phenomena in the current to understand the basis of many power quality problems.
Why Are We Concerned about Power Quality?
The quality of power can have a direct economic impact on many industrial consumers.
Continuous process industry where short outage of power may loss synchronizing of
machinery and may result in large quantity of semi processed product – Paper making
where cleanup process is long and expensive
Outage in multistage batch process may destroy the value of previous process –
Semiconductor industry – Production of wafer requires few dozen process over
several days.
Residential customers typically do not suffer direct financial loss or the inability to
earn income as a result of most power quality problems, but they can be a major force
when they notice that the utility is providing poor service.
3. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 3
The Power Quality Evaluation Procedure
There are wide range of Power quality problems each problem has different causes
and different solutions that can be used to improve the power quality and equipment
performance. The general steps that are associated with investigating many of these
problems, are given in Figure below.
Basic Steps involved in Power Quality Evaluation.
The general procedure must also consider whether the evaluation involves an existing
power quality problem or one that could result from a new design or from proposed changes
to the system. Measurements will play an important role for almost any power quality
concern.
This is the primary method of characterizing the problem or the existing system that is by
measuring the parameters (i.e voltage, freq, etc) the variations at the same time so that
problems can be correlated with possible causes.
Solutions need to be evaluated using a system perspective, and both the economics and the
technical limitations must be considered. Possible solutions are identified at all levels of the
system from utility supply to the end-use equipment being affected. Solutions that are not
technically viable get thrown out, and the rest of the alternatives are compared on an
economic basis. The optimum solution will depend on the type of problem, the number of
end users being impacted, and the possible solutions.
4. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 4
General Classification of Power Quality Problems
In order to categorize the power quality problems using electromagnetic phenomena
some parameters (attributes) are considered, appropriate attributes for steady state and non
steady state are given below .
For steady-state phenomena, the following attributes can be used:
i. Amplitude
ii. Frequency
iii. Spectrum
iv. Modulation
v. Source impedance
vi. Notch depth
vii. Notch area
For non-steady-state phenomena, other attributes may be required:
i. Rate of rise
ii. Amplitude
iii. Duration
iv. Spectrum
v. Frequency
vi. Rate of occurrence
vii. Energy potential
viii. Source impedance
Based on the above attributes power quality problems can be categorized as:
1. Voltage sag
2. Voltage swell
3. Voltage Flicker
4. Harmonics
5. Over voltage
6. Under voltage
7. Transients
Voltage sags are considered the most common power quality problem. These can be caused
by the utility or by customer loads. When sourced from the utility, they are most commonly
caused by faults on the distribution system. These sags will be from 3 to 30 cycles and can be
single or three phase. Depending on the design of the distribution system, a ground fault on 1
phase can cause a simultaneous swell on another phase.
Power quality problems are related to grounding, ground bonds and neutral to ground
voltages, ground loops, ground current or ground associated issues.
5. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 5
Harmonics are distortions in the AC waveform. These distortions are caused by loads on the
electrical system that use the electrical power at a different frequency than the fundamental
50 or 60 Hz.
Terms and Definitions:
Power Quality: It is any deviation of the voltage or current waveform from its normal
sinusoidal wave shape.
Voltage quality: Deviations of the voltage from a sinusoidal waveform.
Current quality: Deviations of the current from a sinusoidal waveform.
Frequency Deviation: An increase or decrease in the power frequency.
Impulsive transient: A sudden, non power frequency change in the steady state condition of
voltage or current that is unidirectional in polarity.
Oscillatory transients: A sudden, non power frequency change in the steady state condition
of voltage or current that is bidirectional in polarity.
DC Offset: The presence of a DC voltage or current in an AC power system.
Noises: An unwanted electric signal in the power system.
Long duration Variation: A variation of the RMS value of the voltage from nominal
voltage for a time greater than 1 min.
Short Duration Variation: A variation of the RMS value of the voltage from nominal
voltage for a time less than 1 min.
Sag: A decrease in RMS value of voltage or current for durations of 0.5 cycles to 1 min.
Swell: A Temporary increase in RMS value of voltage or current for durations of 0.5 cycles
to 1 min.
Under voltage: 10% below the nominal voltage for a period of time greater than 1 min.
Over voltage: 10% above the nominal voltage for a period of time greater than 1 min.
Voltage fluctuation: A cyclical variation of the voltage that results in flicker of lightning.
Voltage imbalance: Three phase voltages differ in amplitude.
Harmonic: It is a sinusoidal component of a periodic wave or quantity having a frequency
that is an integral multiple of the fundamental power frequency.
Distortion: Any deviation from the normal sine wave for an AC quantity.
Total Harmonic Distortion: The ratio of the root mean square of the harmonic content to
the RMS value of the fundamental quantity.
6. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 6
Interruption: The complete loss of voltage on one or more phase conductors for a time
greater than 1 min.
Concepts of transients:
1. Transient over voltages in electrical transmission and distribution networks result
from the unavoidable effects of lightning strike and network switching operations.
2. Response of an electrical network to a sudden change in network conditions.
3. Oscillation is an effect caused by a transient response of a circuit or system. It is a
momentary event preceding the steady state (electronics) during a sudden change of a
circuit.
4. An example of transient oscillation can be found in digital (pulse) signals in computer
networks. Each pulse produces two transients, an oscillation resulting from the sudden
rise in voltage and another oscillation from the sudden drop in voltage. This is
generally considered an undesirable effect as it introduces variations in the high and
low voltages of a signal, causing instability.
Types of transient:
a. Impulsive transient
b. Oscillatory transient
Impulse transient:
A sudden, non power frequency change in the steady state condition of voltage or current that
is unidirectional in polarity.
Oscillatory transient: A sudden, non power frequency change in the steady state condition
of voltage or current that is bidirectional in polarity.
7. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 7
Short duration variations – Interruption The complete loss of voltage on one or more
phase conductors for a time less than 1 min.
Types of Short Duration interruption:
a. Momentary Interruption < 1 min , <0.1 pu
b. Temporary Interruption < 1 min , <0.1 pu
Long duration variations – Sustained interruption: The complete loss of voltage on one or
more phase conductors for a time greater than 1 min.
8. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 8
Sags and Swells:
Voltage sag:
A voltage sag or voltage dip is a short duration reduction in RMS voltage which can
be caused by a short circuit, overload or starting of electric motors.
Voltage sag happens when the RMS voltage decreases between 10 and 90 percent of
nominal voltage for one-half cycle to one minute.
Some references define the duration of sag for a period of 0.5 cycles to a few seconds,
and longer duration of low voltage would be called “sustained sag".
There are several factors which cause voltage sag to happen:
Since the electric motors draw more current when they are starting than when they are
running at their rated speed, starting an electric motor can be a reason of voltage sag.
When a line-to-ground fault occurs, there will be voltage sag until the protective
switch gear operates.
Some accidents in power lines such as lightning or falling an object can be a cause of
line-to-ground fault and voltage sag as a result.
Sudden load changes or excessive loads can cause voltage sag.
Depending on the transformer connections, transformers energizing could be another
reason for happening voltage sags.
Voltage sags can arrive from the utility but most are caused by in-building equipment.
In residential homes, we usually see voltage sags when the refrigerator, air-
conditioner or furnace fan starts up.
9. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 9
Voltage Swell:
Swell - an increase to between 1.1pu and 1.8 pu in rms voltage or current at the power
frequency durations from 0.5 to 1 minute
In the case of a voltage swell due to a single line-to-ground (SLG) fault on the system, the
result is a temporary voltage rise on the un faulted phases, which last for the duration of the
fault. This is shown in the figure below:
Instantaneous Voltage Swell Due to SLG fault
Voltage swells can also be caused by the deenergization of a very large load.
It may cause breakdown of components on the power supplies of the equipment, though the
effect may be a gradual, accumulative effect. It can cause control problems and hardware
failure in the equipment, due to overheating that could eventually result to shutdown. Also,
electronics and other sensitive equipment are prone to damage due to voltage swell.
10. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 10
Voltage unbalance:
In a balanced sinusoidal supply system the three line-neutral voltages are equal in
magnitude and are phase displaced from each other by 120 degrees (Figure 1). Any
differences that exist in the three voltage magnitudes and/or a shift in the phase separation
from 120 degrees is said to give rise to an unbalanced supply (Figure 2)
11. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 11
The utility can be the source of unbalanced voltages due to malfunctioning equipment,
including blown capacitor fuses, open-delta regulators, and open-delta transformers. Open-
delta equipment can be more susceptible to voltage unbalance than closed-delta since they
only utilize two phases to perform their transformations.
Also, voltage unbalance can also be caused by uneven single-phase load distribution among
the three phases - the likely culprit for a voltage unbalance of less than 2%. Furthermore,
severe cases (greater than 5%) can be attributed to single-phasing in the utility’s distribution
lateral feeders because of a blown fuse due to fault or overloading on one phase.
Voltage Fluctuation:
Voltage fluctuations can be described as repetitive or random variations of the voltage
envelope due to sudden changes in the real and reactive power drawn by a load. The
characteristics of voltage fluctuations depend on the load type and size and the power
system capacity.
Figure 1 illustrates an example of a fluctuating voltage waveform. The voltage
waveform exhibits variations in magnitude due to the fluctuating nature or
intermittent operation of connected loads.
The frequency of the voltage envelope is often referred to as the flicker frequency.
Thus there are two important parameters to voltage fluctuations, the frequency of
fluctuation and the magnitude of fluctuation. Both of these components are significant
in the adverse effects of voltage fluctuations.
12. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 12
Voltage fluctuations are caused when loads draw currents having significant sudden or
periodic variations. The fluctuating current that is drawn from the supply causes additional
voltage drops in the power system leading to fluctuations in the supply voltage. Loads that
exhibit continuous rapid variations are thus the most likely cause of voltage fluctuations.
i. Arc furnaces
ii. Arc welders
iii. Installations with frequent motor starts (air conditioner units, fans)
iv. Motor drives with cyclic operation (mine hoists, rolling mills)
v. Equipment with excessive motor speed changes (wood chippers, car shredders)
Power frequency variations:
i. Power frequency variations are a deviation from the nominal supply frequency. The
supply frequency is a function of the rotational speed of the generators used to
produce the electrical energy.
ii. At any instant, the frequency depends on the balance between the load and the
capacity of the available generation.
iii. A frequency variation occurs if a generator becomes un-synchronous with the power
system, causing an inconsistency that is manifested in the form of a variation.
iv. The specified frequency variation should be within the limits Hz at all times for grid
network.
International Standards of power quality:
IEEE Standards:
i. IEEE power quality standards: Institute Of Electrical and Electronics Engineer.
ii. IEEE power quality standards: International Electro Technical Commission.
iii. IEEE power quality standards: Semiconductor Equipment and Material International.
iv. IEEE power quality standards: The International Union for Electricity Applications
v. IEEE Std 519-1992: IEEE Recommended practices and requirements for Harmonic
control in Electric power systems.
vi. IEEE Std 1159-1995: IEEE Recommended practices for monitoring electrical power
vii. IEEE std 141-1993, IEEE Recommended practice for electric power distribution for
industrial plants.
viii. IEEE std 1159-1995, IEEE recommended practice for Monitoring electrical power
quality.
13. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 13
IEC Standards:
i. Definitions and methodology 61000-1-X
ii. Environment 61000-2-X
iii. Limits 61000-3-X
iv. Tests and measurements 61000-4-X
v. Installation and mitigation 61000-5-X
vi. Generic immunity and emissions 61000-6-X
Responsibilities of The Suppliers and Users of Electric Power
i. Suppliers argue – Critical users must bear the cost of ensuring quality of supply.
ii. Rather than expecting the supply industry to provide very high reliability to every
customer everywhere on the network.
iii. Some quality problems are the result of shared infrastructure.
iv. Fault on a one part of network may cause dip that will affect some customers
v. Higher the level of the fault, the greater will be the number of customers affected.
vi. Problem on one customer’s site may cause a transient that affects all the customers on
the same subsystem.
vii. Harmonics, arise within the customer’s won installation may propagate onto the
network and affect other customers.
CBEMA and ITI Curves:
One of the most frequently employed displays of data to represent the power quality is the so-
called CBEMA curve.
A portion of the curve adapted from IEEE Standard 4469 that we typically use in our
nalysis of power quality monitoring results is shown in Fig. 1.5.
This curve was originally developed by CBEMA to describe the tolerance of
mainframe computer equipment to the magnitude and duration of voltage variations
on the power system.
While many modern computers have greater tolerance than this, the curve has become
a standard design target for sensitive equipment to be applied on the power system
and a common format for reporting power quality variation data.
The axes represent magnitude and duration of the event. Points below the envelope
are presumed to cause the load to drop out due to lack of energy. Points above the
envelope are presumed to cause other malfunctions such as insulation failure,
overvoltage trip, and over excitation.
The upper curve is actually defined down to 0.001 cycle where it has a value of about
375 percent voltage.
14. Power Quality Material Unit-I
Dept of EEE, KVSW, Kurnool Page 14
We typically employ the curve only from 0.1 cycles and higher due to limitations in
power quality monitoring instruments and differences in opinion over defining the
magnitude values in the sub cycle time frame.
The CBEMA organization has been replaced by ITI, and a modified curve has been
developed that specifically applies to common 120-V computer equipment (see Fig.
1.6). The concept is similar to the CBEMA curve. Although developed for 120-V
computer equipment, the curve has been applied to general power quality evaluation
like its predecessor curve.
Both curves are used as a reference in this book to define the withstand capability of
various loads and devices for protection from power quality variations.
For display of large quantities of power quality monitoring data, we frequently add a
third axis to the plot to denote the number of events within a certain predefined cell of
magnitude and duration.
A portion of the CBEMA curve commonly used as a design target for equipment And a
format for reporting power quality variation data.