The existence of modern society and its efficient functioning are more than anything else dependent on one single product - electricity. All electricity users - industry, commercial organizations, telecommunications, hospitals, educational institutions, and millions of private citizens - fully expect that electric power will always be available at a simple flick of a switch, in whatever quantity is required, and with the all the quality attributes that are required for safe, efficient and continuous operation of the devices it powers. In our society, electricity is a product where availability and quality is taken for granted. Yet in contrast to other products, electricity cannot be effectively stockpiled and carefully inspected for quality before it is delivered. Electrical supply must continuously match load demand every second of the day, each and every day, month and year, making it difficult to control and maintain power quality. Slight disturbances such as momentary voltage sags and spikes, power harmonics and voltage unbalances are intrinsic characteristics of electricity that directly impact the efficiency and performance of the electric equipment. Very often these problems will go undetected until after more serious disturbances occur interrupting the manufacturing process, damaging equipment or spoiling products. Unless the sources of these power quality disturbances are quickly identified and the underlying causes diagnosed and corrected, the cost to the user can be very high. As electricity permeates virtually every aspect of contemporary society, poor power quality will affect a large number of users. A number of studies have estimated the annual cost of power quality problems to the American economy at 12 billion dollars annually.
Determining the sources of poor power quality can prove to be a complex task. There are hundreds of possible factors. Some disturbances may originate within the electricity supply network while others may be located within the users' systems. In addition, many of the sources of power quality disturbances are interactive, making it difficult to accurately trace them and to diagnose the root cause of the problem.
Power quality also involves a large number of stakeholders, from electrical utilities, electrical equipment manufacturers and suppliers, regulators, consultants, educational institutions, right to the multitude of electricity users. To properly resolve power quality issues, it is important that the stakeholders not only have a common understanding of those issues, but also work in coordinated and cooperative ways to find solutions.
To remain competitive in today's global market, developed nations must expand the "knowledge economy" which is based on skills, cutting-edge technologies and high productivity. Such efforts cannot be achieved without an affordable, reliable and high quality electrical power base. It has long been recognized that power quality will continue to play an increasingly important role in defining the competitive capability of national economies and infrastructure systems. The increasing role of power quality will be further accelerated by the proliferation of non-linear loads - such as switched power supplies which are found in most of today's electronic equipment. Also to be considered is an increasing penetration of small distributed generators with electronic interfaces between the device and the power system, such as photovoltaic cells, fuel cells, wind turbine generators, etc. Additionally, the commercial aspects of open electricity markets are increasingly stretching power systems' operation closer to their technical limits and narrowing the operational safety margins needed to cope with larger power quality disturbances. Real or perceived decrease of power quality levels will also influence public opinion and, indirectly, government regulators who in turn will develop and assert the policy framework in which the electricity industry will be regulated.
To deal with power quality concerns, many leading utilities around the world are examining the economic impacts of the problem and revising their planning and operation practices. Many are also heavily involved in the establishment of equipment protection standards and regulatory guidelines, in the ultimate goal of minimizing the combined cost of supply and use of electricity by achieving a high degree of electromagnetic compatibility between the electrical service providers and the electricity end users.
To facilitate and coordinate these efforts, CEA Technologies Inc. (CEATI) has organized a Power Quality Interest Group, composed of electric utilities that pool their financial resources to sponsor power quality technology developments.
The Power Quality interest group is currently financing several key projects:
• Power Quality impact assessment of distributed wind generation
• Techniques for locating voltage sag disturbances
• Utility incentives and penalties for power quality under performance based Government regulation
• Assessing power quality disturbances using power quality monitoring features of distribution network equipment
Power Quality Impact Assessment of Distributed Wind Generation
With wind generation receiving increasing political and environmental attention, it is expected that the number and capacity of wind generation installations will grow substantially across North America. Many of these installations will be significant in size and will be connected directly to the distribution system. In these distributed applications it is quite common for turbines to be connected to rural distribution feeders that also serve load customers, and that may exhibit significant differences between the maximum and minimum loads. In such cases, turbines may noticeably influence the distribution feeder voltage, both in magnitude and in waveform shape, for either the benefit or detriment of the customers served by the same feeder. The impact on voltage regulation, voltage flicker, and voltage unbalance is one of the most common limiting factors for distributed generation and especially distributed wind turbine generators. Under some circumstances there may also be a possibility of formation of isolated electrical islands, where the local feeder load would be supplied by the local distributed generators, but disconnected from the grid and its voltage and frequency-regulating influence. In such cases there is a danger of damage to the end user equipment due to possible overvoltages and frequency variations.
The above issues can be addressed quantitatively by using advanced simulation tools. Detailed computer simulation of representative commercial wind turbine technologies on typical distribution feeders would provide insight into the impact wind generation would have on rural distribution systems. Time- and frequency-domain system models could be used to quantitatively characterize wind turbine impacts on system voltage, with parametric evaluation of various feeder characteristics, wind regimes, and turbine technologies.
Because of the growing interest and penetration of wind generation, the CEATI’s Power Quality Interest Group has initiated research that would identify the potential problems associated with wind generation and allow utilities to model and assess the potential impact of wind turbine generators on feeder voltage regulation, reliably predicting voltage flicker problems, voltage unbalance and harmonic emissions to ensure sustainment of high quality electrical supply to their customers.
The model will also allow sensitivity analysis of system impact on various types of wind turbine generators to ensure acceptable and reliable connections for the generators.
Techniques for Locating Sources of Voltage Sag Disturbances Utility operating experience indicates that momentary voltage sags are one of the most disruptive short duration power quality disturbances on customer operations. A significant amount of work has been done in developing protocols for measuring and indexing power quality disturbances, including voltage sags.
However, relatively little work has been reported on the development of techniques for reliably identifying and locating the origins of voltage sags. In order to maintain an appropriate level of electrical service quality, utilities are increasingly interested in quantifying the individual contributions to the "aggregate" power quality problems and determining the level of responsibilities for such problems. In this context, the ability to locate the sources of voltage sags has become very important.
The existing technical literature describes several voltage sag source locating techniques. However, these have not been sufficiently tested and evaluated in the field to determine their respective advantages, disadvantages and limitations, and above all, their dependability in accurately locating the origins of voltage sags. For this reason CEATI’s Power Quality Interest Group has initiated a project, aimed at evaluating various voltage sag source locating techniques and developing a practical, step-by-step implementation guide which will provide sound technical measurement tools and a methodology that could be readily used by utility staff to quickly identify and locate sources of voltage sags on theirs systems.
Utility Incentives and Penalties for Power Quality under Performance-based Government Regulation
In a regulated environment, the goal of public utilities is to provide safe, reliable, and least-cost service to consumers. To achieve this goal, regulatory commissions have traditionally relied on a cost-of-service/rate-of-return basis to determine appropriate utility rates thus permitting utilities to recover reasonable operating expenses and to earn a fair return on investment. In the deregulated market, however, utilities no longer have incentives to provide additional power quality or reliability service improvements. To remedy the situation there has been in recent years a considerable interest from utility regulators to entertain the well-known theory of performance-based rates. The expectation is that price-based incentive mechanisms will allow utilities to proactively invest in reliability and quality improvement initiatives. In several countries the price and penalty-based incentives for reliability improvement are already in effect, with regulators now looking more closely at measures for power quality improvement incentives as well. To prepare the participating utilities for the upcoming regulatory environment, CEATI's Power Quality Interest Group has initiated a study that would acquaint them with various power quality and reliability metrics and methodologies used in price-based incentive schemes. The main objective of this project is to provide sponsors with a detailed overview of how power quality and reliability performance-based rates are being implemented in other parts of the world. The final report will describe several options for measuring and predicting the value of power quality investments. It will also outline a framework for responding to price-based incentive mechanisms and creating the appropriate power quality and reliability metrics.
Based on an extensive analysis of the existing and proposed schemes that are currently being implemented in different parts of the world, the project will also outline the future role for utility power quality engineers.
Assessing Power Quality Disturbances using Power Quality Monitoring features of Distribution Network Equipment
Power quality disturbances are a real concern for both utilities and consumers. Detecting, recording and processing power quality data is crucial for monitoring network performance, and identifying and resolving power quality problems. In the past, such effort required installation of dedicated power quality monitors and communication channels for downloading the collected data for further analysis and archiving. Today's monitoring systems involve distribution network equipment already in place such as reclosers, voltage regulators and revenue meters, equipped with controls featuring a PQ option allowing for the recording and analysis of voltage and current signals to detect disturbances and to perform the statistical analysis of measurements. This approach to power quality monitoring will be much more cost-effective and allow for greater coverage of the distribution network. On the other hand, such a monitoring network will generate huge volumes of data, often in different formats, that will have to be processed, archived and displayed in order to provide useful information to the end users.
The CEATI Power Quality Interest Group has initiated a study that will provide utilities with a list of distribution equipment suitable for power quality monitoring, including a description of the methods used for assessing power quality disturbances. The report will include recommended monitoring equipment configuration suitable for recording and processing power quality information, including planning and operating requirements, and the methods for assessing and displaying the network power quality performance.
Joining Together To Fund Power Quality Research
The Power Quality Interest Group (PQIG) was established as one of the many "interest groups" of CEA Technologies Inc. (CEATI). The PQIG participants jointly sponsor studies and research projects in the area of power quality that will benefit them, the electrical utility industry and customers at large.
Participation in the group is open to all electrical utilities, power producers and government organizations that have interest in power quality related issues. The group identifies areas of common concern or specific problems, defines research objectives to solve those concerns. The individual group participants can then select to co-fund the projects of interest or benefit to their organizations. This flexible and collaborative approach provides substantial cost-benefit advantage to the participants. The products of the research are made available to the sponsors of the projects.
About the Author
Mr. Jerry Lepka heads CEA Technologies' Power Quality Interest Group. Mr. Lepka, a graduate from the University of Manitoba, has worked both abroad and in Canada managing complex technical operations and implementing new technologies. His most recent project was with the Gestore Rete Transmissione Nazionale in Italy, where he was a member of the Advisory Committee analyzing the causes of the September 2003 Italian system blackout and recommending preventive measures. At Ontario Power Generation, Jerry was involved in development of the performance-based Protection and Control Technical Training Program as well as Maintenance Strategies for their high voltage equipment. He also led Ontario Hydro's province-wide power quality monitoring program aimed at reducing system disturbances and their impact on electrical supply to major customers. For more information please visit www.ceatech.ca.
Determining the sources of poor power quality can prove to be a complex task. There are hundreds of possible factors. Some disturbances may originate within the electricity supply network while others may be located within the users' systems. In addition, many of the sources of power quality disturbances are interactive, making it difficult to accurately trace them and to diagnose the root cause of the problem.
Power quality also involves a large number of stakeholders, from electrical utilities, electrical equipment manufacturers and suppliers, regulators, consultants, educational institutions, right to the multitude of electricity users. To properly resolve power quality issues, it is important that the stakeholders not only have a common understanding of those issues, but also work in coordinated and cooperative ways to find solutions.
To remain competitive in today's global market, developed nations must expand the "knowledge economy" which is based on skills, cutting-edge technologies and high productivity. Such efforts cannot be achieved without an affordable, reliable and high quality electrical power base. It has long been recognized that power quality will continue to play an increasingly important role in defining the competitive capability of national economies and infrastructure systems. The increasing role of power quality will be further accelerated by the proliferation of non-linear loads - such as switched power supplies which are found in most of today's electronic equipment. Also to be considered is an increasing penetration of small distributed generators with electronic interfaces between the device and the power system, such as photovoltaic cells, fuel cells, wind turbine generators, etc. Additionally, the commercial aspects of open electricity markets are increasingly stretching power systems' operation closer to their technical limits and narrowing the operational safety margins needed to cope with larger power quality disturbances. Real or perceived decrease of power quality levels will also influence public opinion and, indirectly, government regulators who in turn will develop and assert the policy framework in which the electricity industry will be regulated.
To deal with power quality concerns, many leading utilities around the world are examining the economic impacts of the problem and revising their planning and operation practices. Many are also heavily involved in the establishment of equipment protection standards and regulatory guidelines, in the ultimate goal of minimizing the combined cost of supply and use of electricity by achieving a high degree of electromagnetic compatibility between the electrical service providers and the electricity end users.
To facilitate and coordinate these efforts, CEA Technologies Inc. (CEATI) has organized a Power Quality Interest Group, composed of electric utilities that pool their financial resources to sponsor power quality technology developments.
The Power Quality interest group is currently financing several key projects:
• Power Quality impact assessment of distributed wind generation
• Techniques for locating voltage sag disturbances
• Utility incentives and penalties for power quality under performance based Government regulation
• Assessing power quality disturbances using power quality monitoring features of distribution network equipment
Power Quality Impact Assessment of Distributed Wind Generation
With wind generation receiving increasing political and environmental attention, it is expected that the number and capacity of wind generation installations will grow substantially across North America. Many of these installations will be significant in size and will be connected directly to the distribution system. In these distributed applications it is quite common for turbines to be connected to rural distribution feeders that also serve load customers, and that may exhibit significant differences between the maximum and minimum loads. In such cases, turbines may noticeably influence the distribution feeder voltage, both in magnitude and in waveform shape, for either the benefit or detriment of the customers served by the same feeder. The impact on voltage regulation, voltage flicker, and voltage unbalance is one of the most common limiting factors for distributed generation and especially distributed wind turbine generators. Under some circumstances there may also be a possibility of formation of isolated electrical islands, where the local feeder load would be supplied by the local distributed generators, but disconnected from the grid and its voltage and frequency-regulating influence. In such cases there is a danger of damage to the end user equipment due to possible overvoltages and frequency variations.
The above issues can be addressed quantitatively by using advanced simulation tools. Detailed computer simulation of representative commercial wind turbine technologies on typical distribution feeders would provide insight into the impact wind generation would have on rural distribution systems. Time- and frequency-domain system models could be used to quantitatively characterize wind turbine impacts on system voltage, with parametric evaluation of various feeder characteristics, wind regimes, and turbine technologies.
Because of the growing interest and penetration of wind generation, the CEATI’s Power Quality Interest Group has initiated research that would identify the potential problems associated with wind generation and allow utilities to model and assess the potential impact of wind turbine generators on feeder voltage regulation, reliably predicting voltage flicker problems, voltage unbalance and harmonic emissions to ensure sustainment of high quality electrical supply to their customers.
The model will also allow sensitivity analysis of system impact on various types of wind turbine generators to ensure acceptable and reliable connections for the generators.
Techniques for Locating Sources of Voltage Sag Disturbances Utility operating experience indicates that momentary voltage sags are one of the most disruptive short duration power quality disturbances on customer operations. A significant amount of work has been done in developing protocols for measuring and indexing power quality disturbances, including voltage sags.
However, relatively little work has been reported on the development of techniques for reliably identifying and locating the origins of voltage sags. In order to maintain an appropriate level of electrical service quality, utilities are increasingly interested in quantifying the individual contributions to the "aggregate" power quality problems and determining the level of responsibilities for such problems. In this context, the ability to locate the sources of voltage sags has become very important.
The existing technical literature describes several voltage sag source locating techniques. However, these have not been sufficiently tested and evaluated in the field to determine their respective advantages, disadvantages and limitations, and above all, their dependability in accurately locating the origins of voltage sags. For this reason CEATI’s Power Quality Interest Group has initiated a project, aimed at evaluating various voltage sag source locating techniques and developing a practical, step-by-step implementation guide which will provide sound technical measurement tools and a methodology that could be readily used by utility staff to quickly identify and locate sources of voltage sags on theirs systems.
Utility Incentives and Penalties for Power Quality under Performance-based Government Regulation
In a regulated environment, the goal of public utilities is to provide safe, reliable, and least-cost service to consumers. To achieve this goal, regulatory commissions have traditionally relied on a cost-of-service/rate-of-return basis to determine appropriate utility rates thus permitting utilities to recover reasonable operating expenses and to earn a fair return on investment. In the deregulated market, however, utilities no longer have incentives to provide additional power quality or reliability service improvements. To remedy the situation there has been in recent years a considerable interest from utility regulators to entertain the well-known theory of performance-based rates. The expectation is that price-based incentive mechanisms will allow utilities to proactively invest in reliability and quality improvement initiatives. In several countries the price and penalty-based incentives for reliability improvement are already in effect, with regulators now looking more closely at measures for power quality improvement incentives as well. To prepare the participating utilities for the upcoming regulatory environment, CEATI's Power Quality Interest Group has initiated a study that would acquaint them with various power quality and reliability metrics and methodologies used in price-based incentive schemes. The main objective of this project is to provide sponsors with a detailed overview of how power quality and reliability performance-based rates are being implemented in other parts of the world. The final report will describe several options for measuring and predicting the value of power quality investments. It will also outline a framework for responding to price-based incentive mechanisms and creating the appropriate power quality and reliability metrics.
Based on an extensive analysis of the existing and proposed schemes that are currently being implemented in different parts of the world, the project will also outline the future role for utility power quality engineers.
Assessing Power Quality Disturbances using Power Quality Monitoring features of Distribution Network Equipment
Power quality disturbances are a real concern for both utilities and consumers. Detecting, recording and processing power quality data is crucial for monitoring network performance, and identifying and resolving power quality problems. In the past, such effort required installation of dedicated power quality monitors and communication channels for downloading the collected data for further analysis and archiving. Today's monitoring systems involve distribution network equipment already in place such as reclosers, voltage regulators and revenue meters, equipped with controls featuring a PQ option allowing for the recording and analysis of voltage and current signals to detect disturbances and to perform the statistical analysis of measurements. This approach to power quality monitoring will be much more cost-effective and allow for greater coverage of the distribution network. On the other hand, such a monitoring network will generate huge volumes of data, often in different formats, that will have to be processed, archived and displayed in order to provide useful information to the end users.
The CEATI Power Quality Interest Group has initiated a study that will provide utilities with a list of distribution equipment suitable for power quality monitoring, including a description of the methods used for assessing power quality disturbances. The report will include recommended monitoring equipment configuration suitable for recording and processing power quality information, including planning and operating requirements, and the methods for assessing and displaying the network power quality performance.
Joining Together To Fund Power Quality Research
The Power Quality Interest Group (PQIG) was established as one of the many "interest groups" of CEA Technologies Inc. (CEATI). The PQIG participants jointly sponsor studies and research projects in the area of power quality that will benefit them, the electrical utility industry and customers at large.
Participation in the group is open to all electrical utilities, power producers and government organizations that have interest in power quality related issues. The group identifies areas of common concern or specific problems, defines research objectives to solve those concerns. The individual group participants can then select to co-fund the projects of interest or benefit to their organizations. This flexible and collaborative approach provides substantial cost-benefit advantage to the participants. The products of the research are made available to the sponsors of the projects.
About the Author
Mr. Jerry Lepka heads CEA Technologies' Power Quality Interest Group. Mr. Lepka, a graduate from the University of Manitoba, has worked both abroad and in Canada managing complex technical operations and implementing new technologies. His most recent project was with the Gestore Rete Transmissione Nazionale in Italy, where he was a member of the Advisory Committee analyzing the causes of the September 2003 Italian system blackout and recommending preventive measures. At Ontario Power Generation, Jerry was involved in development of the performance-based Protection and Control Technical Training Program as well as Maintenance Strategies for their high voltage equipment. He also led Ontario Hydro's province-wide power quality monitoring program aimed at reducing system disturbances and their impact on electrical supply to major customers. For more information please visit www.ceatech.ca.
