Tag Archive for: EN50160

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Project study: Resonance suppression through a special active filter

Problem description

After installing a second photovoltaic system on a low-voltage grid with a high proportion of inverters, frequent faults were detected in the first and larger solar system. The inverters of this system, but also of the newer PV system, frequently switched off with the message “grid fault”.

During a grid quality measurement carried out by the local power supply company, high voltage distortions and exceeding of the limit values according to EN 50160 as well as EN 61000-2-2 could be determined at times. However, no cause was given or determined.

Since a CHP unit with a higher output is to be connected to this network and further disturbances were to be expected, we were commissioned with a network and harmonic analysis. The goal here is always the clear determination of the cause and the subsequent planning of suitable solutions.

Approach and analysis

First, we obtained an overview of the overall situation of the voltage supply by measuring with a special network analyzer. Already after connecting the first measurement to the transformer infeed, very high voltage distortions were detected (see the following picture of the voltage and current waveform).

Voltage distortions

Since this is a customer-owned grid, we applied the limit values of EN 61000-2-4 class 2 for the evaluation of the voltage quality. Of course, these limits were also exceeded, in some cases very significantly in the case of individual harmonics and interharmonics.

Two causes are already evident in the current and voltage waveforms. Firstly, the grid is almost exclusively loaded with 6-pulse converters (typical for frequency converters). And secondly, a clear resonance oscillation is recognisable. The latter can usually be seen as the main cause of fault messages from sensitive or particularly protected electrical equipment, such as solar inverters.

Parallel resonance arises as an interaction between transformer inductance and capacitive components in the low-voltage grid. In most cases, these are distributed over several systems and therefore cannot be specifically eliminated as the cause of the problem. During further measurements in this network, we were therefore able to identify several feeders that are involved in the resonance. On the one hand, these were mainly lighting systems and, on the other hand, the disturbed photovoltaic systems. In both cases, the use of unchoked or only slightly choked capacitors as main or filter components is typical. Thus, the disturbed system components are also involved in the disturbance itself. In addition, there was also a frequent shift of the resonance frequency, the cause of which was the switching on and off of the components involved.

The solution

Therefore, there were only two possible solutions. The first way would be a comprehensive restructuring of the network and therefore very time-consuming and expensive. The second way turned out to be feasible in the short term and was preferred by the customer.

As a short-term solution, a special active filter was installed and parameterized by us. Selection, installation, and commissioning were carried out in close cooperation with our customer and the supplier of the filter. The objective was to eliminate the resonance oscillation as the cause of the inverter’s fault messages and also the greatest risk of faults in the CHP to be installed later.

The results are clear:

At the time of commissioning, the resonance was not so pronounced. Therefore, the voltage in the image without the filter is also less distorted than in the first image. Nevertheless, the installed filter also caused a permanent and reliable suppression of the resonance oscillation in the course of the verification measurement over two weeks.

The remaining voltage distortions in the right picture are due to the frequency inverters and contain only slight exceedances of the limit values according to EN 61000-2-4. These do not lead to disturbances at the solar inverters but can be reduced to below the limit values by an additional filter if necessary.

All the systems, including the CHP unit that has since been put into operation, have been working trouble-free since the filter was put into operation.

Imprint:
PQ Professionals GmbH
Landsberger Street 4
04157 Leipzig
represented by the Managing Director Dipl.-Ing. (FH) Frank Strobel

 

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Electrical data security

Data center data security reliability depends on many different factors. For example, from the energy supply and operational reliability of the power supply. This is what we refer to in this blog as electrical data security. Electrical data security conditions must be constantly monitored to achieve Tier 1 – 4 levels. It is advisable for you to monitor parameters of power quality, energy and fault current detection as well as cyber security together.

Figure 1: https://www.hpe.com/ch/de/what-is/data-center-tiers.html (31.1.2020); Source: Camille Bauer Metrawatt AG (own design)

Electrical data security and the problem

Various studies have shown that poor network quality causes costs. These run into the billions every year. As early as 2007, the Pan-European LPQI Power Quality Survey estimated that the damage amounts to the equivalent of $150 billion annually. In the meantime, the challenges this poses for everyone have steadily increased. And that’s especially true for data centers.

The basic requirements for a data center

There are many requirements to consider when planning the power supply for a data center:

  • Secure location in terms of energy supply and environmental conditions
  • High energy efficiency to minimize operating costs
  • Maximum availability due to redundancies (UPS, generators)
  • High security (fire protection, access, defense against cyberattacks)
  • System stability and reliability of the devices used
  • Possibility for later expansion
  • Compatibility with the standard e.g. according to DIN EN 50600,etc.
  • etc.

Possible solutions for electrical data security

1. investment protection through good power quality (PQ)

Figure 2: Power quality simplified; Source: Camille Bauer Metrawatt AG

2. system protection by residual current and fault current monitoring

The risk

Residual current monitoring (RCM) in low-voltage networks (e.g. data centers) that is not detected or is detected too late represents a significant safety risk:

  • Fault currents and insulation decay are caused by defective / bad components (e.g. switching power supplies, LEDs, server systems, PV, etc.)
  • In the data center should / must not be switched off in the event of a fault!
  • Overheated cable insulation causes a fire risk!
The solution

Detection of risky fault currents by means of permanent residual current measurement, thereby increasing the safe operation of electrical systems.

Figure 3: Residual current monitoring Source: Camille Bauer Metrawatt AG

Advantages
  • Time-consuming manual checks are no longer required (shutdown issue)
  • Continuous monitoring instead of status quo
  • Legal security with regard to the law, auditors (asset protection) and insurance companies
  • Permanent damage prevention to people and equipment

3. electrical data security through cyber security

Threat from cyber attacks

Figure 4: Threat of cyber attacks

The topic of cyber security is becoming increasingly important due to the constantly growing level of networking. Especially in the areas of critical infrastructure. Due to the threat situation, effective cyber security is essential there. Thus also very specific in data centers and considered under the topic of “electrical data security”.

You can find the complete blog post on cyber security here

Find complete solutions for your data center here

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Fields of application of measuring instruments

In this article we will show you possible fields of application for measuring instruments. Certainly, this is only one option and not conclusive.

 

Fields of application of measuring instruments

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Ensuring grid quality on a small scale

Ensure power quality! These claims are becoming stronger and louder. This is confirmed by utilities, industrial companies, but also by many of the electrical specialists who are increasingly confronted with the topic on the part of their customers. The question often arises as to which measuring device should be used, with which expertise and with which budget.

Ensure the quality of the network for industrial needs. This is now offered by the LINAX PQ1000 series power analyzer according to IEC61000-4-30 class S. The measuring instrument is specially designed for the area of “Demand Side Power Quality” (DSPQ). There you will find the process for securing the power quality on the consumer side (according to the PoCC as per IEC TR 63191).

But why class S and not class A

Standards

Measuring instruments according to IEC 61000-4-30 Class A generally provide measured values that are comparable across measuring instruments and manufacturers. In case of legal cases, class A is mandatory and is particularly relevant for distribution system operators.

IEC 61000-4-30 class S power quality analysers are intended for basic / advanced power quality analysis and provide useful monitoring data. Instruments that meet Class S performance requirements are used for statistical power quality surveys and other applications and measurement services. There are no potential disputes there. Thus, comparable measurements are also not mandatory. The performance requirements for Class S are less stringent than for Class A. Among other things, this also results in a lower price. They are often used in industrial and supply engineering at the IPC(according to IEC [TR] 63191 this is the network distribution according to the Point of Common Coupling (PoCC)). Even in data centers, these are strongly recommended according to EN50600-2-2:2019-08 [Kapitel 6.2.3 Spannungsqualität] within the infrastructure.

Ensuring power quality with certification even for class S

A very important criterion for correct and repeatable measurement of power quality is compliance with standards for the measurement procedure. These are not to be confused with power quality compliance standards. For this reason, class S measuring devices should also be certified. With the LINAX PQ1000, this is ensured on the basis of the big brothers LINAX PQ3000 & PQ5000 by METAS, the Swiss Federal Institute of Metrology. Swiss precision.

Ensuring network quality with the highest standards of cyber security

Cyber Security

The topic of cyber security is also becoming more and more important due to the constantly growing networking. Especially in the areas of power distribution, whether in public or private networks. Due to the threat situation, effective cyber security is essential. To this end, the LINAX PQ1000offers many of the same effective protective features as its larger siblings. These include:

Designs of the LINAX PQ1000

LINAX PQ1000 all views

The PQI, according to Definition according to IEC 62586-1/2 for the analysis of power quality in power supply systems also called Power Quality Instrument (PQI), is available in various options. With the common 96x96mm form factor, the meter fits well anywhere. Whether for panel mounting with TFT display or for DIN rail mounting with or without TFT display. All variants are possible and offer high flexibility. Added to this is the simplest operation and communication via integrated web browser. Without additional software, operation, parameterization and monitoring are made child’s play.

More tutorials (e.g. on the topics UPS, PQ analysis, PQEasy reporting, data export, etc.) can be found here.

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Infrastructure from the manager’s perspective

Would you like to see energy infrastructure from a manager’s perspective? This is how you might want it to be as a business manager or even as an overall responsible manager. In fact, this allows you to monitor specific individual performance indicators of a factory, a single plant, an entire complex, etc. Last but not least, to possible benchmark with other comparable companies or locations.

The Areal View: The interactive & areal view from the manager’s perspective

 

Interactive Areal View

The Areal View of the SmartCollect SC² offers you an interactive display from different perspectives. For this purpose, you can define photos, graphics, floor drawings, renderings, infographics, and much more as backgrounds. Depending on your needs and available budget, you can store the views both in a 2D format and in an interactive 3D model.

 

Floor plan data center

Example floor plan of a data center for visualization from the manager’s perspective

 

Floor plan

Example floor plan of a single floor from the manager’s perspective

The advantage of interactivity

In the overall view of the Areal View, you keep the overview from the bird’s eye view. However, if you want to take a closer look at individual objects or even analyze them, click on the area and open the details. There, the complete measuring point is grouped in various panels, just as it was set up for you. You can view real-time data in a trend history. In addition, you will be able to define historical time periods and contextualize the measurement data to each other. This allows you to perform meaningful and beneficial comparisons and analyses. Synchronized zoom functions and various selection options of individual data support you. This makes it possible to keep the full overview in a simple way.

Full Dashboard

Dashboard of a measuring point with trend and analysis functions

And if you are no longer satisfied with your individual display in the course of the application, then simply adapt it again to your new circumstances. Because flexibility in visualization is part of the SmartCollect SC² as an easy-to-use HMI. And if you want to align yourself according to ISO 50001, then the energy monitoring system of the SmartCollect SC² will help you advantageously.

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EPRI Power Quality Knowledge Development and Transfer: 2020 Year-End Update and 2021 Outlook

The EPRI Power Quality Knowledge Development and Transfer supplemental project provides a wealth of high-impact resources in a well-designed, readable, and accessible format. Paramount among these are numerous and highly readable documents covering a wide range of PQ topics, written not only for use by busy PQ professionals, but also to expedite problem solving and education of important end-use customers and internal utility management.

The EPRI PQ Knowledge Development and Transfer supplemental project (PQK) is pleased to announce the completion of over two dozen new documents, online resources, and PQ Hotline Calls of the Month for the 2020 deliverable year.

From PQTBlog

*Please note that the links to documents included on this Web page require a valid EPRI login for access to full documents.

  • For more information about the EPRI PQ Portfolio in general or to see the new 2021 EPRI PQ Research Portfolio, please visit epri.com or contact: Bill Howe, PE, at email: bhowe@epri.com, or tel: 720-565-6888.

PQ TechWatches

The PQ TechWatch gives in-depth coverage of a power quality topic, including practical advice for diagnosing, preventing, and resolving common problems. Reports feature easy navigation, illustrative case studies, and quality graphics.

Five new TechWatch documents are now complete and posted for the 2020deliverable year:

  • Guiding End-Use Customers on Mitigation of PQ Phenomena (3002019387)
  • Despite the availability of solutions, problems around power quality (PQ) that have accompanied the increased use of power electronics have persisted, indicating that end-use customers are in need of some guidance to find those solutions. Given that these customers may have a general lack of awareness regarding the causes of PQ issues, possible mitigation methods, and the possibility of incorporating more robust control designs at reasonable cost, the purpose of this PQ TechWatch is to provide useful information about these topics.

    Sales of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) have increased in recent years, and the charging of the batteries in those vehicles has brought a new load to the residential electrical grid. Although presently the numbers of EVs and PHEVs compared to conventional gasoline-powered vehicles remains relatively small in the United States as a whole, individual states and large municipalities may have greater numbers, and the magnitude of effects on the distribution system may depend on the numbers of vehicles connecting to each distribution circuit. As these numbers rise, so also may the PQ effects. EPRI has not only conducted an in-depth study on the impact of this increased load on the distribution grid, but also taken a look at the PQ effects of the electrical supply on these vehicle chargers and their charging behavior and at the effects of the charging systems on the existing electrical supply. Higher-voltage, fast-charging systems are of particular interest and concern. This PQ TechWatch gives an overview of testing that has been done on electric vehicle supply equipment and the effects of electric vehicles and chargers on modeled systems. Indications of voltage effects and current harmonics are discussed. In addition, the various industry standards and codes that apply to these new loads are explored.

    Utilities are in need of software to assist with their various levels of power quality(PQ) monitoring, which can range from single-site investigations to grid-wide fleets of more than a thousand meters. During the past five years, significant growth in PQ monitoring has taken place not only at the industrial and commercial level, but also at the distribution and transmission levels as new viable grid applications such as fault location, grid health, asset health, lightning correlation, and incipient fault detection have been discovered. In this PQ TechWatch, existing PQ monitoring software resources are researched and assessed. While PQ View and the open-source Open PQ Dashboard have been innovative and helpful for gathering data from many formats into a usable database, utilities are widening their software searches, looking for more capabilities, better ease of use, or new turnkey solutions. Before reviewing these resources, the report covers what is required from PQ monitoring. PQ monitoring can be broken up into three areas—gathering, processing, and reporting. Software could provide a complete enterprise solution, covering all of these areas, or it could support an individual area. Our assessments include both varieties of products.

    The impacts of harmonics can be difficult for utilities to quantify. Because of this, harmonics and power quality in general are not treated the same way as power factor, for example, with the utility response to harmonics more “reactionary” than “precautionary.” However, as utilities integrate distributed energy resources (DERs)and end-use loads employing power electronic circuits into their power grids, harmonics are once again receiving attention. Although efforts have been made by some organizations to develop frameworks for assessing the economic impact of harmonics, these efforts have largely remained confined to literature, and utilities are still some ways off from understanding the economic impact that harmonics-producing loads in general, and DERs and power electronics devices in particular, have on their systems. This PQ TechWatch is part of an attempt to bridge this gap in knowledge. A new framework is proposed here that couples the Harmonic Losses Calculator, which quantifies the losses to a utility caused by the flow of harmonic currents on a distribution circuit and assigns a dollar value to them, with the preexisting Harmonics Evaluation Module to accurately determine the economic impact of nonlinear load or DER penetration. The objective is to evaluate the adverse impacts of harmonic load or savings due to DER penetration at the planning stage. In addition to understanding the economic value, good power quality can be used as another yardstick while planning for expansion on an existing feeder, or for a new feeder altogether. The impact of penetration of harmonic load and DER on two known distribution circuits in the OpenDSS simulation framework is shown, and is followed by a discussion of the increase (or decrease) in operating costs of the feeder due to such load or generation. The document closes with a discussion of anticipated future research and expected capabilities to be added to this framework.

    Distributed energy resources (DERs) and microgrids promise to revolutionize the traditional power-system paradigm, providing a more environment-friendly means of energy generation, increased reliability of supply, and more choice and flexibility for the end user. However, along with these positive changes come challenges, especially in the power quality (PQ) domain. For example, DERs tend to be mostly inverter-interfaced, and this coupled with more power electronics in end-use load may lead to a rise in PQ events in the future. To cope with this change in production and consumption, PQ engineers must reanalyze and reassess the framework in which the grid operates. Standards and regulations should be revisited, keeping in mind that these standards now apply to sources of generation as well as load. For example, integration of inverter-interfaced resources has forced a reevaluation of the voltage and current harmonic limits, but a framework to assess the potential impact of such changes is missing. Similarly, the change from centralized to decentralized power generation has shown the need to rethink the traditional definition of the power factor metric and how PQ engineers view it. This PQ TechWatch discusses some of the gaps and needs in PQ standards today (e.g., the lack of a common format to exchange PQ data and differences in the way the duration of events such as sags are calculated). Considering the dynamic nature of the grid and the pace at which changes happen, these gaps in standards and regulations need to be closed, and PQ monitoring and enforcement of PQ regulations need to be more proactive. Finally, the document takes a look at the unique problem of supraharmonics, which requires significant research and the likely creation of a new standard of measurement. The attempt here is to give the reader the most up-to-date information possible and to clarify why some gaps exist and the background behind them. Where possible, examples from real-life situations have been provided to put these discussions into a utility perspective.

    PQ Two-Pages

    The PQ Two-Pager is a short-format treatment of a single, important PQ topic in a concise, readable format. They are intended to help utilities to educate end-use customers on complex subjects, but in a non-intimidating way.

    Three new Two-Pager documents are now complete and posted for the 2020deliverable year:

    Power-conditioning equipment changes or controls the electrical environment to make it acceptable for electrical end-use equipment. In the real world of electrical aberrations, the designers of electronic equipment cannot economically produce competitive designs that take care of all possible electrical anomalies. When a compatibility issue exists between the electrical system and end use sensitive electrical or electronic equipment, power conditioners may be useful when properly applied. However, misapplying power-conditioning equipment is a commonplace occurrence. A good understanding of power-line disturbances, how end-use electrical equipment operates, and how power-conditioning devices can help (or hurt)is essential to the proper resolution of a PQ-related problem using power conditioners.

    The energy efficiency of a particular process is the measure of the power consumed by that process as work compared to the power supplied to the process. In mechanical processes, much of the energy lost may result from friction and other heat losses. In electrical processes, heat may be generated and lost due to the resistance in wiring and other factors. Before energy can be saved, the ways it is lost or wasted must first be identified. For example, power quality variations such as harmonic distortion may cause energy losses in the form of heat released to the environment. After these losses are understood, then methods for saving the lost energy can be identified. The topics that follow concern approaches to power quality and energy efficiency and how they may or may not be related.

    The study of any subject requires an understanding of terminology, and an understanding of power factor involves several concepts.

    Training Videos

    The subject of this Power Quality (PQ) Training Module video is Understanding and Applying PQ Standards. This product is part of EPRI’s PQ Training, a series of modules providing information and expertise from EPRI to those interested in learning about power quality phenomena and methods of addressing the effects of these phenomena.

    The subject of this Power Quality (PQ) Training Module video is Understanding Power Factor. This product is part of EPRI’s PQ Training, a series of modules providing information and expertise from EPRI to those interested in learning about power quality phenomena and methods of addressing the effects of these phenomena.

    The subject of this Power Quality (PQ) Training Module video is Facility Design for PQ — Power Conditioning. This product is part of EPRI’s Power Quality Training, a series of modules providing information and expertise from EPRI to those interested in learning about power quality phenomena and methods of addressing the effects of these phenomena.

    EPRI PQ Color Book

    In 2017, the EPRI PQ program produced its first comprehensive PQ Color Book, comprising the 24 chapters of the

    PQ Encyclopedia

    in one continuous, integrated volume. The current edition contains over 600 pages, including the following chapters:

    • What Is Power Quality?
    • The Economics of Power Quality
    • Understanding Voltage Sags
    • Mitigation Techniques for Power Quality
    • Understanding Voltage Flicker
    • Understanding Harmonics
    • PQ Standards for System Compatibility
    • Adjustable-Speed Drive Technology and Power Quality Considerations
    • Power Quality Monitoring: Concepts, Equipment, and Applications
    • Understanding Power Factor
    • Understanding Voltage Unbalance
    • Transient and Temporary Overvoltage Protection
    • Grounding: A Broad-Spectrum Requirement for Power Quality
    • Facility Design for PQ: Introduction and Equipment Needs
    • Facility Design for PQ: Voltage Quality and Regulation
    • Facility Design for PQ: Power Conditioning and Mitigation
    • Conducting a Power Quality Audit
    • Electromagnetic Compatibility for Power Quality Engineering
    • Electromagnetic Shielding: A Power Quality Engineering Perspective
    • Electromagnetic Interference of Power Lines with Co-Located Telephony and Communications Cables
    • Understanding Stray and Contact Voltage
    • Application of Small Uninterruptible Power Supply (UPS) Systems
    • Power Quality and Energy Efficiency
    • Distribution Harmonics: Impacts, Management, and Practical Considerations

    In 2020, EPRI updated three chapters:

    • Chapter 4: Mitigation Techniques for Power Quality
    • Chapter 9: Power Quality Monitoring: Concepts, Equipment, and Applications
    • Chapter 12: Transient and Temporary Overvoltage Protection

    Download the EPRI PQ Color Book (3002019378)

    PQ Hotline

    Every year, dozens of inquiries from participating PQ Knowledge utilities pour into the EPRI Power Quality Hotline, comprising all manner of PQ issues, including measurement concerns, equipment performance and compatibility, electrical system configurations, management issues, and more. Experience timely responses to your individual concerns and access to over 60 PQ experts at EPRI.

    Access to the PQ Hotline is an exclusive benefit of PQ Knowledge participation and is available 24/7. Most questions are addressed within a single business day.

    Submit your question to the PQ Hotline:

    Email: PQHotline@epri.com

    Online: mypq.epri.com

    PQ Hotline Calls of the Month

    Each month, one call received by the Power Quality Hotline is explored in detail by the EPRI staff and shared with PQ Knowledge members via email in the very popular PQ Hotline Call of the Month.

    Below are the twelve PQ Calls of the Month provided in 2020:

    For the complete archive of Hotline Calls of the Month, visit mypq.epri.com.

    The 2020 PQ Hotline Call of the Month Compendium is available at the EPRI Member Center (3002016842).

    Online Catalog of EPRI PQ Reports

    Find the research you need—the first detailed catalog of previously created EPRI reports is available to PQ Knowledge funders. This catalog of over 600 documents available from EPRI offers intuitive search tools and user-driven results. For the complete archive, visit mypq.epri.com.

    MyPQ Power Quality Online Resource Center

    The PQ Knowledge subscriber website—MyPQ.epri.com—is rich with content and functions. It features access to over 1,500 authoritative EPRI-authored PQ resources(documents, videos, and other items). The upgrade of MyPQ to Version 4.0 began in2018 and was completed in 2020. New features include:

    • Database of grid-side solutions.
    • Free training videos.
    • Improved Hotline database searching.
    • Addition of PQ Two-Pagers.

    Below is a snapshot of that content and functions available to PQ Knowledge funders in 2020 (in addition to those already discussed).

    Serial Publications

    • PQ TechWatches
      The PQ TechWatch series builds on EPRI’s broad expertise and power quality testing and evaluation work to provide a vital flow of information, including important information on emerging trends powering ebusinesses and developments in next-generation power quality mitigation and energy-storage technologies.
    • PQ Two-Pagers
      The PQ Two-Pager is a short-format treatment of a single, important PQ topic in a concise, readable format. They are intended to help utilities to educate end-use customers on complex subjects, but in a non-intimidating way.
    • PQ Encyclopedia
      The EPRI PQ Color Book provides a definitive desk reference for power quality phenomena, and their effects on utility and end-user processes and mitigation technologies. This document serves as the ultimate guide for training, client education, and general support of all aspects of power quality management and problem solving.
    • PQ Technical Library
      The PQ Technical Library comprises a number of expert EPRI technical resources.

    Applications are packed with valuable “how to” information composed for utility customers, who can use them to solve or prevent power quality problems. The level of technical detail in PQTN Applications varies depending upon the audience so that end users can understand and, more importantly, use the information.
    Briefs report the results of equipment-characterization tests and discuss the significance of the results to the discipline of power quality research. Each Brief includes a historical or technical overview of the problem or opportunity that engendered the need for testing, an objective of the conducted tests, detailed test results, and a discussion of the test results. The content is moderately to highly technical.

    The subject of Commentaries varies widely. Some are detailed explanations of current or emerging technologies, the benefits of their applications, and trends in their development. Some Commentaries also discuss power quality theory so that utility engineers can better understand real and perceived threats to a healthy power system, such as harmonic currents. Other Commentaries offer a detailed explanation of a particular power quality technique, such as wiring and grounding. Of the documents in the PQ Technical Library, Commentaries are by far the most technical.

    Solutions describe power quality problems encountered by utility engineers and the solutions to those problems. The anecdotal information in Solutions can be extrapolated to other power quality problems, but perhaps the most useful feature of a Solution is the detailed analysis of problem-solving procedures. The content is moderately technical.

    • Case Studies
      Case Studies are similar to Solutions but focus more on measurements, monitoring equipment, and system compatibility issues than troubleshooting procedures. The content is moderately technical.
    • PQ News
      View the latest news in EPRI power quality, as well as the archive of past news items.

    Continuing in 2021, the Expanded EPRI PQ Online Newsletter Article Library (News Builder)

    The EPRI PQ Online Newsletter Library (News Builder) was launched as a new PQ Knowledge feature in 2010, resulting from goals set in the EPRI PQ Strategic Plan and strong feedback from funders. In 2013, EPRI expanded this new resource, consisting of a growing library of 500- to 1,000-word articles that are provided to PQ Knowledge funders in both RTF and HTML formats for distribution either as standalone articles or for inclusion in website or newsletter formats. The library currently contains dozens of articles with many more planned for 2020 and beyond, drawing upon our over 500 detailed articles in the EPRI PQ Online Resource Center.

    Hotline Calls and Hotline Calls of the Month

    The site has an abundant log of Power Quality Hotline calls from funders, real-life problem-solving in a convenient access point.

    Hotline Database

    This database has hundreds of records and comments based on Hotline Calls that Program 1 receives every year.

    Case Study Database

    This database currently has around 300 case studies. Each case study has been tagged with keyword by our experts.

    Power Quality in Transmission and Distribution

    The PQTD section of MyPQ was created to provide tools and resources to improve customer reliability and power quality. PQTD contains article downloads and links toother resources and concentrates on practices and equipment that can be used to minimize the effect of faults on customers.

    Standards and Guidance Documents

    MyPQ contains four categories of standards and guidance documents: IEEE, Power Quality, Power Quality Standards, and Power Systems.

    Global Document Search

    Documents accessible from MyPQ can be searched by document type, title keyword, and published year.

    Video Center

    This feature provides technical content via video clips, such as training videos and webcasts.

    EPRI Industrial PQ Training Videos

    This feature provides complementary training videos to help solidify the concepts for both the utility members and their customers.

    Services

    The Services menu contains two services associated with the EPRI Power Quality Program: SEMI F47 Testing and Industrial Assessments.

    Online Tools

    The EPRI PQ Knowledge Program offers a variety of online tools for busy power quality professionals, including:

    • Conductor Derating Calculator
      This tool evaluates conductor rating in non-sinusoidal environments. This methodology was developed from Adjustable-Speed Drives and Power Rectifier Harmonics—Their Effect on Power System Components, written by David Rice of GE. Just enter the conductor type and size of the conductor, fundamental current, and system frequency, and the calculator returns total harmonic distortion, harmonic load factor, RMS current, conductor ampacity, derated conductor ampacity, and conductor derating value.
    • Power Factor Correction
      Enter the transformer size, transformer impedance, size of the load being served (in kW), and current and desired power factor. The kVAr required to correct the power factor to the desired level will be calculated. Other values such as the voltage rise on the bus will be calculated as well.
    • Voltage Drop Calculator
      Conveniently calculate the voltage drop in single-phase or polyphase systems for a wide variety of voltages, conductor sizes, and amperages.

    Visit mypq.epri.com to see all the features, documents, and tools available to PQ Knowledge subscribers.

    Conference and Events

    As part of EPRI’s effort to prevent the spread of the COVID-19 virus, EPRI postponed many of it’s scheduled 2020 events, including the 2020 EPRI Grid Analytics and Power Quality Conference and Exhibition and PQ Week.

    The EPRI PQ Knowledge Project in 2021

    In 2021, the EPRI PQ Knowledge Development and Transfer supplemental project will continue to provide vital support for the base-funded EPRI Program 1, Power Quality. PQ Knowledge in 2021 will continue to offer a wealth of new and insightful documents, online resources, access to the EPRI PQ Hotline and Call-of-the-Month articles, events, and other resources essential for busy PQ professionals. PQ Knowledge is one of the most highly leveraged offerings in the EPRI portfolio because of the large number of utility and government funders. We look forward to working with you in 2021.

    For more information about PQ Knowledge for 2021, please download the brochure.

    For more information about the EPRI PQ Portfolio in general, please visit epri.com. to see the new 2021 EPRI PQ Research Portfolio, or contact:

    Bill Howe, PE, at email: bhowe@epri.com, or tel: 720-565-6888.

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The use of suitable current transformer sensors pays off

Accuracy of the measurement questioned.

Measuring instruments are usually classified according to standards and accuracy. Accuracy is an important indicator for being able to usefully build on a solid measurement result in the analysis and its resulting measures. However, it can be observed that although the measuring devices used correspond to a required accuracy class, the necessary sensors are often less in focus.

It can be seen that although class A measuring devices used in power quality applications correspond to a data sheet accuracy of 0.1% for U/I and 0.2S at the energy meter, upstream current transformers are often designed significantly worse (e.g. 0.5% or worse). And this is apart from the fact that not only accuracy plays a role in power quality measurements, but also the inevitable compatibility against harmonics – one of the modern and growing main players in power quality. Read more

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Singing circuit breakers in the metalworking industry

Problem

Risks for electrical equipment in installations are often only noticed by listening carefully.

This is also the case here, although it is not uncommon in the metalworking industry. The cause of the extreme voltage distortions shown above in a broad frequency spectrum up to slightly above 20 kHz are powerful converters in the presses. A common disturbance pattern is disturbingly loud whistling tones in open circuit breakers, through which the largest proportion of the causing clock frequency currents must flow. Rightly Read more

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PQaaS: The Power Quality as a Service website goes live

Innovative and informative website on the topic of power quality

The topic of power quality is rapidly gaining importance in the context of the energy transition and smart grids and smart metering. As a result, the question marks of the supposedly affected and involved parties are piling up to the same extent. What does this mean for the distribution grid operator, the authorities, the industrial companies, the electrical inspectors, the electrical contractors, the professional associations, the infrastructure companies such as airports, railways, etc.?

Bringing more light into the dark

For stakeholders, whether already familiar with the topic of power quality today or not, the new Read more

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