Die Kraft der elektrischen Energie ist schwer vorstellbar, wenn man sie nicht anhand anderer Energieformen erklärt. Umso schwieriger ist es, die Bedeutung von exzellenter Netzqualität zu verstehen, da alle Bemühung ihrer Aufrechterhaltung den gewohnten und hervorragenden Status quo weiter verbessern.

1 – Einführung

Back to the Basics

While the energy and electric power supply is rightfully considered a complex and interdisciplinary topic, it certainly affects everyone. In today’s society, a safe and reliable power supply only allows us to casually charge our phones or make life easier by various household devices. Electric power is much more – you could say it is essential for the functioning of our day-to-day life. It is hard to fully appreciate, because we are almost never left without it. In the rare case it happened or may happen again, our view changes dramatically.

Power Quality Explained – Welcome to our Multipart-Series

Throw away old Power Quality books, stop looking for new ones. In 2021, the NEO Power Quality Blog explains what you need to know about Power Quality Management. Over the next chapters we give you an introduction to the world of electric power and Power Quality. Starting with the grid operator’s perspective will help us talking about real-life deviations from the ideal power supply. Thereby we will automatically underline the importance of Power Quality and how it affects both industrial and private consumer.

You will be surprised how diverse the effects of poor Power Quality can be. Even more intrigued about how both challenging and easy it can be to troubleshoot.

There are definitely many topics and phenomena to manage in the PQ field. We decided to create a multipart-series diving a little bit deeper in each chapter.

Power Quality – A Reintroduction served as introductory chapter, focusing on the challenges and emerging PQ phenomena we see in today’s power grid. Among other topics like Wind and PV testing or Supraharmonics effects on Power Line Communication (PLC) of Smart Meters, we will certainly cover a wide range of topics in upcoming publications. As of today, we start on square zero.

One last thing before you start reading

You maybe ask yourself why we started this Power Quality Blog in the first place? Well, it is a great platform to share our experience and knowledge. Experience that we have gained in the last 20 years in the fields of hardware and software development and the PQ Analysis and Monitoring Market.

Power Quality also means working together for a safe and reliable power supply. Similar to that, this blog aims to start conversations and highlight the importance of co-operation by every party involved. Let’s hear from you – we’re ready to answer your comments, questions or suggestions for future articles!

2 – The grid operator’s perspective

Coming back to the introductory chapters of this article, we highlighted the importance of electric power in our day-to-day life. Talking about the increasing challenges, grid operators ensure that Power Quality phenomena stay within given limits according to standards and Grid Codes.

Power Quality defines the framework of the electric power delivery consumers need – and expect – to run their equipment properly. While a power failure may be the obvious worst case scenario for every end user or factories, even small disturbances like voltage dips, transient currents or unbalance endanger the continuity of power supply as well. Very often end users start to notice problems because of their sensitive equipment. On the other side, PQ also holds end users accountable to limit their influence on the power system. For example by means of limiting harmonic currents.

By monitoring and analysing voltage and current over a certain period of time, both grid operators and consumers gather information about the current state of the grid. Furthermore they are able to manage problems, as certain PQ phenomena can often be traced back to a certain cause.

3 – Foundational Knowledge Power Quality

Classic PQ Phenomena

Whenever electric wave signals deviate from ideal sinus waveforms, Power Quality phenomena arise. As a result, Power Quality Analysers and Monitors are needed and used to ensure grid stability. From our experience, PQ Management nowadays goes way beyond EN50160 and other reports. We will cover the following phenomena in Chapter 2 very soon:

• Power and Energy (Apparent, Active and Reactive Power, Power Factor, Distortion)
• Voltage Variations (Dips, Swells, Spikes, Rapid Voltage Changes)
• Harmonics (Interharmonics, Total Harmonic Distortion (THD))
• Flicker (Short- and Long-time Flicker, Pinst, Pst, Plt, Flicker current, phase angles)
• Unbalance (Symmetrical components: Zero, Positive and Negative Sequence)

Emerging PQ Phenomena

As we have already discussed in our previous article, a various number of PQ phenomena shift into the focus of our customers and the Analysis and Monitoring market in general. For these phenomena we will go into greater detail in future blog posts. Furthermore, you can soon access specific AppNotes in your personal NEO Download Area.

4 – Fundamentals on Computer-based PQ Analyzer

Skip the past. Look at present-day technology.

Nachwievor sehen wir Mess-Setups mit einer Vielzahl an unterschiedlichen und veralteten Geräten. Die Folgen sind zumeist Datenverlust, Probleme mit unterschiedlichen Zeitstempeln und Dateiformaten und definitiv mit einem erheblichem Mehraufwand. All das kann durch den Umstieg auf ein voll-integriertes Gerät bzw. System vermieden werden.

Also nichts wie ran an computerbasierte PQ-Analyzer. Weil wir glauben, dass Sie keine einzige Stunde mit Geräten verbringen sollten, die für das Stromnetz der Vergangenheit entworfen wurden. Messgeräte dürfen Ingenieure nicht länger einschränken. Wir wollen uns nicht auf separate Instrumente mit unterschiedlichen Zeitstempeln und Dateiformaten verlassen, wenn man alles auf einem einzigen Instrument oder einer einzigen Plattform haben kann. Nehmen wir unsere Geräte als Beispiel: Sie vereinen die Funktionalität mehrerer Instrumente. Außerdem messen und analysieren sie gemäß den internationalen Normen IEC 61000-4-7, IEC 61000-4-15, EN 50160, und die Analyzer entsprechen vollständig der Norm IEC 61000-4-30 Klasse A.

Foundations of AC-Conversion

The performance of hardware, bandwidth, accuracy and resolution has increased dramatically over the past 10 years to the point that the performance of computer-based digitizers is comparable to traditional instruments. Today, virtually all common measurements and complex applications, such as FFTs and signal processing routines, can be done in less time and at a lower cost due to the declining prices of measurement components. Moreover, these components are tightly integrated with the software. It is easy to reconfigure the computer-based system to follow your demands.

Choosing the right amplifier

In terms of isolation voltage, this is very important for a safe and reliable measurement setup. In order to avoid electrical accidents, we strongly emphasize the importance of safe instrument design. Unfortunately, we quite often see instruments that don’t even fulfil the required safety categories for the respective measurements (CAT III 1000V / CAT IV 600V). As a matter of fact, the High-Voltage inputs of our PQA 8000 instrument (CAT IV 600V) are isolated up to 6kVp – while maintaining high precision (0.05%) and sampling rate (up to 1MS/s).

Ist Ihre Lösung zur Analyse und Überwachung der Netzqualität noch zeitgemäß?

Measurement range & Resolution

Selecting the right measurement range for input channels is vital for the further conditioning and analysis of signals. Configurable amplifiers allow users to select the right measurement range via the software. At this point we would like to take a closer look at how the selected range is vital for the accuracy and reliable results.

• Choosing a range that is smaller than the expected input signal will result in a channel overload.
• Choosing a range that is too big, the inaccuracy within this measurement range will result in a high uncertainty of the read-off signal value. Which means it is impossible to make correct readings.

Are your analysis results limited by inadequate converter resolution?

Choosing the right range actually means taking advantage of the best resolution offered by the equipment you use.

Frequency-dependent sensor correction

Following the discussion about the wide frequency spectrum of power grid applications, we also need to take phase shift and amplitude damping effects of sensors into account. We tackle this topic by generally providing highest quality sensors und calibrating them over the full bandwidth. Needless to say, the calibration is done over multiple points for each measurement range. Which improves the accuracy and precision especially at low currents, e.g. of 1% of the nominal measurement range. By doing so we ensure that our customers receive measurement equipment that is ready to use for their particular application.

Sensor correction ensures validity of your measurement results.

5 Summary and Outlook

In this first part of our Multi-Part-Series, we built up the foundational knowledge on Power Quality Analysis. By starting with the grid operator’s perspective, we have come to understand the importance of Power Quality as well as expectations and benefits for all parties involved. Furthermore, it helped us differentiate between classic and emerging PQ phenomena of today and tomorrow. Complementing these parameters with a fundamental yet compact knowledge on data acquisition gives us a common ground for upcoming articles. This allows us to discuss the first batch of PQ parameters in the upcoming Chapter 2.

Ihre NEO Messtechnik Experten

Further reading

Chapter 2 – Electric Power & Energy Explained

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