Tag Archive for: Power Quality

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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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Power quality issues emerge

Power quality issues challenge utilities as solar is added to the grid, survey finds

Power quality issues emerge in terms of voltage swags, swells, flickers, and harmonic distortions, among other things. Many utilities said they are not happy with their ability to gather useful data to address the problems.

Editor: David Wagman

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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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Load Study with DranXperT

DranXperT Survey Study: officially published by Dranetz

Introduction on this load study

The National Fire Protection Association (NFPA) publishes NFPA 70, the National Electric Code (NEC). The NEC is the US reference for the safe installation of electrical systems. Although the NEC is not mandated by the US federal government, most states and/or municipalities in the US require compliance with NEC requirements.

NEC article 220 is for branch circuit, feeder, and service calculations and section 220.87 covers the requirements to determine existing loads. Compliance with NEC 220.87 is a requirement to determine available capacity when adding loads. For this purpose a load study with DranXperT was executed.

NEC 220.87 requirements

NEC 220.87 states that it is permissible to use the actual maximum demand when determining existing loads, but there are conditions.

The first condition is that the maximum demand data is available for 1 year. Practically speaking, unless the facility has existing branch circuit or other monitoring, 1 year of demand data may only be available at the utility service from utility billing.

There is an exception if maximum demand data is not available for 1 year – the calculated load can be measured at the feeder or service. Such a measurement requires a minimum 30-day load study by a power logger measuring the demand averaged over a 15-minute period. The load study must be taken while the space is occupied and include
measurements or calculations of the heating and cooling equipment (whichever is larger). Refer to NEC 220.87 for specific details.

Another condition is that 125% of the maximum demand plus the new load does not overload the circuit. The requirements for overload protection are covered elsewhere in the NEC.

Configuring the measurement device for the load study

For this study a DranXperT device has been used. Configuring DranXperT for a NEC 220.87 load survey is simple, and the settings are virtually identical to any other load study. It is important that you do the following to meet the requirements of NEC 220.87:

  • On the Survey Setup page set the Demand Interval to 15 minutes and the Journal Interval to 900 seconds (15 minutes). Doing so will program DranXperT to record the 15-minute average information required by NEC 220.87.
  • On the Instrument Setup page make sure that the Max DB File Seconds setting is set to the default of 31 days (or longer). This will meet the requirement of a minimum 30-day survey, and the data will recorded in one data file.

Determining the maximum demand

Determining the maximum demand or amperage is as simple as loading the data file into Dran-View XP (or Pro & Enterprise) and reading the maximum values for demand and amperage directly off the 30+ day trend plot.

 

In the right, the maximum demand and amperage occurred on June 7, 2021. The maximum demand was 260Kw and the maximum amperage was 891A on phase C. This is the information required to determine the available capacity for additional loads.

 

 

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Current version of PQDiffractor

“The latest version PQDiffractor is now available for download online.”

But what is actually the current version of the PQDiffractor?

Power Quality software, such as PQView 4 or DranView 7, provides you with a smooth interface for viewing PQDIF and COMTRADE files. In addition, the software solutions offer a wealth of other functions, for example for monitoring and analyzing power quality. But what if you are afraid to invest in software because you only need a view for rough analysis? There are two possible solutions for this. First, the latest version of PQDiffractor and second, a multifunctional web interface.

The current version of PQDiffractor works as a PQDIF and COMTRADE viewer for viewing, searching, diagnosing and converting PQDIF and COMTRADE files. And this free of charge.

Option 1: The viewing and analysis of the data using the current version of PQDiffractor.

PQDIFFRACTOR

If you only need one viewer, PQDiffractor® the free PQDIF and COMTRADE viewer is just what you need.

Main functions of current version PQDiffractor:

  • Reading binary PQDIF files using IEEE Std 1159.3-2003 specifications
  • Reading of ASCII or binary COMTRADE files using the specifications of IEEE Std C37.111-1991 or C37.111-1999
  • View lists of the data source records in each PQDIF file.
  • Displaying lists of analog and digital channels from COMTRADE configuration files
  • Create interactive graphs from PQDIF observations with channels of any size type.
  • Displaying samples from analog COMTRADE waveforms and digital status channels
  • Exporting the displayed observations to Microsoft Excel as CSV files

And you have read correctly. The current version PQDiffractor is free of charge and connects you to the latest MAVOWATT, HDPQ, LINAX PQ3000, LINAX PQ5000, LINAX PQ1000 and LINAX PQ5000-MOBILE devices without any problems.

Option 2: The viewing and analysis of the recorded PQ data via integrated web-browser.

Web Browser

No external software is required for parameterization of the measuring device or evaluation of the measurement results. Das Webinterface stellt alle notwendigen Funktionen zur Verfügung. These functions can be accessed via end devices (e.g. smartphone, tablet, laptop, desktop, server via LAN or WLAN interface) using an IP address. A responsible WebGui guides the user through the menus. The simplicity of operation is to be emphasised. Because the advantage is obvious: There is no need for external software that causes additional headaches for administrators. And this for mobile as well as stationary applications. And it’s Cyber Secure.

Fields of application for the current version of the PQDiffractor as well as the integrated web browser

  • Smaller distribution grid systems
  • Municipal utilities
  • Energy generators (e.g. large PV plants, wind farms, hydropower, coal and gas, nuclear, etc.)
  • Industry (e.g. semiconductor, steel, automotive, pharmaceutical, aviation, etc.)
  • Infrastructure (e.g. rail, metro, airport, etc.)
  • Data centres
  • Clinics
  • Laboratories
  • Institutes
  • Higher education institutions
  • Universities
  • Authorities
  • Military
  • Applications to be reached remotely via VPN
  • etc.
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Cyber security is essential

The topic of cyber security is becoming increasingly important due to the constantly growing level of networking. Especially in the areas of energy and SmartGrid. Due to the threat situation, effective cyber security is essential there.

Cyber security is essential

Cyber security is essential

Potential risks (data theft & data manipulation)

  • Hacking & Cracking
  • Listening
  • Datamining
  • Theft of passwords and other information
  • Unauthorized access (intranet, end devices, servers, …)
  • Modification of data & data telegrams
  • Delete data
  • Changing configurations
  • etc.
Data flow in the context of the 7 network layer
The seven network layers

The seven network layers

  • Electrical interconnections must communicate with each other
  • Integration into the World Wide Web (www)
  • Integration of more measuring points
  • Users on grid level 7 (local distribution grid <1kV) become (app) specialists (e.g. SmartHome, energy procurement, …)
  • SmartGrid applications are becoming popular and also demanded
  • Planning with simulation and trends are becoming increasingly important for the networks
  • Dynamic load management (e.g. Redispatch, …)

The basic problem of cyber security

Risks cyber attacks

Risks in the energy infrastructure during cyber attacks

  • Individual approaches take up only partial aspects of essential cyber security
  • IT experts mostly have a technical focus and less on the overall context
  • ISO/IEC27001 on cyber security provides a complete, holistic management system and is very complex
  • IEC62443 on cyber security is in principle only applicable to the subarea of industrial automation
  • There is still no IT security standard according to IEC for power quality instruments as well as power monitoring devices at device level. This is currently in the committees of EC TC 85 / WG 20 – Equipment for measuring and monitoring of steady state and dynamic quantities in Power Distribution Systems under the project title: “Cybersecurity aspects of devices used for power metering and monitoring, power quality monitoring, data collection and analysis “is discussed.

Potential solutions on cyber security

Cyber security is essential - and here are the solutions

Cyber security is essential and here possible solutions are presented

In this blog, solution approaches are to be found at the level of measuring devices, which are also used in sub-areas of software solutions. From this, approaches from ISO/IEC27001 (Annex A; Reference measure objectives and measures) can be found, such as. For instance:

  • Access control for systems and applications
  • Cryptographic measures
  • Physical and environmental security
  • Protection from malware
  • Data backup
  • Logging and monitoring
The following approaches should make a significant contribution to a significant increase in safety at the level of measuring instruments:

Learn more while klicking.

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New Release: SmartCollect® SC²

SmartCollect® SC² is a scalable HMI/SCADA software. Unlike the usual less visually appealing SCADA software systems, SmartCollect®SC² is built on an ultra-modern platform with a web-based 2D/3D graphical user interface. In addition to the high user-friendliness of SmartCollectt®SC², the system offers powerful communication and software interfaces as well as flexible expansion options.

The software is currently available in 4 editions:

  • Starter Edition
  • Standard Edition
  • Professional Edition
  • Enterprise Edition

In addition, the software can be equipped with a modern Energy Monitoring System (EMS) as a plug-in.

Key Features of Software:

  • Interactive single line diagrams
  • Functional dashboards
  • Secure web based design
  • Event and warning messages
  • Flexible data communications
  • Integration of devices from different manufacturers
  • Interactive 2D/3D views
  • EMS: Energy Monitoring System (Dashboard & Reporting)
  • Sophisticated zoom functions
  • Custom WebGUI integrations

 

 

 

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PQ meters looking for trouble!

“Electricity comes out of the socket” and why should it be of different quality? Does this mean that not all electricity is the same?

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