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The importance of managing Power Quality and how to reduce the financial losses caused by disturbances


Reliability and consistency of electricity supply is one of the most important conditions for the activities of industrial and service companies. Problems originating from poor Power Quality include interruptions, dips or harmonic pollution. Therefore the loads connected to a network with such problems will fail, have a short lifetime and the efficiency of the system will decrease.

According to Leonardo Energy organization the financial losses due to poor Power Quality amount to a total of €150 billion annually in the EU-25. And its impact in the rest of the world is in the same order of magnitude.

COST OF POOR POWER QUALITY

The ideal state of a load would have a constant magnitude and frequency voltage waveform. However this is not possible in real installations (outages, non-zero impedance, etc. ).  The consequences of poor Power Quality include:
  • Unexpected power supply failures (breakers tripping, fuses blowing).
  • Equipment failure or malfunctioning
  • Equipment overheating (transformers, motors, …) leading to their lifetime reduction.
  • Damage to sensitive equipment (PC‟s, production line control systems, etc.).
  • Electronic communication interferences.
  • Increase of system losses.
  • Need to oversize installations to cope with additional electrical stress with consequential increase of installation and running costs and associated higher carbon footprint.
  • Penalties imposed by utilities because the site pollutes the supply network too much.
  • Connection refusal of new sites because the site would pollute the supply network too much.

Electrex -The importance of managing  Power Quality  and reduce the financial losses caused by disturbances

The evaluation of the quality of the power supply considers mainly two parameters:

  • the continuity of power supply, understood as no interruptions in the supply of electricity
  • the voltage quality, understood as the quality of the waveform (amplitude, frequency, variations, etc.).


There are many factors affecting the quality of electricity. Some of the most important ones are:

  • utility related factors (management and functioning of the grid, maintenance, …)
  • factors related to the end-user (failures at the user facility, noise emitted on the network, ...)
  • independent (environmental factors, weather phenomena, damages caused by third parties, ...)

Monitoring Power Quality and Harmonics

Power Quality monitoring is already a service provided by the grid utilities to their core customers (big industrial  and commercial  energy users). Anyway many studies have demonstrated that most of the problems happen within the customer's facility. This fact means that monitoring the Power Quality after the utility meter provides a range of benefits both for the utility and end-user. This is even more true in a scenario where many end-users are also energy producers.

Monitoring the  Power Quality will make possible to detect the sources/causes of problems within the end-user's network. The solution would be either removing the source or making immune the installation from the the poor power quality. Both solutions usually cost far less than the potential damages that may derive.

Anyway still a large number of end-users do not invest in this field and ignore the efficiency that may derive from fixing the problems with poor Power Quality.

In addition to the lacking of informative awareness among stakeholders, one of the main reasons is also that the a large part of the cost of poor PQ is often hidden. Therefore a monitoring system is one of the fist steps toward the optimization of Power Quality.

How we can help you

Our Power Quality Energy Analyzer & Data Manager Electrex of the Kilo PQ product family, in addition to measuring and managing power consumption, are designed to monitor the Power quality and control whether the installation and the equipment handle properly the workloads.

The Kilo PQ devices are used for:

  • the recording of PQ events
  • preventive maintenance
  • PQ problem detection
  • PQ measurement campaigns for specific time periods defined from the user
  • monitoring of the compliance with PQ standards or service standards


Power Quality (Class S - EN 61000-4-30): Events Log

The Kilo D6 PQ detects and logs various events with a resolution of one cycle (with date / time * of each event, type of event, phase involved, duration, min / max value reached during the event and UNIPEDE classification) useful for monitoring the quality of energy (functions related also to the EN 50160 and EN 61000-4-30 standards for the S class). The parameters for defining abnormal events are programmable.

The parameters for defining abnormal events are programmable.

Event types:

  • Voltage Dip
  • Voltage Swell
  • Over current (and its direction)
  • Interruption


Electrex-Power-Quality-Events

(*) Date/hour expressed in hours, minutes, seconds and milliseconds referring to the instruments' (local time). In the table are displayed also some functioning logs as the ones related with the start and configuration settings.


EVENT'S GRAPHIC DETAIL

The Kilo D6 PQ includes the functionality named "event's graphic detail" that allows to record and display the trends of the beginning and end of the event with a time frame (for both beginning and end) of a second (programmable).


Kilo D6 PQ Electrex-Power-Quality-Overcurrent-PH3-graph


Kilo D6 PQ Electrex-Power-Quality-Dip-PH1-graph



Kilo D6 PQ Electrex-Power-Quality-Swell-PH1-graph


EVENTS TIMELINE AND THE UNIPEDE TABLE

The Kilo D6 PQ can display a timeline of the succession of events


Kilo D6 PQ Electrex-Power-Quality-Events-Timeline



Kilo D6 PQ Electrex-Power-Quality-Events-Timeline-Swell

and maintains a diagram of distribution of events based on the % of the parameter considered in relation to its reference value and duration, according to the dictates of UNIPEDE (International Union of Producers and Distributors of Energy).


Kilo D6 PQ Electrex-Power-Quality-UNIPEDE-table


Example: in the last column of the table here below , the S1 denotes a Voltage Swell with a duration between 10 and 500 mS (refer to the UNIPEDE table above), while the X2 denotes a Voltage Dip lower than 5% of the nominal voltage value with a duration between the 10 and 200 mS.


Kilo D6 PQ Electrex-Power-Quality-Events


MEASUREMENT CAMPAIGN

With the Kilo D6 PQ it is possible to configure the measurement campaign in order to log, in the built-in memory, the various parameters with a programmable sampling.

Example of a daily measurement campaign of the 3 phase voltages:


Kilo D6 PQ Electrex-Power-Quality-Modbus-logger-Harmonics



Kilo D6 PQ Electrex-Power-Quality-Modbus-logger-Harmonics-2


Regarding the quality of the voltage the Kilo PQ refers to the European standard EN 50160 which distinguishes the different disturbances in continuous phenomena and voltage events.

The continuous phenomena include:

  • frequency variations
  • variations of the supply voltage
  • voltage unbalance
  • harmonic voltages


The voltage events include:

  • interruptions of the supply voltage
  • voltage dips
  • super-elevations at industrial frequency and transient voltage


Origin of disturbances

Noises are always present in electrical networks and are mainly produced by:

  • failure on the supply line of the user or on the other lines connected to it
  • failures of internal networks of customers
  • inrush currents of transformers and capacitors
  • rapidly varying loads and peak currents of motors
  • non-linear loads


Voltage quality indicators. What to measure.

The monitoring voltage quality examines the following parameters:

  • amplitude and rapid / slow changes of voltage
  • voltage dips
  • harmonic
  • voltage unbalance

When running a Power Quality monitoring program, it is important to consider that the network changes continuously. Traditional measuring devices are not suitable for monitoring non linear loads as the equipment used must measure in True RMS and must specify the range of single Harmonic measured.

Electrex is a brand of Akse s.r.l. - Via Aldo Moro, 39 - Reggio Emilia - Italy - Tel: +39 0522 924244 Fax: +39 0522 924245 - VAT IT01544980350 - info@electrex.it
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