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What causes poor power quality?

What causes poor power quality?
As grids have been evolving towards more complex structures and consumer’s demand for reliable, secure electricity increases, the quality of power is more critical ever than before to meet these expectations. In addition, electrical equipment works in defined certain limits of voltage and frequency while operating in these tolerance limits. 

First, what good power quality means?
Hence, we can define good power quality as a power supply that is always available for everyone in safe limits. However,  poor power quality can be defined as basically the one unreliable and not always available in tolerance limits, and so causes lots of problems.  

It is better to know what causes the poor quality to solve many related issues, like economic losses, not meeting industrial standards etc. 

Why we have poor power quality? 
As power quality is quite a complex subject itself, we can’t assume only one reason for having poor quality. There could be many reasons for the poor power quality. Still, we can summarise them under main topics which are listed below, and each of these has different solutions to be addressed best practice.
Besides this, there is always a solution for each power quality problems, and some improvement strategies have been listed below.

DIPS or SAGS
Symptoms• Lighting dimming, computer lockups, relay and contactor chatter or complete dropout, equipment and system shutdowns
• Spurious and unexplained alarms and shutdowns
Potential causes• Starting large loads, especially large inductive
• Similar operations in neighboring facilities
• Short-circuit faults
• Severe weather conditions
How to Solve• Uninterruptable Power Supply (UPS)
• Dynamic Voltage Restorer (DVR)
Click to see ENDOKS DVR Solution
SWELLS
Symptoms• Overvoltage shutdowns and alarms on variable frequency drives (VFDs) and other electronic devices
• Failure and damage on equipment and loads
Potential causes• Fault on single phase of three-phase system
• Sudden load decrease
• Capacitor bank switching
How to Solve• Uninterruptable Power Supply (UPS)
• Dynamic Voltage Restorer (DVR)
Click to see ENDOKS DVR Solution
UNDERVOLTAGE / OVERVOLTAGE
Symptoms• Overheating of equipment
• Insulation failures
• Performance and life time degradation on equipment
Potential causes• Uncontrolled reactive power flow in transmission and distribution systems
• Variations in the generation of PV and wind power systems
How to Solve• Static VAR Compensator (SVC)
Click to see ENDOKS SVC Solution
• Static Synchronous Compensator (STATCOM)
Click to see ENDOKS STATCOM Solution
• Magnetically Coupled Reactor (MCR)
Click to see ENDOKS MCR Solution
• Voltage Regulator
VOLTAGE FLUCTUATIONS / FLICKER
Symptoms• Light flicker
• Nuisance tripping due to misoperation of electronic devices
Potential causes• Intermitted loads like electric arc furnaces and welding machines
• Variations in the generation of PV and wind power systems
How to Solve• Static VAR Compensator (SVC)
Click to see ENDOKS SVC Solution
• Static Synchronous Compensator (STATCOM)
Click to see ENDOKS STATCOM Solution
• Magnetically Coupled Reactor (MCR)
Click to see ENDOKS MCR Solution
• Voltage Regulator
TRANSIENTS
Symptoms• Flashover and arcing effects in distribution equipment
• Damaged insulation
• Failed electronics
• Computer lockups
Potential causes• Lightning strikes
• Switching of capacitors
• Reenergizing systems after a power failure
• Sudden stoppage of large equipment
• Dirty or worn contactors
How to Solve• Surge Arresters
• Isolation Transformers
INTERRUPTIONS
Symptoms• Equipment shutdowns
Potential causes• Momentary loss of utility power
How to Solve• Uninterruptable Power Supply (UPS)
UNBALANCE
Symptoms• Overheated three-phase motors and transformers
• Overvoltage and overloading problems in neutral conductors
Potential causes• Unbalanced loads across individual phases of three-phase panelboards
• Unbalanced utility supply
• Operation of large single-phase loads
• Open-delta transformers
How to Solve• Static Synchronous Compensator (STATCOM)
Click to see ENDOKS STATCOM Solution
HARMONICS
Symptoms• Overheated line and neutral conductors
• Overheated motors and transformers
• Spurious and unexplained alarms and shutdowns of electronic equipment
Potential causes• Nonlinear loads such as switching power supplies
• Converter sections of uninterruptible power supply (UPS), VFDs and battery chargers
• Welders
• Arc furnaces
How to Solve• Passive and Active Harmonic filters
Click to see ENDOKS Pasif and Active Harmonic Solutions

We are here to help you empower your grid or your operations in your business. We have different power quality solutions for your business need.

For more information, please, Contact Us

Case Studies

EULOMOGO STATCOM PROJECT

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SCOPE
Design, Supply, Erection Supervision and Commissioning of 11 kV, 2x ±4 MVAr Containerized Statcom Systems for 66 kV Bus Voltage Regulation.

PROBLEM
66 kV voltage will vary after installation of Nevertire SF rated 105 MW, which is connected to the Essential Energy network.

REQUIREMENT
Fluctuations in Solar Farm output must not produce more than the allowable voltage changes as per AS 61000.3.7

SOLUTION

  • Installation of 2 Statcom Systems rated ±4 MVAr at Eulomogo Substation at 11 kV bus.
  • Each Statcom System is connected to 11 kV bus via 4.5 MVA, 11/0.48 kV coupling transformer.
  • Parallel operation of 480 V, ±400 kVAr forced air-cooled Statcom Panels are implemented.
  • 20 panels inside 4 air-conditioned containers are operated in parallel by a Master Controller, which generates a set point for inductive/capacitive reactive power as per droop characteristics specified for 66 kV bus.
  • The overload rating of the Statcom System is 3xInom for 2s.

TEST RESULTS

The voltage reference test was completed successfully at the of December 2019 in coordination with Essential Energy. Test results showed the ability of the Statcom System to operate according to the required droop control characteristics.

ACCEPTANCE CRITERIAPass
The reactive power output at 11KV busbar voltage level corresponds to the expected output as per the given droop characteristic within acceptable tolerance limits (+/- 10%)Yes
The output of the STATCOM unit can be maintained for the duration that
the tap is held.
Yes
The settling time of voltage response to the tap change is sufficient for the Nevertire solar farm to comply with its GPS requirements.Yes
Measurement data is successfully downloaded and confirmed.Yes
Blog

What is the electrical power quality?

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It is possible to find different definitions in various sources related to electrical power quality. According to some sources, electric power quality is defined as the reliability of the electrical network systems and only voltage quality. However, these definitions are insufficient to explain the concept of electric power quality.

To make a comprehensive definition, we can say that electrical power quality can be defined as a series of electrical parameters and limits that enable end-user loads or equipment connected to the electrical network to operate in the desired manner without any significant performance and lifetime loss.

On the other hand, electrical power quality problems can be defined as power problems caused by voltage, current, and frequency changes that cause malfunction or malfunction of end-user loads or equipment connected to the mains.