What is Power Quality Study?
Electric power quality study is a systematic analysis to identify power qualities issues, look for the root causes and recommendations for improvement in an electrical system. Those issues are such as surges, harmonics, high frequency noise, transient voltages, wave distortion, interruptions, frequency variations, etc. Power quality studies are also meant a focused and systematic approach to solve complex problems in a power system. Power qualities analysis is for new builds and for existing plants. All are to can make electrical system and loads operation run smooth and more efficient. Omazaki Engineering is a consultant company who provides power quality studies and analysis to audit and assessment for commercial and industrial facilities. If you are looking for power quality study consultants for your project in Indonesia and South East Asia, please contact us by sending an email to firstname.lastname@example.org or by filling in the form in contact.
Power Quality Assessment and Audit
Power quality assessment and audit is an activity to evaluate that the electrical energy entering the equipment has enabled the system to operate properly, efficiently and minimizes long-term risk to the equipment. Proper power quality maintains control over process automation equipment, digital controls and motor drives. Poor voltage wave forms can cause unnecessary and costly disruptions to electronically controlled equipment.
Definition of Power Quality
There are many definitions for power quality. They are:
- According to Utilities, power quality is about reliability
- From the aspect of load – power quality is defined as the power supplied to get a satisfactory performance from all equipment, especially all sensitive electronic equipment
- From the point of view of the end user (end-user) – power quality is defined as “problems that have an impact in the form of deviations in voltage, current, or frequency resulting in failure or misoperation of customer equipment”
- In the IEEE dictionary, power quality is defined as “the concept of providing electric power supply and earthing (grounding) sensitive equipment to conform to the principle of operation of the equipment”
- IEC (International Electrotechnical Commission) defines power quality as “a set of parameters that determine the properties of the power supply delivered to the user under normal operating conditions in terms of supply continuity and voltage characteristics (magnitude, frequency, waveform)”.
Power Quality is a measure of how well a system supports reliable operation of its loads. A power disturbance or event can involve voltage, current or frequency. Power disturbances can originate in consumer power systems, consumer loads or the utility.
Standard on Power Quality
IEEE Power Quality Standards
There are several kinds of electrical power quality standards published by the IEEE (Institute of Electrical and Electronic Engineers). You can read the link below:
- IEEE SCC-22: Power Quality Standards Coordinating Committee
- IEEE 1159: Monitoring Electric Power Quality
- IEEE 1159.1: Guide For Recorder and Data Acquisition Requirements
- IEEE 1159.2: Power Quality Event Characterization
- IEEE 1159.3: Data File Format for Power Quality Data Interchange
- IEEE P1564: Voltage Sag Indices
- IEEE 1346: Power System Compatibility with Process Equipment
- IEEE P1100: Power and Grounding Electronic Equipment (Emerald Book)
- IEEE 1433: Power Quality Definitions
- IEEE P1453: Voltage flicker
- IEEE 519: Harmonic Control in Electrical Power Systems
- IEEE P519A: Guide for Applying Harmonic Limits on Power Systems
IEC Power Quality Standards
- IEC 61000-4-11 – voltage sag immunity – 16 Amps or less
- IEC 61000-4-34 – voltage sag immunity – more than 16 Amps
- IEC 61000-4-30 – power quality measurement methods
General Classes of Power Quality Problems
The IEC classifies electromagnetic phenomena into the groups as given below:
- Conducted low-frequency phenomena
- Signal systems (power line carrier)
- Voltage fluctuations (flicker)
- Voltage dips and interruptions
- Voltage imbalance (unbalance)
- Power frequency variations
- Induced low-frequency voltages
- DC in ac networks
- Radiated low-frequency phenomena
- Magnetic fields
- Electric fields
- Conducted high-frequency phenomena
- Induced continuous-wave (CW) voltages or currents
- Unidirectional transients
- Oscillatory transients
- Radiated high-frequency phenomena
- Magnetic fields
- Electric fields
- Electromagnetic fields
- Continuous waves
- Electrostatic discharge phenomena (ESD)
- Nuclear Electromagnetic Pulse (NEMP)
We will explain each of the above power quality phenomena in the next article.
Why We Need Power Quality Study?
Recent developments in technology have increased the penetration of non-linear loads in power systems of all capacities. Non-linear loads in the form of computers used in offices, converter and VFD use in industry, even in residential areas use a lot of inverter-regulated air conditioners. These devices are a source of harmonic emissions. Its characteristic harmonic emissions must be identified, studied and corrected by corrective action to save power consumption costs and meet utility standards.
Power quality problems can cause equipment failures and equipment/process nuisance shutdowns, often costing many thousands of dollars. Power system analysis will assess the root cause of these issues, then recommend cost effective solutions which including grounding improvements, surge protection, power conditioning, uninterruptible power supplies, and harmonic filters.
Electrical disturbances occur constantly in electrical distribution systems. When a disturbance exceeds a specified value, it’s said to create a power quality event. Because power quality is the study of the voltage and current in your distribution system, you can measure and monitor many events by looking at the 50-Hz or 60-Hz sine wave.
This is where the use of a power quality study becomes imperative, as it can be critical in reducing the facility downtime and enhancing productivity.
Dangerous of Poor Power Qualities
Most power quality issues result in performance, safety and overheating problems. In particular, electrical power systems polluted by poor power qualities, especially harmonic, can lead to:
- Over voltage/current in the electrical systems
- Overheating of equipment
- Nuisance tripping
- Malfunction of automated controls
- Damage to capacitor
- Inaccuracy of instrument measurement
- Interference in telecommunication systems
Causes and Risks of Poor Power Qualities
There are several causes for poor power quality. The most common is the use of electrical equipment with modern electronics, or implementing modern equipment into existing electrical installations. Examples include replacing conventional lighting with LED lighting, installing solar panels, and installing inverters on electric motors. Modern electronic equipment is very sensitive to contaminated and disturbed electricity, resulting in more interruptions, failures or malfunctions, and shortens the life of electronic equipment.
Unnecessary Costs, Disruptions and Energy Losses
Poor power quality also affects the efficiency, continuity and safety of electrical installations. It also increases the risk of malfunction and damage, increases maintenance costs, and unnecessary energy loss. Poor electrical quality can be experienced in the form of flashing lights or buzzing sounds from the factory, and may also go unnoticed and eventually have adverse consequences. Poor power quality can lead to production outages, self-igniting cables, and premature aging of electrical plants and equipment.
Power quality studies are increasingly needed because of the increasing use of electronic devices that are much more sensitive to electrical interference. Power quality studies allow us to take the necessary measures to avoid electrical damage to equipment and stoppage of installation work.
When to Consider a Power Quality Study?
- Experiencing frequent down time
- Experiencing problems when certain equipment is running
- Your computer systems are locking up or you are losing data
- Your equipment’s circuit boards or other critical electrical components are being damaged
Symptoms of Poor Power Qualities
There many symptoms of power quality problems. The several are:
- Lights blinking
- High ground current
- Poor performance & unexpected shutdowns
- Sudden equipment maloperation
- Sudden tripping of circuit breakers
- Premature equipment failure symptom of power outage no electricity for more than 60s
- Premature equipment failures
- Lost data in electronics
- Capacitor bank failure
Objectives of Power Quality Study
Main objective of a power quality study is to explore and evaluate the root causes of power quality problems in the area under study. The study results will recommend corrective actions to minimize the impact of poor power quality, ensure energy savings, and achieve compliance with applicable standards.
With power quality studies, critical equipment will have appropriate protective measures and reduce stoppage time.
Benefits of Power Quality Studies and Analysis
- Increased reliability of better power grids
- Improve electricity infrastructure
- Reduces equipment failure
- Increase machine life
- Reduce energy consumption with significant energy savings
- Reduction of carbon emissions
- Optimization of the electrical network
- Avoid electricity bill penalties
How to Conduct Power Quality Studies?
Power quality investigations in commercial and industrial include:
- Installing and monitoring power quality instruments to record and collect data under operating conditions
- Analyzing data to identify the root causes of the power quality issues
- Referencing IEEE 141, IEEE 399, and IEEE 519 when conducting power quality studies
Consult with the power quality study consultant to determine the scope and focus of the study, or analysis, or assessment to be carried out.
Brief Power Quality Study Methodology
In brief, the power quality study methodology consists of:
- Monitoring through Power-Quality Instruments
Power quality instruments or meters are set-up at key locations throughout the area under study, they are programmed to record any power quality parameters for one or more cycles of the daily routine activities of the facility.
- Identification of Sources of Harmonic Emission
Once a fair duration is recorded, it is thoroughly analyzed and patterns of power qualities parameter generations are critically studied. Power qualities consultant and engineers may recommend a remedial action at this stage of study after assessing the recorded data.
- Modelling and Simulation
The power system under consideration is modeled using the industry standard Electrical Transient and Analysis Program (ETAP) and a complete ‘worst case’ power quality issues scenario is simulated on the software.
- Designing a Suitable Mitigation Scheme
An analysis with the power quality analysis tools in ETAP is then used to design the most optimum, cost effective and efficient poor power quality reduction scheme for the facility.
Power Quality Measurement and Instruments
Power Quality Instruments
- Harmonic Analyzers
- Transient Disturbance Analyzers
- Data Loggers and Chart Recorders
- True RMS Meters
Power Quality Measurements
- The first step in solving power quality problems is to determine the test location or locations. Even the best available power quality instrumentation is only as good as the personnel using it.
- Setting up instrumentation at a location that is not optimum with respect to the affected equipment can yield misleading or insufficient information. Electrical transients are especially prone to errors depending on the type of the instrument used and its location.
- The best approach to investigating power quality problems is to first examine the power quality to the affected equipment at a point as close as possible to the equipment
Number of Test Locations
The number of test locations will depend on the nature of the problem and the nature of the equipment affected. If possible, power quality tests should be carried out at several locations simultaneously. Data obtained in this way is useful in determining the nature of power quality problems and in finding possible sources of their causes quickly.
If simultaneous measurement or monitoring is not possible due to cost or other factors, each site can be monitored individually.
As a general rule, each location needs to be tested for at least one week. If the measurement is made at a location which is certain to be the source of the problem, the interval can be shortened.
Most power quality issues or tendencies present themselves within this time frame. The actual test durations depend on the experience of the power quality engineers and their comfort level for deriving conclusions based on the data produced.
Test duration may be shortened if different power system operating conditions that can cause power system disturbances can be created to generate an adequate amount of data for a solution.
The end result of a power quality study is a report that presents findings and recommendations. The final report usually includes:
- Detail of the original system under consideration
- Detail of the points of common coupling and points where PQ meters were set-up
- Detail of a typical routine cycle of the facility inferred through PQ monitoring
- Identification of the sources and patterns of power quality issues
- Preliminary observations and recommendations.
- Design parameters and specifications of the impact reduction method of power quality problem
Contact Omazaki Engineering if you are looking for a power quality study and analysis consultant to help your project or existing electrical system more efficient and reliable in Indonesia and South East Asia.
- Power System Study & Analysis
- Load Flow Study & Analysis
- Short-Circuit Study & Analysis
- Protection Coordination Study
- Motor Starting Study and Analysis
- Power System Transient Stability Study
- Arc Flash Study & Assessment
- Voltage Drop Study & Analysis
- Voltage Imbalance (Unbalance) Study