Harmonics is one of the vital concepts of a power system as it affects the power quality and the functioning of the equipment. High levels of harmonics can lead to overheating of components resulting in the shortened life of the equipment. The presence of harmonics distorts the pure sinusoidal wave coming from an ideal power source.
Harmonic distortion disrupts a company’s production and business. Some of how harmonic distortion affects business are
- Harmonics cause additional losses (Joule effect) in components
- The presence of harmonics causes higher subscribed power, consequently higher costs which leads to the increase in cost for customer services
- Oversizing of equipment due to derating of power sources
- Life of various components is reduced when the distortion level reaches 10% leading to reduced productivity
- Harmonics introduce peak currents leading to the nuisance tripping of old technology units resulting in production losses as well as the high cost for the time that is required for the system to be functional again
Causes of Harmonics:
Harmonics are created by components with nonlinear loads which take in current in abrupt short pulses. These pulses cause distorted current waves which in turn cause those harmonic currents to flow into other parts of the power system.
The presence of harmonics degrades the level of power quality and its efficiency in industries. Most of the companies have an electrical system that can withstand up to 15% non-linear loads without concern.
If the non-linear loads exceed above 15%, they may lead to the development of harmonic distortions having negative consequences. So, it is important to keep track of the harmonic levels to make sure that they are exceeding the tolerable limits
Thus, a harmonic study and analysis helps to keep insight into the potential risks and causes which can help in avoiding harmonic-related problems at the design stage and reduce the possibility of undesired effects happenings.
Steps in Harmonic Analysis:
Even though the possibility of harmonic problems is narrow, a timely harmonic analysis must be done to ensure the harmonics are at tolerable levels. The steps in harmonic levels include
- The first step includes obtaining the electrical one-line diagram and highlighting available nonlinear loads
- Place of the common coupling (PCC) is focused in the diagram
- Plant in system buses that are prone to distortions are highlighted
- All the harmonics related data are gathered
- Obtain the predetermined values of PCC including highest and lowest short circuit fault levels and the tolerable values of current and voltage harmonics from the utility companies
- A mock harmonic analysis is conducted using accessible software
- Perform the harmonic analysis for the electrical system
- Evaluate whole and discrete current and voltage distortions at the buses and PCC
- Plot the harmonic frequency spectrum
- Choose suitable harmonic control measures the harmonic distortion outpaces the permitted levels
- Reperform the harmonic analysis after adding mitigation methods.
Compatibility levels for harmonic voltages in Australia
For even harmonics
For odd harmonics multiple of 3
The figures show the permissible harmonic distortion levels according to the Australian standard AS/NZS61000.3.6.This standard allows the company to record the harmonic levels before and after a new connection is made.
Care Labs is an authorized provider of harmonic study and analysis. Experienced professionals are allowed to have clear and safe analyses to identify potential harmonic levels and can help in maintaining the harmonics at tolerable levels without causing problems in the future.
Benefits of Care Labs Service:
- Safer power systems according to government standard rules and guidelines
- Save time and money with fully integrated power systems
- Ensure a safer working environment
- Propose quick alternatives in case of emergency
- Increase safety margins
- Save time by automatic generation of arc flash label and work permits
- Avoid potential fines and litigation costs
Australian Standards for Harmonic Analysis
Australian standard AS/NZS 61000.3.6 covers the harmonics due to large installations. This standard assesses the systems in two stages.
Stage 1 includes a conservative quick assessment on the ratio of converter rating to the fault level at the PCC. Stage 2 includes measurements of existing or background harmonics.
- If the background is less than 25% stage 2 allows converter size depending on the fault level and converter type
- If the background is between 25% and 75% converter ratings of half that given in the first step is used
- For backgrounds higher than 75%, a full harmonic investigation is suggested
Care Labs have their crew members deployed in various locations, so our specialists are nearby in case of a routine or emergency. In a very short period, Care Labs have been established as an ISO 9001:2008 certified organization and have acquired a reputed client base with excellent feedbacks.
Care Labs offer harmonic study and analysis services in all the major cities of Queensland, New South Wales, South Australia, Victoria, Tasmania, and Western Australia.
