One of Canada’s largest manufacturers of innovative and sustainable packaging products was facing multiple transformer failures and production stops due to power quality issues at one of its many sites. The manufacturer needed to find a way to eliminate these recurring problems and troublesome interruptions. Multiple studies on power quality were performed by different contractors. Comsys Partner, ADM Engineering, was one of the companies performing power studies and providing analysis report.
The challenge facing ADM was to determine what was causing the periodic failures in the main transformers and to recommend a reliable remedy. Following site measurements and subsequent analysis of the data captured by ADM and Comsys, the root of the problem was identified. The culprit was the resonance caused by the interaction between the natural resonant frequency of the power system, tuned capacitor banks, and nonlinear loads. Based on these findings, ADM was able to recommend ADF as the only viable solution to the site’s persisting problems.
ADF P300 – Active Harmonic Filters engineered and assembled by ADM using PPM300 modules.
The ADF solution has been operating successfully since January 2020, eliminating resonance and harmonics as well as providing near unity power factor. Cost savings alone have amounted to around CAD 30,000 per month by eliminating harmonics and correcting the power factor. Increased uptime and productivity provide even more value.
- Mill power outage frequency significantly reduced
- Oil cooled transformer runs much cooler and requires less frequent oil changes
- Significantly reduced running temperature of several transformers
- Reduced nuisance trips and blown fuses of 600V switchgear
- Reduced saturation of feeding transformers, reduces voltage variations to nominal values
Current THD – before & after installing ADF
Power Factor – before & after installing ADF
Machine drives system supply voltages before active filters installation
Machine drives system supply voltages after active filters installation
Active Harmonic Filters are becoming cheaper and very competitive compared to other active mitigation solutions such as Active Front End, which we explained here. In some applications that are not too dynamic, a passive harmonic filter makes perfect sense to reduce the investment. A combination of active and passive filters can be the best solution to reduce the investment cost while still being able to cope with dynamic loads. In such an application the passive harmonic filter focuses on the dominant harmonic component. This solution is currently used by for example the German auto industry in their production lines.
PQ Nosswitz, a German power quality solutions firm, devised a system to allow a flexible combination of active harmonic filters and passive harmonic filters to enable the most flexible and cost efficient solution for every project.
Power quality mitigation products are not only used to fulfil regulations such as IEEE-519 and G5/4. They have actual effects saving both power and increasing productivity. This presentation by ABB exemplifies some of their early case studies indicating savings of up to 10%. Note that these savings compare to having no harmonic mitigation.
The cases below clearly show the great business value of implementing a high power quality standard within your facility. The secondary effects of complying with IEEE 519 or similar standards enables the local grid to be dimensioned for less reactive power and harmonic current thus saving money through thinner cabling, smaller transformers etc. Power quality mitigation is not only a cost in the general investment calculation but a tool to save money.
What is Harmonics
Simply put: Harmonics are unwanted frequency components and unbalance in terms of uneven power distribution between the phases in the electrical network.
More exactly: Harmonics are disturbances to the sinusoidal voltage waveform. They are multiples of the supply frequency, in other words if the supply frequency is 50 Hz the fifth harmonic would be 250 Hz. These variations from the pure sine form are caused by non-linear loads from electrical machinery and appliances. These non-linear loads can be caused by anything from battery chargers to variable speed drives or flourescent lighting. High levels of harmonics can cause power quality problems and voltage distortions.
Harmonics and the power quality problems they cause can have expensive and often detrimental effects on machinery and appliances. Flourescent lighting may need to be changed continuously, electric motors may have a higher frequency of break downs and a shortened life span. Some common direct impacts of poor power quality in the shape of harmonics are:
- Lower production speed
- Increased energy consumption
- Charges for reactive power consumption
- Damaged equipment
- Premature equipment aging
- Data loss
The fact is that harmonics have become a problem for many business sectors and the costs are consistently rising. The number of disturbances are increasing and modern production equipment is becoming more sensitive to these disturbances.
Harmonic Distortion Standards
Harmonics caused by large machine parks can also have an effect the grid. This is why there has been an increase in regulations and standards required by municipals. Some examples of standards governing harmonics emissions are IEEE 519, G5/4, EN 61000, EN 50160, D-A-CH-CZ, among others. Some standards are also specific to certain applications, such as DNV or ABS for offshore applications. The standards most commonly require a voltage harmonic distortion below 5-8%.