Arnau Sans, Lead Engineer, HyTEPS
‘Supraharmonics’ refers to disturbances in electrical systems within a specific frequency range: for European 50 Hz systems, this is between 2.5 kHz and 150 kHz; with 60 Hz systems, the range starts at 3.0 kHz. Modern electronics, regardless of price range, generally operate at higher switching frequencies. These switching frequencies tend to inject less interference into the current running through cables. However, the resulting higher harmonics in electrical installations present unique challenges, unlike those associated with ‘traditional’ harmonics up to about 2.5 kHz.
Supraharmonics are becoming increasingly common in electrical installations for various reasons. Modern electrical systems are more complex than ever, with interconnected systems and devices interacting in ways that generate supraharmonics. New electronics are more compact, increasing installation complexity. This leads to interference, causing equipment malfunctions, unintended alarm signals, or power supply failures, as capacitors (passive components) often absorb higher frequencies.
Power electronics
A major cause of the increase in supraharmonics is the widespread use of devices that use power electronics with higher switching frequencies. Another contributing factor is the rise of power converters in systems such as solar energy installations, electric vehicle chargers, and battery storage systems. Modern electronics are often more sensitive to supraharmonics. Interference-related issues can lead to production losses (as systems shut down), as well as audible noise and vibrations in transformers, switching equipment, and other electrical components. Continuous Electromagnetic Interference (EMI), voltage distortions, fluctuations, and harmonic resonances degrade the lifespan of components, as well as the stability and quality of the power supply.
Challenges in dealing with supraharmonics
In the past, systems contained very few electronics, so there was little awareness of the potential for higher frequencies to cause problems. As a result, there is currently no comprehensive standardization or regulation concerning supraharmonic limits and mitigation. This means devices and systems are not always designed with adequate measures in mind. Every device will inject a certain level of supraharmonic current. If six identical loads are installed, higher harmonics will be observed in most cases. Ultimately, the degree of disturbance is determined by how much the current builds up on the voltage waveform or if power cables are placed close to near communication cables.
As power electronics become more prevalent, supraharmonic issues are becoming more common. Sometimes auxiliary loads, such as those near a battery inverter, are more sensitive to interference. Supraharmonics can also travel through the shared ground and affect loads (computers and monitors, for example). When mitigating ‘regular’ harmonics, techniques such as passive and active filters and smart electrical system designs are relied on. However, traditional harmonic filters are ineffective for addressing supraharmonics.
Solutions: smart analysis and specialized techniques
Measuring and mitigating supraharmonics requires specialized equipment. Standard Power Quality analyzers and harmonic meters are often inadequate for measuring and analyzing waveforms. Understanding and mitigating supraharmonic problems in electrical installations also demands specialized methods and in-depth knowledge. Supraharmonics can vary greatly between installations, requiring advanced monitoring, analysis tools, and specific training. With the right PQ meters, oscilloscopes, spectrum analyzers, and data collection and analysis, it becomes possible to identify supraharmonic frequencies and magnitudes, and locate sources and patterns. Based on this information, EMI filters, shielding, and grounding can be implemented to dampen unwanted frequencies and address issues like resonance.
A deep understanding of power quality issues, including supraharmonics, is essential to comprehend the complex interactions between components of an electrical system and map how these interactions cause or amplify supraharmonics. With the right expertise, it becomes possible to ensure that solutions comply with current and emerging regulations and best practices. Engaging specialists ensures that all steps are executed effectively, leading to improved power quality and the reliable, long-term operation of electrical systems.
