By Arnau Sans | October 2021

 

“Yachts present a number of very specific, complex Power Quality challenges. Applying pur experience in this area and coming up with solutions is always a fun challenge.”

“At the request of a customer, HyTEPS recently performed harmonic load flow simulations on a yacht’s electrical installation, to analyze and identify the magnitude of harmonic pollution. That’s quite a challenge. Yachts aren’t static and there are many variables involved: load type, weather, number of people on board, number of generators, load power usage and so on. With this in mind, we performed simulations to get a clear picture of voltage and current waveform distortion for manouvring, anchoring, sailing and other  scenarios.”

“Yachts present a combination of luxury loads and loads only found off-shore. Therefore, this type of project is completely different to what I am used to seeing in on-shore projects, for example in factories and data centers. What’s more, power comes from diesel generators instead of from the strong public on-shore grid - any simulation result can be expected in this type of weak electrical network. It is also challenging to define harmonic distortion on yachts  with different voltage levels. The presence of transformers means pollution must be simulated and taken care of on each voltage level, in order to define the proper harmonic filtering solution.”

“It is amazing to see the harmonic output for different case scenario and where the worst distortion is to be expected. Also, you can see how the type of electronics in front of big loads play an important role. For example, a bow thruster with Active Front End (AFE) technology pollutes significantly less than a 6 pulse Voltage Frequency Drive (VFD), thus lowering distortion levels.”

“Ongoing communication with the yacht electrical installer, to obtain the data in a structured, transparent way, made the simulation faster and more reliable. Miscommunication can make simulations very time consuming, as the single line diagram model might change at any time. It is also important to understand how generators behave on the harmonics range and the influence of the impedance on every electrical point of the installation. By doing simulations, you develop a sixth sense in which you can tell by the simulation results if they are correct and make sense. In this way you can find possible mistakes faster and easier.”

“To avoid malfunctions, and for safety reasons, Lloyd’s Register, DNV-GL and ABS impose a Total Harmonic Distortion in voltage (THDu) limit of 8%. However, HyTEPS strongly recommends customers limit THDu to below 3%. We dimensioned high-tech Active Harmonic Filters and distortion was reduced from levels that regularly exceeded 8% to less than 3%. No problems have been reported since commissioning, and customer feedback is very positive. We are proud to help our customers improve and excel using our knowledge in the field of Power Quality!”