The Delta Works is the Netherlands’ most important defense system against high water levels from the sea. The Oosterscheldekering, or Eastern Scheldt storm surge barrier is the largest, most well-known of the Delta Works. In the event of imminent high tide, the nine kilometer long Eastern Scheldt storm surge barrier closes off the Oosterschelde river.
The storm surge barrier features 65 colossal pillars, between which sliders with a length of some 42 m and a height of 6-12 m are suspended. These sliders weigh between 260 and 480 tons. On average, the gates are lowered once a year, as a result of high water levels of 3 m above sea level. The storm surge barrier is operated by a special team from the Netherlands’ Department of Waterways and Public Works from a building on the work island of Neeltje Jans: the J.W. Topshuis in Vrouwenpolder.
At Heijmans ‘ request, HyTEPS carried out a two-week Power Quality analysis and a one-day on-site Electromagnetic Compatibility and earthing study on the electrical installation of the Topshuis and the traffic shafts. The goal was to determine the Power Quality and identify any deviations in both voltage and current that may be related to failures.
Strategic, smart measurement
“The Oosterscheldekering electrical network has been modernized over the last ten years,” says Arnau Sans, Lead Engineer, HyTEPS. “For example, more electronic loads are being introduced. The client wanted to map the effects of this, and also, for example, the effects of the increasing number of wind farms in the area. In this case, we weren’t looking for a solution based on a specific problem that had occurred at a specific time. Instead, we had to take strategically smart measurements, analyze these, and report our findings. It was important to first determine what the most logical places would be to place measuring equipment, and also choose the right equipment. Some locations were hard to reach, strict safety protocols were in place, and the distances to be covered were sometimes very large.”
With Power Quality meters at various locations (Topshuis, Roompot and Hammen), both AC and DC voltage were measured. All electricity parameters and voltage and current events are monitored and analyzed. A grounding current measurement was also carried out on the Main Earth Conductor to gain insight into the residual current over the earth cables. All data was analyzed, conclusions were reached, and recommendations formulated.
The installation complied with the EN50160 standard “Voltage Quality at Point of Connection” under steady state conditions where the voltage level and harmonic distortion of the voltage are within the limits in the standard. “However, we found that with a certain combination of events and load scenarios, failures could occur that might jeopardize compliance with the standard. The conclusions summarized and emphasized quality behaviors/events that could cause problems. It was also found that certain measurements, such as THDu peaks, high zero voltage, and irregularities in neutral voltage, DC voltage level, and at the main earth conductor, require additional investigation.
Making connections
“A large part of the Netherlands lies below sea level and is susceptible to flooding. HyTEPS is, therefore, proud to play a role in safeguarding national security. This project was a fun challenge: “Okay, let’s see if we can find anything interesting!”. The hardest part is combining all the data, analyzing it, and finding correlation between measurements. By talking to different stakeholders, it becomes possible to connect what is being measured and what we’re seeing.”
You really need to know what to look for. For each deviating parameter, you have to consider possible causes. Which kind of distortion in one place is causing distortion somewhere else? That requires considerable experience, I think. You might have all the data, but you still have to really understand how all parts of the installation interact with each other in order to derive something meaningful from that data!”
Gertjan Noordstra (Heijmans) has been responsible for the maintenance of the 10 kV installation on the barrier for eight years now. “Our assignment is to stay ahead of any possible issues. When push comes to shove, we can’t risk the installation not working. Together with our team and specialists such as HyTEPS, we are able to pre-empt these problems and ensure one of the world’s most unique installations is always ready.”
