Design of the 400 kV power line, Płock, Poland

Eltel Networks Engineering SA under cooperation with PKN ORLEN SA participated in the project of construction of the new 400 kV power line connecting the planned power and heating plant, located on the premises of the manufacturing facility in Płock, to the National Power System.

The task included the entire design process , including obtaining a building permit – in particular amending and drawing up local spatial development plans, obtaining a decision on environmental conditions, establishing transmission easements, preparing construction designs and drawing up a Functional and Utility Programme for the purpose of a tender procedure to select a contractor for the construction works.
At the implementation stage, our office played the role of technical advisor responsible for verifying the execution documentation and giving an opinion on the solutions proposed by the Contractor. Due to technical, formal and scheduling considerations, it proved impossible to construct the entire line as an overhead line, so underground cable sections are present along the route. Underground cable inserts were designed due to crossings with existing 400 kV and 110 kV overhead lines, which could not be crossed overhead.

The section from the 400 kV substation at the production site to the 400/110 kV Płock substation is a line of approximately 7.5 km in length, with two underground sections of approximately 250 m and 500 m in length. Placing the underground section in the middle of the overhead line required to design a new 400 kV switch tower, to make it possible to join the overhead and underground lines. Designed by Eltel Networks Engineering SA employees, this structure is the first of its kind in Poland for 400 kV. As an innovative solution, it was registered with the Polish Patent Office as a utility model.

Despite the short length of the section connecting the new power and heating plant with the 400/110 kV Płock substation, several unusual solutions were used in the line to adapt it to the prevailing terrain conditions. The need for 400 kV underground cable sections led to the design of a new support structure to connect the overhead and underground lines. The new 400 kV switch tower – the first of its kind in Poland – was used at four sites, enabling execution of two 400 kV underground sections. The designed structure can be used in the design of other 400 kV lines in situations where, as in Płock, it is not possible to construct a 400 kV line entirely as an overhead line.
After the completion of construction and trouble-free operation period we know that innovative construction solutions designed and reserved by Eltel Networks Engineering SA fulfil their tasks and expectations of the Investor.