Temporary Power Line Used During the Upgrade of the “Łodygowice” MV Line

Companies Tauron Dystrybucja, Ensto, and Energy Composites have jointly installed a temporary power line made of composite poles and flexible multiple-use cables. The line can be used in the event of a breakdown or an upgrade of the existing lines but also, for example, to supply electricity to construction sites or outdoor events. The line is nearly one kilometer long and its elements are easy to transport, hence they can be used multiple times in various locations.

We asked the investor and, at the same time, the main author of the idea who implemented the project, Mr. Janusz Juraszek, Manager of the Żywiec LV and MV Network Region, why is it necessary to build a service line in Łodygowice?

Due to the constant need to upgrade the existing power distribution infrastructure, there are a number of problems with ensuring continuous power supply to customers.  This is the problem that we faced during the upgrade of the 15 kV overhead “Łodygowice” line. The schedule of works submitted by the contractor for the upgrade of the line assumed a large number of shutdowns of the entire line and shutting down six transformers for several hours each day. This is when I thought about building a temporary 15 kV overhead line that would make it possible to supply the customers without interruptions.

Which factors determined your choice of the solution proposed by Ensto and Energy Composites?

Having learned how the Contractor works and the number of power shutdowns for customers, we had to consider the actions that had to be taken to reduce the number power supply interruptions and to reduce the work time. This is because cutting off power supply to all customers is currently not feasible. In order to reduce the time of power supply shutdowns, we had to consider installing six power generators for all transformer stations for the entire duration of the shutdowns. Another solution was to use the innovative solution proposed by Ensto and Energy Composites, which consisted in construction of a temporary 15 kV service line. Having performed a preliminary legal and technical analysis and an estimation of the costs of construction, I found that construction of a service line is a perfect solution to the problem of power supply interruptions. A very big advantage of this solution was the estimated cost of construction of the line and the speed of its installation. Keep in mind that light, divided composite poles and a self-supporting MV cable called FXCEL were used in the construction of the 15 kV service line.

What are the technical parameters of the line and how long it took to build it?

The basic property of the MV service line is the ease and simplicity of its construction. The technical parameters of the self-supporting FXCEL cable and of the ECOdp divided composite poles, along with all the accessories, make it possible to use them multiple times. This is why the cost of construction should include only a fraction of their price depending on other accounting regulations. Consequently, the cost of construction of the service line is not high and consists most of all of the cost of labor and transport.

The self-supporting FXCEL 3*16/10 mm2 cable as a copper multiwire service conductor and XLPE insulation, which improves the ability to roll and unroll the cable multiple times. The transmission capacity of the cable is as high as 1.7 MVA in a 15 kV network, which is completely sufficient for this service line.  The divided composite poles, together with their grating base, make it possible to set the line without interfering with the ground. The height of the poles, equal to 9.0 m, makes it possible to route the line so as to ensure sufficient distance of the cable above the ground. Construction of the first service line, which was about 600 m long, took about one week, including the preparatory works.

How long will the line operate in that location?

The operation time of the MV overhead service line will depend on external factors, including any possible changes in the target line or any “surprises” in the ground or in the legal situation. We are ready to work for 120 days in accordance with the official permission and decision and we have made preliminary estimates that the operation time of the line may be in the range of 7 to 12 days. The 15 kV overhead service line was started on 18 February 2016 and worker for three and a half weeks.

What was the difference between that line and the construction of standard power distribution lines?

The very nature of this line makes it different from the “traditional” solutions that we have used so far. The poles of the temporary line are set on the ground without digging in. Such poles are supported on a grating base burdened with weights. The use of temporary composite poles in the line is also a novelty. In such a solution, construction of a corner, support, and end station in the temporary line is done my installing one or more guy-ropes, which is not a standard solution in Poland. The self-supporting FXCEL cable was used on this construction project for the first time.

What are the benefits for a distribution company and the end customers from the use of the temporary service line?

The key benefit from the construction of the temporary MV service line is the possibility to efficiently perform the project and to reduce the number and the duration of the power shutdowns.  This solution improves the technical-organizational possibilities of the company in the area of upgrade of power supply lines, reconstruction after random events, or construction of power supply lines for temporary facilities. From the point of view of the customers, the advantage is the lack of noticeable and cumbersome power supply outages.  As for benefits for a distribution company, these are certainly a reduction of the SAIDI and SAIFI ratios in the event of simultaneous performance of urgent projects.

Based on the experiences from the construction of the temporary service line and its current operation, does it meet your requirements?

The innovative MV service line fully meets our requirements. It was a big challenge for all employees. In the course of its construction, we benefited from our long professional experience, including those related to construction of EXCEL insulated overhead lines and PAS lines. The construction of the service line resulted in new experiences, including organization of work and manual and technical skills. From the practical standpoint, the line makes sense if it can be built quickly, efficiently, and effectively.  The end result confirmed the low cost of the construction. The service line allowed us to avoid down time at the construction site and certainly reduced the power outage time for the customers. The construction of the first service line that was based on new products supplied by Ensto and Energy Composites was a big technical and logistical challenge. In conclusion, I must say that the method of supplying customers that we used will be repeated and used extensively in practice, not only in the commercial power sector. The experience we have gained in the course of construction of the first line will result in improved indicators of distribution companies and reduced costs.

Photos: Paweł Ziobro