SAFER, SMARTER, GREENER

An innovAtive tool for the investigAtion of hv-interferences

The ChallengeHigh-voltage interferences (HVI) on pipelines, cable systems, etc., caused by AC power transmission systems can be induc-tive, ohmic or capacitive. They can cause problems regarding personal safety (touch voltages) and equipment safety (AC corrosion, insulation strength) on the affected equipment. With regard to the increasing bundling of routes subject to regulation in Germany and appearing on an international level, inductive interferences play a particularly important role. In this context, multiple interferences occur on a regular basis. For example, modern pipeline systems have a very high insulation resistance (faultless PE insulation) which can cause collective electrical interferences in a radius of more than 200 km. Pipelines are frequently interconnected and electrically coupled, creating vast

Efficient and accurate calculation of inductive interferences.

EnErgy

interference areas that have to be taken into account in calcula-tions. Based on the extensive data regarding inductive interfer-ences on pipelines and cables in large interference areas, DNV GL has developed a calculation tool. With this tool it is possible to automatically determine proximity relationships on the basis of GIS data in accordance with DIN VDE 0845 6 1 (VDE 0845 6 1) and TE 1/3 and TE 7 issued by the Schiedsstelle für Beeinflus-sungsfragen [arbitration board for issues of interference] (SfB), and on this basis calculate the inductive interference voltage. The tool thus constitutes an alternative to the rather complicated field calculations previously used for this purpose (e.g. with the CDEGS software and/or the Excel solutions in combination with the obsolete ERDUNG program, the applicability of which is limited).

KEMA - IEV INGENIEURUNTERNEHMEN FÜR ENERGIEVERSORGUNG GMBH, Gostritzer Str. 67, 01217 Dresden Deutschland, Tel: +49 351 8719200, dresden@dnvgl.com www.dnvgl.com

Our Approach and Solution With the tool developed by DNV GL, it is now possible to cal-culate even highly interconnected, electrically coupled systems subject to multiple interferences. By utilizing GIS data in a standardized coordinate system, the complicated geometrical proximity calculations have been automated and objectified (see Figure 1). Using the electrical substitute parameters for pipelines according to TE 7 of the SfB, it is possible to calculate the interference currents and pipeline potential against refer-ence ground in one step by means of the node method, which is based on MATLAB. Investigations of systems with more than 4,000 nodes have already been successfully carried out.Insulation points, isolation amplifiers, delimiters, grounding electrodes, etc., are taken into account, making it possible to quickly perform variant calculations for the reduction of touch voltages to admissible levels.

The calculations of long-term and short-term interferences (short circuits) are carried out. The short-circuit location of the maximum interference is automatically calculated, taking the short-circuit diagrams of the overhead line into account. The results can be displayed in a chart along with the GIS data.

DNV GL’s tool efficiently and accurately calculates inductive in-terferences according to DIN VDE 0228 2 and DIN E VDE E 0845 6 2 (VDE E 0845 6 2). Future development plans include adapt-ing the tool to meet international standards as well as additional national standards.

If you are dealing with the interference issues described above, we would be happy to assist you and introduce the tool to you.

dnv gl

Driven by our purpose of safeguarding life, property and the environment, DNV GL enables organisations to advance the safety and sustainability of their business. We provide classification and technical assurance along with software and independent expert advisory services to the maritime, oil & gas and energy industries. We also provide certification services to customers across a wide range of industries.Combining leading technical and operational expertise, risk methodology and in-depth industry knowledge, we empower our customers’ decisions and actions with trust and confidence. As a company, we continuously invest in research and collaborative innovation to provide customers and society with operational and technological foresight. With our origins stretching back to 1864, our reach today is global. Operating in more than 100 countries, our 16,000 professionals are dedicated to helping customers make the world safer, smarter and greener.

In the Energy industryDNV GL delivers world-renowned testing and advisory services to the energy value chain including renewables and energy efficiency. Our expertise spans onshore and offshore wind power, solar, conventional generation, transmis-sion and distribution, smart grids, and sustainable energy use, as well as energy markets and regulations. Our 3000 energy experts support clients around the globe in delivering a safe, reliable, efficient, and sustainable energy supply.

Figure 1: An example of multiple interferences (blue) of several overhead lines (red) on gas pipelines (green).

The planning and operation of electric power supply systems pose significant challenges, such as the integration of renew-able energy sources, adjustment to new client requirements and determination of the most cost-effective replacement for aging operating equipment. In this context, DNV GL offers a compre-hensive range of services:

■ Steady-state and dynamic analyses of transmission systems and distribution networks, network optimization and target network planning

■ Design, specification, call for tenders and field inspection of electrical systems

■ Consulting and measurement services in connection with is-sues of life cycle diagnosis, earthing, equipotential bonding and surge protection, EMC, and high-voltage interference

Our offer: ■ Planning and dimensioning for high- and extra-high-voltage cable systems

■ Planning and testing of earthing and surge protection systems ■ EMC investigations, including measurements ■ Analyses of, concepts for and measurements of the power quality

■ Fault diagnosis and analysis for selected operating equipment ■ Special investigations (neutral-point treatment, network protec-tion design, insulation coordination)

■ Thermography, PD measurements, FAT assistance ■ NEW: Consulting on high-voltage direct current power trans-mission (HVDC)