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Electromagnetic Influence Within Residential Areas

Nowadays the demand for both an increase in energy supply and an increase in newly built housing requires significant adaptation of the electricity grid. With less construction space available electrical substations, powerlines and residential areas are placed much closer to each other. This article covers a case where the inductive influence is determined by Witteveen+Bos on piping nearby the new substation.

1. Introduction

A substation near a residential area might cause adverse effects for residents. Electromagnetic fields caused by large currents can induce dangerous voltages on nearby piping, but also adversely affect children $[1]$. For new situations where residential areas and the power grid intersect, the influence of electromagnetic fields should be investigated.

Witteveen+Bos delivers consultancy services regarding high-voltage systems, like power substations. In this article a hypothetical case is investigated where a substation is to be built close to a residential area. There exist different types of electromagnetic influences. This article covers a case where the inductive influence is determined on piping nearby the new substation. This gives the reader an example on how work is executed at Witteveen+Bos. With projects, such as described in this article, Witteveen+Bos contributes to better environments for man and nature, which is one of the main objectives of Witteveen+Bos.

2. Approach to investigating inductive influence

Figure 1 shows a case where a new substation is going to be built close to a residential area. Witteveen+Bos is asked by the grid operating companies to investigate if the placement of the substation and power lines has an intolerable inductive influence on the surrounding environment. The case is tackled by starting at a crude approximate and refined in four different steps.

Figure 1: New substation with close by data cable and gas pipe

Figure 1: New substation with close by data cable and gas pipe

Step 1: Distance and the parallel run of power lines

Figure 1 shows both a gas pipe and a data cable that can be adversely effected by the new power station and lines. In this step we determine the distance and the parallel run between the power lines and the to be influenced objects.

Based on the distance and the parallel run an estimate can be made of the inductive influence, which shows if further investigation is required. To this end, norm NEN3654 ‘Mutual influence of pipelines and high-voltage circuits’ is used.

Step 2: Unity check

In this step more details are considered to determine if there is an unacceptable amount of inductive influence. This is done through the Unity Check (UC):

$UC_1=l \times K_1 \times log(K_2) - log(a)$

Where $l$ is the length of the parallel run of the lines (in km), $a$ the heart-to-heart distance between the pipe and the high voltage line measured horizontally in meters, $K_1$ and $K_2$ are constants dictated by NEN 3654. In the case presented in Figure 1, the UC gives a value larger than one. This suggests an unacceptable amount of inductive influence is exerted from the high voltage lines on the gas pipe and the data cable requiring more detailed steps.

Step 3: Adjusting the unity check

In step 2 the values for $K_1$ and $K_2$ might be overestimated and are therefore adjusted in this step to be specific to the situation. More information, such as the local earth resistivity is used to refine $K_1$ and $K_2$. On-site investigation and measurements might be required. After adjustments, if the UC-value is still larger than one, the next step is necessary.

Step 4: Refined calculations

To determine the exact amount of inductive influence we calculate in this step from the geometry and Carson’s equations the induced voltages $[2]$. Based on the comparison between the calculated voltages and the current standards and regulations, we determine if the design of the power station in combination with the data cable and gas pipe complies with the law and regulations.

Continuation

Witteveen+Bos closely collaborates with the client about the continuation of the project. If the design does not comply with law and regulations the design has to be adjusted. To this end, together with the client Witteveen+Bos starts a discovery process on redesigning the station.

3. Conclusion

Witteveen+Bos, in collaboration with the parties involved, is investigating whether inadmissible electromagnetic influencing may take place and advises on possible alternatives where necessary. The goal is to work together on a safe environment in which there is space for both the increasing energy demand as well as the growing need for residential areas.

4. References

$[1]$ RIVM, „Electromagnetic fields in daily life,” RIVM, november 30th 2020. $[$Online$]$. Available: https://www.rivm.nl/en/electromagnetic-fields/emf-dailylife. $[$Accessed July 1st 2021$]$

$[2]$ J.R. Carson, “Wave propagation in overhead wires with ground return,” in The Bell System Technical Journal, vol. 5, no.4, pp. 539-554, Oct. 1926

Author

ir. J.G. Tams

Jelle graduated his master’s studies in microelectronics at the TU Delf and is working at Witteveen+Bos since 2020. At Witteveen+Bos he advises in matters of electromagnetic compatibility and does computations on magnetic fields around power stations.