**2. Comparison Approach**

Various anti-icing and de-icing methods have been developed in different countries and important research efforts have been deployed for several decades [9]. This article presents a comparative analysis of the different countermeasures that have been proposed to protect the power line infrastructure based on the following two approaches:

First, a comparative study was carried by analyzing a certain number of publications and technical reports that reviewed the proposed countermeasures over the past four decades. This comparison was carried out with the following objectives:


The following comprehensive references were considered for this part of the study. The selection includes publications before and after the 1998 Eastern Canada ice storm:


The results of this comparative analysis are presented in Section 3.

Second, the application and integration of countermeasures into field operations are reported by reviewing various references in order to identify those, which found real life applications. The actions of Hydro Québec after the 1998 Eastern Canada ice storm could be analyzed using various publicly available publications (e.g., annual reports). Other studies with recommendations for future applications were analyzed for China, Italy, and Norway.

The following references were considered for this part of the study:


The results for this second part are presented in Section 4.

#### **3. Comparison of the Various Countermeasures Proposed over the Last Four Decades against Power Line Icing**

#### *3.1. Classification of Various Countermeasures*

In order to compare various countermeasures that were proposed over the past four decades, different anti-icing and de-icing methods are compiled in Table 1. Each analyzed publication is represented by a column. The two catastrophic ice storms (1998 in Eastern Canada and 2008 in southern and central China) were also included as time reference.

Different approaches may be used to classify the anti-icing and de-icing technologies [7,9]. This study started by adopting four groups that were presented in reference [9]: passive methods, active coatings and devices, mechanical methods, and thermal methods. During compilation, a separate group was formed for line design considerations as previously done in references [6,11]. The group of passive methods was split into two separate groups for passive devices and passive coatings as their effects on the ice-and snow accumulations are different. A seventh group for miscellaneous methods was added in order to list some proposed countermeasures that did not seem to fit in the other groups (as previously done by reference [2]).

A brief description for each group of countermeasures is given next. The reader is encouraged to read references [1,2,6–11] for detailed information on each individual anti-icing and de-icing method.

#### 3.1.1. Line Design Considerations

These considerations can be applied for new line constructions or the reconstruction of heavily damaged lines in order to prevent either ice or snow accumulations (by avoiding critical regions or by putting the lines underground) or to strengthen the withstand capability of the lines (stronger towers or increase in distance between phases). The choice of the conductor or bundle may have different effects; it can either influence the amount of accumulation, the speed of ice shedding, or the torsional strength of power lines.


**Table 1.** Comparison of various anti-icing and de-icing methods proposed over the last four decades (for time reference, the table also includes the two catastrophic

icing event).


**Table 1.** *Cont.*

## 3.1.2. Passive Devices

These devices do not prevent or reduce the amount of ice or snow that may accumulate on power lines, but reduce the negative impacts of these accumulations. For example, counterweights will lead to non-cylindrical ice deposits that will shed faster. Interphase spacers will maintain the distance between phase conductors even if they are not loaded with the same amount of ice or snow. Due to these kinds of indirect effects, problems such as phase-to-phase short-circuits or tower collapse can be avoided.
