# A Review of Health Assessment Techniques for Distribution Transformers in Smart Distribution Grids
## 3 Transformer Health Assessment Techniques
### Hybrid Artificial Intelligence Approaches
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Methods**} & **Dependency** & \begin{tabular}{c} **Dependency** \\ **on the** \\ **Datasets** \\ \end{tabular} & \begin{tabular}{c} **Number of** \\ **Weighted** \\ **Parameters** \\ \end{tabular} & **Accuracy** & **Complexity** & **Implement** & **Cost** & **Effort** \\ \hline \begin{tabular}{c} Health index \\ calculation \\ [33; 34; 56; 57; 58; 59; 60] \\ \end{tabular} & & \(\surd\) & Small & Low & Low & High & High \\ \hline \begin{tabular}{c} Fuzzy logic \\ [38; 39; 41; 61; 62; 63] \\ \end{tabular} & & \(\surd\) & Small & Low & Low & High & Low \\ \hline \begin{tabular}{c} Artificial neural \\ networks effort \\ [45; 46; 64; 65] \\ \end{tabular} & \(\surd\) & & Large & Good & Low & Low & Low \\ \hline \begin{tabular}{c} Machine learning \\ algorithms using \\ Random Forest \\ [66; 67] \\ \end{tabular} & \(\surd\) & & Large & Good & Low & Low & Low \\ \hline \begin{tabular}{c} GA based health \\ index \\ determination [32] \\ \end{tabular} & & \(\surd\) & Small & Good & High & High & High \\ \hline \
\begin{tabular}{c} Combination of \\ GA and support \\ vector machine \\ [52; 53] \\ \end{tabular} & \(\surd\) & & Large & High & High & Low & High \\ \hline
\begin{tabular}{c} PSO and Support \\ Vector Machine \\ SVM [68] \\ \end{tabular} & \(\surd\) & & Large & High & High & Low & High \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Transformer health assessment methodologies comparison. It is necessary to consider the dependency of the studied methods on the load condition, temperature and the effect of transformer aging over time. It is investigated that the root causes of these  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Method** & **Advantages** & **Disadvantages** \\ \hline \multirow{4}{*}{1} & \multirow{4}{*}{Health index calculation} & - & Reliable & - & The accuracy depends heavily on \\  & & - & Reliable & - & The condition monitoring may costly and the \\  & & - & Can work with small number of samples & - & results only reflect the preferences of \\  & [33, 34, 56, 57, 58, 59, 60] & - & The weights can be regulated depending on the & the human-expert \\  & & & assets under investigation & - & Low accuracy for the systems and devices are \\  & & & & controlled linguistically, or have a \\  & & & & contradictory condition \\ \hline \multirow{4}{*}{2} & \multirow{4}{*}{Fuzzy logic} & - & Reliable & - & The accuracy depends heavily on \\  & & - & Easy to apply. & - & The accuracy depends heavily on \\  & & - & Provides a more effective solution to & selected parameters. & - \\  & & complex issues & - & Validation and Verification of a fuzzy \\  & [80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 98, 99, 99, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99, 98, 99, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 103, 108, 109, 104, 105, 106, 107, 108, 109, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163] & - & Need lots of data, especially for architectures with many layers & - \\  & & - & Reliable & - & When the difference between the training \\  & & - & Ability to work with incomplete knowledge & samples and the fault samples is very large, \\
3 & networks effort & - & Less computational effort & the reasoning used by ANN to conclude \\  & [45, 46, 4,failures on distribution transformers are mainly due to the overloading and unbalanced loading [69; 70]. The transformer loading effects directly on the current in the winding and hence, raise the temperature in the winding and the oil of the transformer which results in accelerating the transformer aging, reduce the service life of the distribution transformers [71; 72].