docs(user_manual): updated the expressions of transformer eletric model

Signed-off-by: jhe <[email protected]>

Author: Plusero

docs/user_manual/components.md

@@ -223,8 +223,8 @@ In this case the winding voltage is decreased if the tap position is increased.
 
 $$
     \begin{eqnarray}
-        & |Z_{\text{series}}| = \frac{u_k}{z_{\text{base}}} \\
-        & \mathrm{Re}(Z_{\text{series}}) = \frac{p_k / s_n}{z_{\text{base}}} \\
+        & |Z_{\text{series}}| = u_k*z_{\text{base,transformer}} \\
+        & \mathrm{Re}(Z_{\text{series}}) = \frac{p_k}{s_n}*z_{\text{base,transformer}} \\
         & \mathrm{Im}(Z_{\text{series}}) = \sqrt{|Z_{\text{series}}|^2-\mathrm{Re}(Z_{\text{series}})^2} \\
     \end{eqnarray}
 $$
@@ -233,14 +233,14 @@ and $Y_{\text{shunt}}$ can be computed as
 
 $$
     \begin{eqnarray}
-        & |Y_{\text{shunt}}| = \frac{i_0}{y_{\text{base}}} \\
-        & \mathrm{Re}(Y_{\text{shunt}}) = \frac{s_n / p_0}{y_{\text{base}}} \\
+        & |Y_{\text{shunt}}| = i_0*y_{\text{base,transformer}} \\
+        & \mathrm{Re}(Y_{\text{shunt}}) = \frac{s_n}{p_0}*y_{\text{base,transformer}} \\
         & \mathrm{Im}(Y_{\text{shunt}}) = -\sqrt{|Y_{\text{shunt}}|^2-\mathrm{Re}(Y_{\text{shunt}})^2} \\
    \end{eqnarray}
 $$
 
-where $z_{\text{base}} = 1 / y_{\text{base}} = {u_{\text{2, rated}}}^2 / s_{\text{base}}$.
-Here, $s_{\text{base}}$ is a constant value determined by the solver and $u_{\text{2, rated}}$ is rated voltage at
+where $z_{\text{base,transformer}} = 1 / y_{\text{base,transformer}} = {u_{\text{2}}}^2 / s_{\text{n}}$.
+Here, $s_{\text{n}}$ is the rated power of the transformer and $u_{\text{2}}$ is rated voltage at
 `to_node`.
 
 ### Generic Branch