Corrected examples

Note that AC_Plug was also corrected in the next "model"
Closes modelica#2564

chapters/connectors.tex

@@ -1047,8 +1047,9 @@ \subsubsection{An Overdetermined Connector for Power Systems}\doublelabel{an-ove
 \begin{lstlisting}[language=modelica]
 model AC_Inductor
   parameter Real X[3,3], Y[3,3]; // component constants
-  AC_plug p;
-  AC_plug n;
+  AC_Plug p;
+  AC_Plug n;
+  Real omega;
 equation
   Connections.branch(p.theta,n.theta); //edge in virtual graph
   // since n.theta = p.theta
@@ -1061,7 +1062,7 @@ \subsubsection{An Overdetermined Connector for Power Systems}\doublelabel{an-ove
 At the place where the source frequency, i.e., essentially
 variable theta, is defined, a \lstinline!Connections.root(..)! must be present:
 \begin{lstlisting}[language=modelica]
-  AC_plug p;
+  AC_Plug p;
 equation
   Connections.root(p.theta);
   der(p.theta) = 2*Modelica.Constants.pi*50 // 50 Hz;