Invalid == on Reals IEEEST (OpenIPSL#325)

* Invalid == on Reals IEEEST

Meant to apply to OpenIPSL#315 .  OpenIPSL.Tests.Controls.PSSE.PSS.IEEEST builds and runs in WSM 13.2.

Co-authored-by: Dietmar Winkler <dietmar.winkler@dwe.no>

Author: gkhalley

OpenIPSL/Electrical/Controls/PSSE/PSS/IEEEST.mo

@@ -129,19 +129,19 @@ initial equation
   end if;
   V_S0 = V_S;
 equation
-  if V_CU == 0 and not V_CL == 0 then
+  if not (V_CU > 0 or V_CU < 0) and (V_CL > 0 or V_CL < 0) then
     if V_CT > V_CL then
       VOTHSG = Vs;
     else
       VOTHSG = 0;
     end if;
-  elseif V_CL == 0 and not V_CU == 0 then
+  elseif not (V_CL > 0 or V_CL < 0) and (V_CU > 0 or V_CU < 0) then
     if V_CT < V_CU then
       VOTHSG = Vs;
     else
       VOTHSG = 0;
     end if;
-  elseif V_CU == 0 and V_CL == 0 then
+  elseif not (V_CU > 0 or V_CU < 0) and not (V_CL > 0 or V_CL < 0) then
     VOTHSG = Vs;
   elseif V_CT > V_CL and V_CT < V_CU then
     VOTHSG = Vs;