Voltage Control


PRISM Voltage Reduction monitors system conditions to automatically issue voltage reduction commands.  If the system load reaches the start target system load and the time criteria is correct, the program will issue controls to configured voltage control devices.  When the load is higher than the start target load limit, the program will increment the reduction step command for LTC devices if the specified criteria for voltage reduction are met.  The criteria involve user defined days and time of day windows for possible activation.  After issuing the control, the system load is checked against the target following a configurable time delay.  If the load is still higher than the start limit, the program will increment the load reduction scheme value again. This process continues until reaching the highest tap changer step.  If the subsequent check of the load versus the target is lower than the stop target, the program will then reduce the voltage by one step.  This control process will continue until the lowest step is reached.  The program will follow this algorithm as long as the logic is armed. 


If the Voltage Reduction program is in an active reduction mode and the set time period expires, the application will reduce the load reduction by one step per delay period until the load reduction is at step zero.  The Voltage Reduction application provides a simple-to-use interface for entering the parameter values necessary for the operation of the program. 



Standard features:

  • Configurable  days/dates  or days of the week 
  • Configurable time ranges per day for program execution
  • Selectable global enable/disable target
  • Configurable device definition and control information, allowing specific devices to be excluded from the reduction scheme.   This includes the ability to set Supervisory mode versus Local Automatic mode for the LTCs.
  • Configurable database points in the PRISM system for monitoring operation of the devices and system load.



VR control parameters: 

  • Weekday or dates for potential voltage reduction
  • Time of day ranges for reduction on active dates – 2 ranges
  • Target Load Value for start of reduction (MW or units just match input)
  • Target Load Value of stop of reduction (MW or units just match input)
  • Max value of load reduction step – (0->n)
  • Monitor time delay (secs)  (monitor delay when not controlling)
  • Delay time after step in reduction (secs)
  • List of devices to be controlled when reduction is active 



Device selection




VR parameter definition