What is power plant controller ?

PPC or Power plant controller is usually a PLC controller or controller which basically controls the power plant individual IBRs like Solar PV, Wind, BESS, SVG/STATCOMs, Capacitor banks etc. It is generally utilized to control steady state active and reactive power control in the plant and usually operates in steady state voltage range i.e typically +/-10% from nominal and when voltage is outside this range, it freezes its outputs to avoid interfering during transient conditions. PPC takes input from grid interconnection point (usually called POI or point of interconnection and sometimes PCC) like voltage, current, frequency, active and reactive power and compares it with the pre-defined or user settable set points of active and reactive power control and accordingly generates the active power and reactive power commands for respective IBRs within the plant. PPC broadly has two controls one is active power and another one reactive power controls. Active power control comprises of ramp rate control including frequency control. Whereas the reactive power can be controlled via three ways like direct Q control or reactive setpoint control, voltage droop control and power factor control. Any of these reactive control can be activated at a time using HMI, in general voltage droop control is generally enabled to control grid voltage profile. PPC controls the plant output in close loop system and utilizes basic PI control philosophy to minimize the error. For sensing the grid parameters PQM (power quality meter) is used usually communication system is fiber optic + CAT6. PPC usually can communicate in various protocols like IEC61850, MODBUS TCP/IP or any other standard protocols for communication among IBRs and PQM.