Combined Voltage and Frequency Control of Multiarea Multisource System Using CPDN-PIDN Controller

Abstract

This paper discusses a multiarea multi-source system in combined automatic load frequency control (ALFC) and an automatic voltage regulator (AVR) model. The multiarea system comprises thermal and wind in Area-1, thermal-geothermal in Area-2, and hydrothermal plant in Area-3. Appropriate nonlinearity constraints are provided for both hydro and thermal plants. A maiden attempt has been made to employ a cascade proportional-derivative (PD) with filter coefficient (N) and PID with filter coefficient (N) (CPDN-PIDN) as a secondary controller in the combined ALFC-AVR system and optimized controller gains using artificial flora algorithm (AFA). It is examined that the CPDN-PIDN controller yields better dynamics responses than the PI and PIDN controllers. Analyze reflects that the system performance enhanced in the presence of AVR loop. This paper discusses the effect of renewable sources like wind and geothermal on the system dynamics. Analysis reveals that the geothermal power plant is more reliable than the wind plant. The parameter variations of the temporary and permanent droop and hydro turbine time constant (HTTC) of the hydro plant are examined through system responses. System response deteriorates significantly as permanent droop and HTTC are reduced. Peak overshoot and undershoot are reduced considerably as the temporary droop value is increased. Sensitivity analysis reveals that the AFA optimized CPDN-PIDN controller parameters obtained under the nominal condition are resilient enough and need not be reset with the system's substantial random variation. An experimental justification has been provided of the investigated system using a real-time simulation with the OPAL-RT OP4510 real-time setup.