Phase locked loop parameterisation in AC/DC interconnected system for a multi-source AGC system under open market environment

Abstract

This article emphasises on deregulated AGC of a realistic multi-machine gas - thermal plant with dish-Stirling solar-thermal (DSTS) as additional power generation sources in each control area by taking into accounts of AC/DC with phase locked loop (PLL) dynamics. Eigenvalue analysis confirms the steadiness of the reasonable power system with various interconnections such as AC, AC/DC link and AC/DC with PLL dynamics. A series form of proportional-integral-derivative (PID) namely proportional gain cascaded with integral and double-derivative (PI+DD+) controller is employed as secondary controller in each control areas for robust AGC to carry out market transactions under deregulated environment. Exploring the system with different type of interconnections infer that proper tuning of PLL function parameters may synchronise the grid better than without employing PLL. The performance of PI+DD+ controller along with optimum PLL gains commensurate with wide variations in governor, turbine, fuel and compressor discharge time constant of gas turbine plant.