Impact of RFB and PLL Dynamic on Combined ALFC-AVR Regulation of Multiarea Multisource System Under Deregulated Environment with AC/Accurate HVDC link
Biswanath Dekaraja, Lalit Chandra Saikia
Abstract
The paper discusses the coordinated effect of redox flow battery (RFB) and accurate high voltage dc (AHVDC) link on the combined voltage and frequency control of two-area systems under deregulated environment. Each area has three generating companies (GENCOs) and three distribution companies. GENCOs in Area-1 are thermal, realistic dish-Stirling solar thermal system (RDSTS) and solar thermal power plants, and in Area-2 GENCOs are hydro, RDSTS, and geothermal power plants. Appropriate nonlinearity constraints are equipped with both hydro and thermal units. A maiden attempt has been made to employ a cascaded fractional-order PD with filter and PID with filter (CFOPDN-PIDN) as a secondary controller for the considered system. Artificial flora algorithm is used to optimize the controller parameters under various system conditions. The proposed CFOPDN-PIDN controller yields better system dynamic responses than the PIDN controller for the Poolco, bilateral, and contract violation power transactions. The investigations reveal that the parallel operation of the AC/AHVDC links deteriorates the system dynamics having more oscillations and peak deviations compared to individual AC and AHVDC links. The dynamic effect of Phase-Lock-Loop (PLL) is important for the realistic operation of AHVDC link. A novel approach for analyzing the dynamic effect of the AHVDC links considering PLL effects during the coordination with the AC system is presented. By adding the dynamic model of PLL to the parallel AC/AHVDC link, the system's performance is improved. The analysis reflects that the RFB-AHVDC links with PLL dynamics provided better system damping than the RFB-AC tie-line and AC tie-line alone.