Effect of Time Constant Parameter Uncertainties on Dynamic Performance of interconnected Power Systems with EHVAC/HVDC Transmission Links

This paper presents a comprehensive study on dynamic performance of two-area interconnected power systems when subjected to Time constant parametric uncertainties. Power system model consists of one area with reheat thermal power plants and other area with hydro power plants having identical capacity. the system interconnection considered as namely EHVAC transmission link only, HVDC transmission link with ΔPdc taken as state variable, HVDC transmission link with ΔPdc taken as control variable, EHVAC in parallel with HVDC transmission link with ΔPdc taken as state variable and EHVAC in parallel with HVDC transmission link with ΔPdc taken as control variable. The dynamic model of incremental power flow through HVDC transmission link is derived based on frequency deviation at rectifier end only. Moreover, the HVDC link is considered to be operating in constant current control mode. To carry out the investigations, optimal AGC regulators are designed using proportional-plus-integral control strategy and implemented on the system under consideration in the wake of 1% step load perturbation in area-1. The effect of ± 50% variation in system Time constant parameters from their nominal parameter values on system dynamic performance has been studied by investigating the response plots with (i) nominal system Time constant parameters and (ii) ± 50% variation in system Time constant parameter values. The system responses have been simulated in Mat lab. Responses of Δf1, Δf2, ΔPtie, ΔPdc, IACE1 and IACE2 have been plotted for each Time constant parameter variation. The most significant parameters, which influence the system dynamic performance, are identified.