Influence of Uncertainties in Mechanical Parameters

Abstract

This chapter presents comprehensive analysis of the effect of the uncertainties in mechanical parameters of the turbine generator on SSR in meshed AC/DC network. The chapter begins with case studies performed to compare the influence of uncertainties in mechanical parameters on subsynchronous resonance in a meshed power network with conventional line commutated converter (LCC) and voltage source converter (VSC) HVDC transmission lines. The uncertainties in various mechanical parameters are modelled using probability density functions. Based on case studies covering different operating conditions, it is shown that VSC-HVDC system leads to better damping of torsional modes and smaller magnitudes of the torsional torques compared to LCC-HVDC system. After establishing that the peak torques are higher and modal damping is lower with LCC-HVDC, a series of case studies are performed for different fault types in a meshed AC network with LCC-HVDC line. Following this, analysis of the effect of uncertainties on SSR is extended to compensated AC network. Case studies are performed with two types of series compensation schemes, symmetrical and asymmetrical series compensation. The range of uncertainty is adopted as realistically as possible, to assess the extent to which the uncertainties can affect the risk of SSR in series compensated power networks.