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Evaluating the rated MVA sizes of the Circuit Breaker (CB) requires calculating reactance parameters from fault analysis and synchronizing these parameters with the reference re-striking voltage. In this paper two ways are used in controlling X/R ratio of the system to reduce CB size in order to save cost on system configuration. PSS/E program was introduced to facilitate and illustrate the solution. X/R ratio and subtransient reactance were calculated to provide an approach to assess the current and duty interruption of generator buses with contributions from all other buses. The effect of reduction factors and NACD for the symmetrical component of the short circuit current is also applied in our proposed method. The obtained results proved that applying the reduction factor technique in New England system reduces the rated interruptions of C.Bs, and CB rate is also minimized in Bismayah132kV power plant from Iraqi grid utilizing effective switching which economizes choosing CB. It is concluded that the two techniques can be used successfully for designing CB ratings with a minimum cost. [ABSTRACT FROM AUTHOR]

Series compensation is used to improve power system transmission capacity. Subsynchronous resonance (SSR) associated with such a system is a challenging issue. Today, with increasing integration of wind farm (WF) to power network, the stability of the system gets deteriorated due to variation in wind speed at the WFs. The reaction between the SSR modes and the doubly fed induction generator converters is known as subsynchronous control interaction (SSCI), due to which, it becomes more challenging to achieve power system stability. To overcome these issues, in this paper, a synchrophasor data-based control (SDC) technique is proposed. The proposed controller diminishes induction generator effect, torsional interaction, and the SSCI effect on the series compensated network, integrating multiple WFs. The SDC provides an auxiliary SSR damping control (SSRDC) with thyristor controlled series compensation (TCSC). This SSRDC uses synchrophasor data from WF connected point of common couplings (PCCs) inside the grid to improve the SSR oscillation damping. The proposed method maintains reference voltage angle of the PCCs by controlling equivalent impedance of the grid. The impedance provides significant damping for SSR along with the TCSC control. The proposed SDC is tested for modified 39-bus New England system with WFs and is found to be effective. Comparison of this method with conventional local control demonstrates its superior performance. [ABSTRACT FROM AUTHOR]