Inductive Voltage dro‎p Compensation in Transmission Lines by Using Series Capacitor and Thyristor Converter

4/13/2019 12:00:00 AM

Abstract: Consumers demand for energy has risen steadily in recent years. With the help of series compensation, the limit of loading of transmission lines can be increased and considered as a great alternative compared to the traditional way of building new transmission lines that are very costly, involve environmental issues and the need for wide areas . On the other hand, the series compensation increases the transient stability of power systems, and if the compensation is controlled, it is possible to divide the load between the parallel transmission lines. However, one of the problems of the lines compensated by the series capacitor is the phenomenon of Sub-Synchronous Resonance (SSR), which, if not adequately controlled, can damage the turbine-generator. Flexible Alternative Current Transmission Systems (FACTS) are mainly used to solve various problems in steady state; dynamic and transient power system control. Thyristor Controlled Series Capacitor (TCSC) is an important member of the FACTS family, which is used in power systems to increase power transmission as well as system stability. The type of control used in the TCSC plays an important role in the removal of Sub-synchronous oscillations. One of these methods, which provides the best response in the mitigation of sub-synchronous oscillations, is the "Synchronous Voltage Reversal" (SVR) method. In this thesis, we first outline the constraints of the non-compensated transmission line and describe the effect of the types of reactive compensations on the line characteristics. Subsequently, the phenomenon of sub-synchronous resonance has been described and the conditions for the occurrence of SSR in compensated systems with series capacitors have been investigated. In the following, the TCSC model and the SVR control method are described in detail, and how the TCSCs are modeled by low frequency oscillations. It is worth noting that the studies and simulations carried out in this thesis are done in MATLAB software. Also, to study the phenomenon of SSR, the IEEE Second Benchmark Model has been used. Keywords: Series compensation, Thyristor Controlled Series Capacitor, Sub-Synchronous Resonance, SVR control.