Fixed series compensation protection evaluation using transmission lines faults simulations

The power demands of Brazilian national industries need an economical solution to increase power transmission capacity of existing transmission lines. Due to environmental and economical difficulties for construction of new power transmission lines, the use of fixed series compensation (FSC) has turned into a common practice of power transmission companies in Brazil. The FSC is presented as the best choice, because not only does it make possible to increase power transmission capacity as well as it stabilizes the interconnected energy nets through reduction of the impedance of the transmission line. The main purpose of this work is to present the FSC protection evaluation installed at Rio Verde 230 kV substation with 216 MVAr (FURNAS Centrais Eletricas S.A. - Brazilian Power Transmission Utility). This evaluation will be realized simulating faults internal and external to the 230 kV transmission line where the FSC were installed. The final conclusion of the work is to present the importance of the FSC to a transmission system and a complete evaluation of the FSC protection, observing the dimensioning and the situations that this protection operates in the transmission system with the purpose to keep the energy flow against faults due to lightning discharges and other causes.

I. Introduction

Aworlwide trend in the development of power systems is to built interconnections with the goal to achieve economical benefits. Such large interconnection systems can cover many countries or even wide continental areas. Interconnections of power systems may offer significant technical, economical and environmental advantages, such as pooling of large power generation stations, sharing of spinning reserve and the use of most economic energy resources taking into account also ecological constrains [1]. The Fixed Series Compensation (FSC) utilizes series capacitors to cancel a portion of the inductive reactance of the transmission line, and thereby improving the power transmission capability of the line. The FSC has been applied mostly to long transmission lines, such as those found in the Brazilian Power Transmission System, and other locations where the transmission distances are great and where large power transfers over these distances are required.