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Current transformer (CT) core has non-linear magnetic characteristics and may achieve high flux values when exposed to high fault currents. In this case, the CT primary current is not fully reflected in their secondary side and the relay cannot operate in the desired time. Several papers have been published about computational methods to compensate saturation of CTs due transient conditions. However, the use of CT simulated signal for practical tests in protection relays is rare. This paper presents an environment that allows performing secondary tests in physical relays when computational methods are applied to minimize the effects caused by CT saturation. The CT model and saturation compensation methods are implemented in MATLAB. The secondary signals resulting of this modeling are converted to COMTRADE format to be loaded into injection test device in order to evaluate the overcurrent numerical relay response for each CT saturation compensation method presented. [ABSTRACT FROM AUTHOR]

• Static var compensator causes a delay in operation of loss of excitation protection. • Delay also depends on the power dispatch and the severity of the loss of excitation. • Static var compensator causes under-reach of commercial loss of excitation relay. • Presence of static var compensator causes a displacement of impedance trajectory. • Positive offset relay adjustment seems to be more adequate than negative adjustment. The static var compensator (SVC) is one of the devices that has been widely used for reactive compensation to improve the capacity and flexibility of power transfer in the electrical power system. However, the SVC changes the voltages and currents of the power network to which it is connected. Consequently, the measured impedance can be changed and affect protection relays operation based on this characteristic. Several papers have been published about the SVC effects on distance protection applied in transmission lines (TL). However, it is not widely known the impact of SVC on the transient behavior of generators, such as protection against loss of excitation (LOE) in synchronous machines connected to TL with SVC. In this sense, based on the modeling of a test electrical power system in the PSCAD/EMTDC simulation environment, the assessment of the effects of SVC on the behavior of the ANSI 40 protection function for the conditions of the total LOE and partial LOE since these events can cause the synchronous machine to operate in conditions above the rated ones. In addition, this paper presents a testbed that allows performing secondary tests in physical relays when simulated signals are applied to perform protection studies in the presence of SVC in power systems. [ABSTRACT FROM AUTHOR]