Conference Agenda

This paper presents a case study of measurements of switching transient overvoltages using a capacitive electric field sensor. The system was developed and installed in a substation after the failure of a surge arrester during the energization of a 420 kV transmission line. First, the closing operation was simulated in an electromagnetic transient simulation program to estimate the switching transient overvoltages for this event. Then, the concept and design of the measurement system are explained. The system calibration performed in the high-voltage laboratory is presented. Afterward, the installation of the measurement system in the substation is discussed, with a special focus on the calibration of the voltage ratio considering the physical configuration where it is installed. Finally, the measurement results are presented and compared with simulations. The results show that the transient overvoltages caused by the energization of the transmission line should not cause the failure of the surge arrester. The measurement system has been demonstrated to be capable of measuring switching transient voltages of a 420 kV transmission line and can be considered a flexible solution for the long-term monitoring of transient overvoltages in substatio

The transmission system expansion plan of Germany foresees several new EHV (Extra High Voltage) transmission lines to transmit bulk power generated by wind farms in the north of Germany to the South. Some of these EHV lines will be so called "mixed lines" consisting of several underground cable and overhead line sections. The high charging current of XLPE cables has to be compensated by shunt reactors. A planned double-circuit 380-kV transmission line with total length of ca. 110 km is ofinterest for the analysis of SPAR (single-phase autoreclosure)operation in this paper, where a cable section along the line has alength of 5.5 km. By means of electromagnetic transientssimulations the maximum secondary arc duration will bedetermined for the mixed line under various operating conditions.

Transient events that result from the incorporation of HVDC into the HVAC power transmission system make fault identification a difficult task. To minimize transient power outages, anomalies must be identified and categorized as quickly as feasible using robust schemes. In the proposed scheme, the multi-classification of AC faults in hybrid transmission lines is performed. A neural network has been employed for the correct recognition and classification of AC faults. The proposed scheme initially uses squaring and lowpass filtering techniques along with, transient energy, negative sequence of voltage, and current as features to pre-process the fault voltage and current signals. The extracted features are then used to form the neural network's input for training and testing. We performed a complete assessment study on the developed ac/dc test system employing MATLAB/Simulink software to ensure the stability and reliability of the presented technique. The technique is verified under noise-added data and compared with other schemes to ensure efficacy. The test result shows that the proposed technique has successfully classified the AC faults with an accuracy of 99.3% in ac/dc transmission lines.

A fault current limiter (FCL) is an economical option to limit the increased fault current levels, which may also improve the rotor angle stability. Previous studies on this topic mainly focused on the FCLs with quick recovery and concluded that the FCL improves the rotor angle stability. However, some
commercially available FCLs have delayed recovery, which may pose different challenges and need to be studied. This paper studies the impact of a superconducting fault current limiter (SCFCL) with delayed recovery on transient rotor angle stability. This paper first develops an analytical understanding of the stability of a system with SCFCL using the equal area criterion. Later, time-domain simulations are employed to demonstrate the impacts of the SCFCL on the rotor angle stability of a single-machine infinite-bus system. The results show that the SCFCL with delayed recovery leads to rotor angle instability in some cases.