Power line communication (PLC), which is often used in advanced metering infrastructure (AMI), may be disturbed by adjacent high-power converters. Due to the inherent features of this type of communication, classic methods of improving communication reliability (filtration and circuit separation) cannot be fully applied. Information coding (modulation) methods are used in PLC to increase the data transfer rate and improve noise immunity. Random modulations (RanM) are used in converters to lower emission levels. Therefore, we investigate how the converters’ modulation parameters and coding methods may affect PLC communication reliability in the paper. To this end, we employ an experimental approach. In particular, the analysis of the influence of deterministic modulation (DetM) and (RanM) on the performance of narrowband G3-PLC is shown. We emulated an actual situation where EMI generated by the DC/DC converter disturbed the PLC transmission. The experimental results show the transmission error rates for different operating scenarios. The natural (experimental) system results, due to the complexity of the disturbing signals, differ from the literature data obtained by simulation for normalized signals.

Superconducting fault current limiters (SFCL) can be an alternative to conventional devices limiting short-circuit currents in power systems. SFCL use high-temperature superconducting tapes of the second generation (HTS 2G) in SFCL, which, after reaching the characteristic critical current of the tape, go into the resistive state (quenching), limiting the short-circuit current. The critical current determines the moment of activation of the SFCL. Therefore, its value should not change during the operation of the device due to repeated limitation of short-circuit currents. The constancy of the critical current is a prerequisite for proper cooperation with the power system protection devices. Multiple quenching can cause microdamage in the superconducting layers responsible for lowering of the value of the critical current of the HTS tapes. The article presents the research results on the degradation processes of 2G HTS tapes intended for the construction of SFCL due to the action of prospective short-circuit currents with values exceeding the critical current of the tested tapes. The decrease in the value of the critical current of the HTS tape as a result of multiple transitions to the resistive state was investigated. The amount of energy emitted during the test current pulse of 0.2 s duration was determined. The limitation values of the voltage drop on the tape, which does not cause accelerated degradation processes, were defined. The microstructural tests of cross-sections of new HTS tapes subjected to prospective short-circuit currents were performed.

In this paper, superconducting fault current limiter (SFCL) operation in the presence of a long-duration fault is presented. The SFCL device utilizes second-generation high-temperature superconducting (2G HTS) tapes, which exhibit zero resistance under normal operating conditions. When the current exceeds the critical threshold specific to the superconducting tape, then it undergoes a transition to a resistive state—a phenomenon known as quenching. As a consequence, this leads to introducing impedance into the circuit, effectively limiting the magnitude of the fault current. Additionally, this transition dissipates electrical energy as heat within the material. The generated energy corresponds to the product of the voltage drop across the quenched region and the current flowing through it during the fault duration. In specific configurations of the power system, it is expected that the SFCL should limit the fault current for an extended period of time. In such a situation, a certain amount of energy will be generated, and it must be verified that the tape loses its properties or parameters (e.g., lowering the critical current value) or is destroyed. Therefore, experimental tests of the tapes were conducted for various short-circuit current, voltage drop, and short-circuit duration values to assess the effect of the amount of generated energy on the 2G HTS tape. Additionally, recommendations are presented on how to protect the SFCL during long-lasting short circuits.

HTS 2G tapes used in Superconducting Fault Current Limiters (SFCLs) have properties that allow for the effective limitation of short-circuit currents; however, due to the specificity of the device operation, they should be characterized by the high stability of the parameters when repeatedly leaving the superconducting state. During the operation of SFCLs, a situation may occur in which the parameters of the HTS tapes used will change several times as a result of the action of short-circuit currents that exceed the critical current I_C of the superconductor of the tape used. This paper presents the results of microstructural tests of 2G HTS tapes intended for SFCLs, subjected to surge currents corresponding to prospective short-circuit currents with values higher than their critical currents I_C and for which I_C changes were observed. The HTS tapes were examined using a JEOL 7600F field emission scanning electron microscope (SEM), and their chemical composition was analyzed using Energy-Dispersive X-ray Spectroscopy (EDS). The test results indicate the possibility of micro-damage in the form of cracks in the superconductor layer, as well as the interruption of the buffer layers and the oxidation of the silver layers. The analysis of the chemical composition of the HTS tape layers may indicate the occurrence of diffusion processes.

In this paper the method of the selection of dv/dt for EMI current ringing attenuation has been presented. The mechanism for the attenuation is first identified using the theoretical approach. It is shown that the attenuation occurs for rise time of the voltage equal to the inverse of the frequency of current ringing. The concept has been experimentally verified in DC chopper and frequency converter arrangements. The proposed method of ringing attenuation can be applied in power converters with flexible gate control and can be also utilized in a wide area of electronic circuits with a trapezoidal excitation for a signal integrity improvement.