Hongshun Liu

Impact Research of Inductive FCL on the Rate of Rise of Recovery Voltage With Circuit Breakers

Fault current limiter (FCL) is expected to ease the burden on circuit breakers by limiting the fault current to a desired level. However, the burden on the circuit breakers depends not only on the interrupting current but also on the rate of rise of recovery voltage (RRRV). Based on an equivalent model of the inductive FCL and with respect to FCL terminal fault and short-line fault respectively, strict mathematical formula are presented to describe the relationship between the RRRV and the current limit factor, the stray capacitance as well as the short-line fault distance. Further, detailed computations were carried out regarding a 220-kV transmission line with three-phase-to-ground faults to fully account for the concrete impacts on the RRRV from key influential factors. The calculation results by the proposed theoretical formula in this paper coincide well with the simulations in some previous publications. The specific investigation presents analytical basis and theoretical reference for optimal parameter design of inductive FCLs and reliable selection of the interrupting characteristics of HV circuit breakers.

Impact of the Inductive FCL on the Interrupting Characteristics of High-Voltage CBs During Out-of-Phase Faults

With respect to power systems installed with inductive fault current limiters (FCLs), the impact of an FCL on the out-of-phase fault current level was first analyzed, and thereby a method for determining the critical length of the power transmission tie lines was also given. Based on theoretical analysis and deduction, strict mathematical formulas were obtained to properly describe the relationship between the current limit factor and the recovery voltage of a circuit breaker (CB) as well as the rate of rise of recovery voltage (RRRV). Further, the concrete impacts of an FCL on the maximum and the RRRV of the recovery voltage were analyzed. Regarding out-of-phase faults, a conception of interruption severity as well as its quantitative expression for CBs was introduced, and a formula was established to incorporate the influence from the current limit factor and stray capacitance on the interruption severity of CBs, subsequently followed by detailed investigations. The aforementioned proposed research presents analytical methodology and practical reference for the parameter optimization of the inductive FCL and reliable selection of the interrupting characteristics of the high-voltage CBs.

Space charge characteristics of multiple reigniting secondary arc in atmospheric air

In order to investigate the electrical characteristics and the morphologic development of secondary arc in atmospheric air, a simulative experimental platform of secondary arc for UHV transmission lines was built and the corresponding experimental procedure was introduced in this paper. The discharge waveforms were categorized into three stages: the short-circuit arc period, the transition period of short-circuit arc and the secondary arc, as well as the secondary arc period. And the electrical characteristics of each stage were analyzed, involved with discharge power and discharge energy. By observing the arc discharge images, the forming process and the multiple reignition phenomenon of secondary arc were displayed and analyzed in associated with the corresponding discharge waveforms. A short-cutting event of the plasma column may happen when suddenly a new, shorter current path forms and the former arc path gradually disappears because of larger arc resistance. It was also found that the arc length and the arc diameter in the experiment were consistent to the computational values. The research results present analytical basis and theoretical reference for explanation and suppression of secondary arc on UHV transmission lines.

The characteristics of secondary arc current in UHV transmission line with hybrid reactive power compensation

The hybrid reactive power compensation (HRPC) for UHV transmission lines is expected to be applied, and its mutual influence with power grid is urgent to be studied. In this paper, the characteristics of secondary arc current before and after the installation of HRPC are compared and analyzed in this model. And the characteristics of secondary arc with different neural reactors, compensation degrees and fault location are also analyzed. From the research in this paper, it can be get that the installation of HRPC has significant effect on the extinction of secondary arc, and the arcing time and secondary arc current decrease by the compensation degree of series compensation but have little connection with the shunt controlled reactor. The relation between fault position and secondary arc as well as the optimal value of neural reactor are obtained. The bypass of capacitor bank before extinction may lead to the rise of LF component frequency and it also accelerate the extinction. When it comes to the compensation degree, the bigger shunt compensation degree is, the lower frequency of LF component is, and the attenuation speed gets faster. Nevertheless, the compensation degree of series compensation acts the opposite way compared with the compensation degree of shunt controlled reactor.

Analysis and Simulation of the PMFCL Based on Coupled Field-circuit Modeling Methodology

Fault current limiter based on permanent magnet biased saturation (PMFCL) is believed to foresee considerable application potentials in power systems due to its obvious advantages both technically and economically. In this paper, a new equivalent model of the PMFCL is presented based on a coupled field-circuit modeling methodology. Firstly, the governing equations of the PMFCL are obtained based on equivalent magnetic circuit analysis. Then the analysis of magnetic field of the PMFCL is done by FEM. Finally, a coupled equation for the PMFCL is presented to be solved. The simulation results compared with that of prototype experiments indicate that, the proposed modeling scheme provides theoretical basis for further comprehensive optimization of the PMFCL.