Development of the intelligent single phase-to-ground-fault current compensation system for 6–35 kV networks

Author(s):  
A. A. Kuzmin
Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1330
Author(s):  
Dumitru Toader ◽  
Marian Greconici ◽  
Daniela Vesa ◽  
Maria Vintan ◽  
Claudiu Solea

Settings of protection are essential to ensure the sensitivity and selectivity needed to detect defects. Making the correct settings requires the calculation of the fault currents with as little error as possible. Fault currents are influenced by the parameters of the electrical networks, including the state of the insulation and the Petersen coil, which changes during their operation electrical networks. This paper analyzes how the insulation parameters of medium voltage power lines, the parameters of the Petersen coil used to treat the neutral of the medium voltage electrical network and the value of the resistance at the fault location influence the fault current in the case of a single-phase fault. The large number of single-phase faults that occur in medium voltage electrical networks justifies this analysis. The symmetrical components method was used to calculate the fault current. The results obtained by calculation were verified experimentally by causing a single-phase-to-ground fault in a real medium voltage network. The paper presents the situations in which the analytical calculation of the single-phase-to-ground fault current can lead to inadmissibly large errors, even over 50%, but also the situations in which the errors fall below 3%.


2019 ◽  
Vol 140 ◽  
pp. 05001
Author(s):  
Andrei Brilinskii ◽  
Georgiy Evdokunin ◽  
Anna Petrova ◽  
Irina Ryndina

The article comprises the results of the research defining open-flame arcs self-quenching conditions in the event of a single phase-to-ground fault in overhead medium-voltage distribution networks according to existing theories of arc extinguishing. The calculations included metallic and arc faults modeling in a network with low phase-to-ground fault current. The arc gap simulation based on the mathematical channel model of a cylindrically symmetrical upright arc stabilized by rising convective gas flow was carried out in ATPDraw software program. The single phase-to-ground arc fault calculations results indicated an increase in high-frequency currents’ attenuation rate during transient processes as well as a reduce reduction in the electric arc lifetime from 8 ms to 2 ms in case of the breakdown voltage decrease from the peak value to zero. Notably, in case of low single phase-to-ground fault current the arc extinguishing took place at the first high-frequency current zero. For the cases of nonzero breakdown voltages, the electric arc extinguishing was detected at the fundamental frequency current component zero-crossing instant. The maximum overvoltage ratio of K = 2.8 was obtained as athe result of the single phase-to-ground fault at the peak phase voltage.


Author(s):  
И.Е. Кажекин ◽  
С.П. Финько ◽  
М.С. Харитонов

Описаны результаты исследований влияния показателей качества электроэнергии на токи однофазных замыканий в судовых электроустановках. Выявлены основные элементы бортовых электроустановок, влияющие на качество электроэнергии. Проанализировано формирование высших гармоник в токе однофазного замыкания. На физической модели электроустановки проведены исследования влияния нелинейной нагрузки на ток однофазного замыкания. Результаты экспериментов подтвердили установленные закономерности. Выявлено, что в установившемся режиме ток однофазного замыкания определяется не только величиной фазной емкости и напряжением сети, но и несинусоидальностью тока нагрузки. Экспериментально показано, что высшие гармоники, присутствующие в токе нагрузки, усиливаются в токе однофазного замыкания. При этом увеличение их амплитуд пропорционально номеру гармоники и ее амплитуде в токе нагрузки. Экспериментально установлено, что формирование высших гармоник в токе однофазного замыкания в результате эмиссии нелинейной нагрузкой приводит к увеличению его действующего значения. The paper represents the research results of the power quality indicators influence on the currents of single-phase ground faults in ship electrical installations. The main elements of on-board electrical installations that affect the quality of electricity are identified. The process of higher harmonics formation in the single-phase ground fault current is analyzed. Studies of the nonlinear load influence on the single-phase fault current are carried out on the physical model of the electrical installation. The experimental results confirmed the established patterns. For the steady-state mode it was discovered that the single-phase ground fault current is determined not only by the phase capacitance value and the mains voltage, but also by the non-sinusoidality of the load current. It has been shown experimentally that the higher harmonics of the load current are amplified in the single-phase ground fault current. In this case, the increase at their amplitudes is proportional to the harmonic number and its amplitude in the load current. It has been experimentally established that the formation of higher harmonics at a single-phase ground fault current as a result of emission by a nonlinear load leads to an increase in its effective value.


2014 ◽  
Vol 960-961 ◽  
pp. 755-758
Author(s):  
Meng Zhang ◽  
Jian Wen Ren

When the single phase ground fault occurs in resonant grounded system, there are significant differences in the components of fault phase current between fault line and non-fault line. This feature can be reflected by intrinsic mode entropy (IMEn) of fault current. IMEn is a new signal analysis over multiple oscillation levels. It corresponds to the sample entropy (SampEn) and the empirical mode decomposition (EMD). The results of fault simulations in different conditions indicate that the method is reliable.


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