With the rapid development of DC metro system, stray current may bring new challenges to AC power system. Especially, system flowing in cause many serious consequences such as corrosion grounding grids, plenty harmonics, and dc bias transformers. Therefore, it is significant evaluate distribution caused by current. In order distribution, a coupled simulation model both considering proposed this paper. Moreover, earth are used coupling elements model. The correctness verified comparison...

In DC metro systems, the stray current may cause many challenges for nearby metal structures and AC power such as corrosion of buried pipes grounding grids substations. Therefore, calculating analyzing distribution characteristics are necessary design pipelines To obtain current, considering through-type structure return system traction supply system, a multiple sections simulation model (multiple-section model) is proposed. proposed model, train equivalent to two dc sources, dynamic results...

The calculation of rail potential and stray current in the DC traction power system can guide protection against overvoltage problem mitigate electrolytic corrosion due to current. To obtain accurate distribution, infinitesimal method based metro multiple supply sections (PPSs) is studied this paper. through-type structure characteristics that return which constituted rails - collection mats tunnel reinforcements ground (RSTG) are considered proposed method. In system, currents injected into...

With the rapid development of dc metro system, hazard stray current is increasingly serious. Due to direct grounding track and lack a collector system (SCCS), depot has become weak link in protection against current. In order evaluate analyze distribution depot, evaluation model proposed this article. Based on piecewise-linearized volt-ampere characteristic, one-way conduction device (OWCD) modeled by source paralleled with resistor. The calculated based nodal analysis method. validity...

With the rapid development of metro, a series problems caused by stray current is becoming increasingly serious. Evaluation primary but difficult step for dealing with problems. In fact, since metros are usually constructed cut-an-cover tunnel, shield and viaduct, metro structure one most important factors current. It significant to evaluate in long line variable structures. Based on this, uniform model built this article. The return system equivalent multiple differential units considering...

With the coupling of DC metro network and urban power grid, stray currents flowing into transformers have caused serious bias. There is, therefore, a need to evaluate transformer neutral direct by current. To achieve this, an evaluation model considering grid is proposed. In modeling principle, lines are coupled with grounding grids transfer stations. The system soil systems. train operations on simulated using Monte Carlo method. And, conditions one-way conduction devices (OWCDs)...

During the dynamic operation of dc metro system, excessive neutral direct current (NDC) grounding transformer appears in ac power which has not been clarified until now. Seriously, high-level NDC led under bias, affects lifespan and safety transformers systems. To analyze with train, synchronous monitor schemes traction rail potential system nearby are proposed. The relationship between is analyzed presented. Based on data analysis, negative correlations found directions magnitudes RSP NDC....

Seriously abnormal data exist in the synchronous monitoring of transformer DC bias, which causes serious feature contamination and even affects identification bias. For this reason, paper aims to ensure reliability validity data. This proposes an for bias based on multiple criteria. By analyzing different types, characteristics are obtained. Based this, indexes introduced, including gradient, sliding kurtosis Pearson correlation coefficient. Firstly, Pauta criterion is used determine...

Metro stray currents flowing into transformer-neutral points cause the high neutral DC and a transformer to operate in bias state.Because caused by current varies with time, value cannot be used as only characteristic indicator evaluate risk level. Thus, unified extraction assessment methods are proposed of current, considering signals vibration. In method, primary characteristics obtained comparing magnitude frequency distributions vibration without metro invasion. By analyzing correlation...

Since rail-to-ground insulation decreases, large-level direct currents (DCs) leak from railways and form metro stray currents, corroding the buried metal. To locate deterioration area, a location method is proposed based on parameter identification methods monitored information including station rail potentials, at traction power substations (TPSs), train positions. According to monitoring of two adjacent TPSs, section model line proposed, in which conductances test are equivalent lumped...

In this paper, the explosion accident of a 220kV current transformer in substation is studied.It uses method scene investigation and test to analyses based on principle characteristics transformer.Through analysis, paper holds that reducing main insulation electrical strength caused by Long-term high harmonic voltage breakdown flicker impact are causes accident.And it also proposes variety management methods technical measures avoid kind accident.This provides reference for analysis same...

Metro stray currents flowing into neutral-point-grounded transformers can cause serious direct current (DC) bias. Affected by both metro train and urban power grid operations, transformer neutral-point DC caused is complex, dynamic, time-varying, which changes the bias risk level of transformers. Thus, just installing blocking devices (BDs) at neutral points with high instantaneous may make it difficult to comprehensively mitigate lead increased BD installation. To solve this, through...

We present the direct short pulse generation and spectrum broadening with ultra-high repetition rate fiber lasers that ensure long-term stability of frequency combs.

The stray current of DC metro flowing into the transformer urban power grid leads to increase neutral direct (NDC) and occurrence bias transformer. Due influence operation characteristics, NDC fluctuates randomly alternates positively negatively. distribution characteristics NDCs are complex indistinct. In order obtain among various transformers. Authors have measured transformers in Shenzhen system. Then analysed by correlation analysis during periods. results show that near metro,...

The invasion of stray current from DC metro systems into the power grid substation through cable armoring will cause transformer bias magnetism and affect normal operation grid. Therefore, in order to suppress value invading armor, this paper proposes suppression method establishment a separate grounding armor. Firstly, establishes coupling model nearby considering metal soil structure by using CDEGS software. Secondly, researches influence parameters on current. Finally, results show that...

Due to the shortcomings of current power transmission which is used in ultrasound - assisted machining and different transfer efficiency caused by related parameters electromagnetic converter, this paper proposes an analysis model new non-contact device with more stable output higher efficiency. Then By utilizing Maxwell finite element software, studies law transformer compares type traditional method setting boundary conditions supply device. At last, combining practical application,...