Power transformer is the main part of power grid. After some tests and operations transformers, a certain residual flux density ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$B_{r}$ </tex-math></inline-formula> ) left in iron core due to ferromagnetic material hysteresis phenomenon. When switched on with no load, will lead inrush current. Therefore, research measuring great significance for protection....

Soft magnetic composite (SMC) is composed of ferromagnetic particles surrounded by electrical insulation layer. During the manufacturing process, electric layer may be destroyed and thus eddy current will induced, which makes it difficult to calculate accurate loss. In this paper, inter-particle loss calculated at macro-scale modeling actual sample using measured conductivity sample, moreover intra-particle single particle SMC base on existing model. Then, under different sizes frequencies,...

A serious inrush current may occur when a power transformer is re-energized, which will cause many adverse effects on equipment and the grid. The corresponding potential hazards can be reduced if existing residual flux density (Br) accurately measured. Combined with field-circuit coupling analysis method, novel method for measuring Br based phase difference between applied AC voltage resulting transient proposed in this paper. When same to winding, affects current. calculated by...

The residual flux measurement is one of the difficulties in transformer research field. This article presents a density (B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ) method considering relative differential permeability (μ xmlns:xlink="http://www.w3.org/1999/xlink">rd</sub> core material. First, basic relationship between μ and B analyzed on basis magnetic domain theory. Then, combining experimentally measured , using as an...

When the power transformer is reconnected to grid, if there a large residual flux in iron core, an inrush current may be resulted. To suppress current, detail information of needs known. In this paper, density measurement method for single-phase core based on energy changes proposed. Firstly, when positive and negative DC voltages (referred as direction along or opposite initial density) are applied, source can obtained by measured response currents. Then, determined comparing gained...

Residual flux density in the single-phase transformer core can dramatically increase inrush current when is energized. To reduce current, it necessary to study residual measurement. This paper proposes a new measurement method based on time constant. Firstly, generation principle of analyzed under different magnetization states, and found that positive relative differential permeability smaller than negative at density. obtain permeability, an appropriate DC excitation applied, circuit...

The main disadvantage of transverse flux induction heating (TFIH) is its resulting non-uniform temperature distribution on the surface strip at inductor outlet. For obtaining a uniform distribution, an improved particle swarm optimization (PSO) named velocity-controlled PSO (VCPSO) proposed and applied to optimize this problem. Support vector machine (SVM) adopted establish regression model replace complex time-consuming coupling calculation process involved in TFIH Simulation results...

This paper improves the calculation method of line loss, and uses existing equipment data in low voltage distribution to replace branch current required loss calculation. Finally, actual case shows that when unbalance degree is less than 4%, accuracy traditional equivalent resistance close improved method, but has a smaller error, with an within 1%. Compared reduces difficulty sampling

Nowadays, thirteen ultra-high voltage direct current (UHVDC) transmission projects have commissioned in China, including Jinping-Sunan, Fulong-Fengxian, Yibin-Jinhua project, and so forth. Meanwhile, another two UHVDC are under construction. The highest level is ±1100kV. HVDC superior high capacity long distance, its control response put forward higher requirements for the transient characteristics of DC transformer. At present, there no test method equipment testing Therefore, mastering...

Abstract The fusion of primary and secondary functions refers to integrating the function equipment together. If doing so, working condition for becomes more complex bad, especially transformer in smaller workspace after fusing. Therefore, this paper focuses on used pole-mounted Switchgear establishes temperature field electric simulation model switchgear transformer, respectively, rise environment interference influencing error are analyzed as well. When ranges from -40 70°C, maximum...

This paper focus on the research about probability and practicability of 330 kV GIS structure design with three phase in one tank， which represents miniaturisation compact developing trend GIS. The principle is proposed according to volume tank (structure A) generally smaller than that sum single B). Then, dimension size A presented. To solve weak insulation-level problem between phases A, prevents it from being used high-voltage power system especially above kV, an...

To meet the special insulation demand of DC transmission system with highest voltage in world, a new kind ±1 100 kV divider is designed. The reliability structure under action lightning impulse studied. achieve and electric field strength distribution divider, 3D transient calculation model established test for prototype carried out. results reveal that (1)The distributing on changing time show cumulative effect. (2)The maximum occurs at junction where first grading ring connecting to...

Abstract Nowadays, thirteen ultra-high voltage direct current (UHVDC) transmission projects have commissioned in China, including Jinping-Sunan, Fulong-Fengxian, Yibin-Jinhua project, and so forth. Meanwhile, another two UHVDC are under construction. The highest level is ±1100kV. HVDC superior high capacity long distance, its control response put forward higher requirements for the transient characteristics of DC transformer. At present, there no test method equipment testing Therefore,...

Based on the existing soft magnetic composite (SMC) finite element models, three-dimensional(3D) simulation models of SMC single particle and ring sample were established in this paper. In view fact that do not take into account effect harmonics hysteresis loss SMC, based calculation formula Bertotti separation theory, an improved expression coefficient is derived by introducing correction factor coefficient. And it applied to model so can be used calculate core under non-sinusoidal...

Using ultra high voltage disconnector to switch the fixed series compensation capacitors platform may induce fast transient phenomenon and repetitive strikings of disconnector, amplitude steepness current damage adjacent CVT. This paper build simulation calculation model by ATP-draw resonance circuit consist capacitance earth, inductance transmission lines CVT, results show that decreasing rated CVT can reduce impulse effectively. analyses effecting on error characteristics UHV determines...