Influence of sympathetic inrush on voltage dips caused by transformer energisation

Assessment on energization sequence for reducing sympathetic interaction between wind turbine transformers

“…In the representation set-up for the wind turbine transformers, the nameplate data (8.3% short-circuit impedance and 21 kW copper losses) presented in Arana 7 were used in BCTRAN model; the ATP routine HYSDAT was used to produce hysteretic saturation curve for the Type-96 nonlinear inductor (the saturation point used by HYSDAT to derive the saturation curve is defined at 3% of the wind turbine transformer's rated RMS full-load current and 1.23 pu of the wind turbine transformer's core nominal flux-linkage, which is considered to be reasonable according to the core saturation curves derived in Chiesa et al 19 based on open-circuit test data); beyond the point is a single value line with its slope Reducing sympathetic inrush between wind turbine transformers J. Peng, H. Li and Z. Wang representing core saturation inductance (the value of the saturation inductance is assumed to be identical with the wind turbine transformer short-circuit inductance); as the core representation is connected at the LV of the wind turbine transformer, the equivalent air-cored coil inductance of the wind turbine transformer seen from HV side is twice the wind turbine transformer short-circuit inductance, which has been suggested in previous work 20 and applied in Povh and Schultz 21 and Peng et al 22 In addition, an equivalent winding capacitance is connected on the primary side of the BCTRAN model to represent the initial capacitive charging current upon the energization instant. The value of this capacitance is estimated to be 5 nF based on previous work.…”

Stochastic assessment of voltage dips caused by transformer energisation

“…The network model developed and validated in [8] was used as the basis for the stochastic simulation. The modelling of the system is briefly described as follows: system equivalent source was represented by an ideal voltage source connected in series with a Thevenin equivalent impedance; transmission line was represented by using Bergeron model, with line dimension, length and transposing scheme taken into account; all the loads and shunt devices, such as capacitor banks, were modelled by constant impedances; transformers modelling mainly considered winding resistances, leakage inductances and transformer core saturation characteristics, and this was realised by the use of an admittance matrix-based model (BCTRAN) with delta-formed hysteretic inductors (type-96) externally connected to the low-voltage winding terminal of the BCTRAN model [21].…”

“…Voltage dips caused by transformer energisation can be especially severe in those systems where the network impedance between the source and the energised transformer is high [5], and they are characterised by being non-rectangular and non-symmetrical (each phase has a dip magnitude different from the others due to different degrees of saturation), with long duration of recovery [6]. Tripping of equipment and trigger of low-voltage alarms caused by such kind of voltage dips were reported in [7,8], respectively.…”

Mechanism Analysis of Sympathetic Inrush in Traction Network Cascaded Transformers Based on Flux-Current Circuit Model

“…When the EMU passes the electric phase separation, the locomotive transformer will perform the opening and closing operations in sequence. Moreover, when the locomotive transformer is restored to power, inrush current may occur [3,4].The inrush current generated by the closing transformer will lead to the sympathetic inrush generated by the traction transformer in the same power supply area, which is the main cause of differential protection errors in traction transformers [5][6][7][8].…”